// SPDX-FileCopyrightText: Copyright 2018 yuzu Emulator Project
// SPDX-License-Identifier: GPL-2.0-or-later

#pragma once

#include <array>
#include <functional>
#include <memory>
#include <optional>
#include <span>
#include <string>
#include <type_traits>
#include <vector>

#include "common/assert.h"
#include "common/common_types.h"
#include "common/concepts.h"
#include "common/swap.h"
#include "core/hle/ipc.h"
#include "core/hle/kernel/svc_common.h"

union Result;

namespace Core::Memory {
class Memory;
}

namespace IPC {
class ResponseBuilder;
}

namespace Service {
class ServiceFrameworkBase;
class ServerManager;
} // namespace Service

namespace Kernel {
class KAutoObject;
class KernelCore;
class KHandleTable;
class KServerSession;
class KThread;
} // namespace Kernel

namespace Service {

using Handle = Kernel::Handle;

class HLERequestContext;

/**
 * Interface implemented by HLE Session handlers.
 * This can be provided to a ServerSession in order to hook into several relevant events
 * (such as a new connection or a SyncRequest) so they can be implemented in the emulator.
 */
class SessionRequestHandler : public std::enable_shared_from_this<SessionRequestHandler> {
public:
    SessionRequestHandler(Kernel::KernelCore& kernel_, const char* service_name_);
    virtual ~SessionRequestHandler();

    /**
     * Handles a sync request from the emulated application.
     * @param server_session The ServerSession that was triggered for this sync request,
     * it should be used to differentiate which client (As in ClientSession) we're answering to.
     * TODO(Subv): Use a wrapper structure to hold all the information relevant to
     * this request (ServerSession, Originator thread, Translated command buffer, etc).
     * @returns Result the result code of the translate operation.
     */
    virtual Result HandleSyncRequest(Kernel::KServerSession& session,
                                     HLERequestContext& context) = 0;

protected:
    Kernel::KernelCore& kernel;
};

using SessionRequestHandlerWeakPtr = std::weak_ptr<SessionRequestHandler>;
using SessionRequestHandlerPtr = std::shared_ptr<SessionRequestHandler>;

/**
 * Manages the underlying HLE requests for a session, and whether (or not) the session should be
 * treated as a domain. This is managed separately from server sessions, as this state is shared
 * when objects are cloned.
 */
class SessionRequestManager final {
public:
    explicit SessionRequestManager(Kernel::KernelCore& kernel,
                                   Service::ServerManager& server_manager);
    ~SessionRequestManager();

    bool IsDomain() const {
        return is_domain;
    }

    void ConvertToDomain() {
        domain_handlers = {session_handler};
        is_domain = true;
    }

    void ConvertToDomainOnRequestEnd() {
        convert_to_domain = true;
    }

    std::size_t DomainHandlerCount() const {
        return domain_handlers.size();
    }

    bool HasSessionHandler() const {
        return session_handler != nullptr;
    }

    SessionRequestHandler& SessionHandler() {
        return *session_handler;
    }

    const SessionRequestHandler& SessionHandler() const {
        return *session_handler;
    }

    void CloseDomainHandler(std::size_t index) {
        if (index < DomainHandlerCount()) {
            domain_handlers[index] = nullptr;
        } else {
            ASSERT_MSG(false, "Unexpected handler index {}", index);
        }
    }

    SessionRequestHandlerWeakPtr DomainHandler(std::size_t index) const {
        ASSERT_MSG(index < DomainHandlerCount(), "Unexpected handler index {}", index);
        return domain_handlers.at(index);
    }

    void AppendDomainHandler(SessionRequestHandlerPtr&& handler) {
        domain_handlers.emplace_back(std::move(handler));
    }

    void SetSessionHandler(SessionRequestHandlerPtr&& handler) {
        session_handler = std::move(handler);
    }

    bool HasSessionRequestHandler(const HLERequestContext& context) const;

    Result HandleDomainSyncRequest(Kernel::KServerSession* server_session,
                                   HLERequestContext& context);
    Result CompleteSyncRequest(Kernel::KServerSession* server_session, HLERequestContext& context);

    Service::ServerManager& GetServerManager() {
        return server_manager;
    }

    // TODO: remove this when sm: is implemented with the proper IUserInterface
    // abstraction, creating a new C++ handler object for each session:

    bool GetIsInitializedForSm() const {
        return is_initialized_for_sm;
    }

    void SetIsInitializedForSm() {
        is_initialized_for_sm = true;
    }

private:
    bool convert_to_domain{};
    bool is_domain{};
    bool is_initialized_for_sm{};
    SessionRequestHandlerPtr session_handler;
    std::vector<SessionRequestHandlerPtr> domain_handlers;

private:
    Kernel::KernelCore& kernel;
    Service::ServerManager& server_manager;
};

