#include "shader.hpp"

GLuint LoadShaders(const char * vertex_file_path, const char * fragment_file_path) {

	// Create the shaders
	GLuint VertexShaderID = glCreateShader(GL_VERTEX_SHADER);
	GLuint FragmentShaderID = glCreateShader(GL_FRAGMENT_SHADER);

	// Read the Vertex Shader code from the file
	std::string VertexShaderCode;
	std::ifstream VertexShaderStream(vertex_file_path, std::ios::in);
	if (VertexShaderStream.is_open()) {
		std::stringstream sstr;
		sstr << VertexShaderStream.rdbuf();
		VertexShaderCode = sstr.str();
		VertexShaderStream.close();
	} else {
		timestampedCout("shader.cpp: Impossible to open " << vertex_file_path << ". Are you in the right directory?");
		return 0;
	}

	// Read the Fragment Shader code from the file
	std::string FragmentShaderCode;
	std::ifstream FragmentShaderStream(fragment_file_path, std::ios::in);
	if(FragmentShaderStream.is_open()){
		std::stringstream sstr;
		sstr << FragmentShaderStream.rdbuf();
		FragmentShaderCode = sstr.str();
		FragmentShaderStream.close();
	}

	GLint Result = GL_FALSE;
	int InfoLogLength;


	// Compile Vertex Shader
	timestampedCout("shader.cpp: Compiling shader: " << vertex_file_path << "...");
	char const * VertexSourcePointer = VertexShaderCode.c_str();
	glShaderSource(VertexShaderID, 1, &VertexSourcePointer , NULL);
	glCompileShader(VertexShaderID);

	// Check Vertex Shader
	glGetShaderiv(VertexShaderID, GL_COMPILE_STATUS, &Result);
	glGetShaderiv(VertexShaderID, GL_INFO_LOG_LENGTH, &InfoLogLength);
	if (InfoLogLength > 0) {
		std::vector<char> VertexShaderErrorMessage(InfoLogLength + 1);
		glGetShaderInfoLog(VertexShaderID, InfoLogLength, NULL, &VertexShaderErrorMessage[0]);
		timestampedCout("shader.cpp: VertexErrorMessage " << &VertexShaderErrorMessage[0]);
	}



	// Compile Fragment Shader
	timestampedCout("shader.cpp: Compiling shader: " << fragment_file_path << "...");
	char const * FragmentSourcePointer = FragmentShaderCode.c_str();
	glShaderSource(FragmentShaderID, 1, &FragmentSourcePointer , NULL);
	glCompileShader(FragmentShaderID);

	// Check Fragment Shader
	glGetShaderiv(FragmentShaderID, GL_COMPILE_STATUS, &Result);
	glGetShaderiv(FragmentShaderID, GL_INFO_LOG_LENGTH, &InfoLogLength);
	if (InfoLogLength > 0) {
		std::vector<char> FragmentShaderErrorMessage(InfoLogLength + 1);
		glGetShaderInfoLog(FragmentShaderID, InfoLogLength, NULL, &FragmentShaderErrorMessage[0]);
		timestampedCout("shader.cpp: FragmentShaderErrorMessage " << &FragmentShaderErrorMessage[0]);
	}



	// Link the program
	timestampedCout("shader.cpp: Linking program...");
	GLuint ProgramID = glCreateProgram();
	glAttachShader(ProgramID, VertexShaderID);
	glAttachShader(ProgramID, FragmentShaderID);
	glLinkProgram(ProgramID);

	// Check the program
	glGetProgramiv(ProgramID, GL_LINK_STATUS, &Result);
	glGetProgramiv(ProgramID, GL_INFO_LOG_LENGTH, &InfoLogLength);
	if (InfoLogLength > 0){
		std::vector<char> ProgramErrorMessage(InfoLogLength + 1);
		glGetProgramInfoLog(ProgramID, InfoLogLength, NULL, &ProgramErrorMessage[0]);
		timestampedCout("shader.cpp: ProgramErrorMessage " << &ProgramErrorMessage[0]);
	}

	
	glDetachShader(ProgramID, VertexShaderID);
	glDetachShader(ProgramID, FragmentShaderID);
	
	glDeleteShader(VertexShaderID);
	glDeleteShader(FragmentShaderID);

	return ProgramID;
}