// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
// SPDX-FileCopyrightText: Copyright Contributors to the Kokkos project

#ifndef KOKKOS_SYCL_GRAPH_IMPL_HPP
#define KOKKOS_SYCL_GRAPH_IMPL_HPP

#include <Kokkos_Macros.hpp>

#include <Kokkos_Graph_fwd.hpp>

#include <impl/Kokkos_GraphImpl.hpp>
#include <impl/Kokkos_GraphNodeImpl.hpp>

#include <SYCL/Kokkos_SYCL_GraphNodeKernel.hpp>

#include <optional>

namespace Kokkos {
namespace Impl {
template <>
class GraphImpl<Kokkos::SYCL> {
 private:
  using device_handle_t = Kokkos::Impl::DeviceHandle<Kokkos::SYCL>;

 public:
  using node_details_t   = GraphNodeBackendSpecificDetails<Kokkos::SYCL>;
  using aggregate_impl_t = SYCLGraphNodeAggregate;
  using aggregate_node_impl_t =
      GraphNodeImpl<Kokkos::SYCL, aggregate_impl_t,
                    Kokkos::Experimental::TypeErasedTag>;

  using sycl_graph_t = sycl::ext::oneapi::experimental::command_graph<
      sycl::ext::oneapi::experimental::graph_state::modifiable>;
  using sycl_graph_exec_t = sycl::ext::oneapi::experimental::command_graph<
      sycl::ext::oneapi::experimental::graph_state::executable>;

  // Not movable or copyable; it spends its whole life as a shared_ptr in the
  // Graph object.
  GraphImpl()                            = delete;
  GraphImpl(GraphImpl const&)            = delete;
  GraphImpl(GraphImpl&&)                 = delete;
  GraphImpl& operator=(GraphImpl const&) = delete;
  GraphImpl& operator=(GraphImpl&&)      = delete;

  ~GraphImpl();

  explicit GraphImpl(const device_handle_t& device_handle);

  GraphImpl(const device_handle_t& device_handle, sycl_graph_t graph);

  void add_node(std::shared_ptr<aggregate_node_impl_t> const& arg_node_ptr);

  template <class NodeImpl>
  std::enable_if_t<
      Kokkos::Impl::is_graph_kernel_v<typename NodeImpl::kernel_type>>
  add_node(std::shared_ptr<NodeImpl> arg_node_ptr);

  template <class NodeImpl>
  std::enable_if_t<
      Kokkos::Impl::is_graph_then_host_v<typename NodeImpl::kernel_type>>
  add_node(std::shared_ptr<NodeImpl> arg_node_ptr);

  template <class NodeImpl>
  std::enable_if_t<
      Kokkos::Impl::is_graph_capture_v<typename NodeImpl::kernel_type>>
  add_node(const Kokkos::SYCL& exec, std::shared_ptr<NodeImpl> arg_node_ptr);

  template <class NodeImplPtr, class PredecessorRef>
  void add_predecessor(NodeImplPtr arg_node_ptr, PredecessorRef arg_pred_ref);

  void submit(const Kokkos::SYCL& exec);

  auto get_device_handle() const noexcept -> device_handle_t const&;

  auto create_root_node_ptr();

  template <class... PredecessorRefs>
  auto create_aggregate_ptr(PredecessorRefs&&...);

  void instantiate() {
    KOKKOS_EXPECTS(!m_graph_exec.has_value());
    m_graph_exec = m_graph.finalize();
  }

  auto& sycl_graph() { return m_graph; }
  auto& sycl_graph_exec() { return m_graph_exec; }

 private:
  device_handle_t m_device_handle;
  sycl_graph_t m_graph;
  std::optional<sycl_graph_exec_t> m_graph_exec;

  std::vector<std::shared_ptr<node_details_t>> m_nodes;
};

inline GraphImpl<Kokkos::SYCL>::~GraphImpl() {
  m_device_handle.m_exec.fence(
      "Kokkos::GraphImpl::~GraphImpl: Graph Destruction");
}

inline GraphImpl<Kokkos::SYCL>::GraphImpl(const device_handle_t& device_handle)
    : m_device_handle(device_handle),
      m_graph(m_device_handle.m_exec.sycl_queue().get_context(),
              m_device_handle.m_exec.sycl_queue().get_device()) {}

inline GraphImpl<Kokkos::SYCL>::GraphImpl(const device_handle_t& device_handle,
                                          sycl_graph_t graph)
    : m_device_handle(device_handle), m_graph(std::move(graph)) {}

inline void GraphImpl<Kokkos::SYCL>::add_node(
    std::shared_ptr<aggregate_node_impl_t> const& arg_node_ptr) {
  // add an empty node that needs to be set up before finalizing the graph
  arg_node_ptr->node_details_t::node = m_graph.add();
}

