#include <engine.hpp>

#include <chrono>
#include <cstdio>
#include <memory>
#include <string>
#include <thread>
#include <vector>

#include <boundard.hpp>
#include <camera.hpp>
#include <sprite_actor.hpp>

namespace boundard {
namespace {

std::shared_ptr<Actor> create_actor(const ActorConfig& actor_config, Game& game,
                                    BehaviorRegistry& behaviors) {
    auto mesh = std::make_shared<Mesh>();
    if (actor_config.mesh.shape == "quad") {
        *mesh = Mesh::quad();
    } else {
        // 当前渲染器只提供 quad；未知形状先按 quad 创建，便于后续扩展。
        *mesh = Mesh::quad();
    }
    mesh->set_color(actor_config.mesh.color);
    mesh->texture = actor_config.mesh.texture;

    std::shared_ptr<Actor> actor;
    if (actor_config.type == "camera") {
        actor = std::make_shared<Camera>(actor_config.name, game);
    } else {
        actor = std::make_shared<SpriteActor>(actor_config.name, game, mesh);
    }
    actor->set_position(actor_config.position);
    actor->set_facing(actor_config.facing);
    if (auto* camera = dynamic_cast<Camera*>(actor.get())) {
        camera->set_zoom(actor_config.zoom);
    }

    for (const ActorConfig& child_config : actor_config.children) {
        actor->add_child(create_actor(child_config, game, behaviors));
    }

    if (!actor_config.init_function.empty()) {
        auto handler = behaviors.init(actor_config.init_function);
        if (handler) {
            actor->set_init_handler(std::move(handler));
        } else {
            std::fprintf(stderr, "未找到 init 处理函数: %s\n",
                         actor_config.init_function.c_str());
        }
    }

    if (!actor_config.tick_function.empty()) {
        auto handler = behaviors.tick(actor_config.tick_function);
        if (handler) {
            actor->set_tick_handler(std::move(handler));
        } else {
            std::fprintf(stderr, "未找到 tick 处理函数: %s\n",
                         actor_config.tick_function.c_str());
        }
    }

    return actor;
}

std::shared_ptr<Scene> build_scene(const SceneConfig& scene, Game& game,
                                   BehaviorRegistry& behaviors) {
    auto runtime_scene = std::make_shared<Scene>(scene.name);

    if (scene.grid_background) {
        auto grid = std::make_shared<SpriteActor>("__grid", game,
                                                  std::make_shared<Mesh>(Mesh::grid()));
        grid->mesh()->set_color({0.20F, 0.28F, 0.36F, 0.75F});
        runtime_scene->add_actor(std::move(grid));
    }

    for (const ActorConfig& actor_config : scene.actors) {
        auto actor = create_actor(actor_config, game, behaviors);
        runtime_scene->add_actor(std::move(actor));
    }
    runtime_scene->set_default_camera(scene.default_camera);

    return runtime_scene;
}

const SceneConfig* find_scene(const std::vector<SceneConfig>& scenes,
                              const std::string& name) {
    for (const SceneConfig& scene : scenes) {
        if (scene.name == name) {
            return &scene;
        }
    }
    return nullptr;
}

}  // namespace

int run_engine(int argc, char** argv, const char* default_config_path) {
    std::string config_path = default_config_path != nullptr ? default_config_path : "config.ceg";
    if (argc > 1) {
        config_path = argv[1];
    }

    ConfigLoader loader;
    if (!loader.load(config_path)) {
        std::fprintf(stderr, "%s\n", loader.last_error().c_str());
        return 1;
    }

    const GameConfig& config = loader.config();
    Game& game = Game::getInstance();
    BehaviorRegistry& behaviors = BehaviorRegistry::getInstance();

    std::vector<SceneConfig> scenes = config.scenes;
    if (scenes.empty() && !config.actors.empty()) {
        SceneConfig legacy;
        legacy.name = "default";
        legacy.path = config_path;
        legacy.actors = config.actors;
        scenes.push_back(std::move(legacy));
    }

    std::string start_scene = config.start_scene;
    if (start_scene.empty() && !scenes.empty()) {
        start_scene = scenes.front().name;
    }

    const SceneConfig* active_scene = find_scene(scenes, start_scene);
    if (active_scene == nullptr && !scenes.empty()) {
        active_scene = &scenes.front();
        std::fprintf(stderr, "未找到起始场景 %s，已回退到 %s\n", start_scene.c_str(),
                     active_scene->name.c_str());
    }

    // 把配置文件中的场景包装为运行时 Scene，并注册到 Game。
    for (const SceneConfig& scene_config : scenes) {
        std::shared_ptr<Scene> runtime_scene = build_scene(scene_config, game, behaviors);
        game.add_scene(std::move(runtime_scene));
    }

    render::RenderLoop render_loop;
    for (const InputBindingConfig& binding : config.input_bindings) {
        render_loop.input().add_action(binding.action);
        for (int key : binding.keys) {
            render_loop.input().bind_key(binding.action, key);
        }
        for (int button : binding.mouse_buttons) {
            render_loop.input().bind_mouse_button(binding.action, button);
        }
    }

    // 引擎级默认退出动作，不包含具体游戏逻辑。
    render_loop.input().add_action("quit");
    render_loop.input().bind_key("quit", 256);

    auto apply_scene = [&](const std::string& name) {
        std::shared_ptr<Scene> scene = game.scene(name);
        if (scene == nullptr) {
            std::fprintf(stderr, "未找到场景: %s\n", name.c_str());
            return;
        }

        scene->initialize();
        game.set_current_scene(scene);
        render_loop.set_actors(scene->actors());
        render_loop.set_camera(scene->primary_camera());
    };

    if (active_scene != nullptr) {
        apply_scene(active_scene->name);
    }

    render_loop.start(config.window.width, config.window.height,
                      config.window.title.c_str());

    auto last = std::chrono::steady_clock::now();
    while (!render_loop.should_close()) {
        render_loop.poll_events();
        if (render_loop.input().is_action_just_pressed("quit")) {
            break;
        }

        const std::string requested_scene = game.take_scene_request();
        if (!requested_scene.empty() && requested_scene != game.current_scene_name()) {
            apply_scene(requested_scene);
        }

        const auto now = std::chrono::steady_clock::now();
        const float dt = std::chrono::duration<float>(now - last).count();
        last = now;

        std::shared_ptr<Scene> scene = game.current_scene();
        if (scene != nullptr) {
            scene->process(dt, render_loop.input());
        }

        render_loop.input().end_frame();
        std::this_thread::sleep_for(std::chrono::milliseconds(2));
    }

    render_loop.stop();
    return 0;
}

}  // namespace boundard