#include "M_shader.h"

unsigned int M_loadShader(const char* filename, unsigned int shadertype)
{
	void* shader_source = SDL_LoadFile(filename, NULL);
	unsigned int shader = glCreateShader(shadertype);
	glShaderSource(shader, 1, (const char**)&shader_source, NULL);
	glCompileShader(shader);
	SDL_free(shader_source);

	int success;

	glGetShaderiv(shader, GL_COMPILE_STATUS, &success);
	if (!success) {
		printf("Couldn't compile shader\n");
		return 0;
	}

	return shader;
}

M_ShaderProgram M_createShaderProgram(const char *vertex_shader_file, const char* fragment_shader_file)
{
	unsigned int vertex_shader = M_loadShader(vertex_shader_file, GL_VERTEX_SHADER);
	unsigned int fragment_shader = M_loadShader(fragment_shader_file, GL_FRAGMENT_SHADER);
	return M_compileShaderProgram(vertex_shader, fragment_shader);
}

M_ShaderProgram M_compileShaderProgram(unsigned int vertex_shader, unsigned int fragment_shader)
{
	M_ShaderProgram shader_program;
	shader_program.prog = glCreateProgram();
	glAttachShader(shader_program.prog, vertex_shader);
	glAttachShader(shader_program.prog, fragment_shader);
	glLinkProgram(shader_program.prog);

	shader_program.vertex_shader = vertex_shader;
	shader_program.fragment_shader = fragment_shader;

	int success;
	glGetProgramiv(shader_program.prog, GL_LINK_STATUS, &success);
	if (!success) {
		printf("Couldn't link shader program\n");
	}

	shader_program.transform_loc = glGetUniformLocation(shader_program.prog, "model");
	shader_program.view_loc = glGetUniformLocation(shader_program.prog, "view");
	shader_program.projection_loc = glGetUniformLocation(shader_program.prog, "projection");

	return shader_program;
}

void M_killShaderProgram(M_ShaderProgram *shader_program)
{
	glDeleteShader(shader_program->vertex_shader);
	glDeleteShader(shader_program->fragment_shader);
}