from __future__ import annotations

from decimal import Decimal
from itertools import groupby
import re
import typing as t

from sqlglot import exp, generator, transforms

from sqlglot.dialects.dialect import (
    DATETIME_DELTA,
    JSON_EXTRACT_TYPE,
    approx_count_distinct_sql,
    array_append_sql,
    array_compact_sql,
    array_concat_sql,
    arrow_json_extract_sql,
    count_if_to_sum,
    date_delta_to_binary_interval_op,
    datestrtodate_sql,
    encode_decode_sql,
    explode_to_unnest_sql,
    generate_series_sql,
    getbit_sql,
    groupconcat_sql,
    inline_array_unless_query,
    months_between_sql,
    no_datetime_sql,
    no_comment_column_constraint_sql,
    no_make_interval_sql,
    no_time_sql,
    no_timestamp_sql,
    rename_func,
    remove_from_array_using_filter,
    strposition_sql,
    str_to_time_sql,
    timestrtotime_sql,
    unit_to_str,
)
from sqlglot.generator import unsupported_args
from sqlglot.helper import is_date_unit, seq_get
from builtins import type as Type

# Regex to detect time zones in timestamps of the form [+|-]TT[:tt]
# The pattern matches timezone offsets that appear after the time portion
TIMEZONE_PATTERN = re.compile(r":\d{2}.*?[+\-]\d{2}(?::\d{2})?")

# Characters that must be escaped when building regex expressions in INITCAP
REGEX_ESCAPE_REPLACEMENTS = {
    "\\": "\\\\",
    "-": r"\-",
    "^": r"\^",
    "[": r"\[",
    "]": r"\]",
}

# Used to in RANDSTR transpilation
RANDSTR_CHAR_POOL = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"
RANDSTR_SEED = 123456

# Whitespace control characters that DuckDB must process with `CHR({val})` calls
WS_CONTROL_CHARS_TO_DUCK = {
    "\u000b": 11,
    "\u001c": 28,
    "\u001d": 29,
    "\u001e": 30,
    "\u001f": 31,
}

# Days of week to ISO 8601 day-of-week numbers
# ISO 8601 standard: Monday=1, Tuesday=2, Wednesday=3, Thursday=4, Friday=5, Saturday=6, Sunday=7
WEEK_START_DAY_TO_DOW = {
    "MONDAY": 1,
    "TUESDAY": 2,
    "WEDNESDAY": 3,
    "THURSDAY": 4,
    "FRIDAY": 5,
    "SATURDAY": 6,
    "SUNDAY": 7,
}

MAX_BIT_POSITION = exp.Literal.number(32768)

# cs/as/ps are Snowflake defaults; DuckDB already behaves the same way, so they are safe to drop.
# Note: "as" is also a reserved keyword in DuckDB, making it impossible to pass through.
_SNOWFLAKE_COLLATION_DEFAULTS = frozenset({"cs", "as", "ps"})
_SNOWFLAKE_COLLATION_UNSUPPORTED = frozenset(
    {"ci", "ai", "upper", "lower", "utf8", "bin", "pi", "fl", "fu", "trim", "ltrim", "rtrim"}
)

# Window functions that support IGNORE/RESPECT NULLS in DuckDB
_IGNORE_RESPECT_NULLS_WINDOW_FUNCTIONS = (
    exp.FirstValue,
    exp.Lag,
    exp.LastValue,
    exp.Lead,
    exp.NthValue,
)

# SEQ function constants
_SEQ_BASE: exp.Expr = exp.maybe_parse("(ROW_NUMBER() OVER (ORDER BY 1) - 1)")
_SEQ_RESTRICTED = (exp.Where, exp.Having, exp.AggFunc, exp.Order, exp.Select)
# Maps SEQ expression types to their byte width (suffix indicates bytes: SEQ1=1, SEQ2=2, etc.)
_SEQ_BYTE_WIDTH = {exp.Seq1: 1, exp.Seq2: 2, exp.Seq4: 4, exp.Seq8: 8}

# Template for generating signed and unsigned SEQ values within a specified range
_SEQ_UNSIGNED: exp.Expr = exp.maybe_parse(":base % :max_val")
_SEQ_SIGNED: exp.Expr = exp.maybe_parse(
    "(CASE WHEN :base % :max_val >= :half "
    "THEN :base % :max_val - :max_val "
    "ELSE :base % :max_val END)"
)


def _apply_base64_alphabet_replacements(
    result: exp.Expr,
    alphabet: exp.Expr | None,
    reverse: bool = False,
) -> exp.Expr:
    """
    Apply base64 alphabet character replacements.

    Base64 alphabet can be 1-3 chars: 1st = index 62 ('+'), 2nd = index 63 ('/'), 3rd = padding ('=').
    zip truncates to the shorter string, so 1-char alphabet only replaces '+', 2-char replaces '+/', etc.

    Args:
        result: The expression to apply replacements to
        alphabet: Custom alphabet literal (expected chars for +/=)
        reverse: If False, replace default with custom (encode)
                 If True, replace custom with default (decode)
    """
    if isinstance(alphabet, exp.Literal) and alphabet.is_string:
        for default_char, new_char in zip("+/=", alphabet.this):
            if new_char != default_char:
                find, replace = (new_char, default_char) if reverse else (default_char, new_char)
                result = exp.Replace(
                    this=result,
                    expression=exp.Literal.string(find),
                    replacement=exp.Literal.string(replace),
                )
    return result


def _base64_decode_sql(self: DuckDBGenerator, expression: exp.Expr, to_string: bool) -> str:
    """
    Transpile Snowflake BASE64_DECODE_STRING/BINARY to DuckDB.

    DuckDB uses FROM_BASE64() which returns BLOB. For string output, wrap with DECODE().
    Custom alphabets require REPLACE() calls to convert to standard base64.
    """
    input_expr = expression.this
    alphabet = expression.args.get("alphabet")

    # Handle custom alphabet by replacing non-standard chars with standard ones
    input_expr = _apply_base64_alphabet_replacements(input_expr, alphabet, reverse=True)

    # FROM_BASE64 returns BLOB
    input_expr = exp.FromBase64(this=input_expr)

    if to_string:
        input_expr = exp.Decode(this=input_expr)

    return self.sql(input_expr)


def _last_day_sql(self: DuckDBGenerator, expression: exp.LastDay) -> str:
    """
    DuckDB's LAST_DAY only supports finding the last day of a month.
    For other date parts (year, quarter, week), we need to implement equivalent logic.
    """
    date_expr = expression.this
    unit = expression.text("unit")

    if not unit or unit.upper() == "MONTH":
        # Default behavior - use DuckDB's native LAST_DAY
        return self.func("LAST_DAY", date_expr)

    if unit.upper() == "YEAR":
        # Last day of year: December 31st of the same year
        year_expr = exp.func("EXTRACT", "YEAR", date_expr)
        make_date_expr = exp.func(
            "MAKE_DATE", year_expr, exp.Literal.number(12), exp.Literal.number(31)
        )
        return self.sql(make_date_expr)

    if unit.upper() == "QUARTER":
        # Last day of quarter
        year_expr = exp.func("EXTRACT", "YEAR", date_expr)
        quarter_expr = exp.func("EXTRACT", "QUARTER", date_expr)

        # Calculate last month of quarter: quarter * 3. Quarter can be 1 to 4
        last_month_expr = exp.Mul(this=quarter_expr, expression=exp.Literal.number(3))
        first_day_last_month_expr = exp.func(
            "MAKE_DATE", year_expr, last_month_expr, exp.Literal.number(1)
        )

        # Last day of the last month of the quarter
        last_day_expr = exp.func("LAST_DAY", first_day_last_month_expr)
        return self.sql(last_day_expr)

    if unit.upper() == "WEEK":
        # DuckDB DAYOFWEEK: Sunday=0, Monday=1, ..., Saturday=6
        dow = exp.func("EXTRACT", "DAYOFWEEK", date_expr)
        # Days to the last day of week: (7 - dayofweek) % 7, assuming the last day of week is Sunday (Snowflake)
        # Wrap in parentheses to ensure correct precedence
        days_to_sunday_expr = exp.Mod(
            this=exp.Paren(this=exp.Sub(this=exp.Literal.number(7), expression=dow)),
            expression=exp.Literal.number(7),
        )
        interval_expr = exp.Interval(this=days_to_sunday_expr, unit=exp.var("DAY"))
        add_expr = exp.Add(this=date_expr, expression=interval_expr)
        cast_expr = exp.cast(add_expr, exp.DType.DATE)
        return self.sql(cast_expr)

    self.unsupported(f"Unsupported date part '{unit}' in LAST_DAY function")
    return self.function_fallback_sql(expression)


def _is_nanosecond_unit(unit: exp.Expr | None) -> bool:
    return isinstance(unit, (exp.Var, exp.Literal)) and unit.name.upper() == "NANOSECOND"


def _handle_nanosecond_diff(
    self: DuckDBGenerator,
    end_time: exp.Expr,
    start_time: exp.Expr,
) -> str:
    """Generate NANOSECOND diff using EPOCH_NS since DATE_DIFF doesn't support it."""
    end_ns = exp.cast(end_time, exp.DType.TIMESTAMP_NS)
    start_ns = exp.cast(start_time, exp.DType.TIMESTAMP_NS)

    # Build expression tree: EPOCH_NS(end) - EPOCH_NS(start)
    return self.sql(
        exp.Sub(this=exp.func("EPOCH_NS", end_ns), expression=exp.func("EPOCH_NS", start_ns))
    )


def _to_boolean_sql(self: DuckDBGenerator, expression: exp.ToBoolean) -> str:
    """
    Transpile TO_BOOLEAN and TRY_TO_BOOLEAN functions from Snowflake to DuckDB equivalent.

    DuckDB's CAST to BOOLEAN supports most of Snowflake's TO_BOOLEAN strings except 'on'/'off'.
    We need to handle the 'on'/'off' cases explicitly.

    For TO_BOOLEAN (safe=False): NaN and INF values cause errors. We use DuckDB's native ERROR()
    function to replicate this behavior with a clear error message.

    For TRY_TO_BOOLEAN (safe=True): Use DuckDB's TRY_CAST for conversion, which returns NULL
    for invalid inputs instead of throwing errors.
    """
    arg = expression.this
    is_safe = expression.args.get("safe", False)

    base_case_expr = (
        exp.case()
        .when(
            # Handle 'on' -> TRUE (case insensitive)
            exp.Upper(this=exp.cast(arg, exp.DType.VARCHAR)).eq(exp.Literal.string("ON")),
            exp.true(),
        )
        .when(
            # Handle 'off' -> FALSE (case insensitive)
            exp.Upper(this=exp.cast(arg, exp.DType.VARCHAR)).eq(exp.Literal.string("OFF")),
            exp.false(),
        )
    )

    if is_safe:
        # TRY_TO_BOOLEAN: handle 'on'/'off' and use TRY_CAST for everything else
        case_expr = base_case_expr.else_(exp.func("TRY_CAST", arg, exp.DType.BOOLEAN.into_expr()))
    else:
        # TO_BOOLEAN: handle NaN/INF errors, 'on'/'off', and use regular CAST
        cast_to_real = exp.func("TRY_CAST", arg, exp.DType.FLOAT.into_expr())

        # Check for NaN and INF values
        nan_inf_check = exp.Or(
            this=exp.func("ISNAN", cast_to_real), expression=exp.func("ISINF", cast_to_real)
        )

        case_expr = base_case_expr.when(
            nan_inf_check,
            exp.func(
                "ERROR",
                exp.Literal.string("TO_BOOLEAN: Non-numeric values NaN and INF are not supported"),
            ),
        ).else_(exp.cast(arg, exp.DType.BOOLEAN))

    return self.sql(case_expr)


# BigQuery -> DuckDB conversion for the DATE function
def _date_sql(self: DuckDBGenerator, expression: exp.Date) -> str:
    this = expression.this
    zone = self.sql(expression, "zone")

    if zone:
        # BigQuery considers "this" at UTC, converts it to the specified
        # time zone and then keeps only the DATE part
        # To micmic that, we:
        #   (1) Cast to TIMESTAMP to remove DuckDB's local tz
        #   (2) Apply consecutive AtTimeZone calls for UTC -> zone conversion
        this = exp.cast(this, exp.DType.TIMESTAMP)
        at_utc = exp.AtTimeZone(this=this, zone=exp.Literal.string("UTC"))
        this = exp.AtTimeZone(this=at_utc, zone=zone)

    return self.sql(exp.cast(expression=this, to=exp.DType.DATE))


# BigQuery -> DuckDB conversion for the TIME_DIFF function
def _timediff_sql(self: DuckDBGenerator, expression: exp.TimeDiff) -> str:
    unit = expression.unit

    if _is_nanosecond_unit(unit):
        return _handle_nanosecond_diff(self, expression.expression, expression.this)

    this = exp.cast(expression.this, exp.DType.TIME)
    expr = exp.cast(expression.expression, exp.DType.TIME)

    # Although the 2 dialects share similar signatures, BQ seems to inverse
    # the sign of the result so the start/end time operands are flipped
    return self.func("DATE_DIFF", unit_to_str(expression), expr, this)


def _date_delta_to_binary_interval_op(
    cast: bool = True,
) -> t.Callable[[DuckDBGenerator, DATETIME_DELTA], str]:
    """
    DuckDB override to handle:
    1. NANOSECOND operations (DuckDB doesn't support INTERVAL ... NANOSECOND)
    2. Float/decimal interval values (DuckDB INTERVAL requires integers)
    """
    base_impl = date_delta_to_binary_interval_op(cast=cast)

    def _duckdb_date_delta_sql(self: DuckDBGenerator, expression: DATETIME_DELTA) -> str:
        unit = expression.unit
        interval_value = expression.expression

        # Handle NANOSECOND unit (DuckDB doesn't support INTERVAL ... NANOSECOND)
        if _is_nanosecond_unit(unit):
            if isinstance(interval_value, exp.Interval):
                interval_value = interval_value.this

            timestamp_ns = exp.cast(expression.this, exp.DType.TIMESTAMP_NS)

            return self.sql(
                exp.func(
                    "MAKE_TIMESTAMP_NS",
                    exp.Add(this=exp.func("EPOCH_NS", timestamp_ns), expression=interval_value),
                )
            )

        # Handle float/decimal interval values as duckDB INTERVAL requires integer expressions
        if not interval_value or isinstance(interval_value, exp.Interval):
            return base_impl(self, expression)

        if interval_value.is_type(*exp.DataType.REAL_TYPES):
            expression.set("expression", exp.cast(exp.func("ROUND", interval_value), "INT"))

        return base_impl(self, expression)

    return _duckdb_date_delta_sql


def _array_insert_sql(self: DuckDBGenerator, expression: exp.ArrayInsert) -> str:
    """
    Transpile ARRAY_INSERT to DuckDB using LIST_CONCAT and slicing.

    Handles:
    - 0-based and 1-based indexing (normalizes to 0-based for calculations)
    - Negative position conversion (requires array length)
    - NULL propagation (source dialects return NULL, DuckDB creates single-element array)
    - Assumes position is within bounds per user constraint

    Note: All dialects that support ARRAY_INSERT (Snowflake, Spark, Databricks) have
    ARRAY_FUNCS_PROPAGATES_NULLS=True, so we always assume source propagates NULLs.

    Args:
        expression: The ArrayInsert expression to transpile.

    Returns:
        SQL string implementing ARRAY_INSERT behavior.
    """
    this = expression.this
    position = expression.args.get("position")
    element = expression.expression
    element_array = exp.Array(expressions=[element])
    index_offset = expression.args.get("offset", 0)

    if not position or not position.is_int:
        self.unsupported("ARRAY_INSERT can only be transpiled with a literal position")
        return self.func("ARRAY_INSERT", this, position, element)

    pos_value = position.to_py()

    # Normalize one-based indexing to zero-based for slice calculations
    # Spark (1-based) -> Snowflake (0-based):
    #   Positive: pos=1 -> pos=0 (subtract 1)
    #   Negative: pos=-2 -> pos=-1 (add 1)
    # Example: Spark array_insert([a,b,c], -2, d) -> [a,b,d,c] is same as Snowflake pos=-1
    if pos_value > 0:
        pos_value = pos_value - index_offset
    elif pos_value < 0:
        pos_value = pos_value + index_offset

    # Build the appropriate list_concat expression based on position
    if pos_value == 0:
        # insert at beginning
        concat_exprs = [element_array, this]
    elif pos_value > 0:
        # Positive position: LIST_CONCAT(arr[1:pos], [elem], arr[pos+1:])
        # 0-based -> DuckDB 1-based slicing

        # left slice: arr[1:pos]
        slice_start = exp.Bracket(
            this=this,
            expressions=[
                exp.Slice(this=exp.Literal.number(1), expression=exp.Literal.number(pos_value))
            ],
        )

        # right slice: arr[pos+1:]
        slice_end = exp.Bracket(
            this=this, expressions=[exp.Slice(this=exp.Literal.number(pos_value + 1))]
        )

        concat_exprs = [slice_start, element_array, slice_end]
    else:
        # Negative position: arr[1:LEN(arr)+pos], [elem], arr[LEN(arr)+pos+1:]
        # pos=-1 means insert before last element
        arr_len = exp.Length(this=this)

        # Calculate slice position: LEN(arr) + pos (e.g., LEN(arr) + (-1) = LEN(arr) - 1)
        slice_end_pos = arr_len + exp.Literal.number(pos_value)
        slice_start_pos = slice_end_pos + exp.Literal.number(1)

        # left slice: arr[1:LEN(arr)+pos]
        slice_start = exp.Bracket(
            this=this,
            expressions=[exp.Slice(this=exp.Literal.number(1), expression=slice_end_pos)],
        )

        # right slice: arr[LEN(arr)+pos+1:]
        slice_end = exp.Bracket(this=this, expressions=[exp.Slice(this=slice_start_pos)])

        concat_exprs = [slice_start, element_array, slice_end]

    # All dialects that support ARRAY_INSERT propagate NULLs (Snowflake/Spark/Databricks)
    # Wrap in CASE WHEN array IS NULL THEN NULL ELSE func_expr END
    return self.sql(
        exp.If(
            this=exp.Is(this=this, expression=exp.Null()),
            true=exp.Null(),
            false=self.func("LIST_CONCAT", *concat_exprs),
        )
    )


def _array_remove_at_sql(self: DuckDBGenerator, expression: exp.ArrayRemoveAt) -> str:
    """
    Transpile ARRAY_REMOVE_AT to DuckDB using LIST_CONCAT and slicing.

    Handles:
    - Positive positions (0-based indexing)
    - Negative positions (from end of array)
    - NULL propagation (Snowflake returns NULL for NULL array, DuckDB doesn't auto-propagate)
    - Only supports literal integer positions (non-literals remain untranspiled)

    Transpilation patterns:
    - pos=0 (first): arr[2:]
    - pos>0 (middle): LIST_CONCAT(arr[1:p], arr[p+2:])
    - pos=-1 (last): arr[1:LEN(arr)-1]
    - pos<-1: LIST_CONCAT(arr[1:LEN(arr)+p], arr[LEN(arr)+p+2:])

    All wrapped in: CASE WHEN arr IS NULL THEN NULL ELSE ... END

    Args:
        expression: The ArrayRemoveAt expression to transpile.

    Returns:
        SQL string implementing ARRAY_REMOVE_AT behavior.
    """
    this = expression.this
    position = expression.args.get("position")

    if not position or not position.is_int:
        self.unsupported("ARRAY_REMOVE_AT can only be transpiled with a literal position")
        return self.func("ARRAY_REMOVE_AT", this, position)

    pos_value = position.to_py()

    # Build the appropriate expression based on position
    if pos_value == 0:
        # Remove first element: arr[2:]
        result_expr: exp.Expr | str = exp.Bracket(
            this=this,
            expressions=[exp.Slice(this=exp.Literal.number(2))],
        )
    elif pos_value > 0:
        # Remove at positive position: LIST_CONCAT(arr[1:pos], arr[pos+2:])
        # DuckDB uses 1-based slicing
        left_slice = exp.Bracket(
            this=this,
            expressions=[
                exp.Slice(this=exp.Literal.number(1), expression=exp.Literal.number(pos_value))
            ],
        )
        right_slice = exp.Bracket(
            this=this,
            expressions=[exp.Slice(this=exp.Literal.number(pos_value + 2))],
        )
        result_expr = self.func("LIST_CONCAT", left_slice, right_slice)
    elif pos_value == -1:
        # Remove last element: arr[1:LEN(arr)-1]
        # Optimization: simpler than general negative case
        arr_len = exp.Length(this=this)
        slice_end = arr_len + exp.Literal.number(-1)
        result_expr = exp.Bracket(
            this=this,
            expressions=[exp.Slice(this=exp.Literal.number(1), expression=slice_end)],
        )
    else:
        # Remove at negative position: LIST_CONCAT(arr[1:LEN(arr)+pos], arr[LEN(arr)+pos+2:])
        arr_len = exp.Length(this=this)
        slice_end_pos = arr_len + exp.Literal.number(pos_value)
        slice_start_pos = slice_end_pos + exp.Literal.number(2)

        left_slice = exp.Bracket(
            this=this,
            expressions=[exp.Slice(this=exp.Literal.number(1), expression=slice_end_pos)],
        )
        right_slice = exp.Bracket(
            this=this,
            expressions=[exp.Slice(this=slice_start_pos)],
        )
        result_expr = self.func("LIST_CONCAT", left_slice, right_slice)

    # Snowflake ARRAY_FUNCS_PROPAGATES_NULLS=True, so wrap in NULL check
    # CASE WHEN array IS NULL THEN NULL ELSE result_expr END
    return self.sql(
        exp.If(
            this=exp.Is(this=this, expression=exp.Null()),
            true=exp.Null(),
            false=result_expr,
        )
    )


@unsupported_args(("expression", "DuckDB's ARRAY_SORT does not support a comparator."))
def _array_sort_sql(self: DuckDBGenerator, expression: exp.ArraySort) -> str:
    return self.func("ARRAY_SORT", expression.this)


def _array_contains_sql(self: DuckDBGenerator, expression: exp.ArrayContains) -> str:
    this = expression.this
    expr = expression.expression

    func = self.func("ARRAY_CONTAINS", this, expr)

    if expression.args.get("check_null"):
        check_null_in_array = exp.Nullif(
            this=exp.NEQ(this=exp.ArraySize(this=this), expression=exp.func("LIST_COUNT", this)),
            expression=exp.false(),
        )
        return self.sql(exp.If(this=expr.is_(exp.Null()), true=check_null_in_array, false=func))

    return func


def _array_overlaps_sql(self: DuckDBGenerator, expression: exp.ArrayOverlaps) -> str:
    """
    Translates Snowflake's NULL-safe ARRAYS_OVERLAP to DuckDB.

