#include<stdio.h>
#include<stdlib.h>
#include<fcntl.h>
#include<unistd.h>
#include<GL/glew.h>
#include<GLFW/glfw3.h>
#include<glm/glm.hpp>
#include<glm/gtc/matrix_transform.hpp>
#include<glm/gtc/type_ptr.hpp>
#include "scolor.hpp"
#include "util.h"

// Will be used for a lot of stuff throughout the demo
// NOTE:  general_buffer is NOT thread safe.  Don't try to load shaders in parallel!
// NOTE on the NOTE:  You probably shouldn't do that anyway!
//#define GBLEN (1024*32)
extern char general_buffer[GBLEN];

GLuint make_shader(const char *filename, GLenum shaderType){
	int fd = open(filename, O_RDONLY);
	size_t readlen = read(fd, general_buffer, GBLEN);
	close(fd);
	if(readlen == GBLEN){
		printf(RED("Buffer Length of %d bytes Inadequate for File %s\n").c_str(), GBLEN, filename);
		return 0;
	}
	general_buffer[readlen] = 0;
	printf(DGREEN("Read shader in file %s (%d bytes)\n").c_str(), filename, readlen);
	puts(general_buffer);
	unsigned int s_reference = glCreateShader(shaderType);
	char *gbc = general_buffer;
	glShaderSource(s_reference, 1, (const char**)&gbc, 0);
	glCompileShader(s_reference);
	glGetShaderInfoLog(s_reference, GBLEN, NULL, general_buffer);
	puts(general_buffer);
	GLint compile_ok;
	glGetShaderiv(s_reference, GL_COMPILE_STATUS, &compile_ok);
	if(compile_ok){
		puts(GREEN("Compile Success").c_str());
		return s_reference;
	}
	puts(RED("Compile Failed\n").c_str());
	return 0;
}

GLuint make_program(const char* v_file, const char* tcs_file, const char* tes_file, const char* g_file, const char* f_file){
	unsigned int vs_reference = make_shader(v_file, GL_VERTEX_SHADER);
	unsigned int tcs_reference = 0, tes_reference = 0;
	if(tcs_file)
	  	if(!(tcs_reference = make_shader(tcs_file, GL_TESS_CONTROL_SHADER)))
			return 0;
	if(tes_file)
		if(!(tes_reference = make_shader(tes_file, GL_TESS_EVALUATION_SHADER)))
			return 0;
	unsigned int gs_reference = 0;
	if(g_file)
		gs_reference = make_shader(g_file, GL_GEOMETRY_SHADER);
	unsigned int fs_reference = make_shader(f_file, GL_FRAGMENT_SHADER);
	if(!(vs_reference && fs_reference))
		return 0;
	if(g_file && !gs_reference)
		return 0;


	unsigned int program = glCreateProgram();
	glAttachShader(program, vs_reference);
	if(g_file)
		glAttachShader(program, gs_reference);
	if(tcs_file)
		glAttachShader(program, tcs_reference);
	if(tes_file)
		glAttachShader(program, tes_reference);
	glAttachShader(program, fs_reference);
	glLinkProgram(program);
	GLint link_ok;
	glGetProgramiv(program, GL_LINK_STATUS, &link_ok);
	if(!link_ok){
		glGetProgramInfoLog(program, GBLEN, NULL, general_buffer);
		puts(general_buffer);
		puts(RED("Link Failed").c_str());
		return 0;
	}
	
	return program;
}