/**
 * Class containing information about an in-flight IPC request being handled by an HLE service
 * implementation.
 */
class HLERequestContext {
public:
    explicit HLERequestContext(Kernel::KernelCore& kernel, Core::Memory::Memory& memory,
                               Kernel::KServerSession* session, Kernel::KThread* thread);
    ~HLERequestContext();

    /// Returns a pointer to the IPC command buffer for this request.
    [[nodiscard]] u32* CommandBuffer() {
        return cmd_buf.data();
    }

    /**
     * Returns the session through which this request was made. This can be used as a map key to
     * access per-client data on services.
     */
    [[nodiscard]] Kernel::KServerSession* Session() {
        return server_session;
    }

    /// Populates this context with data from the requesting process/thread.
    Result PopulateFromIncomingCommandBuffer(const Kernel::KHandleTable& handle_table,
                                             u32_le* src_cmdbuf);

    /// Writes data from this context back to the requesting process/thread.
    Result WriteToOutgoingCommandBuffer(Kernel::KThread& requesting_thread);

    [[nodiscard]] u32_le GetHipcCommand() const {
        return command;
    }

    [[nodiscard]] u32_le GetTipcCommand() const {
        return static_cast<u32_le>(command_header->type.Value()) -
               static_cast<u32_le>(IPC::CommandType::TIPC_CommandRegion);
    }

    [[nodiscard]] u32_le GetCommand() const {
        return command_header->IsTipc() ? GetTipcCommand() : GetHipcCommand();
    }

    [[nodiscard]] bool IsTipc() const {
        return command_header->IsTipc();
    }

    [[nodiscard]] IPC::CommandType GetCommandType() const {
        return command_header->type;
    }

    [[nodiscard]] u64 GetPID() const {
        return pid;
    }

    [[nodiscard]] u32 GetDataPayloadOffset() const {
        return data_payload_offset;
    }

    [[nodiscard]] const std::vector<IPC::BufferDescriptorX>& BufferDescriptorX() const {
        return buffer_x_desciptors;
    }

    [[nodiscard]] const std::vector<IPC::BufferDescriptorABW>& BufferDescriptorA() const {
        return buffer_a_desciptors;
    }

    [[nodiscard]] const std::vector<IPC::BufferDescriptorABW>& BufferDescriptorB() const {
        return buffer_b_desciptors;
    }

    [[nodiscard]] const std::vector<IPC::BufferDescriptorC>& BufferDescriptorC() const {
        return buffer_c_desciptors;
    }

    [[nodiscard]] const IPC::DomainMessageHeader& GetDomainMessageHeader() const {
        return domain_message_header.value();
    }

    [[nodiscard]] bool HasDomainMessageHeader() const {
        return domain_message_header.has_value();
    }

    /// Helper function to get a span of a buffer using the appropriate buffer descriptor
    [[nodiscard]] std::span<const u8> ReadBuffer(std::size_t buffer_index = 0) const;

    /// Helper function to read a copy of a buffer using the appropriate buffer descriptor
    [[nodiscard]] std::vector<u8> ReadBufferCopy(std::size_t buffer_index = 0) const;

    /// Helper function to write a buffer using the appropriate buffer descriptor
    std::size_t WriteBuffer(const void* buffer, std::size_t size,
                            std::size_t buffer_index = 0) const;

    /// Helper function to write buffer B
    std::size_t WriteBufferB(const void* buffer, std::size_t size,
                             std::size_t buffer_index = 0) const;

    /// Helper function to write buffer C
    std::size_t WriteBufferC(const void* buffer, std::size_t size,
                             std::size_t buffer_index = 0) const;

    /* Helper function to write a buffer using the appropriate buffer descriptor
     *
     * @tparam T an arbitrary container that satisfies the
     *         ContiguousContainer concept in the C++ standard library or a trivially copyable type.
     *
     * @param data         The container/data to write into a buffer.
     * @param buffer_index The buffer in particular to write to.
     */
    template <typename T, typename = std::enable_if_t<!std::is_pointer_v<T>>>
    std::size_t WriteBuffer(const T& data, std::size_t buffer_index = 0) const {
        if constexpr (Common::IsContiguousContainer<T>) {
            using ContiguousType = typename T::value_type;
            static_assert(std::is_trivially_copyable_v<ContiguousType>,
                          "Container to WriteBuffer must contain trivially copyable objects");
            return WriteBuffer(std::data(data), std::size(data) * sizeof(ContiguousType),
                               buffer_index);
        } else {
            static_assert(std::is_trivially_copyable_v<T>, "T must be trivially copyable");
            return WriteBuffer(&data, sizeof(T), buffer_index);
        }
    }