    DuckDB's native && operator is not NULL-safe: [1,NULL,3] && [NULL,4,5] returns FALSE.
    Snowflake returns TRUE when both arrays contain NULL (NULLs are treated as known values).

    Generated SQL: (arr1 && arr2) OR (ARRAY_LENGTH(arr1) <> LIST_COUNT(arr1) AND ARRAY_LENGTH(arr2) <> LIST_COUNT(arr2))

    ARRAY_LENGTH counts all elements (including NULLs); LIST_COUNT counts only non-NULLs.
    When they differ, the array contains at least one NULL, matching Snowflake's NULL-safe semantics.
    """
    if not expression.args.get("null_safe"):
        return self.binary(expression, "&&")

    arr1 = expression.this
    arr2 = expression.expression

    check_nulls = exp.and_(
        exp.NEQ(
            this=exp.ArraySize(this=arr1.copy()),
            expression=exp.func("LIST_COUNT", arr1.copy()),
        ),
        exp.NEQ(
            this=exp.ArraySize(this=arr2.copy()),
            expression=exp.func("LIST_COUNT", arr2.copy()),
        ),
        copy=False,
    )

    overlap = exp.ArrayOverlaps(this=arr1.copy(), expression=arr2.copy())

    return self.sql(
        exp.or_(
            exp.paren(overlap, copy=False),
            exp.paren(check_nulls, copy=False),
            copy=False,
            wrap=False,
        )
    )


def _struct_sql(self: DuckDBGenerator, expression: exp.Struct) -> str:
    ancestor_cast = expression.find_ancestor(exp.Cast, exp.Select)
    ancestor_cast = None if isinstance(ancestor_cast, exp.Select) else ancestor_cast

    # Empty struct cast works with MAP() since DuckDB can't parse {}
    if not expression.expressions:
        if isinstance(ancestor_cast, exp.Cast) and ancestor_cast.to.is_type(exp.DType.MAP):
            return "MAP()"

    args: list[str] = []

    # BigQuery allows inline construction such as "STRUCT<a STRING, b INTEGER>('str', 1)" which is
    # canonicalized to "ROW('str', 1) AS STRUCT(a TEXT, b INT)" in DuckDB
    # The transformation to ROW will take place if:
    #  1. The STRUCT itself does not have proper fields (key := value) as a "proper" STRUCT would
    #  2. A cast to STRUCT / ARRAY of STRUCTs is found
    is_bq_inline_struct = (
        (expression.find(exp.PropertyEQ) is None)
        and ancestor_cast
        and any(
            casted_type.is_type(exp.DType.STRUCT)
            for casted_type in ancestor_cast.find_all(exp.DataType)
        )
    )

    for i, expr in enumerate(expression.expressions):
        is_property_eq = isinstance(expr, exp.PropertyEQ)
        this = expr.this
        value = expr.expression if is_property_eq else expr

        if is_bq_inline_struct:
            args.append(self.sql(value))
        else:
            if isinstance(this, exp.Identifier):
                key = self.sql(exp.Literal.string(expr.name))
            elif is_property_eq:
                key = self.sql(this)
            else:
                key = self.sql(exp.Literal.string(f"_{i}"))

            args.append(f"{key}: {self.sql(value)}")

    csv_args = ", ".join(args)

    return f"ROW({csv_args})" if is_bq_inline_struct else f"{{{csv_args}}}"


def _datatype_sql(self: DuckDBGenerator, expression: exp.DataType) -> str:
    if expression.is_type("array"):
        return f"{self.expressions(expression, flat=True)}[{self.expressions(expression, key='values', flat=True)}]"

    # Modifiers are not supported for TIME, [TIME | TIMESTAMP] WITH TIME ZONE
    if expression.is_type(exp.DType.TIME, exp.DType.TIMETZ, exp.DType.TIMESTAMPTZ):
        return expression.this.value

    return self.datatype_sql(expression)


def _json_format_sql(self: DuckDBGenerator, expression: exp.JSONFormat) -> str:
    sql = self.func("TO_JSON", expression.this, expression.args.get("options"))
    return f"CAST({sql} AS TEXT)"


def _build_seq_expression(base: exp.Expr, byte_width: int, signed: bool) -> exp.Expr:
    """Build a SEQ expression with the given base, byte width, and signedness."""
    bits = byte_width * 8
    max_val = exp.Literal.number(2**bits)

    if signed:
        half = exp.Literal.number(2 ** (bits - 1))
        return exp.replace_placeholders(_SEQ_SIGNED.copy(), base=base, max_val=max_val, half=half)
    return exp.replace_placeholders(_SEQ_UNSIGNED.copy(), base=base, max_val=max_val)


def _seq_to_range_in_generator(expression: exp.Expr) -> exp.Expr:
    """
    Transform SEQ functions to `range` column references when inside a GENERATOR context.

    When GENERATOR(ROWCOUNT => N) becomes RANGE(N) in DuckDB, it produces a column
    named `range` with values 0, 1, ..., N-1. SEQ functions produce the same sequence,
    so we replace them with `range % max_val` to avoid nested window function issues.
    """
    if not isinstance(expression, exp.Select):
        return expression

    from_ = expression.args.get("from_")
    if not (
        from_
        and isinstance(from_.this, exp.TableFromRows)
        and isinstance(from_.this.this, exp.Generator)
    ):
        return expression

    def replace_seq(node: exp.Expr) -> exp.Expr:
        if isinstance(node, (exp.Seq1, exp.Seq2, exp.Seq4, exp.Seq8)):
            byte_width = _SEQ_BYTE_WIDTH[type(node)]
            return _build_seq_expression(exp.column("range"), byte_width, signed=node.name == "1")
        return node

    return expression.transform(replace_seq, copy=False)


def _seq_sql(self: DuckDBGenerator, expression: exp.Func, byte_width: int) -> str:
    """
    Transpile Snowflake SEQ1/SEQ2/SEQ4/SEQ8 to DuckDB.

    Generates monotonically increasing integers starting from 0.
    The signed parameter (0 or 1) affects wrap-around behavior:
    - Unsigned (0): wraps at 2^(bits) - 1
    - Signed (1): wraps at 2^(bits-1) - 1, then goes negative
    """
    # Warn if SEQ is in a restricted context (Select stops search at current scope)
    ancestor = expression.find_ancestor(*_SEQ_RESTRICTED)
    if ancestor and (
        (not isinstance(ancestor, (exp.Order, exp.Select)))
        or (isinstance(ancestor, exp.Order) and isinstance(ancestor.parent, exp.Window))
    ):
        self.unsupported("SEQ in restricted context is not supported - use CTE or subquery")

    result = _build_seq_expression(_SEQ_BASE.copy(), byte_width, signed=expression.name == "1")
    return self.sql(result)


def _unix_to_time_sql(self: DuckDBGenerator, expression: exp.UnixToTime) -> str:
    scale = expression.args.get("scale")
    timestamp = expression.this
    target_type = expression.args.get("target_type")

    # Check if we need NTZ (naive timestamp in UTC)
    is_ntz = target_type and target_type.this in (
        exp.DType.TIMESTAMP,
        exp.DType.TIMESTAMPNTZ,
    )

    if scale == exp.UnixToTime.MILLIS:
        # EPOCH_MS already returns TIMESTAMP (naive, UTC)
        return self.func("EPOCH_MS", timestamp)
    if scale == exp.UnixToTime.MICROS:
        # MAKE_TIMESTAMP already returns TIMESTAMP (naive, UTC)
        return self.func("MAKE_TIMESTAMP", timestamp)

    # Other scales: divide and use TO_TIMESTAMP
    if scale not in (None, exp.UnixToTime.SECONDS):
        timestamp = exp.Div(this=timestamp, expression=exp.func("POW", 10, scale))

    to_timestamp: exp.Expr = exp.Anonymous(this="TO_TIMESTAMP", expressions=[timestamp])

    if is_ntz:
        to_timestamp = exp.AtTimeZone(this=to_timestamp, zone=exp.Literal.string("UTC"))

    return self.sql(to_timestamp)


WRAPPED_JSON_EXTRACT_EXPRESSIONS = (exp.Binary, exp.Bracket, exp.In, exp.Not)


def _arrow_json_extract_sql(self: DuckDBGenerator, expression: JSON_EXTRACT_TYPE) -> str:
    arrow_sql = arrow_json_extract_sql(self, expression)
    if not expression.same_parent and isinstance(
        expression.parent, WRAPPED_JSON_EXTRACT_EXPRESSIONS
    ):
        arrow_sql = self.wrap(arrow_sql)
    return arrow_sql


def _implicit_datetime_cast(
    arg: exp.Expr | None, type: exp.DType = exp.DType.DATE
) -> exp.Expr | None:
    if isinstance(arg, exp.Literal) and arg.is_string:
        ts = arg.name
        if type == exp.DType.DATE and ":" in ts:
            type = exp.DType.TIMESTAMPTZ if TIMEZONE_PATTERN.search(ts) else exp.DType.TIMESTAMP

        arg = exp.cast(arg, type)

    return arg


def _week_unit_to_dow(unit: exp.Expr | None) -> int | None:
    """
    Compute the Monday-based day shift to align DATE_DIFF('WEEK', ...) coming
    from other dialects, e.g BigQuery's WEEK(<day>) or ISOWEEK unit parts.

    Args:
        unit: The unit expression (Var for ISOWEEK or WeekStart)

    Returns:
        The ISO 8601 day number (Monday=1, Sunday=7 etc) or None if not a week unit or if day is dynamic (not a constant).

        Examples:
            "WEEK(SUNDAY)" -> 7
            "WEEK(MONDAY)" -> 1
            "ISOWEEK" -> 1
    """
    # Handle plain Var expressions for ISOWEEK only
    if isinstance(unit, exp.Var) and unit.name.upper() in "ISOWEEK":
        return 1

    # Handle WeekStart expressions with explicit day
    if isinstance(unit, exp.WeekStart):
        return WEEK_START_DAY_TO_DOW.get(unit.name.upper())

    return None


def _build_week_trunc_expression(
    date_expr: exp.Expr,
    start_dow: int,
    preserve_start_day: bool = False,
) -> exp.Expr:
    """
    Build DATE_TRUNC expression for week boundaries with custom start day.

    DuckDB's DATE_TRUNC('WEEK', ...) always returns Monday. To align to a different
    start day, we shift the date before truncating.

    Args:
        date_expr: The date expression to truncate.
        start_dow: ISO 8601 day-of-week number (Monday=1, ..., Sunday=7).
        preserve_start_day: If True, reverse the shift after truncating so the result lands on the
            correct week start day. Needed for DATE_TRUNC (absolute result matters) but
            not for DATE_DIFF (only relative alignment matters).

    Shift formula: Sunday (7) gets +1, others get (1 - start_dow).
    """
    shift_days = 1 if start_dow == 7 else 1 - start_dow
    truncated = exp.func("DATE_TRUNC", unit=exp.var("WEEK"), this=date_expr)

    if shift_days == 0:
        return truncated

    shift = exp.Interval(this=exp.Literal.string(str(shift_days)), unit=exp.var("DAY"))
    shifted_date = exp.DateAdd(this=date_expr, expression=shift)
    truncated.set("this", shifted_date)

    if preserve_start_day:
        interval = exp.Interval(this=exp.Literal.string(str(-shift_days)), unit=exp.var("DAY"))
        return exp.cast(
            exp.DateAdd(this=truncated, expression=interval), to=exp.DType.DATE, copy=False
        )

    return truncated


def _date_diff_sql(self: DuckDBGenerator, expression: exp.DateDiff | exp.DatetimeDiff) -> str:
    unit = expression.unit

    if _is_nanosecond_unit(unit):
        return _handle_nanosecond_diff(self, expression.this, expression.expression)

    this = _implicit_datetime_cast(expression.this)
    expr = _implicit_datetime_cast(expression.expression)

    # DuckDB's WEEK diff does not respect Monday crossing (week boundaries), it checks (end_day - start_day) / 7:
    #  SELECT DATE_DIFF('WEEK', CAST('2024-12-13' AS DATE), CAST('2024-12-17' AS DATE)) --> 0 (Monday crossed)
    #  SELECT DATE_DIFF('WEEK', CAST('2024-12-13' AS DATE), CAST('2024-12-20' AS DATE)) --> 1 (7 days difference)
    # Whereas for other units such as MONTH it does respect month boundaries:
    #  SELECT DATE_DIFF('MONTH', CAST('2024-11-30' AS DATE), CAST('2024-12-01' AS DATE)) --> 1 (Month crossed)
    date_part_boundary = expression.args.get("date_part_boundary")

    # Extract week start day; returns None if day is dynamic (column/placeholder)
    week_start = _week_unit_to_dow(unit)
    if date_part_boundary and week_start and this and expr:
        expression.set("unit", exp.Literal.string("WEEK"))

        # Truncate both dates to week boundaries to respect input dialect semantics
        this = _build_week_trunc_expression(this, week_start)
        expr = _build_week_trunc_expression(expr, week_start)

    return self.func("DATE_DIFF", unit_to_str(expression), expr, this)


def _generate_datetime_array_sql(
    self: DuckDBGenerator, expression: exp.GenerateDateArray | exp.GenerateTimestampArray
) -> str:
    is_generate_date_array = isinstance(expression, exp.GenerateDateArray)

    type = exp.DType.DATE if is_generate_date_array else exp.DType.TIMESTAMP
    start = _implicit_datetime_cast(expression.args.get("start"), type=type)
    end = _implicit_datetime_cast(expression.args.get("end"), type=type)

    # BQ's GENERATE_DATE_ARRAY & GENERATE_TIMESTAMP_ARRAY are transformed to DuckDB'S GENERATE_SERIES
    gen_series: exp.GenerateSeries | exp.Cast = exp.GenerateSeries(
        start=start, end=end, step=expression.args.get("step")
    )

    if is_generate_date_array:
        # The GENERATE_SERIES result type is TIMESTAMP array, so to match BQ's semantics for
        # GENERATE_DATE_ARRAY we must cast it back to DATE array
        gen_series = exp.cast(gen_series, exp.DataType.from_str("ARRAY<DATE>"))

    return self.sql(gen_series)


def _json_extract_value_array_sql(
    self: DuckDBGenerator, expression: exp.JSONValueArray | exp.JSONExtractArray
) -> str:
    json_extract = exp.JSONExtract(this=expression.this, expression=expression.expression)
    data_type = "ARRAY<STRING>" if isinstance(expression, exp.JSONValueArray) else "ARRAY<JSON>"
    return self.sql(exp.cast(json_extract, to=exp.DataType.from_str(data_type)))


def _cast_to_varchar(arg: exp.Expr | None) -> exp.Expr | None:
    if arg and arg.type and not arg.is_type(*exp.DataType.TEXT_TYPES, exp.DType.UNKNOWN):
        return exp.cast(arg, exp.DType.VARCHAR)
    return arg


def _cast_to_boolean(arg: exp.Expr | None) -> exp.Expr | None:
    if arg and not arg.is_type(exp.DType.BOOLEAN):
        return exp.cast(arg, exp.DType.BOOLEAN)
    return arg


def _is_binary(arg: exp.Expr) -> bool:
    return arg.is_type(
        exp.DType.BINARY,
        exp.DType.VARBINARY,
        exp.DType.BLOB,
    )


def _gen_with_cast_to_blob(self: DuckDBGenerator, expression: exp.Expr, result_sql: str) -> str:
    if _is_binary(expression):
        blob = exp.DataType.from_str("BLOB", dialect="duckdb")
        result_sql = self.sql(exp.Cast(this=result_sql, to=blob))
    return result_sql


def _cast_to_bit(arg: exp.Expr) -> exp.Expr:
    if not _is_binary(arg):
        return arg

    if isinstance(arg, exp.HexString):
        arg = exp.Unhex(this=exp.Literal.string(arg.this))

    return exp.cast(arg, exp.DType.BIT)


def _prepare_binary_bitwise_args(expression: exp.Binary) -> None:
    if _is_binary(expression.this):
        expression.set("this", _cast_to_bit(expression.this))
    if _is_binary(expression.expression):
        expression.set("expression", _cast_to_bit(expression.expression))


def _day_navigation_sql(self: DuckDBGenerator, expression: exp.NextDay | exp.PreviousDay) -> str:
    """
    Transpile Snowflake's NEXT_DAY / PREVIOUS_DAY to DuckDB using date arithmetic.

    Returns the DATE of the next/previous occurrence of the specified weekday.

    Formulas:
    - NEXT_DAY: (target_dow - current_dow + 6) % 7 + 1
    - PREVIOUS_DAY: (current_dow - target_dow + 6) % 7 + 1

    Supports both literal and non-literal day names:
    - Literal: Direct lookup (e.g., 'Monday' -> 1)
    - Non-literal: CASE statement for runtime evaluation

    Examples:
        NEXT_DAY('2024-01-01' (Monday), 'Monday')
          -> (1 - 1 + 6) % 7 + 1 = 6 % 7 + 1 = 7 days -> 2024-01-08

        PREVIOUS_DAY('2024-01-15' (Monday), 'Friday')
          -> (1 - 5 + 6) % 7 + 1 = 2 % 7 + 1 = 3 days -> 2024-01-12
    """
    date_expr = expression.this
    day_name_expr = expression.expression

    # Build ISODOW call for current day of week
    isodow_call = exp.func("ISODOW", date_expr)

    # Determine target day of week
    if isinstance(day_name_expr, exp.Literal):
        # Literal day name: lookup target_dow directly
        day_name_str = day_name_expr.name.upper()
        matching_day = next(
            (day for day in WEEK_START_DAY_TO_DOW if day.startswith(day_name_str)), None
        )
        if matching_day:
            target_dow: exp.Expr = exp.Literal.number(WEEK_START_DAY_TO_DOW[matching_day])
        else:
            # Unrecognized day name, use fallback
            return self.function_fallback_sql(expression)
    else:
        # Non-literal day name: build CASE statement for runtime mapping
        upper_day_name = exp.Upper(this=day_name_expr)
        target_dow = exp.Case(
            ifs=[
                exp.If(
                    this=exp.func(
                        "STARTS_WITH", upper_day_name.copy(), exp.Literal.string(day[:2])
                    ),
                    true=exp.Literal.number(dow_num),
                )
                for day, dow_num in WEEK_START_DAY_TO_DOW.items()
            ]
        )

    # Calculate days offset and apply interval based on direction
    if isinstance(expression, exp.NextDay):
        # NEXT_DAY: (target_dow - current_dow + 6) % 7 + 1
        days_offset = exp.paren(target_dow - isodow_call + 6, copy=False) % 7 + 1
        date_with_offset = date_expr + exp.Interval(this=days_offset, unit=exp.var("DAY"))
    else:  # exp.PreviousDay
        # PREVIOUS_DAY: (current_dow - target_dow + 6) % 7 + 1
        days_offset = exp.paren(isodow_call - target_dow + 6, copy=False) % 7 + 1
        date_with_offset = date_expr - exp.Interval(this=days_offset, unit=exp.var("DAY"))

    # Build final: CAST(date_with_offset AS DATE)
    return self.sql(exp.cast(date_with_offset, exp.DType.DATE))


def _anyvalue_sql(self: DuckDBGenerator, expression: exp.AnyValue) -> str:
    # Transform ANY_VALUE(expr HAVING MAX/MIN having_expr) to ARG_MAX_NULL/ARG_MIN_NULL
    having = expression.this
    if isinstance(having, exp.HavingMax):
        func_name = "ARG_MAX_NULL" if having.args.get("max") else "ARG_MIN_NULL"
        return self.func(func_name, having.this, having.expression)
    return self.function_fallback_sql(expression)


def _bitwise_agg_sql(
    self: DuckDBGenerator,
    expression: exp.BitwiseOrAgg | exp.BitwiseAndAgg | exp.BitwiseXorAgg,
) -> str:
    """
    DuckDB's bitwise aggregate functions only accept integer types. For other types:
    - DECIMAL/STRING: Use CAST(arg AS INT) to convert directly, will round to nearest int
    - FLOAT/DOUBLE: Use ROUND(arg)::INT to round to nearest integer, required due to float precision loss
    """
    if isinstance(expression, exp.BitwiseOrAgg):
        func_name = "BIT_OR"
    elif isinstance(expression, exp.BitwiseAndAgg):
        func_name = "BIT_AND"
    else:  # exp.BitwiseXorAgg
        func_name = "BIT_XOR"

    arg = expression.this

    if not arg.type:
        from sqlglot.optimizer.annotate_types import annotate_types

        arg = annotate_types(arg, dialect=self.dialect)

    if arg.is_type(*exp.DataType.REAL_TYPES, *exp.DataType.TEXT_TYPES):
        if arg.is_type(*exp.DataType.FLOAT_TYPES):
            # float types need to be rounded first due to precision loss
            arg = exp.func("ROUND", arg)

        arg = exp.cast(arg, exp.DType.INT)

    return self.func(func_name, arg)


def _literal_sql_with_ws_chr(self: DuckDBGenerator, literal: str) -> str:
    # DuckDB does not support \uXXXX escapes, so we must use CHR() instead of replacing them directly
    if not any(ch in WS_CONTROL_CHARS_TO_DUCK for ch in literal):
        return self.sql(exp.Literal.string(literal))

    sql_segments: list[str] = []
    for is_ws_control, group in groupby(literal, key=lambda ch: ch in WS_CONTROL_CHARS_TO_DUCK):
        if is_ws_control:
            for ch in group:
                duckdb_char_code = WS_CONTROL_CHARS_TO_DUCK[ch]
                sql_segments.append(self.func("CHR", exp.Literal.number(str(duckdb_char_code))))
        else:
            sql_segments.append(self.sql(exp.Literal.string("".join(group))))

    sql = " || ".join(sql_segments)
    return sql if len(sql_segments) == 1 else f"({sql})"


def _escape_regex_metachars(
    self: DuckDBGenerator, delimiters: exp.Expr | None, delimiters_sql: str
) -> str:
    r"""
    Escapes regex metacharacters \ - ^ [ ] for use in character classes regex expressions.

