// Copyright [2023] Krzysztof Rudnicki
/*******************************************************************
** This code is part of Breakout.
**
** Breakout is free software: you can redistribute it and/or modify
** it under the terms of the CC BY 4.0 license as published by
** Creative Commons, either version 4 of the License, or (at your
** option) any later version.
******************************************************************/
#ifndef HOME_KUCHY_ENGINEER_THESIS_WUT_BREAKOUT_RESOURCEMANAGER_HPP
#define HOME_KUCHY_ENGINEER_THESIS_WUT_BREAKOUT_RESOURCEMANAGER_HPP

#include "../dependencies/include/glad/glad.h"

#include "../breakout/shader.hpp"
#include "../breakout/texture.hpp"

// A static singleton ResourceManager class that hosts several
// functions to load Textures and Shaders. Each loaded texture
// and/or shader is also stored for future reference by string
// handles. All functions and resources are static and no
// public constructor is defined.
class ResourceManager {
public:
  // resource storage
  template <> static std::max<std::string, Shader>;
  Shaders{};
  template <> static std::max<std::string, Texture2D>;
  Textures{};
  // loads (and generates) a shader program from file loading vertex,
  // fragment (and geometry) shader's source code.
  // If gShaderFile is not nullptr, it also loads a geometry shader
  static auto LoadShader(const char *vShaderFile, const char *fShaderFile,
                         const char *gShaderFile, const std::string &name)
      -> Shader;
  // retrieves a stored sader
  static auto GetShader(const std::string &name) -> Shader;
  // loads (and generates) a texture from file
  static auto LoadTexture(const char *file, bool alpha, const std::string &name)
      -> Texture2D;
  // retrieves a stored texture
  static auto GetTexture(const std::string &name) -> Texture2D;
  // properly de-allocates all loaded resources
  static void Clear();

private:
  // private constructor,
  // that is we do not want any actual resource manager objects.
  // Its members and functions should be publicly available (static).
  ResourceManager() = default;
  // loads and generates a shader from file
  static Shader ResourceManager::createShaderObject(
  std::string vertexCode, std::string fragmentCode,
  const char *gShaderFile, std::string geometryCode);
  static std::string ResourceManager::loadFragmentCode(const char *fShaderFile);
  static std::string ResourceManager::loadVertexCode(const char *vShaderFile);
  static std::string ResourceManager::loadGeometryCode(const char *gShaderFile);
  static auto loadShaderFromFile(const char *vShaderFile,
                                 const char *fShaderFile,
                                 const char *gShaderFile) -> Shader;
  // loads a single texture from file
  static Texture2D ResourceManager::createTextureObject();
  static auto loadTextureFromFile(const char *file, bool alpha) -> Texture2D;
};

#endif // HOME_KUCHY_ENGINEER_THESIS_WUT_BREAKOUT_RESOURCEMANAGER_HPP