#include "shader.hpp"

#ifndef GLAD
#define GLAD
#include <glad/glad.h>
#endif 

char* readFile(const char * fileName){
	std::ifstream file;
	file.open(fileName);
	if (!file.is_open()){
		std::cerr << "Error reading "<<  fileName << std::endl;
		exit(1);
	}

	//Get the length of the vs file
	file.seekg(0,std::ios_base::end);
	int fileLength = (int)file.tellg()+1;
	file.seekg(0);

	char* text=(char*)malloc(fileLength);
	file.read(text,fileLength);
	text[fileLength-1]='\0';
	return text;

}

Shader::Shader(){}
Shader::Shader(const char* vsFileName, const char* fsFileName){
	char* vsSource = readFile(vsFileName);
	char* fsSource = readFile(fsFileName);

	unsigned int vs = glCreateShader(GL_VERTEX_SHADER);
	unsigned int fs = glCreateShader(GL_FRAGMENT_SHADER);

	glShaderSource(vs, 1, &vsSource, NULL);
	glShaderSource(fs, 1, &fsSource, NULL);
	
	int success;
	char log[512];


	glCompileShader(fs);
	free(fsSource);

	glGetShaderiv(fs, GL_COMPILE_STATUS, &success);
	if(!success){
		glGetShaderInfoLog(fs, 512, NULL, log);
		std::cerr << "Error compiling fragment shader: " << log << std::endl;
		exit(1);
	}

	glCompileShader(vs);
	free(vsSource);

	glGetShaderiv(vs, GL_COMPILE_STATUS, &success);
	if(!success){
		glGetShaderInfoLog(vs, 512, NULL, log);
		std::cerr << "Error compiling vertex shader: " << log << std::endl;
		exit(1);
	}

	ID = glCreateProgram();
	glAttachShader(ID,vs);
	glAttachShader(ID,fs);
	glLinkProgram(ID);
	glGetProgramiv(ID, GL_LINK_STATUS, &success);
	if(!success){
		glGetProgramInfoLog(ID,512,NULL,log);
		std::cerr << "Error linking shaders: " << log << std::endl;
		exit(1);
	}
	glDeleteShader(vs);
	glDeleteShader(fs);
	
}

void Shader::activate(){
	glUseProgram(ID);
}

void Shader::setUniformFloat(const char* name, float value){
	glUniform1f(glGetUniformLocation(ID,name),value);
}
void Shader::setUniformVec3(const char* name, Vector3f value){
	glUniform3f(glGetUniformLocation(ID,name),value.x,value.y,value.z);
}
void Shader::setUniformMat4(const char* name, Matrix4f value){
	glUniformMatrix4fv(glGetUniformLocation(ID,name),1,GL_TRUE,&value.M[0][0]);
}
void Shader::shutdown(){
	glDeleteShader(ID);
}