    /// Helper function to get the size of the input buffer
    [[nodiscard]] std::size_t GetReadBufferSize(std::size_t buffer_index = 0) const;

    /// Helper function to get the size of the output buffer
    [[nodiscard]] std::size_t GetWriteBufferSize(std::size_t buffer_index = 0) const;

    /// Helper function to derive the number of elements able to be contained in the read buffer
    template <typename T>
    [[nodiscard]] std::size_t GetReadBufferNumElements(std::size_t buffer_index = 0) const {
        return GetReadBufferSize(buffer_index) / sizeof(T);
    }

    /// Helper function to derive the number of elements able to be contained in the write buffer
    template <typename T>
    [[nodiscard]] std::size_t GetWriteBufferNumElements(std::size_t buffer_index = 0) const {
        return GetWriteBufferSize(buffer_index) / sizeof(T);
    }

    /// Helper function to test whether the input buffer at buffer_index can be read
    [[nodiscard]] bool CanReadBuffer(std::size_t buffer_index = 0) const;

    /// Helper function to test whether the output buffer at buffer_index can be written
    [[nodiscard]] bool CanWriteBuffer(std::size_t buffer_index = 0) const;

    [[nodiscard]] Handle GetCopyHandle(std::size_t index) const {
        return incoming_copy_handles.at(index);
    }

    [[nodiscard]] Handle GetMoveHandle(std::size_t index) const {
        return incoming_move_handles.at(index);
    }

    void AddMoveObject(Kernel::KAutoObject* object) {
        outgoing_move_objects.emplace_back(object);
    }

    void AddCopyObject(Kernel::KAutoObject* object) {
        outgoing_copy_objects.emplace_back(object);
    }

    void AddDomainObject(SessionRequestHandlerPtr object) {
        outgoing_domain_objects.emplace_back(std::move(object));
    }

    template <typename T>
    std::shared_ptr<T> GetDomainHandler(std::size_t index) const {
        return std::static_pointer_cast<T>(GetManager()->DomainHandler(index).lock());
    }

    void SetSessionRequestManager(std::weak_ptr<SessionRequestManager> manager_) {
        manager = manager_;
    }

    [[nodiscard]] std::string Description() const;

    [[nodiscard]] Kernel::KThread& GetThread() {
        return *thread;
    }

    [[nodiscard]] std::shared_ptr<SessionRequestManager> GetManager() const {
        return manager.lock();
    }

    bool GetIsDeferred() const {
        return is_deferred;
    }

    void SetIsDeferred(bool is_deferred_ = true) {
        is_deferred = is_deferred_;
    }

private:
    friend class IPC::ResponseBuilder;

    void ParseCommandBuffer(const Kernel::KHandleTable& handle_table, u32_le* src_cmdbuf,
                            bool incoming);

    std::array<u32, IPC::COMMAND_BUFFER_LENGTH> cmd_buf;
    Kernel::KServerSession* server_session{};
    Kernel::KThread* thread;

    std::vector<Handle> incoming_move_handles;
    std::vector<Handle> incoming_copy_handles;

    std::vector<Kernel::KAutoObject*> outgoing_move_objects;
    std::vector<Kernel::KAutoObject*> outgoing_copy_objects;
    std::vector<SessionRequestHandlerPtr> outgoing_domain_objects;

    std::optional<IPC::CommandHeader> command_header;
    std::optional<IPC::HandleDescriptorHeader> handle_descriptor_header;
    std::optional<IPC::DataPayloadHeader> data_payload_header;
    std::optional<IPC::DomainMessageHeader> domain_message_header;
    std::vector<IPC::BufferDescriptorX> buffer_x_desciptors;
    std::vector<IPC::BufferDescriptorABW> buffer_a_desciptors;
    std::vector<IPC::BufferDescriptorABW> buffer_b_desciptors;
    std::vector<IPC::BufferDescriptorABW> buffer_w_desciptors;
    std::vector<IPC::BufferDescriptorC> buffer_c_desciptors;

    u32_le command{};
    u64 pid{};
    u32 write_size{};
    u32 data_payload_offset{};
    u32 handles_offset{};
    u32 domain_offset{};

    std::weak_ptr<SessionRequestManager> manager{};
    bool is_deferred{false};

    Kernel::KernelCore& kernel;
    Core::Memory::Memory& memory;
};

} // namespace Service