    Literal strings are escaped at transpile time, expressions handled with REPLACE() calls.
    """
    if not delimiters:
        return delimiters_sql

    if delimiters.is_string:
        literal_value = delimiters.this
        escaped_literal = "".join(REGEX_ESCAPE_REPLACEMENTS.get(ch, ch) for ch in literal_value)
        return _literal_sql_with_ws_chr(self, escaped_literal)

    escaped_sql = delimiters_sql
    for raw, escaped in REGEX_ESCAPE_REPLACEMENTS.items():
        escaped_sql = self.func(
            "REPLACE",
            escaped_sql,
            self.sql(exp.Literal.string(raw)),
            self.sql(exp.Literal.string(escaped)),
        )

    return escaped_sql


def _build_capitalization_sql(
    self: DuckDBGenerator,
    value_to_split: str,
    delimiters_sql: str,
) -> str:
    # empty string delimiter --> treat value as one word, no need to split
    if delimiters_sql == "''":
        return f"UPPER(LEFT({value_to_split}, 1)) || LOWER(SUBSTRING({value_to_split}, 2))"

    delim_regex_sql = f"CONCAT('[', {delimiters_sql}, ']')"
    split_regex_sql = f"CONCAT('([', {delimiters_sql}, ']+|[^', {delimiters_sql}, ']+)')"

    # REGEXP_EXTRACT_ALL produces a list of string segments, alternating between delimiter and non-delimiter segments.
    # We do not know whether the first segment is a delimiter or not, so we check the first character of the string
    # with REGEXP_MATCHES. If the first char is a delimiter, we capitalize even list indexes, otherwise capitalize odd.
    return self.func(
        "ARRAY_TO_STRING",
        exp.case()
        .when(
            f"REGEXP_MATCHES(LEFT({value_to_split}, 1), {delim_regex_sql})",
            self.func(
                "LIST_TRANSFORM",
                self.func("REGEXP_EXTRACT_ALL", value_to_split, split_regex_sql),
                "(seg, idx) -> CASE WHEN idx % 2 = 0 THEN UPPER(LEFT(seg, 1)) || LOWER(SUBSTRING(seg, 2)) ELSE seg END",
            ),
        )
        .else_(
            self.func(
                "LIST_TRANSFORM",
                self.func("REGEXP_EXTRACT_ALL", value_to_split, split_regex_sql),
                "(seg, idx) -> CASE WHEN idx % 2 = 1 THEN UPPER(LEFT(seg, 1)) || LOWER(SUBSTRING(seg, 2)) ELSE seg END",
            ),
        ),
        "''",
    )


def _initcap_sql(self: DuckDBGenerator, expression: exp.Initcap) -> str:
    this_sql = self.sql(expression, "this")
    delimiters = expression.args.get("expression")
    if delimiters is None:
        # fallback for manually created exp.Initcap w/o delimiters arg
        delimiters = exp.Literal.string(self.dialect.INITCAP_DEFAULT_DELIMITER_CHARS)
    delimiters_sql = self.sql(delimiters)

    escaped_delimiters_sql = _escape_regex_metachars(self, delimiters, delimiters_sql)

    return _build_capitalization_sql(self, this_sql, escaped_delimiters_sql)


def _boolxor_agg_sql(self: DuckDBGenerator, expression: exp.BoolxorAgg) -> str:
    """
    Snowflake's `BOOLXOR_AGG(col)` returns TRUE if exactly one input in `col` is TRUE, FALSE otherwise;
    Since DuckDB does not have a mapping function, we mimic the behavior by generating `COUNT_IF(col) = 1`.

    DuckDB's COUNT_IF strictly requires boolean inputs, so cast if not already boolean.
    """
    return self.sql(
        exp.EQ(
            this=exp.CountIf(this=_cast_to_boolean(expression.this)),
            expression=exp.Literal.number(1),
        )
    )


def _bitshift_sql(
    self: DuckDBGenerator, expression: exp.BitwiseLeftShift | exp.BitwiseRightShift
) -> str:
    """
    Transform bitshift expressions for DuckDB by injecting BIT/INT128 casts.

    DuckDB's bitwise shift operators don't work with BLOB/BINARY types, so we cast
    them to BIT for the operation, then cast the result back to the original type.

    Note: Assumes type annotation has been applied with the source dialect.
    """
    operator = "<<" if isinstance(expression, exp.BitwiseLeftShift) else ">>"
    result_is_blob = False
    this = expression.this

    if _is_binary(this):
        result_is_blob = True
        expression.set("this", exp.cast(this, exp.DType.BIT))
    elif expression.args.get("requires_int128"):
        this.replace(exp.cast(this, exp.DType.INT128))

    result_sql = self.binary(expression, operator)

    # Wrap in parentheses if parent is a bitwise operator to "fix" DuckDB precedence issue
    # DuckDB parses: a << b | c << d  as  (a << b | c) << d
    if isinstance(expression.parent, exp.Binary):
        result_sql = self.sql(exp.Paren(this=result_sql))

    if result_is_blob:
        result_sql = self.sql(
            exp.Cast(this=result_sql, to=exp.DataType.from_str("BLOB", dialect="duckdb"))
        )

    return result_sql


def _scale_rounding_sql(
    self: DuckDBGenerator,
    expression: exp.Expr,
    rounding_func: Type[exp.Expr],
) -> str | None:
    """
    Handle scale parameter transformation for rounding functions.

    DuckDB doesn't support the scale parameter for certain functions (e.g., FLOOR, CEIL),
    so we transform: FUNC(x, n) to ROUND(FUNC(x * 10^n) / 10^n, n)

    Args:
        self: The DuckDB generator instance
        expression: The expression to transform (must have 'this', 'decimals', and 'to' args)
        rounding_func: The rounding function class to use in the transformation

    Returns:
        The transformed SQL string if decimals parameter exists, None otherwise
    """
    decimals = expression.args.get("decimals")

    if decimals is None or expression.args.get("to") is not None:
        return None

    this = expression.this
    if isinstance(this, exp.Binary):
        this = exp.Paren(this=this)

    n_int = decimals
    if not (decimals.is_int or decimals.is_type(*exp.DataType.INTEGER_TYPES)):
        n_int = exp.cast(decimals, exp.DType.INT)

    pow_ = exp.Pow(this=exp.Literal.number("10"), expression=n_int)
    rounded = rounding_func(this=exp.Mul(this=this, expression=pow_))
    result = exp.Div(this=rounded, expression=pow_.copy())

    return self.round_sql(
        exp.Round(this=result, decimals=decimals, casts_non_integer_decimals=True)
    )


def _ceil_floor(self: DuckDBGenerator, expression: exp.Floor | exp.Ceil) -> str:
    scaled_sql = _scale_rounding_sql(self, expression, type(expression))
    if scaled_sql is not None:
        return scaled_sql
    return self.ceil_floor(expression)


def _regr_val_sql(
    self: DuckDBGenerator,
    expression: exp.RegrValx | exp.RegrValy,
) -> str:
    """
    Transpile Snowflake's REGR_VALX/REGR_VALY to DuckDB equivalent.

    REGR_VALX(y, x) returns NULL if y is NULL; otherwise returns x.
    REGR_VALY(y, x) returns NULL if x is NULL; otherwise returns y.
    """
    from sqlglot.optimizer.annotate_types import annotate_types

    y = expression.this
    x = expression.expression

    # Determine which argument to check for NULL and which to return based on expression type
    if isinstance(expression, exp.RegrValx):
        # REGR_VALX: check y for NULL, return x
        check_for_null = y
        return_value = x
        return_value_attr = "expression"
    else:
        # REGR_VALY: check x for NULL, return y
        check_for_null = x
        return_value = y
        return_value_attr = "this"

    # Get the type from the return argument
    result_type = return_value.type

    # If no type info, annotate the expression to infer types
    if not result_type or result_type.this == exp.DType.UNKNOWN:
        try:
            annotated = annotate_types(expression.copy(), dialect=self.dialect)
            result_type = getattr(annotated, return_value_attr).type
        except Exception:
            pass

    # Default to DOUBLE for regression functions if type still unknown
    if not result_type or result_type.this == exp.DType.UNKNOWN:
        result_type = exp.DType.DOUBLE.into_expr()

    # Cast NULL to the same type as return_value to avoid DuckDB type inference issues
    typed_null = exp.Cast(this=exp.Null(), to=result_type)

    return self.sql(
        exp.If(
            this=exp.Is(this=check_for_null.copy(), expression=exp.Null()),
            true=typed_null,
            false=return_value.copy(),
        )
    )


def _maybe_corr_null_to_false(
    expression: exp.Filter | exp.Window | exp.Corr,
) -> exp.Filter | exp.Window | exp.Corr | None:
    corr = expression
    while isinstance(corr, (exp.Window, exp.Filter)):
        corr = corr.this

    if not isinstance(corr, exp.Corr) or not corr.args.get("null_on_zero_variance"):
        return None

    corr.set("null_on_zero_variance", False)
    return expression


def _date_from_parts_sql(self, expression: exp.DateFromParts) -> str:
    """
    Snowflake's DATE_FROM_PARTS allows out-of-range values for the month and day input.
    E.g., larger values (month=13, day=100), zero-values (month=0, day=0), negative values (month=-13, day=-100).

    DuckDB's MAKE_DATE does not support out-of-range values, but DuckDB's INTERVAL type does.

    We convert to date arithmetic:
    DATE_FROM_PARTS(year, month, day)
    - MAKE_DATE(year, 1, 1) + INTERVAL (month-1) MONTH + INTERVAL (day-1) DAY
    """
    year_expr = expression.args.get("year")
    month_expr = expression.args.get("month")
    day_expr = expression.args.get("day")

    if expression.args.get("allow_overflow"):
        base_date: exp.Expr = exp.func(
            "MAKE_DATE", year_expr, exp.Literal.number(1), exp.Literal.number(1)
        )

        if month_expr:
            base_date = base_date + exp.Interval(this=month_expr - 1, unit=exp.var("MONTH"))

        if day_expr:
            base_date = base_date + exp.Interval(this=day_expr - 1, unit=exp.var("DAY"))

        return self.sql(exp.cast(expression=base_date, to=exp.DType.DATE))

    return self.func("MAKE_DATE", year_expr, month_expr, day_expr)


def _round_arg(arg: exp.Expr, round_input: bool | None = None) -> exp.Expr:
    if round_input:
        return exp.func("ROUND", arg, exp.Literal.number(0))
    return arg


def _boolnot_sql(self: DuckDBGenerator, expression: exp.Boolnot) -> str:
    arg = _round_arg(expression.this, expression.args.get("round_input"))
    return self.sql(exp.not_(exp.paren(arg)))


def _booland_sql(self: DuckDBGenerator, expression: exp.Booland) -> str:
    round_input = expression.args.get("round_input")
    left = _round_arg(expression.this, round_input)
    right = _round_arg(expression.expression, round_input)
    return self.sql(exp.paren(exp.and_(exp.paren(left), exp.paren(right), wrap=False)))


def _boolor_sql(self: DuckDBGenerator, expression: exp.Boolor) -> str:
    round_input = expression.args.get("round_input")
    left = _round_arg(expression.this, round_input)
    right = _round_arg(expression.expression, round_input)
    return self.sql(exp.paren(exp.or_(exp.paren(left), exp.paren(right), wrap=False)))


def _xor_sql(self: DuckDBGenerator, expression: exp.Xor) -> str:
    round_input = expression.args.get("round_input")
    left = _round_arg(expression.this, round_input)
    right = _round_arg(expression.expression, round_input)
    return self.sql(
        exp.or_(
            exp.paren(exp.and_(left.copy(), exp.paren(right.not_()), wrap=False)),
            exp.paren(exp.and_(exp.paren(left.not_()), right.copy(), wrap=False)),
            wrap=False,
        )
    )


def _explode_to_unnest_sql(self: DuckDBGenerator, expression: exp.Lateral) -> str:
    """Handle LATERAL VIEW EXPLODE/INLINE conversion to UNNEST for DuckDB."""
    explode = expression.this

    if isinstance(explode, exp.Inline):
        # For INLINE, create CROSS JOIN LATERAL (SELECT UNNEST(..., max_depth => 2))
        # Build the UNNEST call with DuckDB-style named parameter
        unnest_expr = exp.Unnest(
            expressions=[
                explode.this,
                exp.Kwarg(this=exp.var("max_depth"), expression=exp.Literal.number(2)),
            ]
        )
        select_expr = exp.Select(expressions=[unnest_expr]).subquery()

        alias_expr = expression.args.get("alias")
        if alias_expr and not alias_expr.this:
            # we need to provide a table name if not present
            alias_expr.set("this", exp.to_identifier(f"_u_{expression.index}"))

        transformed_lateral_expr = exp.Lateral(this=select_expr, alias=alias_expr)
        cross_join_lateral_expr = exp.Join(this=transformed_lateral_expr, kind="CROSS")

        return self.sql(cross_join_lateral_expr)

    # For other cases, use the standard conversion
    return explode_to_unnest_sql(self, expression)


def _sha_sql(
    self: DuckDBGenerator,
    expression: exp.Expr,
    hash_func: str,
    is_binary: bool = False,
) -> str:
    arg = expression.this

    # For SHA2 variants, check digest length (DuckDB only supports SHA256)
    if hash_func == "SHA256":
        length = expression.text("length") or "256"
        if length != "256":
            self.unsupported("DuckDB only supports SHA256 hashing algorithm.")

    # Cast if type is incompatible with DuckDB
    if (
        arg.type
        and arg.type.this != exp.DType.UNKNOWN
        and not arg.is_type(*exp.DataType.TEXT_TYPES)
        and not _is_binary(arg)
    ):
        arg = exp.cast(arg, exp.DType.VARCHAR)

    result = self.func(hash_func, arg)
    return self.func("UNHEX", result) if is_binary else result


class DuckDBGenerator(generator.Generator):
    PARAMETER_TOKEN = "$"
    NAMED_PLACEHOLDER_TOKEN = "$"
    JOIN_HINTS = False
    TABLE_HINTS = False
    QUERY_HINTS = False
    LIMIT_FETCH = "LIMIT"
    STRUCT_DELIMITER = ("(", ")")
    RENAME_TABLE_WITH_DB = False
    NVL2_SUPPORTED = False
    SEMI_ANTI_JOIN_WITH_SIDE = False
    TABLESAMPLE_KEYWORDS = "USING SAMPLE"
    TABLESAMPLE_SEED_KEYWORD = "REPEATABLE"
    LAST_DAY_SUPPORTS_DATE_PART = False
    JSON_KEY_VALUE_PAIR_SEP = ","
    IGNORE_NULLS_IN_FUNC = True
    IGNORE_NULLS_BEFORE_ORDER = False
    JSON_PATH_BRACKETED_KEY_SUPPORTED = False
    SUPPORTS_CREATE_TABLE_LIKE = False
    MULTI_ARG_DISTINCT = False
    CAN_IMPLEMENT_ARRAY_ANY = True
    SUPPORTS_TO_NUMBER = False
    SELECT_KINDS: tuple[str, ...] = ()
    SUPPORTS_DECODE_CASE = False
    SUPPORTS_DROP_ALTER_ICEBERG_PROPERTY = False

    AFTER_HAVING_MODIFIER_TRANSFORMS = generator.AFTER_HAVING_MODIFIER_TRANSFORMS
    SUPPORTS_WINDOW_EXCLUDE = True
    COPY_HAS_INTO_KEYWORD = False
    STAR_EXCEPT = "EXCLUDE"
    PAD_FILL_PATTERN_IS_REQUIRED = True
    ARRAY_SIZE_DIM_REQUIRED: bool | None = False
    NORMALIZE_EXTRACT_DATE_PARTS = True
    SUPPORTS_LIKE_QUANTIFIERS = False
    SET_ASSIGNMENT_REQUIRES_VARIABLE_KEYWORD = True

    TRANSFORMS = {
        **generator.Generator.TRANSFORMS,
        exp.AnyValue: _anyvalue_sql,
        exp.ApproxDistinct: approx_count_distinct_sql,
        exp.Boolnot: _boolnot_sql,
        exp.Booland: _booland_sql,
        exp.Boolor: _boolor_sql,
        exp.Array: transforms.preprocess(
            [transforms.inherit_struct_field_names],
            generator=inline_array_unless_query,
        ),
        exp.ArrayAppend: array_append_sql("LIST_APPEND"),
        exp.ArrayCompact: array_compact_sql,
        exp.ArrayConstructCompact: lambda self, e: self.sql(
            exp.ArrayCompact(this=exp.Array(expressions=e.expressions))
        ),
        exp.ArrayConcat: array_concat_sql("LIST_CONCAT"),
        exp.ArrayContains: _array_contains_sql,
        exp.ArrayOverlaps: _array_overlaps_sql,
        exp.ArrayFilter: rename_func("LIST_FILTER"),
        exp.ArrayInsert: _array_insert_sql,
        exp.ArrayPosition: lambda self, e: (
            self.sql(
                exp.Sub(
                    this=exp.ArrayPosition(this=e.this, expression=e.expression),
                    expression=exp.Literal.number(1),
                )
            )
            if e.args.get("zero_based")
            else self.func("ARRAY_POSITION", e.this, e.expression)
        ),
        exp.ArrayRemoveAt: _array_remove_at_sql,
        exp.ArrayRemove: remove_from_array_using_filter,
        exp.ArraySort: _array_sort_sql,
        exp.ArrayPrepend: array_append_sql("LIST_PREPEND", swap_params=True),
        exp.ArraySum: rename_func("LIST_SUM"),
        exp.ArrayMax: rename_func("LIST_MAX"),
        exp.ArrayMin: rename_func("LIST_MIN"),
        exp.Base64DecodeBinary: lambda self, e: _base64_decode_sql(self, e, to_string=False),
        exp.Base64DecodeString: lambda self, e: _base64_decode_sql(self, e, to_string=True),
        exp.BitwiseAnd: lambda self, e: self._bitwise_op(e, "&"),
        exp.BitwiseAndAgg: _bitwise_agg_sql,
        exp.BitwiseCount: rename_func("BIT_COUNT"),
        exp.BitwiseLeftShift: _bitshift_sql,
        exp.BitwiseOr: lambda self, e: self._bitwise_op(e, "|"),
        exp.BitwiseOrAgg: _bitwise_agg_sql,
        exp.BitwiseRightShift: _bitshift_sql,
        exp.BitwiseXorAgg: _bitwise_agg_sql,
        exp.CommentColumnConstraint: no_comment_column_constraint_sql,
        exp.Corr: lambda self, e: self._corr_sql(e),
        exp.CosineDistance: rename_func("LIST_COSINE_DISTANCE"),
        exp.CurrentTime: lambda *_: "CURRENT_TIME",
        exp.CurrentSchemas: lambda self, e: self.func(
            "current_schemas", e.this if e.this else exp.true()
        ),
        exp.CurrentTimestamp: lambda self, e: (
            self.sql(
                exp.AtTimeZone(this=exp.var("CURRENT_TIMESTAMP"), zone=exp.Literal.string("UTC"))
            )
            if e.args.get("sysdate")
            else "CURRENT_TIMESTAMP"
        ),
        exp.CurrentVersion: rename_func("version"),
        exp.Localtime: unsupported_args("this")(lambda *_: "LOCALTIME"),
        exp.DayOfMonth: rename_func("DAYOFMONTH"),
        exp.DayOfWeek: rename_func("DAYOFWEEK"),
        exp.DayOfWeekIso: rename_func("ISODOW"),
        exp.DayOfYear: rename_func("DAYOFYEAR"),
        exp.Dayname: lambda self, e: (
            self.func("STRFTIME", e.this, exp.Literal.string("%a"))
            if e.args.get("abbreviated")
            else self.func("DAYNAME", e.this)
        ),
        exp.Monthname: lambda self, e: (
            self.func("STRFTIME", e.this, exp.Literal.string("%b"))
            if e.args.get("abbreviated")
            else self.func("MONTHNAME", e.this)
        ),
        exp.DataType: _datatype_sql,
        exp.Date: _date_sql,
        exp.DateAdd: _date_delta_to_binary_interval_op(),
        exp.DateFromParts: _date_from_parts_sql,
        exp.DateSub: _date_delta_to_binary_interval_op(),
        exp.DateDiff: _date_diff_sql,
        exp.DateStrToDate: datestrtodate_sql,
        exp.Datetime: no_datetime_sql,
        exp.DatetimeDiff: _date_diff_sql,
        exp.DatetimeSub: _date_delta_to_binary_interval_op(),
        exp.DatetimeAdd: _date_delta_to_binary_interval_op(),
        exp.DateToDi: lambda self, e: (
            f"CAST(STRFTIME({self.sql(e, 'this')}, {self.dialect.DATEINT_FORMAT}) AS INT)"
        ),
        exp.Decode: lambda self, e: encode_decode_sql(self, e, "DECODE", replace=False),
        exp.DiToDate: lambda self, e: (
            f"CAST(STRPTIME(CAST({self.sql(e, 'this')} AS TEXT), {self.dialect.DATEINT_FORMAT}) AS DATE)"
        ),
        exp.Encode: lambda self, e: encode_decode_sql(self, e, "ENCODE", replace=False),
        exp.EqualNull: lambda self, e: self.sql(
            exp.NullSafeEQ(this=e.this, expression=e.expression)
        ),
        exp.EuclideanDistance: rename_func("LIST_DISTANCE"),
        exp.GenerateDateArray: _generate_datetime_array_sql,
        exp.GenerateSeries: generate_series_sql("GENERATE_SERIES", "RANGE"),
        exp.GenerateTimestampArray: _generate_datetime_array_sql,
        exp.Getbit: getbit_sql,
        exp.GroupConcat: lambda self, e: groupconcat_sql(self, e, within_group=False),
        exp.Explode: rename_func("UNNEST"),
        exp.IcebergProperty: lambda *_: "",
        exp.IntDiv: lambda self, e: self.binary(e, "//"),
        exp.IsInf: rename_func("ISINF"),
        exp.IsNan: rename_func("ISNAN"),
        exp.IsNullValue: lambda self, e: self.sql(
            exp.func("JSON_TYPE", e.this).eq(exp.Literal.string("NULL"))
        ),
        exp.IsArray: lambda self, e: self.sql(
            exp.func("JSON_TYPE", e.this).eq(exp.Literal.string("ARRAY"))
        ),
        exp.Ceil: _ceil_floor,
        exp.Floor: _ceil_floor,
        exp.JSONBExists: rename_func("JSON_EXISTS"),
        exp.JSONExtract: _arrow_json_extract_sql,
        exp.JSONExtractArray: _json_extract_value_array_sql,
        exp.JSONFormat: _json_format_sql,
        exp.JSONValueArray: _json_extract_value_array_sql,
        exp.Lateral: _explode_to_unnest_sql,
        exp.LogicalOr: lambda self, e: self.func("BOOL_OR", _cast_to_boolean(e.this)),
        exp.LogicalAnd: lambda self, e: self.func("BOOL_AND", _cast_to_boolean(e.this)),
        exp.Select: transforms.preprocess([_seq_to_range_in_generator]),
        exp.Seq1: lambda self, e: _seq_sql(self, e, 1),
        exp.Seq2: lambda self, e: _seq_sql(self, e, 2),
        exp.Seq4: lambda self, e: _seq_sql(self, e, 4),
        exp.Seq8: lambda self, e: _seq_sql(self, e, 8),
        exp.BoolxorAgg: _boolxor_agg_sql,
        exp.MakeInterval: lambda self, e: no_make_interval_sql(self, e, sep=" "),
        exp.Initcap: _initcap_sql,
        exp.MD5Digest: lambda self, e: self.func("UNHEX", self.func("MD5", e.this)),
        exp.SHA: lambda self, e: _sha_sql(self, e, "SHA1"),
        exp.SHA1Digest: lambda self, e: _sha_sql(self, e, "SHA1", is_binary=True),
        exp.SHA2: lambda self, e: _sha_sql(self, e, "SHA256"),
        exp.SHA2Digest: lambda self, e: _sha_sql(self, e, "SHA256", is_binary=True),
        exp.MonthsBetween: months_between_sql,
        exp.NextDay: _day_navigation_sql,
        exp.PercentileCont: rename_func("QUANTILE_CONT"),
        exp.PercentileDisc: rename_func("QUANTILE_DISC"),
        # DuckDB doesn't allow qualified columns inside of PIVOT expressions.
        # See: https://github.com/duckdb/duckdb/blob/671faf92411182f81dce42ac43de8bfb05d9909e/src/planner/binder/tableref/bind_pivot.cpp#L61-L62
        exp.Pivot: transforms.preprocess([transforms.unqualify_columns]),
        exp.PreviousDay: _day_navigation_sql,
        exp.RegexpILike: lambda self, e: self.func(
            "REGEXP_MATCHES", e.this, e.expression, exp.Literal.string("i")
        ),
        exp.RegexpSplit: rename_func("STR_SPLIT_REGEX"),
        exp.RegrValx: _regr_val_sql,
        exp.RegrValy: _regr_val_sql,
        exp.Return: lambda self, e: self.sql(e, "this"),
        exp.ReturnsProperty: lambda self, e: "TABLE" if isinstance(e.this, exp.Schema) else "",
        exp.StrToUnix: lambda self, e: self.func(
            "EPOCH", self.func("STRPTIME", e.this, self.format_time(e))
        ),
        exp.Struct: _struct_sql,
        exp.Transform: rename_func("LIST_TRANSFORM"),
        exp.TimeAdd: _date_delta_to_binary_interval_op(),
        exp.TimeSub: _date_delta_to_binary_interval_op(),
        exp.Time: no_time_sql,
        exp.TimeDiff: _timediff_sql,
        exp.Timestamp: no_timestamp_sql,
        exp.TimestampAdd: _date_delta_to_binary_interval_op(),
        exp.TimestampDiff: lambda self, e: self.func(
            "DATE_DIFF", exp.Literal.string(e.unit), e.expression, e.this
        ),
        exp.TimestampSub: _date_delta_to_binary_interval_op(),
        exp.TimeStrToDate: lambda self, e: self.sql(exp.cast(e.this, exp.DType.DATE)),
        exp.TimeStrToTime: timestrtotime_sql,
        exp.TimeStrToUnix: lambda self, e: self.func(
            "EPOCH", exp.cast(e.this, exp.DType.TIMESTAMP)
        ),
        exp.TimeToStr: lambda self, e: self.func("STRFTIME", e.this, self.format_time(e)),
        exp.ToBoolean: _to_boolean_sql,
        exp.ToVariant: lambda self, e: self.sql(
            exp.cast(e.this, exp.DataType.from_str("VARIANT", dialect="duckdb"))
        ),
        exp.TimeToUnix: rename_func("EPOCH"),
        exp.TsOrDiToDi: lambda self, e: (
            f"CAST(SUBSTR(REPLACE(CAST({self.sql(e, 'this')} AS TEXT), '-', ''), 1, 8) AS INT)"
        ),
        exp.TsOrDsAdd: _date_delta_to_binary_interval_op(),
        exp.TsOrDsDiff: lambda self, e: self.func(
            "DATE_DIFF",
            f"'{e.args.get('unit') or 'DAY'}'",
            exp.cast(e.expression, exp.DType.TIMESTAMP),
            exp.cast(e.this, exp.DType.TIMESTAMP),
        ),
        exp.UnixMicros: lambda self, e: self.func("EPOCH_US", _implicit_datetime_cast(e.this)),
        exp.UnixMillis: lambda self, e: self.func("EPOCH_MS", _implicit_datetime_cast(e.this)),
        exp.UnixSeconds: lambda self, e: self.sql(
            exp.cast(self.func("EPOCH", _implicit_datetime_cast(e.this)), exp.DType.BIGINT)
        ),
        exp.UnixToStr: lambda self, e: self.func(
            "STRFTIME", self.func("TO_TIMESTAMP", e.this), self.format_time(e)
        ),
        exp.DatetimeTrunc: lambda self, e: self.func(
            "DATE_TRUNC", unit_to_str(e), exp.cast(e.this, exp.DType.DATETIME)
        ),
        exp.UnixToTime: _unix_to_time_sql,
        exp.UnixToTimeStr: lambda self, e: f"CAST(TO_TIMESTAMP({self.sql(e, 'this')}) AS TEXT)",
        exp.VariancePop: rename_func("VAR_POP"),
        exp.WeekOfYear: rename_func("WEEKOFYEAR"),
        exp.YearOfWeek: lambda self, e: self.sql(
            exp.Extract(
                this=exp.Var(this="ISOYEAR"),
                expression=e.this,
            )
        ),
        exp.YearOfWeekIso: lambda self, e: self.sql(
            exp.Extract(
                this=exp.Var(this="ISOYEAR"),
                expression=e.this,
            )
        ),
        exp.Xor: _xor_sql,
        exp.JSONObjectAgg: rename_func("JSON_GROUP_OBJECT"),
        exp.JSONBObjectAgg: rename_func("JSON_GROUP_OBJECT"),
        exp.DateBin: rename_func("TIME_BUCKET"),
        exp.LastDay: _last_day_sql,
    }

