#include "shaderClass.h"
#include "VBO.h"

Shader::Shader(const char* vertexFile, const char* fragFile)
{
	std::string vertexCode = get_file_contents(vertexFile);
	std::string fragCode = get_file_contents(fragFile);

	const char* vertexSource = vertexCode.c_str();
	const char* fragSource = fragCode.c_str();

	unsigned int vertexShader;
	vertexShader = glCreateShader(GL_VERTEX_SHADER);
	glShaderSource(vertexShader, 1, &vertexSource, NULL);
	glCompileShader(vertexShader);

	unsigned int fragmentShader;
	fragmentShader = glCreateShader(GL_FRAGMENT_SHADER);
	glShaderSource(fragmentShader, 1, &fragSource, NULL);
	glCompileShader(fragmentShader);

	ID = glCreateProgram();
	glAttachShader(ID, vertexShader);
	glAttachShader(ID, fragmentShader);
	glLinkProgram(ID);

	glDeleteShader(vertexShader);
	glDeleteShader(fragmentShader);
}

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

void Shader::Delete()
{
	glDeleteProgram(ID);
}

std::string get_file_contents(const char* filename)
{
	std::ifstream in(filename, std::ios::binary);

	if (in) {
		std::string contents;
		in.seekg(0, std::ios::end);
		contents.resize(in.tellg());
		in.seekg(0, std::ios::beg);
		in.read(&contents[0], contents.size());
		in.close();
		return contents;
	}
	std::cout << "GETTING SHADER FILE CONTENTS FAILED\n";
	throw errno;
}