Extra2D/include/graphics/shader_system.h

#pragma once

#include <core/color.h>
#include <core/types.h>
#include <graphics/opengl/gl_shader.h>
#include <functional>
#include <string>
#include <unordered_map>

namespace extra2d {

// ============================================================================
// Shader参数绑定回调
// ============================================================================
using ShaderBindCallback = std::function<void(GLShader &)>;

// ============================================================================
// Shader系统 - 管理所有Shader的加载、缓存和热重载
// ============================================================================
class ShaderSystem {
public:
  // ------------------------------------------------------------------------
  // 单例访问
  // ------------------------------------------------------------------------
  static ShaderSystem &getInstance();

  // ------------------------------------------------------------------------
  // 初始化和关闭
  // ------------------------------------------------------------------------
  bool init();
  void shutdown();

  // ------------------------------------------------------------------------
  // Shader加载
  // ------------------------------------------------------------------------

  /**
   * @brief 从文件加载Shader
   * @param name Shader名称（用于缓存）
   * @param vertPath 顶点着色器文件路径
   * @param fragPath 片段着色器文件路径
   * @return 加载的Shader，失败返回nullptr
   */
  Ptr<GLShader> loadFromFile(const std::string &name,
                             const std::string &vertPath,
                             const std::string &fragPath);

  /**
   * @brief 从源码字符串加载Shader
   * @param name Shader名称（用于缓存）
   * @param vertSource 顶点着色器源码
   * @param fragSource 片段着色器源码
   * @return 加载的Shader，失败返回nullptr
   */
  Ptr<GLShader> loadFromSource(const std::string &name,
                               const std::string &vertSource,
                               const std::string &fragSource);

  /**
   * @brief 从已编译的程序获取Shader
   * @param name Shader名称
   * @return 缓存的Shader，不存在返回nullptr
   */
  Ptr<GLShader> get(const std::string &name);

  /**
   * @brief 检查Shader是否存在
   */
  bool has(const std::string &name) const;

  // ------------------------------------------------------------------------
  // Shader移除
  // ------------------------------------------------------------------------
  void remove(const std::string &name);
  void clear();

  // ------------------------------------------------------------------------
  // 热重载支持
  // ------------------------------------------------------------------------

  /**
   * @brief 启用/禁用文件监视
   */
  void setFileWatching(bool enable);
  bool isFileWatching() const { return fileWatching_; }

  /**
   * @brief 更新文件监视（在主循环中调用）
   */
  void updateFileWatching();

  /**
   * @brief 重载指定Shader
   */
  bool reload(const std::string &name);

  /**
   * @brief 重载所有Shader
   */
  void reloadAll();

  // ------------------------------------------------------------------------
  // 内置Shader获取
  // ------------------------------------------------------------------------
  Ptr<GLShader> getBuiltinSpriteShader();
  Ptr<GLShader> getBuiltinParticleShader();
  Ptr<GLShader> getBuiltinPostProcessShader();
  Ptr<GLShader> getBuiltinShapeShader();

  // ------------------------------------------------------------------------
  // 工具方法
  // ------------------------------------------------------------------------

  /**
   * @brief 从文件读取文本内容
   */
  static std::string readFile(const std::string &filepath);

  /**
   * @brief 获取Shader文件的最后修改时间
   */
  static uint64_t getFileModifiedTime(const std::string &filepath);

private:
  ShaderSystem() = default;
  ~ShaderSystem() = default;
  ShaderSystem(const ShaderSystem &) = delete;
  ShaderSystem &operator=(const ShaderSystem &) = delete;

  struct ShaderInfo {
    Ptr<GLShader> shader;
    std::string vertPath;
    std::string fragPath;
    uint64_t vertModifiedTime;
    uint64_t fragModifiedTime;
    bool isBuiltin;
  };

  std::unordered_map<std::string, ShaderInfo> shaders_;
  bool fileWatching_ = false;
  float watchTimer_ = 0.0f;
  static constexpr float WATCH_INTERVAL = 1.0f; // 检查间隔（秒）

  // 内置Shader缓存
  Ptr<GLShader> builtinSpriteShader_;
  Ptr<GLShader> builtinParticleShader_;
  Ptr<GLShader> builtinPostProcessShader_;
  Ptr<GLShader> builtinShapeShader_;

  bool loadBuiltinShaders();
  void checkAndReload();
};

// ============================================================================
// Shader参数包装器 - 简化Uniform设置
// ============================================================================
class ShaderParams {
public:
  explicit ShaderParams(GLShader &shader);

  ShaderParams &setBool(const std::string &name, bool value);
  ShaderParams &setInt(const std::string &name, int value);
  ShaderParams &setFloat(const std::string &name, float value);
  ShaderParams &setVec2(const std::string &name, const glm::vec2 &value);
  ShaderParams &setVec3(const std::string &name, const glm::vec3 &value);
  ShaderParams &setVec4(const std::string &name, const glm::vec4 &value);
  ShaderParams &setMat4(const std::string &name, const glm::mat4 &value);
  ShaderParams &setColor(const std::string &name, const Color &color);

private:
  GLShader &shader_;
};

// ============================================================================
// 便捷宏
// ============================================================================
#define E2D_SHADER_SYSTEM() ::extra2d::ShaderSystem::getInstance()

} // namespace extra2d