    SUPPORTED_JSON_PATH_PARTS = {
        exp.JSONPathKey,
        exp.JSONPathRoot,
        exp.JSONPathSubscript,
        exp.JSONPathWildcard,
    }

    TYPE_MAPPING = {
        **generator.Generator.TYPE_MAPPING,
        exp.DType.BINARY: "BLOB",
        exp.DType.BPCHAR: "TEXT",
        exp.DType.CHAR: "TEXT",
        exp.DType.DATETIME: "TIMESTAMP",
        exp.DType.DECFLOAT: "DECIMAL(38, 5)",
        exp.DType.FLOAT: "REAL",
        exp.DType.JSONB: "JSON",
        exp.DType.NCHAR: "TEXT",
        exp.DType.NVARCHAR: "TEXT",
        exp.DType.UINT: "UINTEGER",
        exp.DType.VARBINARY: "BLOB",
        exp.DType.ROWVERSION: "BLOB",
        exp.DType.VARCHAR: "TEXT",
        exp.DType.TIMESTAMPLTZ: "TIMESTAMPTZ",
        exp.DType.TIMESTAMPNTZ: "TIMESTAMP",
        exp.DType.TIMESTAMP_S: "TIMESTAMP_S",
        exp.DType.TIMESTAMP_MS: "TIMESTAMP_MS",
        exp.DType.TIMESTAMP_NS: "TIMESTAMP_NS",
        exp.DType.BIGDECIMAL: "DECIMAL(38, 5)",
    }

    # https://github.com/duckdb/duckdb/blob/ff7f24fd8e3128d94371827523dae85ebaf58713/third_party/libpg_query/grammar/keywords/reserved_keywords.list#L1-L77
    RESERVED_KEYWORDS = {
        "array",
        "analyse",
        "union",
        "all",
        "when",
        "in_p",
        "default",
        "create_p",
        "window",
        "asymmetric",
        "to",
        "else",
        "localtime",
        "from",
        "end_p",
        "select",
        "current_date",
        "foreign",
        "with",
        "grant",
        "session_user",
        "or",
        "except",
        "references",
        "fetch",
        "limit",
        "group_p",
        "leading",
        "into",
        "collate",
        "offset",
        "do",
        "then",
        "localtimestamp",
        "check_p",
        "lateral_p",
        "current_role",
        "where",
        "asc_p",
        "placing",
        "desc_p",
        "user",
        "unique",
        "initially",
        "column",
        "both",
        "some",
        "as",
        "any",
        "only",
        "deferrable",
        "null_p",
        "current_time",
        "true_p",
        "table",
        "case",
        "trailing",
        "variadic",
        "for",
        "on",
        "distinct",
        "false_p",
        "not",
        "constraint",
        "current_timestamp",
        "returning",
        "primary",
        "intersect",
        "having",
        "analyze",
        "current_user",
        "and",
        "cast",
        "symmetric",
        "using",
        "order",
        "current_catalog",
    }

    UNWRAPPED_INTERVAL_VALUES = (exp.Literal, exp.Paren)

    # DuckDB doesn't generally support CREATE TABLE .. properties
    # https://duckdb.org/docs/sql/statements/create_table.html
    # There are a few exceptions (e.g. temporary tables) which are supported or
    # can be transpiled to DuckDB, so we explicitly override them accordingly
    PROPERTIES_LOCATION = {
        **{
            prop: exp.Properties.Location.UNSUPPORTED
            for prop in generator.Generator.PROPERTIES_LOCATION
        },
        exp.LikeProperty: exp.Properties.Location.POST_SCHEMA,
        exp.TemporaryProperty: exp.Properties.Location.POST_CREATE,
        exp.ReturnsProperty: exp.Properties.Location.POST_ALIAS,
        exp.SequenceProperties: exp.Properties.Location.POST_EXPRESSION,
        exp.IcebergProperty: exp.Properties.Location.POST_CREATE,
    }

    IGNORE_RESPECT_NULLS_WINDOW_FUNCTIONS: t.ClassVar = _IGNORE_RESPECT_NULLS_WINDOW_FUNCTIONS

    # Template for ZIPF transpilation - placeholders get replaced with actual parameters
    ZIPF_TEMPLATE: exp.Expr = exp.maybe_parse(
        """
        WITH rand AS (SELECT :random_expr AS r),
        weights AS (
            SELECT i, 1.0 / POWER(i, :s) AS w
            FROM RANGE(1, :n + 1) AS t(i)
        ),
        cdf AS (
            SELECT i, SUM(w) OVER (ORDER BY i) / SUM(w) OVER () AS p
            FROM weights
        )
        SELECT MIN(i)
        FROM cdf
        WHERE p >= (SELECT r FROM rand)
        """
    )

    # Template for NORMAL transpilation using Box-Muller transform
    # mean + (stddev * sqrt(-2 * ln(u1)) * cos(2 * pi * u2))
    NORMAL_TEMPLATE: exp.Expr = exp.maybe_parse(
        ":mean + (:stddev * SQRT(-2 * LN(GREATEST(:u1, 1e-10))) * COS(2 * PI() * :u2))"
    )

    # Template for generating a seeded pseudo-random value in [0, 1) from a hash
    SEEDED_RANDOM_TEMPLATE: exp.Expr = exp.maybe_parse("(ABS(HASH(:seed)) % 1000000) / 1000000.0")

    # Template for generating signed and unsigned SEQ values within a specified range
    SEQ_UNSIGNED: exp.Expr = _SEQ_UNSIGNED
    SEQ_SIGNED: exp.Expr = _SEQ_SIGNED

    # Template for MAP_CAT transpilation - Snowflake semantics:
    # 1. Returns NULL if either input is NULL
    # 2. For duplicate keys, prefers non-NULL value (COALESCE(m2[k], m1[k]))
    # 3. Filters out entries with NULL values from the result
    MAPCAT_TEMPLATE: exp.Expr = exp.maybe_parse(
        """
        CASE
            WHEN :map1 IS NULL OR :map2 IS NULL THEN NULL
            ELSE MAP_FROM_ENTRIES(LIST_FILTER(LIST_TRANSFORM(
                LIST_DISTINCT(LIST_CONCAT(MAP_KEYS(:map1), MAP_KEYS(:map2))),
                __k -> STRUCT_PACK(key := __k, value := COALESCE(:map2[__k], :map1[__k]))
            ), __x -> __x.value IS NOT NULL))
        END
        """
    )

    # Mappings for EXTRACT/DATE_PART transpilation
    # Maps Snowflake specifiers unsupported in DuckDB to strftime format codes
    EXTRACT_STRFTIME_MAPPINGS: dict[str, tuple[str, str]] = {
        "WEEKISO": ("%V", "INTEGER"),
        "YEAROFWEEK": ("%G", "INTEGER"),
        "YEAROFWEEKISO": ("%G", "INTEGER"),
        "NANOSECOND": ("%n", "BIGINT"),
    }

    # Maps epoch-based specifiers to DuckDB epoch functions
    EXTRACT_EPOCH_MAPPINGS: dict[str, str] = {
        "EPOCH_SECOND": "EPOCH",
        "EPOCH_MILLISECOND": "EPOCH_MS",
        "EPOCH_MICROSECOND": "EPOCH_US",
        "EPOCH_NANOSECOND": "EPOCH_NS",
    }

    # Template for BITMAP_CONSTRUCT_AGG transpilation
    #
    # BACKGROUND:
    # Snowflake's BITMAP_CONSTRUCT_AGG aggregates integers into a compact binary bitmap.
    # Supports values in range 0-32767, this version returns NULL if any value is out of range
    # See: https://docs.snowflake.com/en/sql-reference/functions/bitmap_construct_agg
    # See: https://docs.snowflake.com/en/user-guide/querying-bitmaps-for-distinct-counts
    #
    # Snowflake uses two different formats based on the number of unique values:
    #
    # Format 1 - Small bitmap (< 5 unique values): Length of 10 bytes
    #   Bytes 0-1: Count of values as 2-byte big-endian integer (e.g., 3 values = 0x0003)
    #   Bytes 2-9: Up to 4 values, each as 2-byte little-endian integers, zero-padded to 8 bytes
    #   Example: Values [1, 2, 3] -> 0x0003 0100 0200 0300 0000 (hex)
    #                                count  v1   v2   v3   pad
    #
    # Format 2 - Large bitmap (>= 5 unique values): Length of 10 + (2 * count) bytes
    #   Bytes 0-9: Fixed header 0x08 followed by 9 zero bytes
    #   Bytes 10+: Each value as 2-byte little-endian integer (no padding)
    #   Example: Values [1,2,3,4,5] -> 0x08 00000000 00000000 00 0100 0200 0300 0400 0500
    #                                  hdr  ----9 zero bytes----  v1   v2   v3   v4   v5
    #
    # TEMPLATE STRUCTURE
    #
    # Phase 1 - Innermost subquery: Data preparation
    #   SELECT LIST_SORT(...) AS l
    #   - Aggregates all input values into a list, remove NULLs, duplicates and sorts
    #   Result: Clean, sorted list of unique non-null integers stored as 'l'
    #
    # Phase 2 - Middle subquery: Hex string construction
    #   LIST_TRANSFORM(...)
    #   - Converts each integer to 2-byte little-endian hex representation
    #   - & 255 extracts low byte, >> 8 extracts high byte
    #   - LIST_REDUCE: Concatenates all hex pairs into single string 'h'
    #   Result: Hex string of all values
    #
    # Phase 3 - Outer SELECT: Final bitmap assembly
    #   LENGTH(l) < 5:
    #   - Small format: 2-byte count (big-endian via %04X) + values + zero padding
    #   LENGTH(l) >= 5:
    #   - Large format: Fixed 10-byte header + values (no padding needed)
    #   Result: Complete binary bitmap as BLOB
    #
    BITMAP_CONSTRUCT_AGG_TEMPLATE: exp.Expr = exp.maybe_parse(
        """
        SELECT CASE
            WHEN l IS NULL OR LENGTH(l) = 0 THEN NULL
            WHEN LENGTH(l) != LENGTH(LIST_FILTER(l, __v -> __v BETWEEN 0 AND 32767)) THEN NULL
            WHEN LENGTH(l) < 5 THEN UNHEX(PRINTF('%04X', LENGTH(l)) || h || REPEAT('00', GREATEST(0, 4 - LENGTH(l)) * 2))
            ELSE UNHEX('08000000000000000000' || h)
        END
        FROM (
            SELECT l, COALESCE(LIST_REDUCE(
                LIST_TRANSFORM(l, __x -> PRINTF('%02X%02X', CAST(__x AS INT) & 255, (CAST(__x AS INT) >> 8) & 255)),
                (__a, __b) -> __a || __b, ''
            ), '') AS h
            FROM (SELECT LIST_SORT(LIST_DISTINCT(LIST(:arg) FILTER(NOT :arg IS NULL))) AS l)
        )
        """
    )

    # Template for RANDSTR transpilation - placeholders get replaced with actual parameters
    RANDSTR_TEMPLATE: exp.Expr = exp.maybe_parse(
        f"""
        SELECT LISTAGG(
            SUBSTRING(
                '{RANDSTR_CHAR_POOL}',
                1 + CAST(FLOOR(random_value * 62) AS INT),
                1
            ),
            ''
        )
        FROM (
            SELECT (ABS(HASH(i + :seed)) % 1000) / 1000.0 AS random_value
            FROM RANGE(:length) AS t(i)
        )
        """,
    )

    # Template for MINHASH transpilation
    # Computes k minimum hash values across aggregated data using DuckDB list functions
    # Returns JSON matching Snowflake format: {"state": [...], "type": "minhash", "version": 1}
    MINHASH_TEMPLATE: exp.Expr = exp.maybe_parse(
        """
        SELECT JSON_OBJECT('state', LIST(min_h ORDER BY seed), 'type', 'minhash', 'version', 1)
        FROM (
            SELECT seed, LIST_MIN(LIST_TRANSFORM(vals, __v -> HASH(CAST(__v AS VARCHAR) || CAST(seed AS VARCHAR)))) AS min_h
            FROM (SELECT LIST(:expr) AS vals), RANGE(0, :k) AS t(seed)
        )
        """,
    )

    # Template for MINHASH_COMBINE transpilation
    # Combines multiple minhash signatures by taking element-wise minimum
    MINHASH_COMBINE_TEMPLATE: exp.Expr = exp.maybe_parse(
        """
        SELECT JSON_OBJECT('state', LIST(min_h ORDER BY idx), 'type', 'minhash', 'version', 1)
        FROM (
            SELECT
                pos AS idx,
                MIN(val) AS min_h
            FROM
                UNNEST(LIST(:expr)) AS _(sig),
                UNNEST(CAST(sig -> 'state' AS UBIGINT[])) WITH ORDINALITY AS t(val, pos)
            GROUP BY pos
        )
        """,
    )

    # Template for APPROXIMATE_SIMILARITY transpilation
    # Computes multi-way Jaccard similarity: fraction of positions where ALL signatures agree
    APPROXIMATE_SIMILARITY_TEMPLATE: exp.Expr = exp.maybe_parse(
        """
        SELECT CAST(SUM(CASE WHEN num_distinct = 1 THEN 1 ELSE 0 END) AS DOUBLE) / COUNT(*)
        FROM (
            SELECT pos, COUNT(DISTINCT h) AS num_distinct
            FROM (
                SELECT h, pos
                FROM UNNEST(LIST(:expr)) AS _(sig),
                     UNNEST(CAST(sig -> 'state' AS UBIGINT[])) WITH ORDINALITY AS s(h, pos)
            )
            GROUP BY pos
        )
        """,
    )

    # Template for ARRAYS_ZIP transpilation
    # Snowflake pads to longest array; DuckDB LIST_ZIP truncates to shortest
    # Uses RANGE + indexing to match Snowflake behavior
    ARRAYS_ZIP_TEMPLATE: exp.Expr = exp.maybe_parse(
        """
        CASE WHEN :null_check THEN NULL
        WHEN :all_empty_check THEN [:empty_struct]
        ELSE LIST_TRANSFORM(RANGE(0, :max_len), __i -> :transform_struct)
        END
        """,
    )

    UUID_V5_TEMPLATE: exp.Expr = exp.maybe_parse(
        """
        (SELECT
            LOWER(
                SUBSTR(h, 1, 8) || '-' ||
                SUBSTR(h, 9, 4) || '-' ||
                '5' || SUBSTR(h, 14, 3) || '-' ||
                FORMAT('{:02x}', CAST('0x' || SUBSTR(h, 17, 2) AS INT) & 63 | 128) || SUBSTR(h, 19, 2) || '-' ||
                SUBSTR(h, 21, 12)
            )
        FROM (
            SELECT SUBSTR(SHA1(UNHEX(REPLACE(:namespace, '-', '')) || ENCODE(:name, 'utf8')), 1, 32) AS h
        ))
        """
    )

    # Shared bag semantics outer frame for ARRAY_EXCEPT and ARRAY_INTERSECTION.
    # Each element is paired with its 1-based position via LIST_ZIP, then filtered
    # by a comparison operator (supplied via :cond) that determines the operation:
    #   EXCEPT (>):        keep the N-th occurrence only if N > count in arr2
    #                      e.g. [2,2,2] EXCEPT [2,2] -> [2]
    #   INTERSECTION (<=): keep the N-th occurrence only if N <= count in arr2
    #                      e.g. [2,2,2] INTERSECT [2,2] -> [2,2]
    # IS NOT DISTINCT FROM is used for NULL-safe element comparison.
    ARRAY_BAG_TEMPLATE: exp.Expr = exp.maybe_parse(
        """
        CASE
            WHEN :arr1 IS NULL OR :arr2 IS NULL THEN NULL
            ELSE LIST_TRANSFORM(
                LIST_FILTER(
                    LIST_ZIP(:arr1, GENERATE_SERIES(1, LEN(:arr1))),
                    pair -> :cond
                ),
                pair -> pair[0]
            )
        END
        """
    )

    ARRAY_EXCEPT_CONDITION: exp.Expr = exp.maybe_parse(
        "LEN(LIST_FILTER(:arr1[1:pair[1]], e -> e IS NOT DISTINCT FROM pair[0]))"
        " > LEN(LIST_FILTER(:arr2, e -> e IS NOT DISTINCT FROM pair[0]))"
    )

    ARRAY_INTERSECTION_CONDITION: exp.Expr = exp.maybe_parse(
        "LEN(LIST_FILTER(:arr1[1:pair[1]], e -> e IS NOT DISTINCT FROM pair[0]))"
        " <= LEN(LIST_FILTER(:arr2, e -> e IS NOT DISTINCT FROM pair[0]))"
    )

    # Set semantics for ARRAY_EXCEPT. Deduplicates arr1 via LIST_DISTINCT, then
    # filters out any element that appears at least once in arr2.
    #   e.g. [1,1,2,3] EXCEPT [1] -> [2,3]
    # IS NOT DISTINCT FROM is used for NULL-safe element comparison.
    ARRAY_EXCEPT_SET_TEMPLATE: exp.Expr = exp.maybe_parse(
        """
        CASE
            WHEN :arr1 IS NULL OR :arr2 IS NULL THEN NULL
            ELSE LIST_FILTER(
                LIST_DISTINCT(:arr1),
                e -> LEN(LIST_FILTER(:arr2, x -> x IS NOT DISTINCT FROM e)) = 0
            )
        END
        """
    )

    STRTOK_TO_ARRAY_TEMPLATE: exp.Expr = exp.maybe_parse(
        """
        CASE WHEN :delimiter IS NULL THEN NULL
        ELSE LIST_FILTER(
            REGEXP_SPLIT_TO_ARRAY(:string, CASE WHEN :delimiter = '' THEN '.^' ELSE CONCAT('[', :escaped, ']') END),
            x -> NOT x = ''
        ) END
        """
    )

    # Template for STRTOK function transpilation
    #
    # DuckDB itself doesn't have a strtok function. This handles the transpilation from Snowflake to DuckDB.
    # We may need to adjust this if we want to support transpilation from other dialects
    #
    # CASE
    #     -- Snowflake: empty delimiter + empty input string -> NULL
    #     WHEN delimiter = '' AND input_str = '' THEN NULL
    #
    #     -- Snowflake: empty delimiter + non-empty input string -> treats whole input as 1 token -> return input string if index is 1
    #     WHEN delimiter = '' AND index = 1 THEN input_str
    #
    #     -- Snowflake: empty delimiter + non-empty input string -> treats whole input as 1 token -> return NULL if index is not 1
    #     WHEN delimiter = '' THEN NULL
    #
    #     -- Snowflake: negative indices return NULL
    #     WHEN index < 0 THEN NULL
    #
    #     -- Snowflake: return NULL if any argument is NULL
    #     WHEN input_str IS NULL OR delimiter IS NULL OR index IS NULL THEN NULL
    #
    #
    #     ELSE LIST_FILTER(
    #         REGEXP_SPLIT_TO_ARRAY(
    #             input_str,
    #             CASE
    #                 -- if delimiter is '', we don't want to surround it with '[' and ']' as '[]' is invalid for DuckDB
    #                 WHEN delimiter = '' THEN ''
    #
    #                 -- handle problematic regex characters in delimiter with REGEXP_REPLACE
    #                 -- turn delimiter into a regex char set, otherwise DuckDB will match in order, which we don't want
    #                 ELSE '[' || REGEXP_REPLACE(delimiter, problematic_char_set, '\\\1', 'g') || ']'
    #             END
    #         ),
    #
    #         -- Snowflake: don't return empty strings
    #         x -> NOT x = ''
    #     )[index]
    # END
    STRTOK_TEMPLATE: exp.Expr = exp.maybe_parse(
        """
        CASE
            WHEN :delimiter = '' AND :string = '' THEN NULL
            WHEN :delimiter = '' AND :part_index = 1 THEN :string
            WHEN :delimiter = '' THEN NULL
            WHEN :part_index < 0 THEN NULL
            WHEN :string IS NULL OR :delimiter IS NULL OR :part_index IS NULL THEN NULL
            ELSE :base_func
        END
        """
    )

    def _array_bag_sql(self, condition: exp.Expr, arr1: exp.Expr, arr2: exp.Expr) -> str:
        cond = exp.Paren(this=exp.replace_placeholders(condition, arr1=arr1, arr2=arr2))
        return self.sql(
            exp.replace_placeholders(self.ARRAY_BAG_TEMPLATE, arr1=arr1, arr2=arr2, cond=cond)
        )

    def timeslice_sql(self, expression: exp.TimeSlice) -> str:
        """
        Transform Snowflake's TIME_SLICE to DuckDB's time_bucket.

