#pragma once 

#include <map>
#include <string>

#include <glad/glad.h>

#include "texture2d.h"
#include "shader.h"


// 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
    static std::map<std::string, Shader>    Shaders;
    static std::map<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 Shader    LoadShader(const char *vShaderFile, const char *fShaderFile, const char *gShaderFile, std::string name);
    // retrieves a stored sader
    static Shader    GetShader(std::string name);
    // loads (and generates) a texture from file
    static Texture2D LoadTexture(const char *file, bool alpha, std::string name);
    // retrieves a stored texture
    static Texture2D GetTexture(std::string name);
    // 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() { }
    // loads and generates a shader from file
    static Shader    loadShaderFromFile(const char *vShaderFile, const char *fShaderFile, const char *gShaderFile = nullptr);
    // loads a single texture from file
    static Texture2D loadTextureFromFile(const char *file, bool alpha);
};