#include "Shader.h"
#include <fstream>
#include <sstream>
#include <iostream>

#include <glm/gtc/type_ptr.hpp>
#include <GL/glew.h>
#include <glm/glm.hpp>

// Shader constructor
Shader::Shader(const GLchar* vertexPath, const GLchar* fragmentPath)
{
    // 1. Retrieve the vertex/fragment source code from filePath
    std::string vertexCode;
    std::string fragmentCode;
    std::ifstream vShaderFile;
    std::ifstream fShaderFile;

    // Ensure ifstream objects can throw exceptions
    vShaderFile.exceptions(std::ifstream::failbit | std::ifstream::badbit);
    fShaderFile.exceptions(std::ifstream::failbit | std::ifstream::badbit);
    try
    {
        // Open files
        vShaderFile.open(vertexPath);
        fShaderFile.open(fragmentPath);
        std::stringstream vShaderStream, fShaderStream;
        // Read file's buffer contents into streams
        vShaderStream << vShaderFile.rdbuf();
        fShaderStream << fShaderFile.rdbuf();
        // Close file handlers
        vShaderFile.close();
        fShaderFile.close();
        // Convert stream into string
        vertexCode = vShaderStream.str();
        fragmentCode = fShaderStream.str();
    }
    catch (std::ifstream::failure& e)
    {
        std::cerr << "ERROR::SHADER::FILE_NOT_SUCCESSFULLY_READ\n";
    }
    const GLchar* vShaderCode = vertexCode.c_str();
    const GLchar* fShaderCode = fragmentCode.c_str();

    // 2. Compile shaders
    GLuint vertex, fragment;
    GLint success;
    GLchar infoLog[512];

    // Vertex Shader
    vertex = glCreateShader(GL_VERTEX_SHADER);
    glShaderSource(vertex, 1, &vShaderCode, NULL);
    glCompileShader(vertex);
    // Check compile errors
    glGetShaderiv(vertex, GL_COMPILE_STATUS, &success);
    if (!success)
    {
        glGetShaderInfoLog(vertex, 512, NULL, infoLog);
        std::cerr << "ERROR::SHADER::VERTEX::COMPILATION_FAILED\n" << infoLog << '\n';
    }

    // Fragment Shader
    fragment = glCreateShader(GL_FRAGMENT_SHADER);
    glShaderSource(fragment, 1, &fShaderCode, NULL);
    glCompileShader(fragment);
    // Check compile errors
    glGetShaderiv(fragment, GL_COMPILE_STATUS, &success);
    if (!success)
    {
        glGetShaderInfoLog(fragment, 512, NULL, infoLog);
        std::cerr << "ERROR::SHADER::FRAGMENT::COMPILATION_FAILED\n" << infoLog << '\n';
    }

    // Shader Program
    Program = glCreateProgram();
    glAttachShader(Program, vertex);
    glAttachShader(Program, fragment);
    glLinkProgram(Program);
    // Check linking errors
    glGetProgramiv(Program, GL_LINK_STATUS, &success);
    if (!success)
    {
        glGetProgramInfoLog(Program, 512, NULL, infoLog);
        std::cerr << "ERROR::SHADER::PROGRAM::LINKING_FAILED\n" << infoLog << '\n';
    }

    // Delete the shaders
    glDeleteShader(vertex);
    glDeleteShader(fragment);
}

// Activate the shader
void Shader::Use()
{
    glUseProgram(Program);
}

// Set integer uniform
void Shader::setInt(const std::string& name, int value) const
{
    glUniform1i(glGetUniformLocation(Program, name.c_str()), value);
}

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

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

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

void Shader::SetVec3(const std::string &name, const glm::vec3 &value) const
{ 
    glUniform3fv(glGetUniformLocation(Program, name.c_str()), 1, glm::value_ptr(value)); 
}