#pragma once
#include <string>
#include <vector>
#include <memory>
#include <GL/glew.h>
#include <functional>
#include "glm/gtc/type_ptr.hpp"

#include "Light.h"
#include "SceneContext.h"
#include "Loader.h"
#include "Texture.h"

enum ShaderFlags
{
	NO_UNIFORM = 0,
	KD_FLAG = 1,
	KA_FLAG = 2,
	KS_FLAG = 4,
	SHINE_FLAG = 8,
	MVP_FLAG = 16,
	NORMAL_MAT_FLAG = 32,
	MODELVIEW_FLAG = 64,
	LIGHTS_FLAG = 128,	
	MODEL_MATRIX_FLAG = 256,
	SKYBOX_TEX_FLAG = 512,	
};

class Shader
{
public:
	Shader() {};
	Shader(const std::string vtx_name, const std::string frag_name);
	~Shader();
	
	int uniformFlags = KD_FLAG | KA_FLAG | KS_FLAG | SHINE_FLAG | MVP_FLAG | NORMAL_MAT_FLAG | MODELVIEW_FLAG | LIGHTS_FLAG;	
	Light::LightType light_type = Light::LightType::BASE;
	Material mat;

	void enable();
	void disable();

	int addSubroutine(GLenum shadertype, const std::string uniformName);
	void enableSubroutine(const std::string uniformName);

	
public:
	void setUniforms(SceneContext ctx);	

	void addUniform(const std::string name, glm::vec3 data)
	{
		_program.use(); glUniform3fv(_program.addUniform(name), 1, glm::value_ptr(data)); 
	}

	void addUniform(const std::string name, int data)
	{
		_program.use(); glUniform1i(_program.addUniform(name), data);
	}

	void addUniform(const std::string name, float data)
	{
		_program.use(); glUniform1fv(_program.addUniform(name), 1, &data); 
	}

	void addUniform(const std::string name, glm::mat4x4 &data)
	{
		_program.use(); glUniformMatrix4fv(_program.addUniform(name), 1, GL_FALSE, glm::value_ptr(data));
	}

	void applyTextureMaterial(Texture &tex)
	{				
		if (mat.enabled)
		{
			addUniform("Ka", tex.mat.ka);
			addUniform("Kd", tex.mat.kd);
			addUniform("Ks", tex.mat.ks);
		}
	}

private:
	void setMaterial(SceneContext ctx);
	void setCamera(SceneContext ctx);
	void setLights(SceneContext ctx);
	
	ShaderProgram _program;
};