        Snowflake: TIME_SLICE(date_expr, slice_length, 'UNIT' [, 'START'|'END'])
        DuckDB:    time_bucket(INTERVAL 'slice_length' UNIT, date_expr)

        For 'END' kind, add the interval to get the end of the slice.
        For DATE type with 'END', cast result back to DATE to preserve type.
        """
        date_expr = expression.this
        slice_length = expression.expression
        unit = expression.unit
        kind = expression.text("kind").upper()

        # Create INTERVAL expression: INTERVAL 'N' UNIT
        interval_expr = exp.Interval(this=slice_length, unit=unit)

        # Create base time_bucket expression
        time_bucket_expr = exp.func("time_bucket", interval_expr, date_expr)

        # Check if we need the end of the slice (default is start)
        if not kind == "END":
            # For 'START', return time_bucket directly
            return self.sql(time_bucket_expr)

        # For 'END', add the interval to get end of slice
        add_expr = exp.Add(this=time_bucket_expr, expression=interval_expr.copy())

        # If input is DATE type, cast result back to DATE to preserve type
        # DuckDB converts DATE to TIMESTAMP when adding intervals
        if date_expr.is_type(exp.DType.DATE):
            return self.sql(exp.cast(add_expr, exp.DType.DATE))

        return self.sql(add_expr)

    def bitmapbucketnumber_sql(self, expression: exp.BitmapBucketNumber) -> str:
        """
        Transpile BITMAP_BUCKET_NUMBER function from Snowflake to DuckDB equivalent.

        Snowflake's BITMAP_BUCKET_NUMBER returns a 1-based bucket identifier where:
        - Each bucket covers 32,768 values
        - Bucket numbering starts at 1
        - Formula: ((value - 1) // 32768) + 1 for positive values

        For non-positive values (0 and negative), we use value // 32768 to avoid
        producing bucket 0 or positive bucket IDs for negative inputs.
        """
        value = expression.this

        positive_formula = ((value - 1) // 32768) + 1
        non_positive_formula = value // 32768

        # CASE WHEN value > 0 THEN ((value - 1) // 32768) + 1 ELSE value // 32768 END
        case_expr = (
            exp.case()
            .when(exp.GT(this=value, expression=exp.Literal.number(0)), positive_formula)
            .else_(non_positive_formula)
        )
        return self.sql(case_expr)

    def bitmapbitposition_sql(self, expression: exp.BitmapBitPosition) -> str:
        """
        Transpile Snowflake's BITMAP_BIT_POSITION to DuckDB CASE expression.

        Snowflake's BITMAP_BIT_POSITION behavior:
        - For n <= 0: returns ABS(n) % 32768
        - For n > 0: returns (n - 1) % 32768 (maximum return value is 32767)
        """
        this = expression.this

        return self.sql(
            exp.Mod(
                this=exp.Paren(
                    this=exp.If(
                        this=exp.GT(this=this, expression=exp.Literal.number(0)),
                        true=this - exp.Literal.number(1),
                        false=exp.Abs(this=this),
                    )
                ),
                expression=MAX_BIT_POSITION,
            )
        )

    def bitmapconstructagg_sql(self, expression: exp.BitmapConstructAgg) -> str:
        """
        Transpile Snowflake's BITMAP_CONSTRUCT_AGG to DuckDB equivalent.
        Uses a pre-parsed template with placeholders replaced by expression nodes.

        Snowflake bitmap format:
        - Small (< 5 unique values): 2-byte count (big-endian) + values (little-endian) + padding to 10 bytes
        - Large (>= 5 unique values): 10-byte header (0x08 + 9 zeros) + values (little-endian)
        """
        arg = expression.this
        return (
            f"({self.sql(exp.replace_placeholders(self.BITMAP_CONSTRUCT_AGG_TEMPLATE, arg=arg))})"
        )

    def compress_sql(self, expression: exp.Compress) -> str:
        self.unsupported("DuckDB does not support the COMPRESS() function")
        return self.function_fallback_sql(expression)

    def encrypt_sql(self, expression: exp.Encrypt) -> str:
        self.unsupported("ENCRYPT is not supported in DuckDB")
        return self.function_fallback_sql(expression)

    def decrypt_sql(self, expression: exp.Decrypt) -> str:
        func_name = "TRY_DECRYPT" if expression.args.get("safe") else "DECRYPT"
        self.unsupported(f"{func_name} is not supported in DuckDB")
        return self.function_fallback_sql(expression)

    def decryptraw_sql(self, expression: exp.DecryptRaw) -> str:
        func_name = "TRY_DECRYPT_RAW" if expression.args.get("safe") else "DECRYPT_RAW"
        self.unsupported(f"{func_name} is not supported in DuckDB")
        return self.function_fallback_sql(expression)

    def encryptraw_sql(self, expression: exp.EncryptRaw) -> str:
        self.unsupported("ENCRYPT_RAW is not supported in DuckDB")
        return self.function_fallback_sql(expression)

    def parseurl_sql(self, expression: exp.ParseUrl) -> str:
        self.unsupported("PARSE_URL is not supported in DuckDB")
        return self.function_fallback_sql(expression)

    def parseip_sql(self, expression: exp.ParseIp) -> str:
        self.unsupported("PARSE_IP is not supported in DuckDB")
        return self.function_fallback_sql(expression)

    def decompressstring_sql(self, expression: exp.DecompressString) -> str:
        self.unsupported("DECOMPRESS_STRING is not supported in DuckDB")
        return self.function_fallback_sql(expression)

    def decompressbinary_sql(self, expression: exp.DecompressBinary) -> str:
        self.unsupported("DECOMPRESS_BINARY is not supported in DuckDB")
        return self.function_fallback_sql(expression)

    def jarowinklersimilarity_sql(self, expression: exp.JarowinklerSimilarity) -> str:
        this = expression.this
        expr = expression.expression

        if expression.args.get("case_insensitive"):
            this = exp.Upper(this=this)
            expr = exp.Upper(this=expr)

        result = exp.func("JARO_WINKLER_SIMILARITY", this, expr)

        if expression.args.get("integer_scale"):
            result = exp.cast(result * 100, "INTEGER")

        return self.sql(result)

    def nthvalue_sql(self, expression: exp.NthValue) -> str:
        from_first = expression.args.get("from_first", True)
        if not from_first:
            self.unsupported("DuckDB's NTH_VALUE doesn't support starting from the end ")

        return self.function_fallback_sql(expression)

    def randstr_sql(self, expression: exp.Randstr) -> str:
        """
        Transpile Snowflake's RANDSTR to DuckDB equivalent using deterministic hash-based random.
        Uses a pre-parsed template with placeholders replaced by expression nodes.

        RANDSTR(length, generator) generates a random string of specified length.
        - With numeric seed: Use HASH(i + seed) for deterministic output (same seed = same result)
        - With RANDOM(): Use RANDOM() in the hash for non-deterministic output
        - No generator: Use default seed value
        """
        length = expression.this
        generator = expression.args.get("generator")

        if generator:
            if isinstance(generator, exp.Rand):
                # If it's RANDOM(), use its seed if available, otherwise use RANDOM() itself
                seed_value = generator.this or generator
            else:
                # Const/int or other expression - use as seed directly
                seed_value = generator
        else:
            # No generator specified, use default seed (arbitrary but deterministic)
            seed_value = exp.Literal.number(RANDSTR_SEED)

        replacements = {"seed": seed_value, "length": length}
        return f"({self.sql(exp.replace_placeholders(self.RANDSTR_TEMPLATE, **replacements))})"

    @unsupported_args("finish")
    def reduce_sql(self, expression: exp.Reduce) -> str:
        array_arg = expression.this
        initial_value = expression.args.get("initial")
        merge_lambda = expression.args.get("merge")

        if merge_lambda:
            merge_lambda.set("colon", True)

        return self.func("list_reduce", array_arg, merge_lambda, initial_value)

    def zipf_sql(self, expression: exp.Zipf) -> str:
        """
        Transpile Snowflake's ZIPF to DuckDB using CDF-based inverse sampling.
        Uses a pre-parsed template with placeholders replaced by expression nodes.
        """
        s = expression.this
        n = expression.args["elementcount"]
        gen = expression.args["gen"]

        if not isinstance(gen, exp.Rand):
            # (ABS(HASH(seed)) % 1000000) / 1000000.0
            random_expr: exp.Expr = exp.Div(
                this=exp.Paren(
                    this=exp.Mod(
                        this=exp.Abs(this=exp.Anonymous(this="HASH", expressions=[gen.copy()])),
                        expression=exp.Literal.number(1000000),
                    )
                ),
                expression=exp.Literal.number(1000000.0),
            )
        else:
            # Use RANDOM() for non-deterministic output
            random_expr = exp.Rand()

        replacements = {"s": s, "n": n, "random_expr": random_expr}
        return f"({self.sql(exp.replace_placeholders(self.ZIPF_TEMPLATE, **replacements))})"

    def tobinary_sql(self, expression: exp.ToBinary) -> str:
        """
        TO_BINARY and TRY_TO_BINARY transpilation:
        - 'HEX': TO_BINARY('48454C50', 'HEX') -> UNHEX('48454C50')
        - 'UTF-8': TO_BINARY('TEST', 'UTF-8') -> ENCODE('TEST')
        - 'BASE64': TO_BINARY('SEVMUA==', 'BASE64') -> FROM_BASE64('SEVMUA==')

        For TRY_TO_BINARY (safe=True), wrap with TRY():
        - 'HEX': TRY_TO_BINARY('invalid', 'HEX') -> TRY(UNHEX('invalid'))
        """
        value = expression.this
        format_arg = expression.args.get("format")
        is_safe = expression.args.get("safe")
        is_binary = _is_binary(expression)

        if not format_arg and not is_binary:
            func_name = "TRY_TO_BINARY" if is_safe else "TO_BINARY"
            return self.func(func_name, value)

        # Snowflake defaults to HEX encoding when no format is specified
        fmt = format_arg.name.upper() if format_arg else "HEX"

        if fmt in ("UTF-8", "UTF8"):
            # DuckDB ENCODE always uses UTF-8, no charset parameter needed
            result = self.func("ENCODE", value)
        elif fmt == "BASE64":
            result = self.func("FROM_BASE64", value)
        elif fmt == "HEX":
            result = self.func("UNHEX", value)
        else:
            if is_safe:
                return self.sql(exp.null())
            else:
                self.unsupported(f"format {fmt} is not supported")
                result = self.func("TO_BINARY", value)
        return f"TRY({result})" if is_safe else result

    def tonumber_sql(self, expression: exp.ToNumber) -> str:
        fmt = expression.args.get("format")
        precision = expression.args.get("precision")
        scale = expression.args.get("scale")

        if not fmt and precision and scale:
            return self.sql(
                exp.cast(
                    expression.this, f"DECIMAL({precision.name}, {scale.name})", dialect="duckdb"
                )
            )

        return super().tonumber_sql(expression)

    def _greatest_least_sql(self, expression: exp.Greatest | exp.Least) -> str:
        """
        Handle GREATEST/LEAST functions with dialect-aware NULL behavior.

        - If ignore_nulls=False (BigQuery-style): return NULL if any argument is NULL
        - If ignore_nulls=True (DuckDB/PostgreSQL-style): ignore NULLs, return greatest/least non-NULL value
        """
        # Get all arguments
        all_args = [expression.this, *expression.expressions]
        fallback_sql = self.function_fallback_sql(expression)

        if expression.args.get("ignore_nulls"):
            # DuckDB/PostgreSQL behavior: use native GREATEST/LEAST (ignores NULLs)
            return self.sql(fallback_sql)

        # return NULL if any argument is NULL
        case_expr = exp.case().when(
            exp.or_(*[arg.is_(exp.null()) for arg in all_args], copy=False),
            exp.null(),
            copy=False,
        )
        case_expr.set("default", fallback_sql)
        return self.sql(case_expr)

    def generator_sql(self, expression: exp.Generator) -> str:
        # Transpile Snowflake GENERATOR to DuckDB range()
        rowcount = expression.args.get("rowcount")
        time_limit = expression.args.get("time_limit")

        if time_limit:
            self.unsupported("GENERATOR TIMELIMIT parameter is not supported in DuckDB")

        if not rowcount:
            self.unsupported("GENERATOR without ROWCOUNT is not supported in DuckDB")
            return self.func("range", exp.Literal.number(0))

        return self.func("range", rowcount)

    def greatest_sql(self, expression: exp.Greatest) -> str:
        return self._greatest_least_sql(expression)

    def least_sql(self, expression: exp.Least) -> str:
        return self._greatest_least_sql(expression)

    def lambda_sql(self, expression: exp.Lambda, arrow_sep: str = "->", wrap: bool = True) -> str:
        if expression.args.get("colon"):
            prefix = "LAMBDA "
            arrow_sep = ":"
            wrap = False
        else:
            prefix = ""

        lambda_sql = super().lambda_sql(expression, arrow_sep=arrow_sep, wrap=wrap)
        return f"{prefix}{lambda_sql}"

    def show_sql(self, expression: exp.Show) -> str:
        from_ = self.sql(expression, "from_")
        from_ = f" FROM {from_}" if from_ else ""
        return f"SHOW {expression.name}{from_}"

    def soundex_sql(self, expression: exp.Soundex) -> str:
        self.unsupported("SOUNDEX is not supported in DuckDB")
        return self.func("SOUNDEX", expression.this)

    def sortarray_sql(self, expression: exp.SortArray) -> str:
        arr = expression.this
        asc = expression.args.get("asc")
        nulls_first = expression.args.get("nulls_first")

        if not isinstance(asc, exp.Boolean) and not isinstance(nulls_first, exp.Boolean):
            return self.func("LIST_SORT", arr, asc, nulls_first)

        nulls_are_first = nulls_first == exp.true()
        nulls_first_sql = exp.Literal.string("NULLS FIRST") if nulls_are_first else None

        if not isinstance(asc, exp.Boolean):
            return self.func("LIST_SORT", arr, asc, nulls_first_sql)

        descending = asc == exp.false()

        if not descending and not nulls_are_first:
            return self.func("LIST_SORT", arr)
        if not nulls_are_first:
            return self.func("ARRAY_REVERSE_SORT", arr)
        return self.func(
            "LIST_SORT",
            arr,
            exp.Literal.string("DESC" if descending else "ASC"),
            exp.Literal.string("NULLS FIRST"),
        )

    def install_sql(self, expression: exp.Install) -> str:
        force = "FORCE " if expression.args.get("force") else ""
        this = self.sql(expression, "this")
        from_clause = expression.args.get("from_")
        from_clause = f" FROM {from_clause}" if from_clause else ""
        return f"{force}INSTALL {this}{from_clause}"

    def approxtopk_sql(self, expression: exp.ApproxTopK) -> str:
        self.unsupported(
            "APPROX_TOP_K cannot be transpiled to DuckDB due to incompatible return types. "
        )
        return self.function_fallback_sql(expression)

    def fromiso8601timestamp_sql(self, expression: exp.FromISO8601Timestamp) -> str:
        return self.sql(exp.cast(expression.this, exp.DType.TIMESTAMPTZ))

    def strposition_sql(self, expression: exp.StrPosition) -> str:
        this = expression.this
        substr = expression.args.get("substr")
        position = expression.args.get("position")

        # For BINARY/BLOB: DuckDB's STRPOS doesn't support BLOB types
        # Convert to HEX strings, use STRPOS, then convert hex position to byte position
        if _is_binary(this):
            # Build expression: STRPOS(HEX(haystack), HEX(needle))
            hex_strpos = exp.StrPosition(
                this=exp.Hex(this=this),
                substr=exp.Hex(this=substr),
            )

            return self.sql(exp.cast((hex_strpos + 1) / 2, exp.DType.INT))

        # For VARCHAR: handle clamp_position
        if expression.args.get("clamp_position") and position:
            expression = expression.copy()
            expression.set(
                "position",
                exp.If(
                    this=exp.LTE(this=position, expression=exp.Literal.number(0)),
                    true=exp.Literal.number(1),
                    false=position.copy(),
                ),
            )

        return strposition_sql(self, expression)

    def substring_sql(self, expression: exp.Substring) -> str:
        if expression.args.get("zero_start"):
            start = expression.args.get("start")
            length = expression.args.get("length")

            if start := expression.args.get("start"):
                start = exp.If(this=start.eq(0), true=exp.Literal.number(1), false=start)
            if length := expression.args.get("length"):
                length = exp.If(this=length < 0, true=exp.Literal.number(0), false=length)

            return self.func("SUBSTRING", expression.this, start, length)

        return self.function_fallback_sql(expression)

    def strtotime_sql(self, expression: exp.StrToTime) -> str:
        # Check if target_type requires TIMESTAMPTZ (for LTZ/TZ variants)
        target_type = expression.args.get("target_type")
        needs_tz = target_type and target_type.this in (
            exp.DType.TIMESTAMPLTZ,
            exp.DType.TIMESTAMPTZ,
        )

        if expression.args.get("safe"):
            formatted_time = self.format_time(expression)
            cast_type = exp.DType.TIMESTAMPTZ if needs_tz else exp.DType.TIMESTAMP
            return self.sql(
                exp.cast(self.func("TRY_STRPTIME", expression.this, formatted_time), cast_type)
            )

        base_sql = str_to_time_sql(self, expression)
        if needs_tz:
            return self.sql(
                exp.cast(
                    base_sql,
                    exp.DataType(this=exp.DType.TIMESTAMPTZ),
                )
            )
        return base_sql

    def strtodate_sql(self, expression: exp.StrToDate) -> str:
        formatted_time = self.format_time(expression)
        function_name = "STRPTIME" if not expression.args.get("safe") else "TRY_STRPTIME"
        return self.sql(
            exp.cast(
                self.func(function_name, expression.this, formatted_time),
                exp.DataType(this=exp.DType.DATE),
            )
        )

    def tsordstotime_sql(self, expression: exp.TsOrDsToTime) -> str:
        this = expression.this
        time_format = self.format_time(expression)
        safe = expression.args.get("safe")
        time_type = exp.DataType.from_str("TIME", dialect="duckdb")
        cast_expr = exp.TryCast if safe else exp.Cast

        if time_format:
            func_name = "TRY_STRPTIME" if safe else "STRPTIME"
            strptime = exp.Anonymous(this=func_name, expressions=[this, time_format])
            return self.sql(cast_expr(this=strptime, to=time_type))

        if isinstance(this, exp.TsOrDsToTime) or this.is_type(exp.DType.TIME):
            return self.sql(this)

        return self.sql(cast_expr(this=this, to=time_type))

    def currentdate_sql(self, expression: exp.CurrentDate) -> str:
        if not expression.this:
            return "CURRENT_DATE"

        expr = exp.Cast(
            this=exp.AtTimeZone(this=exp.CurrentTimestamp(), zone=expression.this),
            to=exp.DataType(this=exp.DType.DATE),
        )
        return self.sql(expr)

    def checkjson_sql(self, expression: exp.CheckJson) -> str:
        arg = expression.this
        return self.sql(
            exp.case()
            .when(
                exp.or_(arg.is_(exp.Null()), arg.eq(""), exp.func("json_valid", arg)),
                exp.null(),
            )
            .else_(exp.Literal.string("Invalid JSON"))
        )

    def parsejson_sql(self, expression: exp.ParseJSON) -> str:
        arg = expression.this
        if expression.args.get("safe"):
            return self.sql(
                exp.case()
                .when(exp.func("json_valid", arg), exp.cast(arg.copy(), "JSON"))
                .else_(exp.null())
            )
        return self.func("JSON", arg)

    def unicode_sql(self, expression: exp.Unicode) -> str:
        if expression.args.get("empty_is_zero"):
            return self.sql(
                exp.case()
                .when(expression.this.eq(exp.Literal.string("")), exp.Literal.number(0))
                .else_(exp.Anonymous(this="UNICODE", expressions=[expression.this]))
            )

        return self.func("UNICODE", expression.this)

    def stripnullvalue_sql(self, expression: exp.StripNullValue) -> str:
        return self.sql(
            exp.case()
            .when(exp.func("json_type", expression.this).eq("NULL"), exp.null())
            .else_(expression.this)
        )

    def trunc_sql(self, expression: exp.Trunc) -> str:
        decimals = expression.args.get("decimals")
        if (
            expression.args.get("fractions_supported")
            and decimals
            and not decimals.is_type(exp.DType.INT)
        ):
            decimals = exp.cast(decimals, exp.DType.INT, dialect="duckdb")

        return self.func("TRUNC", expression.this, decimals)

    def normal_sql(self, expression: exp.Normal) -> str:
        """
        Transpile Snowflake's NORMAL(mean, stddev, gen) to DuckDB.