template <class NodeImpl>
inline std::enable_if_t<
    Kokkos::Impl::is_graph_kernel_v<typename NodeImpl::kernel_type>>
GraphImpl<Kokkos::SYCL>::add_node(std::shared_ptr<NodeImpl> arg_node_ptr) {
  static_assert(Kokkos::Impl::is_specialization_of_v<NodeImpl, GraphNodeImpl>);
  KOKKOS_EXPECTS(arg_node_ptr);
  // The Kernel launch from the execute() method has been shimmed to insert
  // the node into the graph
  auto& kernel = arg_node_ptr->get_kernel();
  auto& node   = static_cast<node_details_t*>(arg_node_ptr.get())->node;
  KOKKOS_EXPECTS(!node);
  kernel.set_sycl_graph_ptr(&m_graph);
  kernel.set_sycl_graph_node_ptr(&node);
  kernel.execute();
  KOKKOS_ENSURES(node);
  m_nodes.push_back(std::move(arg_node_ptr));
}

template <class NodeImpl>
std::enable_if_t<
    Kokkos::Impl::is_graph_then_host_v<typename NodeImpl::kernel_type>>
GraphImpl<Kokkos::SYCL>::add_node(std::shared_ptr<NodeImpl> arg_node_ptr) {
  static_assert(Kokkos::Impl::is_specialization_of_v<NodeImpl, GraphNodeImpl>);
  KOKKOS_EXPECTS(arg_node_ptr);

  auto& kernel = arg_node_ptr->get_kernel();
  kernel.add_to_graph(m_graph);
  static_cast<node_details_t*>(arg_node_ptr.get())->node = kernel.m_node;

  m_nodes.push_back(std::move(arg_node_ptr));
}

template <class NodeImpl>
std::enable_if_t<
    Kokkos::Impl::is_graph_capture_v<typename NodeImpl::kernel_type>>
GraphImpl<Kokkos::SYCL>::add_node(const Kokkos::SYCL& exec,
                                  std::shared_ptr<NodeImpl> arg_node_ptr) {
  static_assert(Kokkos::Impl::is_specialization_of_v<NodeImpl, GraphNodeImpl>);
  KOKKOS_EXPECTS(arg_node_ptr);

  auto& kernel = arg_node_ptr->get_kernel();
  kernel.capture(exec, m_graph);
  static_cast<node_details_t*>(arg_node_ptr.get())->node = kernel.m_node;

  m_nodes.push_back(std::move(arg_node_ptr));
}

// Requires PredecessorRef is a specialization of GraphNodeRef that has
// already been added to this graph and NodeImpl is a specialization of
// GraphNodeImpl that has already been added to this graph.
template <class NodeImplPtr, class PredecessorRef>
inline void GraphImpl<Kokkos::SYCL>::add_predecessor(
    NodeImplPtr arg_node_ptr, PredecessorRef arg_pred_ref) {
  KOKKOS_EXPECTS(arg_node_ptr);
  auto pred_ptr = GraphAccess::get_node_ptr(arg_pred_ref);
  KOKKOS_EXPECTS(pred_ptr);

  auto& pred_node = pred_ptr->node_details_t::node;
  KOKKOS_EXPECTS(pred_node);

  auto& node = arg_node_ptr->node_details_t::node;
  KOKKOS_EXPECTS(node);

  // NOLINTNEXTLINE(bugprone-unchecked-optional-access)
  m_graph.make_edge(*pred_node, *node);
}

inline void GraphImpl<Kokkos::SYCL>::submit(const Kokkos::SYCL& exec) {
  if (!m_graph_exec) {
    instantiate();
  }
  KOKKOS_ASSERT(m_graph_exec);

  // NOLINTNEXTLINE(bugprone-unchecked-optional-access)
  exec.sycl_queue().ext_oneapi_graph(*m_graph_exec);
}

inline auto GraphImpl<Kokkos::SYCL>::get_device_handle() const noexcept
    -> device_handle_t const& {
  return m_device_handle;
}

inline auto GraphImpl<Kokkos::SYCL>::create_root_node_ptr() {
  KOKKOS_EXPECTS(!m_graph_exec);
  auto rv = std::make_shared<root_impl_t<Kokkos::SYCL>>(
      m_device_handle, _graph_node_is_root_ctor_tag{});
  rv->node_details_t::node = m_graph.add();
  return rv;
}

template <class... PredecessorRefs>
inline auto GraphImpl<Kokkos::SYCL>::create_aggregate_ptr(
    PredecessorRefs&&...) {
  // The attachment to predecessors, which is all we really need, happens
  // in the generic layer, which calls through to add_predecessor for
  // each predecessor ref, so all we need to do here is create the (trivial)
  // aggregate node.
  return std::make_shared<aggregate_node_impl_t>(
      m_device_handle, _graph_node_kernel_ctor_tag{}, aggregate_impl_t{});
}
}  // namespace Impl
}  // namespace Kokkos

#endif
