#include <stdlib.h>
#include <iostream>
#include <glad/glad.h>

#ifdef __linux__
#include <unistd.h>
#endif
#ifdef _WIN32
#include <windows.h>
#endif

#include "Controller.h"

Controller::Controller() {
    if(!glfwInit()) exit(-1);

    glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
    glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
    glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);

    glfwSetErrorCallback(error_callback);

    gameWindow = new Window();
    gameEventHandler = new EventHandler();
}

Controller::~Controller() {
    delete gameWindow;
    delete gameEventHandler;
    glfwTerminate();
}

void Controller::run() {
    glClearColor(0.241f, 0.578f, 0.308f, 1.0f);

    unsigned int vertexShader;
    vertexShader = glCreateShader(GL_VERTEX_SHADER);
    glShaderSource(vertexShader, 1, &vertexShaderSource, NULL);
    glCompileShader(vertexShader);

    int  success;
    char infoLog[512];
    glGetShaderiv(vertexShader, GL_COMPILE_STATUS, &success);
    if(!success) {
        glGetShaderInfoLog(vertexShader, 512, NULL, infoLog);
        std::cout << "ERROR::SHADER::VERTEX::COMPILATION_FAILED\n" << infoLog << std::endl;
    }

    unsigned int fragmentShader;
    fragmentShader = glCreateShader(GL_FRAGMENT_SHADER);
    glShaderSource(fragmentShader, 1, &fragmentShaderSource, NULL);
    glCompileShader(fragmentShader);
    glGetShaderiv(fragmentShader, GL_COMPILE_STATUS, &success);
    if(!success) {
        glGetShaderInfoLog(vertexShader, 512, NULL, infoLog);
        std::cout << "ERROR::SHADER::FRAGMENT::COMPILATION_FAILED\n" << infoLog << std::endl;
    }

    unsigned int shaderProgram;
    shaderProgram = glCreateProgram();
    glAttachShader(shaderProgram, vertexShader);
    glAttachShader(shaderProgram, fragmentShader);
    glLinkProgram(shaderProgram);
    glGetProgramiv(shaderProgram, GL_LINK_STATUS, &success);
    if(!success) {
        glGetProgramInfoLog(shaderProgram, 512, NULL, infoLog);
        std::cout << "ERROR::SHADER::PROGRAM::LINKING_FAILED\n" << infoLog << std::endl;
    }
    glDeleteShader(vertexShader);
    glDeleteShader(fragmentShader);

    unsigned int VBO, VAO;
    glGenVertexArrays(1, &VAO);
    glGenBuffers(1, &VBO);

    glBindVertexArray(VAO);

    float vertices[] = {
        -0.5f, -0.5f, 0.0f,
        0.5f, -0.5f, 0.0f,
        0.0f,  0.5f, 0.0f
    };

    glBindBuffer(GL_ARRAY_BUFFER, VBO);
    glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);

    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), (void*)0);
    glEnableVertexAttribArray(0);

    glBindBuffer(GL_ARRAY_BUFFER, 0);
    glBindVertexArray(0);


    // This is the game loop
    while(!glfwWindowShouldClose(gameWindow->getGLFWwindow())) {
        // Timing
        limit_framerate();
        std::cout << "FPS: " << 1/deltaTime << std::endl;

        // Update game

        // Render and buffer swap
        glClear(GL_COLOR_BUFFER_BIT);

        glUseProgram(shaderProgram);
        glBindVertexArray(VAO);
        glDrawArrays(GL_TRIANGLES, 0, 3);

        glfwSwapBuffers(gameWindow->getGLFWwindow());


        // Check events, handle input
        gameEventHandler->handleEvents(gameWindow->getGLFWwindow());
    }

}

void Controller::error_callback(int error, const char* description) {
    (void)error;
    fprintf(stderr, "Error: %s\n", description);
}

void Controller::limit_framerate() {
    static double startingTime = 0.0;
    static double lastTime = 0.0;

    lastTime = glfwGetTime() - startingTime;

    double frameTime = 1/(double)MAX_FPS;
    if(frameTime > lastTime) {
        #ifdef __linux__
        usleep((frameTime - lastTime) * 1000000);
        #endif
        #ifdef _WIN32
        Sleep((frameTime - lastTime) * 1000);
        #endif
    }

    deltaTime = glfwGetTime() - startingTime;

    startingTime = glfwGetTime();
}