// Vita3K emulator project
// Copyright (C) 2026 Vita3K team
//
// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 2 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License along
// with this program; if not, write to the Free Software Foundation, Inc.,
// 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.

#pragma once

#include <cassert>
#include <cstdint>
#include <functional>
#include <vector>

namespace renderer {
#define REPORT_MISSING(backend) LOG_ERROR("Unimplemented graphics API handler with backend {}", (int)backend)
#define REPORT_STUBBED() LOG_INFO("Stubbed")

struct Command;

using CommandAllocFunc = std::function<Command *()>;
using CommandFreeFunc = std::function<void(Command *)>;

struct Context;
struct State;

enum class CommandOpcode : std::uint8_t {
    // These two functions are sync, and taking pointer as parameter.
    CreateContext,
    CreateRenderTarget,

    MemoryMap,
    MemoryUnmap,

    /**
     * Do draw.
     */
    Draw,

    /**
     * Transfer functions
     */
    TransferCopy,
    TransferDownscale,
    TransferFill,

    /**
     * This is like a NOP. It only signals back to client.
     */
    Nop,

    /**
     * Set a GXM state.
     */
    SetState,

    SetContext,
    SyncSurfaceData,
    MidSceneFlush,

    /**
     * Signal sync object that fragment has been done.
     */
    SignalSyncObject,
    WaitSyncObject,

    SignalNotification,

    SetScreenFilter,

    /**
     * Start rendering a newframe
     */
    NewFrame,

    DestroyRenderTarget,
    DestroyContext
};

enum CommandErrorCode {
    CommandErrorCodeNone = 0,
    CommandErrorCodePending = -1,
    CommandErrorArgumentsTooLarge = -2
};

constexpr std::size_t MAX_COMMAND_DATA_SIZE = 0x20;

struct Command {
    enum {
        FLAG_FROM_HOST = 1 << 0,
        FLAG_NO_FREE = 1 << 1
    };

    CommandOpcode opcode;
    std::uint8_t flags = 0;

    std::uint8_t data[MAX_COMMAND_DATA_SIZE];
    int *status;

    Command *next = nullptr;
};

using CommandPool = std::vector<Command>;

// It's to split a command list easier when ExecuteCommandList is used.
struct CommandList {
    Command *first{ nullptr };
    Command *last{ nullptr };

    Context *context; ///< The HLE context that try to execute this buffer.
};

struct CommandHelper {
    Command *cmd;
    std::uint32_t point;

    explicit CommandHelper(Command *cmd)
        : cmd(cmd)
        , point(0) {
    }

    template <typename T>
    bool push(T &val) {
        if (point + sizeof(T) > MAX_COMMAND_DATA_SIZE) {
            return false;
        }

        *(T *)(cmd->data + point) = val;
        point += sizeof(T);

        return true;
    }

    template <typename T>
    T pop() {
        if (point + sizeof(T) > MAX_COMMAND_DATA_SIZE) {
            // Shouldn't happen
            assert(false);
        }

        T *data = (T *)(cmd->data + point);
        point += sizeof(T);

        return *data;
    }

    void complete(const int code) {
        *cmd->status = code;
    }
};

template <typename Head, typename... Args>
bool do_command_push_data(CommandHelper &helper, Head arg1, Args... args2) {
    if (!helper.push(arg1)) {
        return false;
    }

    if constexpr (sizeof...(args2) > 0) {
        return do_command_push_data(helper, args2...);
    }

    return true;
}

template <typename... Args>
Command *make_command(CommandAllocFunc alloc_func, CommandFreeFunc free_func, const CommandOpcode opcode, int *status, Args... arguments) {
    Command *new_command = alloc_func();

    new_command->opcode = opcode;
    new_command->status = status;
    new_command->next = nullptr;

    CommandHelper helper(new_command);

    if constexpr (sizeof...(arguments) > 0) {
        if (!do_command_push_data(helper, arguments...)) {
            free_func(new_command);
            return nullptr;
        }
    }

    return new_command;
}

void complete_command(State &state, CommandHelper &helper, const int code);
} // namespace renderer