        Uses the Box-Muller transform via NORMAL_TEMPLATE.
        """
        mean = expression.this
        stddev = expression.args["stddev"]
        gen: exp.Expr = expression.args["gen"]

        # Build two uniform random values [0, 1) for Box-Muller transform
        if isinstance(gen, exp.Rand) and gen.this is None:
            u1: exp.Expr = exp.Rand()
            u2: exp.Expr = exp.Rand()
        else:
            # Seeded: derive two values using HASH with different inputs
            seed = gen.this if isinstance(gen, exp.Rand) else gen
            u1 = exp.replace_placeholders(self.SEEDED_RANDOM_TEMPLATE, seed=seed)
            u2 = exp.replace_placeholders(
                self.SEEDED_RANDOM_TEMPLATE,
                seed=exp.Add(this=seed.copy(), expression=exp.Literal.number(1)),
            )

        replacements = {"mean": mean, "stddev": stddev, "u1": u1, "u2": u2}
        return self.sql(exp.replace_placeholders(self.NORMAL_TEMPLATE, **replacements))

    def uniform_sql(self, expression: exp.Uniform) -> str:
        """
        Transpile Snowflake's UNIFORM(min, max, gen) to DuckDB.

        UNIFORM returns a random value in [min, max]:
        - Integer result if both min and max are integers
        - Float result if either min or max is a float
        """
        min_val = expression.this
        max_val = expression.expression
        gen = expression.args.get("gen")

        # Determine if result should be integer (both bounds are integers).
        # We do this to emulate Snowflake's behavior, INT -> INT, FLOAT -> FLOAT
        is_int_result = min_val.is_int and max_val.is_int

        # Build the random value expression [0, 1)
        if not isinstance(gen, exp.Rand):
            # Seed value: (ABS(HASH(seed)) % 1000000) / 1000000.0
            random_expr: exp.Expr = exp.Div(
                this=exp.Paren(
                    this=exp.Mod(
                        this=exp.Abs(this=exp.Anonymous(this="HASH", expressions=[gen])),
                        expression=exp.Literal.number(1000000),
                    )
                ),
                expression=exp.Literal.number(1000000.0),
            )
        else:
            random_expr = exp.Rand()

        # Build: min + random * (max - min [+ 1 for int])
        range_expr: exp.Expr = exp.Sub(this=max_val, expression=min_val)
        if is_int_result:
            range_expr = exp.Add(this=range_expr, expression=exp.Literal.number(1))

        result: exp.Expr = exp.Add(
            this=min_val,
            expression=exp.Mul(this=random_expr, expression=exp.Paren(this=range_expr)),
        )

        if is_int_result:
            result = exp.Cast(this=exp.Floor(this=result), to=exp.DType.BIGINT.into_expr())

        return self.sql(result)

    def timefromparts_sql(self, expression: exp.TimeFromParts) -> str:
        nano = expression.args.get("nano")
        overflow = expression.args.get("overflow")

        # Snowflake's TIME_FROM_PARTS supports overflow
        if overflow:
            hour = expression.args["hour"]
            minute = expression.args["min"]
            sec = expression.args["sec"]

            # Check if values are within normal ranges - use MAKE_TIME for efficiency
            if not nano and all(arg.is_int for arg in [hour, minute, sec]):
                try:
                    h_val = hour.to_py()
                    m_val = minute.to_py()
                    s_val = sec.to_py()
                    if 0 <= h_val <= 23 and 0 <= m_val <= 59 and 0 <= s_val <= 59:
                        return rename_func("MAKE_TIME")(self, expression)
                except ValueError:
                    pass

            # Overflow or nanoseconds detected - use INTERVAL arithmetic
            if nano:
                sec = sec + nano.pop() / exp.Literal.number(1000000000.0)

            total_seconds = hour * exp.Literal.number(3600) + minute * exp.Literal.number(60) + sec

            return self.sql(
                exp.Add(
                    this=exp.Cast(
                        this=exp.Literal.string("00:00:00"), to=exp.DType.TIME.into_expr()
                    ),
                    expression=exp.Interval(this=total_seconds, unit=exp.var("SECOND")),
                )
            )

        # Default: MAKE_TIME
        if nano:
            expression.set(
                "sec", expression.args["sec"] + nano.pop() / exp.Literal.number(1000000000.0)
            )

        return rename_func("MAKE_TIME")(self, expression)

    def extract_sql(self, expression: exp.Extract) -> str:
        """
        Transpile EXTRACT/DATE_PART for DuckDB, handling specifiers not natively supported.

        DuckDB doesn't support: WEEKISO, YEAROFWEEK, YEAROFWEEKISO, NANOSECOND,
        EPOCH_SECOND (as integer), EPOCH_MILLISECOND, EPOCH_MICROSECOND, EPOCH_NANOSECOND
        """
        this = expression.this
        datetime_expr = expression.expression

        # TIMESTAMPTZ extractions may produce different results between Snowflake and DuckDB
        # because Snowflake applies server timezone while DuckDB uses local timezone
        if datetime_expr.is_type(exp.DType.TIMESTAMPTZ, exp.DType.TIMESTAMPLTZ):
            self.unsupported(
                "EXTRACT from TIMESTAMPTZ / TIMESTAMPLTZ may produce different results due to timezone handling differences"
            )

        part_name = this.name.upper()

        if part_name in self.EXTRACT_STRFTIME_MAPPINGS:
            fmt, cast_type = self.EXTRACT_STRFTIME_MAPPINGS[part_name]

            # Problem: strftime doesn't accept TIME and there's no NANOSECOND function
            # So, for NANOSECOND with TIME, fallback to MICROSECOND * 1000
            is_nano_time = part_name == "NANOSECOND" and datetime_expr.is_type(
                exp.DType.TIME, exp.DType.TIMETZ
            )

            if is_nano_time:
                self.unsupported("Parameter NANOSECOND is not supported with TIME type in DuckDB")
                return self.sql(
                    exp.cast(
                        exp.Mul(
                            this=exp.Extract(this=exp.var("MICROSECOND"), expression=datetime_expr),
                            expression=exp.Literal.number(1000),
                        ),
                        exp.DataType.from_str(cast_type, dialect="duckdb"),
                    )
                )

            # For NANOSECOND, cast to TIMESTAMP_NS to preserve nanosecond precision
            strftime_input = datetime_expr
            if part_name == "NANOSECOND":
                strftime_input = exp.cast(datetime_expr, exp.DType.TIMESTAMP_NS)

            return self.sql(
                exp.cast(
                    exp.Anonymous(
                        this="STRFTIME",
                        expressions=[strftime_input, exp.Literal.string(fmt)],
                    ),
                    exp.DataType.from_str(cast_type, dialect="duckdb"),
                )
            )

        if part_name in self.EXTRACT_EPOCH_MAPPINGS:
            func_name = self.EXTRACT_EPOCH_MAPPINGS[part_name]
            result: exp.Expr = exp.Anonymous(this=func_name, expressions=[datetime_expr])
            # EPOCH returns float, cast to BIGINT for integer result
            if part_name == "EPOCH_SECOND":
                result = exp.cast(result, exp.DataType.from_str("BIGINT", dialect="duckdb"))
            return self.sql(result)

        return super().extract_sql(expression)

    def timestampfromparts_sql(self, expression: exp.TimestampFromParts) -> str:
        # Check if this is the date/time expression form: TIMESTAMP_FROM_PARTS(date_expr, time_expr)
        date_expr = expression.this
        time_expr = expression.expression

        if date_expr is not None and time_expr is not None:
            # In DuckDB, DATE + TIME produces TIMESTAMP
            return self.sql(exp.Add(this=date_expr, expression=time_expr))

        # Component-based form: TIMESTAMP_FROM_PARTS(year, month, day, hour, minute, second, ...)
        sec = expression.args.get("sec")
        if sec is None:
            # This shouldn't happen with valid input, but handle gracefully
            return rename_func("MAKE_TIMESTAMP")(self, expression)

        milli = expression.args.get("milli")
        if milli is not None:
            sec += milli.pop() / exp.Literal.number(1000.0)

        nano = expression.args.get("nano")
        if nano is not None:
            sec += nano.pop() / exp.Literal.number(1000000000.0)

        if milli or nano:
            expression.set("sec", sec)

        return rename_func("MAKE_TIMESTAMP")(self, expression)

    @unsupported_args("nano")
    def timestampltzfromparts_sql(self, expression: exp.TimestampLtzFromParts) -> str:
        # Pop nano so rename_func only passes args that MAKE_TIMESTAMP accepts
        if nano := expression.args.get("nano"):
            nano.pop()

        timestamp = rename_func("MAKE_TIMESTAMP")(self, expression)
        return f"CAST({timestamp} AS TIMESTAMPTZ)"

    @unsupported_args("nano")
    def timestamptzfromparts_sql(self, expression: exp.TimestampTzFromParts) -> str:
        # Extract zone before popping
        zone = expression.args.get("zone")
        # Pop zone and nano so rename_func only passes args that MAKE_TIMESTAMP accepts
        if zone:
            zone = zone.pop()

        if nano := expression.args.get("nano"):
            nano.pop()

        timestamp = rename_func("MAKE_TIMESTAMP")(self, expression)

        if zone:
            # Use AT TIME ZONE to apply the explicit timezone
            return f"{timestamp} AT TIME ZONE {self.sql(zone)}"

        return timestamp

    def tablesample_sql(
        self,
        expression: exp.TableSample,
        tablesample_keyword: str | None = None,
    ) -> str:
        if not isinstance(expression.parent, exp.Select):
            # This sample clause only applies to a single source, not the entire resulting relation
            tablesample_keyword = "TABLESAMPLE"

        if expression.args.get("size"):
            method = expression.args.get("method")
            if method and method.name.upper() != "RESERVOIR":
                self.unsupported(
                    f"Sampling method {method} is not supported with a discrete sample count, "
                    "defaulting to reservoir sampling"
                )
                expression.set("method", exp.var("RESERVOIR"))

        return super().tablesample_sql(expression, tablesample_keyword=tablesample_keyword)

    def join_sql(self, expression: exp.Join) -> str:
        if (
            not expression.args.get("using")
            and not expression.args.get("on")
            and not expression.method
            and (expression.kind in ("", "INNER", "OUTER"))
        ):
            # Some dialects support `LEFT/INNER JOIN UNNEST(...)` without an explicit ON clause
            # DuckDB doesn't, but we can just add a dummy ON clause that is always true
            if isinstance(expression.this, exp.Unnest):
                return super().join_sql(expression.on(exp.true()))

            expression.set("side", None)
            expression.set("kind", None)

        return super().join_sql(expression)

    def countif_sql(self, expression: exp.CountIf) -> str:
        if self.dialect.version >= (1, 2):
            return self.function_fallback_sql(expression)

        # https://github.com/tobymao/sqlglot/pull/4749
        return count_if_to_sum(self, expression)

    def bracket_sql(self, expression: exp.Bracket) -> str:
        if self.dialect.version >= (1, 2):
            return super().bracket_sql(expression)

        # https://duckdb.org/2025/02/05/announcing-duckdb-120.html#breaking-changes
        this = expression.this
        if isinstance(this, exp.Array):
            this.replace(exp.paren(this))

        bracket = super().bracket_sql(expression)

        if not expression.args.get("returns_list_for_maps"):
            if not this.type:
                from sqlglot.optimizer.annotate_types import annotate_types

                this = annotate_types(this, dialect=self.dialect)

            if this.is_type(exp.DType.MAP):
                bracket = f"({bracket})[1]"

        return bracket

    def withingroup_sql(self, expression: exp.WithinGroup) -> str:
        func = expression.this

        # For ARRAY_AGG, DuckDB requires ORDER BY inside the function, not in WITHIN GROUP
        # Transform: ARRAY_AGG(x) WITHIN GROUP (ORDER BY y) -> ARRAY_AGG(x ORDER BY y)
        if isinstance(func, exp.ArrayAgg):
            if not isinstance(order := expression.expression, exp.Order):
                return self.sql(func)

            # Save the original column for FILTER clause (before wrapping with Order)
            original_this = func.this

            # Move ORDER BY inside ARRAY_AGG by wrapping its argument with Order
            # ArrayAgg.this should become Order(this=ArrayAgg.this, expressions=order.expressions)
            func.set(
                "this",
                exp.Order(
                    this=func.this.copy(),
                    expressions=order.expressions,
                ),
            )

            # Generate the ARRAY_AGG function with ORDER BY and add FILTER clause if needed
            # Use original_this (not the Order-wrapped version) for the FILTER condition
            array_agg_sql = self.function_fallback_sql(func)
            return self._add_arrayagg_null_filter(array_agg_sql, func, original_this)

        # For other functions (like PERCENTILES), use existing logic
        expression_sql = self.sql(expression, "expression")

        if isinstance(func, exp.PERCENTILES):
            # Make the order key the first arg and slide the fraction to the right
            # https://duckdb.org/docs/sql/aggregates#ordered-set-aggregate-functions
            order_col = expression.find(exp.Ordered)
            if order_col:
                func.set("expression", func.this)
                func.set("this", order_col.this)

        this = self.sql(expression, "this").rstrip(")")

        return f"{this}{expression_sql})"

    def length_sql(self, expression: exp.Length) -> str:
        arg = expression.this

        # Dialects like BQ and Snowflake also accept binary values as args, so
        # DDB will attempt to infer the type or resort to case/when resolution
        if not expression.args.get("binary") or arg.is_string:
            return self.func("LENGTH", arg)

        if not arg.type:
            from sqlglot.optimizer.annotate_types import annotate_types

            arg = annotate_types(arg, dialect=self.dialect)

        if arg.is_type(*exp.DataType.TEXT_TYPES):
            return self.func("LENGTH", arg)

        # We need these casts to make duckdb's static type checker happy
        blob = exp.cast(arg, exp.DType.VARBINARY)
        varchar = exp.cast(arg, exp.DType.VARCHAR)

        case = (
            exp.case(exp.Anonymous(this="TYPEOF", expressions=[arg]))
            .when(exp.Literal.string("BLOB"), exp.ByteLength(this=blob))
            .else_(exp.Anonymous(this="LENGTH", expressions=[varchar]))
        )
        return self.sql(case)

    def bitlength_sql(self, expression: exp.BitLength) -> str:
        if not _is_binary(arg := expression.this):
            return self.func("BIT_LENGTH", arg)

        blob = exp.cast(arg, exp.DataType.Type.VARBINARY)
        return self.sql(exp.ByteLength(this=blob) * exp.Literal.number(8))

    def chr_sql(self, expression: exp.Chr, name: str = "CHR") -> str:
        arg = expression.expressions[0]
        if arg.is_type(*exp.DataType.REAL_TYPES):
            arg = exp.cast(arg, exp.DType.INT)
        return self.func("CHR", arg)

    def collation_sql(self, expression: exp.Collation) -> str:
        self.unsupported("COLLATION function is not supported by DuckDB")
        return self.function_fallback_sql(expression)

    def collate_sql(self, expression: exp.Collate) -> str:
        if not expression.expression.is_string:
            return super().collate_sql(expression)

        raw = expression.expression.name
        if not raw:
            return self.sql(expression.this)

        parts = []
        for part in raw.split("-"):
            lower = part.lower()
            if lower not in _SNOWFLAKE_COLLATION_DEFAULTS:
                if lower in _SNOWFLAKE_COLLATION_UNSUPPORTED:
                    self.unsupported(
                        f"Snowflake collation specifier '{part}' has no DuckDB equivalent"
                    )
                parts.append(lower)

        if not parts:
            return self.sql(expression.this)
        return super().collate_sql(
            exp.Collate(this=expression.this, expression=exp.var(".".join(parts)))
        )

    def _validate_regexp_flags(self, flags: exp.Expr | None, supported_flags: str) -> str | None:
        """
        Validate and filter regexp flags for DuckDB compatibility.

        Args:
            flags: The flags expression to validate
            supported_flags: String of supported flags (e.g., "ims", "cims").
                            Only these flags will be returned.

        Returns:
            Validated/filtered flag string, or None if no valid flags remain
        """
        if not isinstance(flags, exp.Expr):
            return None

        if not flags.is_string:
            self.unsupported("Non-literal regexp flags are not fully supported in DuckDB")
            return None

        flag_str = flags.this
        unsupported = set(flag_str) - set(supported_flags)

        if unsupported:
            self.unsupported(
                f"Regexp flags {sorted(unsupported)} are not supported in this context"
            )

        flag_str = "".join(f for f in flag_str if f in supported_flags)
        return flag_str if flag_str else None

    def regexpcount_sql(self, expression: exp.RegexpCount) -> str:
        this = expression.this
        pattern = expression.expression
        position = expression.args.get("position")
        parameters = expression.args.get("parameters")

        # Validate flags - only "ims" flags are supported for embedded patterns
        validated_flags = self._validate_regexp_flags(parameters, supported_flags="ims")

        if position:
            this = exp.Substring(this=this, start=position)

        # Embed flags in pattern (REGEXP_EXTRACT_ALL doesn't support flags argument)
        if validated_flags:
            pattern = exp.Concat(expressions=[exp.Literal.string(f"(?{validated_flags})"), pattern])

        # Handle empty pattern: Snowflake returns 0, DuckDB would match between every character
        result = (
            exp.case()
            .when(
                exp.EQ(this=pattern, expression=exp.Literal.string("")),
                exp.Literal.number(0),
            )
            .else_(
                exp.Length(
                    this=exp.Anonymous(this="REGEXP_EXTRACT_ALL", expressions=[this, pattern])
                )
            )
        )

        return self.sql(result)

    def regexpreplace_sql(self, expression: exp.RegexpReplace) -> str:
        subject = expression.this
        pattern = expression.expression
        replacement = expression.args.get("replacement") or exp.Literal.string("")
        position = expression.args.get("position")
        occurrence = expression.args.get("occurrence")
        modifiers = expression.args.get("modifiers")

        validated_flags = self._validate_regexp_flags(modifiers, supported_flags="cimsg") or ""

        # Handle occurrence (only literals supported)
        if occurrence and not occurrence.is_int:
            self.unsupported("REGEXP_REPLACE with non-literal occurrence")
        else:
            occurrence = occurrence.to_py() if occurrence and occurrence.is_int else 0
            if occurrence > 1:
                self.unsupported(f"REGEXP_REPLACE occurrence={occurrence} not supported")
            # flag duckdb to do either all or none, single_replace check is for duckdb round trip
            elif (
                occurrence == 0
                and "g" not in validated_flags
                and not expression.args.get("single_replace")
            ):
                validated_flags += "g"

        # Handle position (only literals supported)
        prefix = None
        if position and not position.is_int:
            self.unsupported("REGEXP_REPLACE with non-literal position")
        elif position and position.is_int and position.to_py() > 1:
            pos = position.to_py()
            prefix = exp.Substring(
                this=subject, start=exp.Literal.number(1), length=exp.Literal.number(pos - 1)
            )
            subject = exp.Substring(this=subject, start=exp.Literal.number(pos))

        result: exp.Expr = exp.Anonymous(
            this="REGEXP_REPLACE",
            expressions=[
                subject,
                pattern,
                replacement,
                exp.Literal.string(validated_flags) if validated_flags else None,
            ],
        )

        if prefix:
            result = exp.Concat(expressions=[prefix, result])

        return self.sql(result)

    def regexplike_sql(self, expression: exp.RegexpLike) -> str:
        this = expression.this
        pattern = expression.expression
        flag = expression.args.get("flag")

        if expression.args.get("full_match"):
            validated_flags = self._validate_regexp_flags(flag, supported_flags="cims")
            flag = exp.Literal.string(validated_flags) if validated_flags else None
            return self.func("REGEXP_FULL_MATCH", this, pattern, flag)

        return self.func("REGEXP_MATCHES", this, pattern, flag)

    @unsupported_args("ins_cost", "del_cost", "sub_cost")
    def levenshtein_sql(self, expression: exp.Levenshtein) -> str:
        this = expression.this
        expr = expression.expression
        max_dist = expression.args.get("max_dist")

        if max_dist is None:
            return self.func("LEVENSHTEIN", this, expr)

        # Emulate Snowflake semantics: if distance > max_dist, return max_dist
        levenshtein = exp.Levenshtein(this=this, expression=expr)
        return self.sql(exp.Least(this=levenshtein, expressions=[max_dist]))

    def pad_sql(self, expression: exp.Pad) -> str:
        """
        Handle RPAD/LPAD for VARCHAR and BINARY types.

