#ifndef SHADER_CPP
#define SHADER_CPP

#include <glad/glad.h>

#include <string>
#include <fstream>
#include <sstream>
#include <iostream>
#include "shader.hpp"

const std::string Shader::fileToShader(const std::string shaderPath) 
{
        // 1. retrieve the vertex/fragment source code from filePath
        std::string shaderCode;
        std::ifstream shaderFile;
        // ensure ifstream objects can throw exceptions:
        shaderFile.exceptions (std::ifstream::failbit | std::ifstream::badbit);
        try 
        {
            // open files
            shaderFile.open(shaderPath);
            std::stringstream shaderStream;
            // read file's buffer contents into streams
            shaderStream << shaderFile.rdbuf();
            // close file handlers
            shaderFile.close();
            // convert stream into string
            shaderCode = shaderStream.str();
        }
        catch (std::ifstream::failure& e)
        {
            std::cout << "ERROR::SHADER::FILE_NOT_SUCCESFULLY_READ: " << e.what() << std::endl;
        }
        return shaderCode;
}

Shader::Shader(const std::string vertexPath, const std::string fragmentPath)
{   
        const std::string vshaderCodeString = this -> fileToShader(vertexPath);
        const std::string fShaderCodeString = this -> fileToShader(fragmentPath);
        const char* vShaderCode = vshaderCodeString.c_str();
        const char * fShaderCode = fShaderCodeString.c_str();
        // 2. compile shaders
        unsigned int vertex, fragment;
        // vertex shader
        vertex = glCreateShader(GL_VERTEX_SHADER);
        glShaderSource(vertex, 1, &vShaderCode, NULL);
        glCompileShader(vertex);
        checkCompileErrors(vertex, "VERTEX");
        // fragment Shader
        fragment = glCreateShader(GL_FRAGMENT_SHADER);
        glShaderSource(fragment, 1, &fShaderCode, NULL);
        glCompileShader(fragment);
        checkCompileErrors(fragment, "FRAGMENT");
        // shader Program
        ID = glCreateProgram();
        glAttachShader(ID, vertex);
        glAttachShader(ID, fragment);
        glLinkProgram(ID);
        checkCompileErrors(ID, "PROGRAM");
        // delete the shaders as they're linked into our program now and no longer necessary
        glDeleteShader(vertex);
        glDeleteShader(fragment);
}

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

void Shader::setBool(const std::string &name, bool value) const
{         
    glUniform1i(glGetUniformLocation(ID, name.c_str()), (int)value); 
}

void Shader::setInt(const std::string &name, int value) const
{ 
    glUniform1i(glGetUniformLocation(ID, name.c_str()), value); 
}

void Shader::setFloat(const std::string &name, float value) const
{ 
    glUniform1f(glGetUniformLocation(ID, name.c_str()), value); 
}

void Shader::checkCompileErrors(unsigned int shader, std::string type)
{
    int success;
    char infoLog[1024];
    if (type != "PROGRAM")
    {
        glGetShaderiv(shader, GL_COMPILE_STATUS, &success);
        if (!success)
        {
            glGetShaderInfoLog(shader, 1024, NULL, infoLog);
            std::cout << "ERROR::SHADER_COMPILATION_ERROR of type: " << type << "\n" << infoLog << "\n -- --------------------------------------------------- -- " << std::endl;
        }
    }
    else
    {
        glGetProgramiv(shader, GL_LINK_STATUS, &success);
        if (!success)
        {
            glGetProgramInfoLog(shader, 1024, NULL, infoLog);
            std::cout << "ERROR::PROGRAM_LINKING_ERROR of type: " << type << "\n" << infoLog << "\n -- --------------------------------------------------- -- " << std::endl;
        }
    }
}

#endif // SHADER_CPP