#ifndef  SHADER_CLASS_H
#define SHADER_CLASS_H

#include<glad/glad.h>
#include<GLFW/glfw3.h>
#include<glm/glm.hpp>

#include<string>
#include<unordered_map>
#include<fstream>
#include  <sstream>
#include <iostream>
#include <cerrno>

std::string get_file_contents(const char* filename);

class Shader {
public:
	GLuint ID;
	Shader(const char* vertexFile, const char* fragFile);
	
	void Set1F(const char* uniform, float value) {
		glUniform1f(GetLocation(uniform), value);
	};

	void Set2F(const char* uniform, glm::vec2 value) {
		glUniform2f(GetLocation(uniform), value.x,value.y);
	};

	void Set3F(const char* uniform, glm::vec3 value) {
		glUniform3f(GetLocation(uniform), value.x,value.y,value.z);
	};
	void Set4F(const char* uniform, glm::vec4 value) {
		glUniform4f(GetLocation(uniform), value.x, value.y, value.z, value.w);
	};
	void SetMat4(const char* uniform, glm::mat4 value) {
		glUniformMatrix4fv(GetLocation(uniform),1,GL_FALSE,&value[0][0]);
	};

	// Uploads a whole uniform array in one call
	void SetMat4Array(const char* uniform, const glm::mat4* values, int count) {
		glUniformMatrix4fv(GetLocation(uniform),count,GL_FALSE,&values[0][0][0]);
	};

	void SetInt(const char* uniform, GLuint value) {
		glUniform1i(GetLocation(uniform), value);
	};

	void Activate();
	void Delete();

private:
	// Asking the driver is slow and locations never change once linked.
	// Uniforms the shader doesn't have cache as -1, which glUniform ignores.
	GLint GetLocation(const char* uniform) {
		auto existing = uniformLocations.find(uniform);
		if (existing != uniformLocations.end())
			return existing->second;

		GLint location = glGetUniformLocation(ID, uniform);
		uniformLocations.emplace(uniform, location);
		return location;
	}

	std::unordered_map<std::string, GLint> uniformLocations;
};

#endif