        For VARCHAR: Delegate to parent class
        For BINARY: Lower to: input || REPEAT(pad, GREATEST(0, target_len - OCTET_LENGTH(input)))
        """
        string_arg = expression.this
        fill_arg = expression.args.get("fill_pattern") or exp.Literal.string(" ")

        if _is_binary(string_arg) or _is_binary(fill_arg):
            length_arg = expression.expression
            is_left = expression.args.get("is_left")

            input_len = exp.ByteLength(this=string_arg)
            chars_needed = length_arg - input_len
            pad_count = exp.Greatest(
                this=exp.Literal.number(0), expressions=[chars_needed], ignore_nulls=True
            )
            repeat_expr = exp.Repeat(this=fill_arg, times=pad_count)

            left, right = string_arg, repeat_expr
            if is_left:
                left, right = right, left

            result = exp.DPipe(this=left, expression=right)
            return self.sql(result)

        # For VARCHAR: Delegate to parent class (handles PAD_FILL_PATTERN_IS_REQUIRED)
        return super().pad_sql(expression)

    def minhash_sql(self, expression: exp.Minhash) -> str:
        k = expression.this
        exprs = expression.expressions

        if len(exprs) != 1 or isinstance(exprs[0], exp.Star):
            self.unsupported(
                "MINHASH with multiple expressions or * requires manual query restructuring"
            )
            return self.func("MINHASH", k, *exprs)

        expr = exprs[0]
        result = exp.replace_placeholders(self.MINHASH_TEMPLATE.copy(), expr=expr, k=k)
        return f"({self.sql(result)})"

    def minhashcombine_sql(self, expression: exp.MinhashCombine) -> str:
        expr = expression.this
        result = exp.replace_placeholders(self.MINHASH_COMBINE_TEMPLATE.copy(), expr=expr)
        return f"({self.sql(result)})"

    def approximatesimilarity_sql(self, expression: exp.ApproximateSimilarity) -> str:
        expr = expression.this
        result = exp.replace_placeholders(self.APPROXIMATE_SIMILARITY_TEMPLATE.copy(), expr=expr)
        return f"({self.sql(result)})"

    def arrayuniqueagg_sql(self, expression: exp.ArrayUniqueAgg) -> str:
        return self.sql(
            exp.Filter(
                this=exp.func("LIST", exp.Distinct(expressions=[expression.this])),
                expression=exp.Where(this=expression.this.copy().is_(exp.null()).not_()),
            )
        )

    def arrayunionagg_sql(self, expression: exp.ArrayUnionAgg) -> str:
        self.unsupported("ARRAY_UNION_AGG is not supported in DuckDB")
        return self.function_fallback_sql(expression)

    def arraydistinct_sql(self, expression: exp.ArrayDistinct) -> str:
        arr = expression.this
        func = self.func("LIST_DISTINCT", arr)

        if expression.args.get("check_null"):
            add_null_to_array = exp.func(
                "LIST_APPEND", exp.func("LIST_DISTINCT", exp.ArrayCompact(this=arr)), exp.Null()
            )
            return self.sql(
                exp.If(
                    this=exp.NEQ(
                        this=exp.ArraySize(this=arr), expression=exp.func("LIST_COUNT", arr)
                    ),
                    true=add_null_to_array,
                    false=func,
                )
            )

        return func

    def arrayintersect_sql(self, expression: exp.ArrayIntersect) -> str:
        if expression.args.get("is_multiset") and len(expression.expressions) == 2:
            return self._array_bag_sql(
                self.ARRAY_INTERSECTION_CONDITION,
                expression.expressions[0],
                expression.expressions[1],
            )
        return self.function_fallback_sql(expression)

    def arrayexcept_sql(self, expression: exp.ArrayExcept) -> str:
        arr1, arr2 = expression.this, expression.expression
        if expression.args.get("is_multiset"):
            return self._array_bag_sql(self.ARRAY_EXCEPT_CONDITION, arr1, arr2)
        return self.sql(
            exp.replace_placeholders(self.ARRAY_EXCEPT_SET_TEMPLATE, arr1=arr1, arr2=arr2)
        )

    def arrayslice_sql(self, expression: exp.ArraySlice) -> str:
        """
        Transpiles Snowflake's ARRAY_SLICE (0-indexed, exclusive end) to DuckDB's
        ARRAY_SLICE (1-indexed, inclusive end) by wrapping start and end in CASE
        expressions that adjust the index at query time:
          - start: CASE WHEN start >= 0 THEN start + 1 ELSE start END
          - end:   CASE WHEN end < 0 THEN end - 1 ELSE end END
        """
        start, end = expression.args.get("start"), expression.args.get("end")

        if expression.args.get("zero_based"):
            if start is not None:
                start = (
                    exp.case()
                    .when(
                        exp.GTE(this=start.copy(), expression=exp.Literal.number(0)),
                        exp.Add(this=start.copy(), expression=exp.Literal.number(1)),
                    )
                    .else_(start)
                )
            if end is not None:
                end = (
                    exp.case()
                    .when(
                        exp.LT(this=end.copy(), expression=exp.Literal.number(0)),
                        exp.Sub(this=end.copy(), expression=exp.Literal.number(1)),
                    )
                    .else_(end)
                )

        return self.func("ARRAY_SLICE", expression.this, start, end, expression.args.get("step"))

    def arrayszip_sql(self, expression: exp.ArraysZip) -> str:
        args = expression.expressions

        if not args:
            # Return [{}] - using MAP([], []) since DuckDB can't represent empty structs
            return self.sql(exp.array(exp.Map(keys=exp.array(), values=exp.array())))

        # Build placeholder values for template
        lengths = [exp.Length(this=arg) for arg in args]
        max_len = (
            lengths[0]
            if len(lengths) == 1
            else exp.Greatest(this=lengths[0], expressions=lengths[1:])
        )

        # Empty struct with same schema: {'$1': NULL, '$2': NULL, ...}
        empty_struct = exp.func(
            "STRUCT",
            *[
                exp.PropertyEQ(this=exp.Literal.string(f"${i + 1}"), expression=exp.Null())
                for i in range(len(args))
            ],
        )

        # Struct for transform: {'$1': COALESCE(arr1, [])[__i + 1], ...}
        # COALESCE wrapping handles NULL arrays - prevents invalid NULL[i] syntax
        index = exp.column("__i") + 1
        transform_struct = exp.func(
            "STRUCT",
            *[
                exp.PropertyEQ(
                    this=exp.Literal.string(f"${i + 1}"),
                    expression=exp.func("COALESCE", arg, exp.array())[index],
                )
                for i, arg in enumerate(args)
            ],
        )

        result = exp.replace_placeholders(
            self.ARRAYS_ZIP_TEMPLATE.copy(),
            null_check=exp.or_(*[arg.is_(exp.Null()) for arg in args]),
            all_empty_check=exp.and_(
                *[
                    exp.EQ(this=exp.Length(this=arg), expression=exp.Literal.number(0))
                    for arg in args
                ]
            ),
            empty_struct=empty_struct,
            max_len=max_len,
            transform_struct=transform_struct,
        )
        return self.sql(result)

    def lower_sql(self, expression: exp.Lower) -> str:
        result_sql = self.func("LOWER", _cast_to_varchar(expression.this))
        return _gen_with_cast_to_blob(self, expression, result_sql)

    def upper_sql(self, expression: exp.Upper) -> str:
        result_sql = self.func("UPPER", _cast_to_varchar(expression.this))
        return _gen_with_cast_to_blob(self, expression, result_sql)

    def reverse_sql(self, expression: exp.Reverse) -> str:
        result_sql = self.func("REVERSE", _cast_to_varchar(expression.this))
        return _gen_with_cast_to_blob(self, expression, result_sql)

    def _left_right_sql(self, expression: exp.Left | exp.Right, func_name: str) -> str:
        arg = expression.this
        length = expression.expression
        is_binary = _is_binary(arg)

        if is_binary:
            # LEFT/RIGHT(blob, n) becomes UNHEX(LEFT/RIGHT(HEX(blob), n * 2))
            # Each byte becomes 2 hex chars, so multiply length by 2
            hex_arg = exp.Hex(this=arg)
            hex_length = exp.Mul(this=length, expression=exp.Literal.number(2))
            result: exp.Expression = exp.Unhex(
                this=exp.Anonymous(this=func_name, expressions=[hex_arg, hex_length])
            )
        else:
            result = exp.Anonymous(this=func_name, expressions=[arg, length])

        if expression.args.get("negative_length_returns_empty"):
            empty: exp.Expression = exp.Literal.string("")
            if is_binary:
                empty = exp.Unhex(this=empty)
            result = exp.case().when(length < exp.Literal.number(0), empty).else_(result)

        return self.sql(result)

    def left_sql(self, expression: exp.Left) -> str:
        return self._left_right_sql(expression, "LEFT")

    def right_sql(self, expression: exp.Right) -> str:
        return self._left_right_sql(expression, "RIGHT")

    def rtrimmedlength_sql(self, expression: exp.RtrimmedLength) -> str:
        return self.func("LENGTH", exp.Trim(this=expression.this, position="TRAILING"))

    def stuff_sql(self, expression: exp.Stuff) -> str:
        base = expression.this
        start = expression.args["start"]
        length = expression.args["length"]
        insertion = expression.expression
        is_binary = _is_binary(base)

        if is_binary:
            # DuckDB's SUBSTRING doesn't accept BLOB; operate on the HEX string instead
            # (each byte = 2 hex chars), then UNHEX back to BLOB
            base = exp.Hex(this=base)
            insertion = exp.Hex(this=insertion)
            left = exp.Substring(
                this=base.copy(),
                start=exp.Literal.number(1),
                length=(start.copy() - exp.Literal.number(1)) * exp.Literal.number(2),
            )
            right = exp.Substring(
                this=base.copy(),
                start=((start + length) - exp.Literal.number(1)) * exp.Literal.number(2)
                + exp.Literal.number(1),
            )
        else:
            left = exp.Substring(
                this=base.copy(),
                start=exp.Literal.number(1),
                length=start.copy() - exp.Literal.number(1),
            )
            right = exp.Substring(this=base.copy(), start=start + length)
        result: exp.Expr = exp.DPipe(
            this=exp.DPipe(this=left, expression=insertion), expression=right
        )

        if is_binary:
            result = exp.Unhex(this=result)

        return self.sql(result)

    def rand_sql(self, expression: exp.Rand) -> str:
        seed = expression.this
        if seed is not None:
            self.unsupported("RANDOM with seed is not supported in DuckDB")

        lower = expression.args.get("lower")
        upper = expression.args.get("upper")

        if lower and upper:
            # scale DuckDB's [0,1) to the specified range
            range_size = exp.paren(upper - lower)
            scaled = exp.Add(this=lower, expression=exp.func("random") * range_size)

            # For now we assume that if bounds are set, return type is BIGINT. Snowflake/Teradata
            result = exp.cast(scaled, exp.DType.BIGINT)
            return self.sql(result)

        # Default DuckDB behavior - just return RANDOM() as float
        return "RANDOM()"

    def bytelength_sql(self, expression: exp.ByteLength) -> str:
        arg = expression.this

        # Check if it's a text type (handles both literals and annotated expressions)
        if arg.is_type(*exp.DataType.TEXT_TYPES):
            return self.func("OCTET_LENGTH", exp.Encode(this=arg))

        # Default: pass through as-is (conservative for DuckDB, handles binary and unannotated)
        return self.func("OCTET_LENGTH", arg)

    def base64encode_sql(self, expression: exp.Base64Encode) -> str:
        # DuckDB TO_BASE64 requires BLOB input
        # Snowflake BASE64_ENCODE accepts both VARCHAR and BINARY - for VARCHAR it implicitly
        # encodes UTF-8 bytes. We add ENCODE unless the input is a binary type.
        result = expression.this

        # Check if input is a string type - ENCODE only accepts VARCHAR
        if result.is_type(*exp.DataType.TEXT_TYPES):
            result = exp.Encode(this=result)

        result = exp.ToBase64(this=result)

        max_line_length = expression.args.get("max_line_length")
        alphabet = expression.args.get("alphabet")

        # Handle custom alphabet by replacing standard chars with custom ones
        result = _apply_base64_alphabet_replacements(result, alphabet)

        # Handle max_line_length by inserting newlines every N characters
        line_length = (
            t.cast(int, max_line_length.to_py())
            if isinstance(max_line_length, exp.Literal) and max_line_length.is_number
            else 0
        )
        if line_length > 0:
            newline = exp.Chr(expressions=[exp.Literal.number(10)])
            result = exp.Trim(
                this=exp.RegexpReplace(
                    this=result,
                    expression=exp.Literal.string(f"(.{{{line_length}}})"),
                    replacement=exp.Concat(expressions=[exp.Literal.string("\\1"), newline.copy()]),
                ),
                expression=newline,
                position="TRAILING",
            )

        return self.sql(result)

    def hexencode_sql(self, expression: exp.HexEncode) -> str:
        arg = expression.this
        case = expression.args.get("case")
        hex_expr = exp.Hex(this=arg)

        if not case:
            return self.sql(hex_expr)

        # Emit runtime CASE WHEN to handle NULL propagation and case=0 (lowercase) vs case=1 (uppercase)
        return self.sql(
            exp.case()
            .when(case.is_(exp.null()), exp.null())
            .when(case.copy().eq(0), exp.Lower(this=hex_expr.copy()))
            .else_(hex_expr)
        )

    def replace_sql(self, expression: exp.Replace) -> str:
        result_sql = self.func(
            "REPLACE",
            _cast_to_varchar(expression.this),
            _cast_to_varchar(expression.expression),
            _cast_to_varchar(expression.args.get("replacement")),
        )
        return _gen_with_cast_to_blob(self, expression, result_sql)

    def _bitwise_op(self, expression: exp.Binary, op: str) -> str:
        _prepare_binary_bitwise_args(expression)
        result_sql = self.binary(expression, op)
        return _gen_with_cast_to_blob(self, expression, result_sql)

    def bitwisexor_sql(self, expression: exp.BitwiseXor) -> str:
        _prepare_binary_bitwise_args(expression)
        result_sql = self.func("XOR", expression.this, expression.expression)
        return _gen_with_cast_to_blob(self, expression, result_sql)

    def objectinsert_sql(self, expression: exp.ObjectInsert) -> str:
        this = expression.this
        key = expression.args.get("key")
        key_sql = key.name if isinstance(key, exp.Expr) else ""
        value_sql = self.sql(expression, "value")

        kv_sql = f"{key_sql} := {value_sql}"

        # If the input struct is empty e.g. transpiling OBJECT_INSERT(OBJECT_CONSTRUCT(), key, value) from Snowflake
        # then we can generate STRUCT_PACK which will build it since STRUCT_INSERT({}, key := value) is not valid DuckDB
        if isinstance(this, exp.Struct) and not this.expressions:
            return self.func("STRUCT_PACK", kv_sql)

        return self.func("STRUCT_INSERT", this, kv_sql)

    def mapcat_sql(self, expression: exp.MapCat) -> str:
        result = exp.replace_placeholders(
            self.MAPCAT_TEMPLATE.copy(),
            map1=expression.this,
            map2=expression.expression,
        )
        return self.sql(result)

    def mapcontainskey_sql(self, expression: exp.MapContainsKey) -> str:
        return self.func(
            "ARRAY_CONTAINS", exp.func("MAP_KEYS", expression.args["key"]), expression.this
        )

    def mapdelete_sql(self, expression: exp.MapDelete) -> str:
        map_arg = expression.this
        keys_to_delete = expression.expressions

        x_dot_key = exp.Dot(this=exp.to_identifier("x"), expression=exp.to_identifier("key"))

        lambda_expr = exp.Lambda(
            this=exp.In(this=x_dot_key, expressions=keys_to_delete).not_(),
            expressions=[exp.to_identifier("x")],
        )
        result = exp.func(
            "MAP_FROM_ENTRIES",
            exp.ArrayFilter(this=exp.func("MAP_ENTRIES", map_arg), expression=lambda_expr),
        )
        return self.sql(result)

    def mappick_sql(self, expression: exp.MapPick) -> str:
        map_arg = expression.this
        keys_to_pick = expression.expressions

        x_dot_key = exp.Dot(this=exp.to_identifier("x"), expression=exp.to_identifier("key"))

        if len(keys_to_pick) == 1 and keys_to_pick[0].is_type(exp.DType.ARRAY):
            lambda_expr = exp.Lambda(
                this=exp.func("ARRAY_CONTAINS", keys_to_pick[0], x_dot_key),
                expressions=[exp.to_identifier("x")],
            )
        else:
            lambda_expr = exp.Lambda(
                this=exp.In(this=x_dot_key, expressions=keys_to_pick),
                expressions=[exp.to_identifier("x")],
            )

        result = exp.func(
            "MAP_FROM_ENTRIES",
            exp.func("LIST_FILTER", exp.func("MAP_ENTRIES", map_arg), lambda_expr),
        )
        return self.sql(result)

    def mapsize_sql(self, expression: exp.MapSize) -> str:
        return self.func("CARDINALITY", expression.this)

    @unsupported_args("update_flag")
    def mapinsert_sql(self, expression: exp.MapInsert) -> str:
        map_arg = expression.this
        key = expression.args.get("key")
        value = expression.args.get("value")

        map_type = map_arg.type

        if value is not None:
            if map_type and map_type.expressions and len(map_type.expressions) > 1:
                # Extract the value type from MAP(key_type, value_type)
                value_type = map_type.expressions[1]
                # Cast value to match the map's value type to avoid type conflicts
                value = exp.cast(value, value_type)
            # else: polymorphic MAP case - no type parameters available, use value as-is

        # Create a single-entry map for the new key-value pair
        new_entry_struct = exp.Struct(expressions=[exp.PropertyEQ(this=key, expression=value)])
        new_entry: exp.Expression = exp.ToMap(this=new_entry_struct)

        # Use MAP_CONCAT to merge the original map with the new entry
        # This automatically handles both insert and update cases
        result = exp.func("MAP_CONCAT", map_arg, new_entry)

        return self.sql(result)

    def startswith_sql(self, expression: exp.StartsWith) -> str:
        return self.func(
            "STARTS_WITH",
            _cast_to_varchar(expression.this),
            _cast_to_varchar(expression.expression),
        )

    def space_sql(self, expression: exp.Space) -> str:
        # DuckDB's REPEAT requires BIGINT for the count parameter
        return self.sql(
            exp.Repeat(
                this=exp.Literal.string(" "),
                times=exp.cast(expression.this, exp.DType.BIGINT),
            )
        )

    def tablefromrows_sql(self, expression: exp.TableFromRows) -> str:
        # For GENERATOR, unwrap TABLE() - just emit the Generator (becomes RANGE)
        if isinstance(expression.this, exp.Generator):
            # Preserve alias, joins, and other table-level args
            table = exp.Table(
                this=expression.this,
                alias=expression.args.get("alias"),
                joins=expression.args.get("joins"),
            )
            return self.sql(table)

        return super().tablefromrows_sql(expression)

    def unnest_sql(self, expression: exp.Unnest) -> str:
        explode_array = expression.args.get("explode_array")
        if explode_array:
            # In BigQuery, UNNESTing a nested array leads to explosion of the top-level array & struct
            # This is transpiled to DDB by transforming "FROM UNNEST(...)" to "FROM (SELECT UNNEST(..., max_depth => 2))"
            expression.expressions.append(
                exp.Kwarg(this=exp.var("max_depth"), expression=exp.Literal.number(2))
            )

            # If BQ's UNNEST is aliased, we transform it from a column alias to a table alias in DDB
            alias = expression.args.get("alias")
            if isinstance(alias, exp.TableAlias):
                expression.set("alias", None)
                if alias.columns:
                    alias = exp.TableAlias(this=seq_get(alias.columns, 0))

            unnest_sql = super().unnest_sql(expression)
            select = exp.Select(expressions=[unnest_sql]).subquery(alias)
            return self.sql(select)

        return super().unnest_sql(expression)

    def ignorenulls_sql(self, expression: exp.IgnoreNulls) -> str:
        this = expression.this

        if isinstance(this, self.IGNORE_RESPECT_NULLS_WINDOW_FUNCTIONS):
            # DuckDB should render IGNORE NULLS only for the general-purpose
            # window functions that accept it e.g. FIRST_VALUE(... IGNORE NULLS) OVER (...)
            return super().ignorenulls_sql(expression)

        if isinstance(this, exp.First):
            this = exp.AnyValue(this=this.this)

        if not isinstance(this, (exp.AnyValue, exp.ApproxQuantiles)):
            self.unsupported("IGNORE NULLS is not supported for non-window functions.")

        return self.sql(this)

    def split_sql(self, expression: exp.Split) -> str:
        base_func = exp.func("STR_SPLIT", expression.this, expression.expression)

        case_expr = exp.case().else_(base_func)
        needs_case = False

        if expression.args.get("null_returns_null"):
            case_expr = case_expr.when(expression.expression.is_(exp.null()), exp.null())
            needs_case = True

        if expression.args.get("empty_delimiter_returns_whole"):
            # When delimiter is empty string, return input string as single array element
            array_with_input = exp.array(expression.this)
            case_expr = case_expr.when(
                expression.expression.eq(exp.Literal.string("")), array_with_input
            )
            needs_case = True

        return self.sql(case_expr if needs_case else base_func)

    def splitpart_sql(self, expression: exp.SplitPart) -> str:
        string_arg = expression.this
        delimiter_arg = expression.args.get("delimiter")
        part_index_arg = expression.args.get("part_index")

        if delimiter_arg and part_index_arg:
            # Handle Snowflake's "index 0 and 1 both return first element" behavior
            if expression.args.get("part_index_zero_as_one"):
                # Convert 0 to 1 for compatibility

                part_index_arg = exp.Paren(
                    this=exp.case()
                    .when(part_index_arg.eq(exp.Literal.number("0")), exp.Literal.number("1"))
                    .else_(part_index_arg)
                )

            # Use Anonymous to avoid recursion
            base_func_expr: exp.Expr = exp.Anonymous(
                this="SPLIT_PART", expressions=[string_arg, delimiter_arg, part_index_arg]
            )
            needs_case_transform = False
            case_expr = exp.case().else_(base_func_expr)

            if expression.args.get("empty_delimiter_returns_whole"):
                # When delimiter is empty string:
                # - Return whole string if part_index is 1 or -1
                # - Return empty string otherwise
                empty_case = exp.Paren(
                    this=exp.case()
                    .when(
                        exp.or_(
                            part_index_arg.eq(exp.Literal.number("1")),
                            part_index_arg.eq(exp.Literal.number("-1")),
                        ),
                        string_arg,
                    )
                    .else_(exp.Literal.string(""))
                )

                case_expr = case_expr.when(delimiter_arg.eq(exp.Literal.string("")), empty_case)
                needs_case_transform = True

            """
            Output looks something like this:

            CASE
            WHEN delimiter is '' THEN
                (
                    CASE
                    WHEN adjusted_part_index = 1 OR adjusted_part_index = -1 THEN input
                    ELSE '' END
                )
            ELSE SPLIT_PART(input, delimiter, adjusted_part_index)
            END

            """
            return self.sql(case_expr if needs_case_transform else base_func_expr)

        return self.function_fallback_sql(expression)

    def respectnulls_sql(self, expression: exp.RespectNulls) -> str:
        if isinstance(expression.this, self.IGNORE_RESPECT_NULLS_WINDOW_FUNCTIONS):
            # DuckDB should render RESPECT NULLS only for the general-purpose
            # window functions that accept it e.g. FIRST_VALUE(... RESPECT NULLS) OVER (...)
            return super().respectnulls_sql(expression)

        self.unsupported("RESPECT NULLS is not supported for non-window functions.")
        return self.sql(expression, "this")

    def arraytostring_sql(self, expression: exp.ArrayToString) -> str:
        null = expression.args.get("null")

        if expression.args.get("null_is_empty"):
            x = exp.to_identifier("x")
            list_transform = exp.Transform(
                this=expression.this.copy(),
                expression=exp.Lambda(
                    this=exp.Coalesce(
                        this=exp.cast(x, "TEXT"), expressions=[exp.Literal.string("")]
                    ),
                    expressions=[x],
                ),
            )
            array_to_string = exp.ArrayToString(
                this=list_transform, expression=expression.expression
            )
            if expression.args.get("null_delim_is_null"):
                return self.sql(
                    exp.case()
                    .when(expression.expression.copy().is_(exp.null()), exp.null())
                    .else_(array_to_string)
                )
            return self.sql(array_to_string)

        if null:
            x = exp.to_identifier("x")
            return self.sql(
                exp.ArrayToString(
                    this=exp.Transform(
                        this=expression.this,
                        expression=exp.Lambda(
                            this=exp.Coalesce(this=x, expressions=[null]),
                            expressions=[x],
                        ),
                    ),
                    expression=expression.expression,
                )
            )

        return self.func("ARRAY_TO_STRING", expression.this, expression.expression)

    def concatws_sql(self, expression: exp.ConcatWs) -> str:
        # DuckDB-specific: handle binary types using DPipe (||) operator
        separator = seq_get(expression.expressions, 0)
        args = expression.expressions[1:]

        if any(_is_binary(arg) for arg in [separator, *args]):
            result = args[0]
            for arg in args[1:]:
                result = exp.DPipe(
                    this=exp.DPipe(this=result, expression=separator), expression=arg
                )
            return self.sql(result)

        return super().concatws_sql(expression)

    def _regexp_extract_sql(self, expression: exp.RegexpExtract | exp.RegexpExtractAll) -> str:
        this = expression.this
        group = expression.args.get("group")
        params = expression.args.get("parameters")
        position = expression.args.get("position")
        occurrence = expression.args.get("occurrence")
        null_if_pos_overflow = expression.args.get("null_if_pos_overflow")

