#include "shader.h"

#include <glad/glad.h>
#include <glm/glm.hpp>
#include <glm/gtc/type_ptr.hpp>

#include <string>
#include <fstream>
#include <sstream>
#include <iostream>

Shader::Shader(const char* vertex_path, const char* fragment_path)
{
    // 1. retrieve the vertex/fragment source code from filePath
    std::string vertex_code;
    std::string fragment_code;
    std::ifstream vertex_shader_file;
    std::ifstream fragment_shader_file;
    // ensure ifstream objects can throw exceptions:
    vertex_shader_file.exceptions(std::ifstream::failbit | std::ifstream::badbit);
    fragment_shader_file.exceptions(std::ifstream::failbit | std::ifstream::badbit);
    try {
        // open files
        vertex_shader_file.open(vertex_path);
        fragment_shader_file.open(fragment_path);
        std::stringstream vertex_shader_stream;
        std::stringstream fragment_shader_stream;
        // read file's buffer contents into streams
        vertex_shader_stream << vertex_shader_file.rdbuf();
        fragment_shader_stream << fragment_shader_file.rdbuf();
        // close file handlers
        vertex_shader_file.close();
        fragment_shader_file.close();
        // convert stream into string
        vertex_code = vertex_shader_stream.str();
        fragment_code = fragment_shader_stream.str();
    } catch (std::ifstream::failure e) {
        std::cout << "ERROR::SHADER::FILE_NOT_SUCCESFULLY_READ" << std::endl;
    }
    const char* vertex_shader_code = vertex_code.c_str();
    const char* fragment_shader_code = fragment_code.c_str();

    // 2. compile shaders
    unsigned int vertex, fragment;
    int success;
    char infoLog[512];

    // vertex Shader
    vertex = glCreateShader(GL_VERTEX_SHADER);
    glShaderSource(vertex, 1, &vertex_shader_code, NULL);
    glCompileShader(vertex);
    // print compile errors if any
    glGetShaderiv(vertex, GL_COMPILE_STATUS, &success);
    if (!success) {
        glGetShaderInfoLog(vertex, 512, NULL, infoLog);
        std::cout << "ERROR::SHADER::VERTEX::COMPILATION_FAILED\n" << infoLog << std::endl;
    };

    // similiar for Fragment Shader
    fragment = glCreateShader(GL_FRAGMENT_SHADER);
    glShaderSource(fragment, 1, &fragment_shader_code, NULL);
    glCompileShader(fragment);
    // print compile errors if any
    glGetShaderiv(vertex, GL_COMPILE_STATUS, &success);
    if (!success) {
        glGetShaderInfoLog(vertex, 512, NULL, infoLog);
        std::cout << "ERROR::SHADER::FRAGMENT::COMPILATION_FAILED\n" << infoLog << std::endl;
    };

    // shader Program
    m_id = glCreateProgram();
    glAttachShader(m_id, vertex);
    glAttachShader(m_id, fragment);
    glLinkProgram(m_id);
    // print linking errors if any
    glGetProgramiv(m_id, GL_LINK_STATUS, &success);
    if (!success) {
        glGetProgramInfoLog(m_id, 512, NULL, infoLog);
        std::cout << "ERROR::SHADER::PROGRAM::LINKING_FAILED\n" << infoLog << std::endl;
    }

    // delete the shaders as they're linked into our program now and no longer necessary
    glDeleteShader(vertex);
    glDeleteShader(fragment);
}

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

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

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

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

void Shader::set_mat4(const std::string& name, glm::mat4 value) const
{
    glUniformMatrix4fv(glGetUniformLocation(m_id, name.c_str()), 1, GL_FALSE, glm::value_ptr(value));
}