//// Bacontsu's Shader utilities - adapted for reading directly from strings.

#include "hud.h"
#include "ShaderUtil.h"
//#include "windows.h"
#include <GL/glew.h>
#include <iostream>
#include <fstream>
#include <filesystem>

#ifdef _WIN32
#include <io.h> 
#define access    _access_s
#else
#include <unistd.h>
#endif

bool FileExists(const std::string& Filename)
{
	return access(Filename.c_str(), 0) == 0;
}

//unsigned int ShaderUtil::GetCompiledShader(unsigned int shader_type, const std::string& shader_source, const std::string& path)
//{
//	unsigned int shader_id = glCreateShader(shader_type);
//
//	const char* c_source = shader_source.c_str();
//	glShaderSource(shader_id, 1, &c_source, nullptr);
//	glCompileShader(shader_id);
//
//	GLint result;
//	glGetShaderiv(shader_id, GL_COMPILE_STATUS, &result);
//
//	if (result == GL_FALSE)
//	{
//		int length;
//		glGetShaderiv(shader_id, GL_INFO_LOG_LENGTH, &length);
//
//		GLchar* strInfoLog = new GLchar[length + 1];
//		glGetShaderInfoLog(shader_id, length, &length, strInfoLog);
//
//		//fprintf(stderr, "Compilation error in shader: %s\n", strInfoLog);
//		gEngfuncs.Con_Printf("[GLEW] Compilation error in shader: %s\n[GLEW] ERROR: %s\n", path.c_str(), strInfoLog);
//
//		delete[] strInfoLog;
//	}
//	else
//		gEngfuncs.Con_Printf("[GLEW] Compiling %s shader success!\n", path.c_str());
//
//	return shader_id;
//}

unsigned int ShaderUtil::GetCompiledShader(unsigned int shader_type, const std::string& shader_source)
{
	unsigned int shader_id = glCreateShader(shader_type);

	const char* c_source = shader_source.c_str();
	glShaderSource(shader_id, 1, &c_source, nullptr);
	glCompileShader(shader_id);

	GLint result;
	glGetShaderiv(shader_id, GL_COMPILE_STATUS, &result);

	if (result == GL_FALSE)
	{
		int length;
		glGetShaderiv(shader_id, GL_INFO_LOG_LENGTH, &length);

		GLchar* strInfoLog = new GLchar[length + 1];
		glGetShaderInfoLog(shader_id, length, &length, strInfoLog);

		//fprintf(stderr, "Compilation error in shader: %s\n", strInfoLog);
		gEngfuncs.Con_Printf("[GLEW] Compilation error in shader: %d\n[GLEW] ERROR: %s\n", shader_type, strInfoLog);

		delete[] strInfoLog;
	}
	else
		gEngfuncs.Con_Printf("[GLEW] Compiling %d shader success!\n", shader_type);

	return shader_id;
}

//bool ShaderUtil::LoadFromFile(const std::string& vertexShaderFile, const std::string& fragmentShaderFile)
//{
//	std::ifstream is_vs(vertexShaderFile);
//	const std::string f_vs((std::istreambuf_iterator<char>(is_vs)), std::istreambuf_iterator<char>());
//
//	std::ifstream is_fs(fragmentShaderFile);
//	const std::string f_fs((std::istreambuf_iterator<char>(is_fs)), std::istreambuf_iterator<char>());
//
//	bool failToLoad = false;
//	if (!FileExists(vertexShaderFile))
//	{
//		gEngfuncs.Con_Printf("[GLEW] Cannot find %s shader!\n", vertexShaderFile.c_str());
//		failToLoad = true;
//	}
//	if (!FileExists(fragmentShaderFile))
//	{
//		gEngfuncs.Con_Printf("[GLEW] Cannot find %s shader!\n", fragmentShaderFile.c_str());
//		failToLoad = true;
//	}
//	if (failToLoad)
//	{
//		return false;
//	}
//
//	mProgramId = glCreateProgram();
//
//	unsigned int vs = GetCompiledShader(GL_VERTEX_SHADER, f_vs, vertexShaderFile);
//	unsigned int fs = GetCompiledShader(GL_FRAGMENT_SHADER, f_fs, fragmentShaderFile);
//
//	glAttachShader(mProgramId, vs);
//	glAttachShader(mProgramId, fs);
//
//	glLinkProgram(mProgramId);
//	glValidateProgram(mProgramId);
//
//	glDeleteShader(vs);
//	glDeleteShader(fs);
//
//	return true;
//}

bool ShaderUtil::LoadFromString(const std::string& vertexShader, const std::string& fragmentShader)
{
	mProgramId = glCreateProgram();

	unsigned int vs = GetCompiledShader(GL_VERTEX_SHADER, vertexShader);
	unsigned int fs = GetCompiledShader(GL_FRAGMENT_SHADER, fragmentShader);

	glAttachShader(mProgramId, vs);
	glAttachShader(mProgramId, fs);

	glLinkProgram(mProgramId);
	glValidateProgram(mProgramId);

	glDeleteShader(vs);
	glDeleteShader(fs);

	return true;
}

void ShaderUtil::Use()
{
	glUseProgram(mProgramId);
}

void ShaderUtil::Delete()
{
	glDeleteProgram(mProgramId);
}