        # Handle Snowflake's 'e' flag: it enables capture group extraction
        # In DuckDB, this is controlled by the group parameter directly
        if params and params.is_string and "e" in params.name:
            params = exp.Literal.string(params.name.replace("e", ""))

        validated_flags = self._validate_regexp_flags(params, supported_flags="cims")

        # Strip default group when no following params (DuckDB default is same as group=0)
        if (
            not validated_flags
            and group
            and group.name == str(self.dialect.REGEXP_EXTRACT_DEFAULT_GROUP)
        ):
            group = None

        flags_expr = exp.Literal.string(validated_flags) if validated_flags else None

        # use substring to handle position argument
        if position and (not position.is_int or position.to_py() > 1):
            this = exp.Substring(this=this, start=position)

            if null_if_pos_overflow:
                this = exp.Nullif(this=this, expression=exp.Literal.string(""))

        is_extract_all = isinstance(expression, exp.RegexpExtractAll)
        non_single_occurrence = occurrence and (not occurrence.is_int or occurrence.to_py() > 1)

        if is_extract_all or non_single_occurrence:
            name = "REGEXP_EXTRACT_ALL"
        else:
            name = "REGEXP_EXTRACT"

        result: exp.Expr = exp.Anonymous(
            this=name, expressions=[this, expression.expression, group, flags_expr]
        )

        # Array slicing for REGEXP_EXTRACT_ALL with occurrence
        if is_extract_all and non_single_occurrence:
            result = exp.Bracket(this=result, expressions=[exp.Slice(this=occurrence)])
        # ARRAY_EXTRACT for REGEXP_EXTRACT with occurrence > 1
        elif non_single_occurrence:
            result = exp.Anonymous(this="ARRAY_EXTRACT", expressions=[result, occurrence])

        return self.sql(result)

    def regexpextract_sql(self, expression: exp.RegexpExtract) -> str:
        return self._regexp_extract_sql(expression)

    def regexpextractall_sql(self, expression: exp.RegexpExtractAll) -> str:
        return self._regexp_extract_sql(expression)

    def regexpinstr_sql(self, expression: exp.RegexpInstr) -> str:
        this = expression.this
        pattern = expression.expression
        position = expression.args.get("position")
        orig_occ = expression.args.get("occurrence")
        occurrence = orig_occ or exp.Literal.number(1)
        option = expression.args.get("option")
        parameters = expression.args.get("parameters")

        validated_flags = self._validate_regexp_flags(parameters, supported_flags="ims")
        if validated_flags:
            pattern = exp.Concat(expressions=[exp.Literal.string(f"(?{validated_flags})"), pattern])

        # Handle starting position offset
        pos_offset: exp.Expr = exp.Literal.number(0)
        if position and (not position.is_int or position.to_py() > 1):
            this = exp.Substring(this=this, start=position)
            pos_offset = position - exp.Literal.number(1)

        # Helper: LIST_SUM(LIST_TRANSFORM(list[1:end], x -> LENGTH(x)))
        def sum_lengths(func_name: str, end: exp.Expr) -> exp.Expr:
            lst = exp.Bracket(
                this=exp.Anonymous(this=func_name, expressions=[this, pattern]),
                expressions=[exp.Slice(this=exp.Literal.number(1), expression=end)],
                offset=1,
            )
            transform = exp.Anonymous(
                this="LIST_TRANSFORM",
                expressions=[
                    lst,
                    exp.Lambda(
                        this=exp.Length(this=exp.to_identifier("x")),
                        expressions=[exp.to_identifier("x")],
                    ),
                ],
            )
            return exp.Coalesce(
                this=exp.Anonymous(this="LIST_SUM", expressions=[transform]),
                expressions=[exp.Literal.number(0)],
            )

        # Position = 1 + sum(split_lengths[1:occ]) + sum(match_lengths[1:occ-1]) + offset
        base_pos: exp.Expr = (
            exp.Literal.number(1)
            + sum_lengths("STRING_SPLIT_REGEX", occurrence)
            + sum_lengths("REGEXP_EXTRACT_ALL", occurrence - exp.Literal.number(1))
            + pos_offset
        )

        # option=1: add match length for end position
        if option and option.is_int and option.to_py() == 1:
            match_at_occ = exp.Bracket(
                this=exp.Anonymous(this="REGEXP_EXTRACT_ALL", expressions=[this, pattern]),
                expressions=[occurrence],
                offset=1,
            )
            base_pos = base_pos + exp.Coalesce(
                this=exp.Length(this=match_at_occ), expressions=[exp.Literal.number(0)]
            )

        # NULL checks for all provided arguments
        # .copy() is used strictly because .is_() alters the node's parent pointer, mutating the parsed AST
        null_args = [
            expression.this,
            expression.expression,
            position,
            orig_occ,
            option,
            parameters,
        ]
        null_checks = [arg.copy().is_(exp.Null()) for arg in null_args if arg]

        matches = exp.Anonymous(this="REGEXP_EXTRACT_ALL", expressions=[this, pattern])

        return self.sql(
            exp.case()
            .when(exp.or_(*null_checks), exp.Null())
            .when(pattern.copy().eq(exp.Literal.string("")), exp.Literal.number(0))
            .when(exp.Length(this=matches) < occurrence, exp.Literal.number(0))
            .else_(base_pos)
        )

    @unsupported_args("culture")
    def numbertostr_sql(self, expression: exp.NumberToStr) -> str:
        fmt = expression.args.get("format")
        if fmt and fmt.is_int:
            return self.func("FORMAT", f"'{{:,.{fmt.name}f}}'", expression.this)

        self.unsupported("Only integer formats are supported by NumberToStr")
        return self.function_fallback_sql(expression)

    def autoincrementcolumnconstraint_sql(self, _) -> str:
        self.unsupported("The AUTOINCREMENT column constraint is not supported by DuckDB")
        return ""

    def aliases_sql(self, expression: exp.Aliases) -> str:
        this = expression.this
        if isinstance(this, exp.Posexplode):
            return self.posexplode_sql(this)

        return super().aliases_sql(expression)

    def posexplode_sql(self, expression: exp.Posexplode) -> str:
        this = expression.this
        parent = expression.parent

        # The default Spark aliases are "pos" and "col", unless specified otherwise
        pos, col = exp.to_identifier("pos"), exp.to_identifier("col")

        if isinstance(parent, exp.Aliases):
            # Column case: SELECT POSEXPLODE(col) [AS (a, b)]
            pos, col = parent.expressions
        elif isinstance(parent, exp.Table):
            # Table case: SELECT * FROM POSEXPLODE(col) [AS (a, b)]
            alias = parent.args.get("alias")
            if alias:
                pos, col = alias.columns or [pos, col]
                alias.pop()

        # Translate POSEXPLODE to UNNEST + GENERATE_SUBSCRIPTS
        # Note: In Spark pos is 0-indexed, but in DuckDB it's 1-indexed, so we subtract 1 from GENERATE_SUBSCRIPTS
        unnest_sql = self.sql(exp.Unnest(expressions=[this], alias=col))
        gen_subscripts = self.sql(
            exp.Alias(
                this=exp.Anonymous(
                    this="GENERATE_SUBSCRIPTS", expressions=[this, exp.Literal.number(1)]
                )
                - exp.Literal.number(1),
                alias=pos,
            )
        )

        posexplode_sql = self.format_args(gen_subscripts, unnest_sql)

        if isinstance(parent, exp.From) or (parent and isinstance(parent.parent, exp.From)):
            # SELECT * FROM POSEXPLODE(col) -> SELECT * FROM (SELECT GENERATE_SUBSCRIPTS(...), UNNEST(...))
            return self.sql(exp.Subquery(this=exp.Select(expressions=[posexplode_sql])))

        return posexplode_sql

    def addmonths_sql(self, expression: exp.AddMonths) -> str:
        """
        Handles three key issues:
        1. Float/decimal months: e.g., Snowflake rounds, whereas DuckDB INTERVAL requires integers
        2. End-of-month preservation: If input is last day of month, result is last day of result month
        3. Type preservation: Maintains DATE/TIMESTAMPTZ types (DuckDB defaults to TIMESTAMP)
        """
        from sqlglot.optimizer.annotate_types import annotate_types

        this = expression.this
        if not this.type:
            this = annotate_types(this, dialect=self.dialect)

        if this.is_type(*exp.DataType.TEXT_TYPES):
            this = exp.Cast(this=this, to=exp.DataType(this=exp.DType.TIMESTAMP))

        # Detect float/decimal months to apply rounding (Snowflake behavior)
        # DuckDB INTERVAL syntax doesn't support non-integer expressions, so use TO_MONTHS
        months_expr = expression.expression
        if not months_expr.type:
            months_expr = annotate_types(months_expr, dialect=self.dialect)

        # Build interval or to_months expression based on type
        # Float/decimal case: Round and use TO_MONTHS(CAST(ROUND(value) AS INT))
        interval_or_to_months = (
            exp.func("TO_MONTHS", exp.cast(exp.func("ROUND", months_expr), "INT"))
            if months_expr.is_type(
                exp.DType.FLOAT,
                exp.DType.DOUBLE,
                exp.DType.DECIMAL,
            )
            # Integer case: standard INTERVAL N MONTH syntax
            else exp.Interval(this=months_expr, unit=exp.var("MONTH"))
        )

        date_add_expr = exp.Add(this=this, expression=interval_or_to_months)

        # Apply end-of-month preservation if Snowflake flag is set
        # CASE WHEN LAST_DAY(date) = date THEN LAST_DAY(result) ELSE result END
        preserve_eom = expression.args.get("preserve_end_of_month")
        result_expr = (
            exp.case()
            .when(
                exp.EQ(this=exp.func("LAST_DAY", this), expression=this),
                exp.func("LAST_DAY", date_add_expr),
            )
            .else_(date_add_expr)
            if preserve_eom
            else date_add_expr
        )

        # DuckDB's DATE_ADD function returns TIMESTAMP/DATETIME by default, even when the input is DATE
        # To match for example Snowflake's ADD_MONTHS behavior (which preserves the input type)
        # We need to cast the result back to the original type when the input is DATE or TIMESTAMPTZ
        # Example: ADD_MONTHS('2023-01-31'::date, 1) should return DATE, not TIMESTAMP
        if this.is_type(exp.DType.DATE, exp.DType.TIMESTAMPTZ):
            return self.sql(exp.Cast(this=result_expr, to=this.type))
        return self.sql(result_expr)

    def format_sql(self, expression: exp.Format) -> str:
        if expression.name.lower() == "%s" and len(expression.expressions) == 1:
            return self.func("FORMAT", "'{}'", expression.expressions[0])

        return self.function_fallback_sql(expression)

    def hexstring_sql(
        self, expression: exp.HexString, binary_function_repr: str | None = None
    ) -> str:
        # UNHEX('FF') correctly produces blob \xFF in DuckDB
        return super().hexstring_sql(expression, binary_function_repr="UNHEX")

    def datetrunc_sql(self, expression: exp.DateTrunc) -> str:
        unit = expression.args.get("unit")
        date = expression.this

        week_start = _week_unit_to_dow(unit)
        unit = unit_to_str(expression)

        if week_start:
            result = self.sql(
                _build_week_trunc_expression(date, week_start, preserve_start_day=True)
            )
        else:
            result = self.func("DATE_TRUNC", unit, date)

        if (
            expression.args.get("input_type_preserved")
            and date.is_type(*exp.DataType.TEMPORAL_TYPES)
            and not (is_date_unit(unit) and date.is_type(exp.DType.DATE))
        ):
            return self.sql(exp.Cast(this=result, to=date.type))

        return result

    def timestamptrunc_sql(self, expression: exp.TimestampTrunc) -> str:
        unit = unit_to_str(expression)
        zone = expression.args.get("zone")
        timestamp = expression.this
        date_unit = is_date_unit(unit)

        if date_unit and zone:
            # BigQuery's TIMESTAMP_TRUNC with timezone truncates in the target timezone and returns as UTC.
            # Double AT TIME ZONE needed for BigQuery compatibility:
            # 1. First AT TIME ZONE: ensures truncation happens in the target timezone
            # 2. Second AT TIME ZONE: converts the DATE result back to TIMESTAMPTZ (preserving time component)
            timestamp = exp.AtTimeZone(this=timestamp, zone=zone)
            result_sql = self.func("DATE_TRUNC", unit, timestamp)
            return self.sql(exp.AtTimeZone(this=result_sql, zone=zone))

        result = self.func("DATE_TRUNC", unit, timestamp)
        if expression.args.get("input_type_preserved"):
            if timestamp.type and timestamp.is_type(exp.DType.TIME, exp.DType.TIMETZ):
                dummy_date = exp.Cast(
                    this=exp.Literal.string("1970-01-01"),
                    to=exp.DataType(this=exp.DType.DATE),
                )
                date_time = exp.Add(this=dummy_date, expression=timestamp)
                result = self.func("DATE_TRUNC", unit, date_time)
                return self.sql(exp.Cast(this=result, to=timestamp.type))

            if timestamp.is_type(*exp.DataType.TEMPORAL_TYPES) and not (
                date_unit and timestamp.is_type(exp.DType.DATE)
            ):
                return self.sql(exp.Cast(this=result, to=timestamp.type))

        return result

    def trim_sql(self, expression: exp.Trim) -> str:
        expression.this.replace(_cast_to_varchar(expression.this))
        if expression.expression:
            expression.expression.replace(_cast_to_varchar(expression.expression))

        result_sql = super().trim_sql(expression)
        return _gen_with_cast_to_blob(self, expression, result_sql)

    def round_sql(self, expression: exp.Round) -> str:
        this = expression.this
        decimals = expression.args.get("decimals")
        truncate = expression.args.get("truncate")

        # DuckDB requires the scale (decimals) argument to be an INT
        # Some dialects (e.g., Snowflake) allow non-integer scales and cast to an integer internally
        if decimals is not None and expression.args.get("casts_non_integer_decimals"):
            if not (decimals.is_int or decimals.is_type(*exp.DataType.INTEGER_TYPES)):
                decimals = exp.cast(decimals, exp.DType.INT)

        func = "ROUND"
        if truncate:
            # BigQuery uses ROUND_HALF_EVEN; Snowflake uses HALF_TO_EVEN
            if truncate.this in ("ROUND_HALF_EVEN", "HALF_TO_EVEN"):
                func = "ROUND_EVEN"
                truncate = None
            # BigQuery uses ROUND_HALF_AWAY_FROM_ZERO; Snowflake uses HALF_AWAY_FROM_ZERO
            elif truncate.this in ("ROUND_HALF_AWAY_FROM_ZERO", "HALF_AWAY_FROM_ZERO"):
                truncate = None

        return self.func(func, this, decimals, truncate)

    def strtok_sql(self, expression: exp.Strtok) -> str:
        string_arg = expression.this
        delimiter_arg = expression.args.get("delimiter")
        part_index_arg = expression.args.get("part_index")

        if delimiter_arg and part_index_arg:
            # Escape regex chars and build character class at runtime using REGEXP_REPLACE
            escaped_delimiter = exp.Anonymous(
                this="REGEXP_REPLACE",
                expressions=[
                    delimiter_arg,
                    exp.Literal.string(
                        r"([\[\]^.\-*+?(){}|$\\])"
                    ),  # Escape problematic regex chars
                    exp.Literal.string(
                        r"\\\1"
                    ),  # Replace with escaped version using $1 backreference
                    exp.Literal.string("g"),  # Global flag
                ],
            )
            # CASE WHEN delimiter = '' THEN '' ELSE CONCAT('[', escaped_delimiter, ']') END
            regex_pattern = (
                exp.case()
                .when(delimiter_arg.eq(exp.Literal.string("")), exp.Literal.string(""))
                .else_(
                    exp.func(
                        "CONCAT",
                        exp.Literal.string("["),
                        escaped_delimiter,
                        exp.Literal.string("]"),
                    )
                )
            )

            # STRTOK skips empty strings, so we need to filter them out
            # LIST_FILTER(REGEXP_SPLIT_TO_ARRAY(string, pattern), x -> x != '')[index]
            split_array = exp.func("REGEXP_SPLIT_TO_ARRAY", string_arg, regex_pattern)
            x = exp.to_identifier("x")
            is_empty = x.eq(exp.Literal.string(""))
            filtered_array = exp.func(
                "LIST_FILTER",
                split_array,
                exp.Lambda(this=exp.not_(is_empty.copy()), expressions=[x.copy()]),
            )
            base_func = exp.Bracket(
                this=filtered_array,
                expressions=[part_index_arg],
                offset=1,
            )

            # Use template with the built regex pattern
            result = exp.replace_placeholders(
                self.STRTOK_TEMPLATE.copy(),
                string=string_arg,
                delimiter=delimiter_arg,
                part_index=part_index_arg,
                base_func=base_func,
            )

            return self.sql(result)

        return self.function_fallback_sql(expression)

    def strtoktoarray_sql(self, expression: exp.StrtokToArray) -> str:
        string_arg = expression.this
        delimiter_arg = expression.args.get("expression") or exp.Literal.string(" ")

        escaped = exp.RegexpReplace(
            this=delimiter_arg.copy(),
            expression=exp.Literal.string(r"([\[\]^.\-*+?(){}|$\\])"),
            replacement=exp.Literal.string(r"\\\1"),
            modifiers=exp.Literal.string("g"),
        )
        return self.sql(
            exp.replace_placeholders(
                self.STRTOK_TO_ARRAY_TEMPLATE.copy(),
                string=string_arg,
                delimiter=delimiter_arg,
                escaped=escaped,
            )
        )

    def approxquantile_sql(self, expression: exp.ApproxQuantile) -> str:
        result = self.func("APPROX_QUANTILE", expression.this, expression.args.get("quantile"))

        # DuckDB returns integers for APPROX_QUANTILE, cast to DOUBLE if the expected type is a real type
        if expression.is_type(*exp.DataType.REAL_TYPES):
            result = f"CAST({result} AS DOUBLE)"

        return result

    def approxquantiles_sql(self, expression: exp.ApproxQuantiles) -> str:
        """
        BigQuery's APPROX_QUANTILES(expr, n) returns an array of n+1 approximate quantile values
        dividing the input distribution into n equal-sized buckets.

        Both BigQuery and DuckDB use approximate algorithms for quantile estimation, but BigQuery
        does not document the specific algorithm used so results may differ. DuckDB does not
        support RESPECT NULLS.
        """
        this = expression.this
        if isinstance(this, exp.Distinct):
            # APPROX_QUANTILES requires 2 args and DISTINCT node grabs both
            if len(this.expressions) < 2:
                self.unsupported("APPROX_QUANTILES requires a bucket count argument")
                return self.function_fallback_sql(expression)
            num_quantiles_expr = this.expressions[1].pop()
        else:
            num_quantiles_expr = expression.expression

        if not isinstance(num_quantiles_expr, exp.Literal) or not num_quantiles_expr.is_int:
            self.unsupported("APPROX_QUANTILES bucket count must be a positive integer")
            return self.function_fallback_sql(expression)

        num_quantiles = t.cast(int, num_quantiles_expr.to_py())
        if num_quantiles <= 0:
            self.unsupported("APPROX_QUANTILES bucket count must be a positive integer")
            return self.function_fallback_sql(expression)

        quantiles = [
            exp.Literal.number(Decimal(i) / Decimal(num_quantiles))
            for i in range(num_quantiles + 1)
        ]

        return self.sql(exp.ApproxQuantile(this=this, quantile=exp.Array(expressions=quantiles)))

    def jsonextractscalar_sql(self, expression: exp.JSONExtractScalar) -> str:
        if expression.args.get("scalar_only"):
            expression = exp.JSONExtractScalar(
                this=rename_func("JSON_VALUE")(self, expression), expression="'$'"
            )
        return _arrow_json_extract_sql(self, expression)

    def bitwisenot_sql(self, expression: exp.BitwiseNot) -> str:
        this = expression.this

        if _is_binary(this):
            expression.type = exp.DType.BINARY.into_expr()

        arg = _cast_to_bit(this)

        if isinstance(this, exp.Neg):
            arg = exp.Paren(this=arg)

        expression.set("this", arg)

        result_sql = f"~{self.sql(expression, 'this')}"

        return _gen_with_cast_to_blob(self, expression, result_sql)

    def window_sql(self, expression: exp.Window) -> str:
        this = expression.this
        if isinstance(this, exp.Corr) or (
            isinstance(this, exp.Filter) and isinstance(this.this, exp.Corr)
        ):
            return self._corr_sql(expression)

        return super().window_sql(expression)

    def filter_sql(self, expression: exp.Filter) -> str:
        if isinstance(expression.this, exp.Corr):
            return self._corr_sql(expression)

        return super().filter_sql(expression)

    def _corr_sql(
        self,
        expression: exp.Filter | exp.Window | exp.Corr,
    ) -> str:
        if isinstance(expression, exp.Corr) and not expression.args.get("null_on_zero_variance"):
            return self.func("CORR", expression.this, expression.expression)

        corr_expr = _maybe_corr_null_to_false(expression)
        if corr_expr is None:
            if isinstance(expression, exp.Window):
                return super().window_sql(expression)
            if isinstance(expression, exp.Filter):
                return super().filter_sql(expression)
            corr_expr = expression  # make mypy happy

        return self.sql(exp.case().when(exp.IsNan(this=corr_expr), exp.null()).else_(corr_expr))

    def uuid_sql(self, expression: exp.Uuid) -> str:
        namespace = expression.this
        name = expression.args.get("name")

        # UUID v5 (namespace + name) - Emulate using SHA1
        if namespace and name:
            result = exp.replace_placeholders(
                self.UUID_V5_TEMPLATE.copy(),
                namespace=namespace,
                name=name,
            )
            return self.sql(result)

        return super().uuid_sql(expression)
