/**
 * CLASS ENGINE
 *
 * Classe principale du moteur de jeu
 *
 * @author François Autin
 *
 */
package engine;

import engine.object.ObjectGl;
import org.lwjgl.glfw.GLFWFramebufferSizeCallback;
import org.lwjgl.glfw.GLFWVidMode;
import org.lwjgl.opengl.GL;

import java.util.ArrayList;
import java.util.List;
import java.util.ListIterator;

import static org.lwjgl.glfw.GLFW.*;
import static org.lwjgl.opengl.GL11.*;
import static org.lwjgl.system.MemoryUtil.*;

public class Engine {

    private long window;

    private List<ObjectGl> objectsGl;

    private boolean running;

    /**
     * Create the engine and initial attributes use .init() to start the engine
     */
    public Engine() {
        this.running = false;
        this.objectsGl = new ArrayList<ObjectGl>();
    }

    /**
     * Start the engine
     * Create the window
     */
    private void init() {
        glfwInit();

        this.running = true;

        glfwWindowHint(GLFW_RESIZABLE, GL_TRUE);
        glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3); //On utilise la version 3.3 d'openGL
        glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
        glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE); //Compatible MAC
        glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE); //Le core profile est l'interface 'avancé' d'openGL

        int width = 1280;
        int height = 720;
        this.window = glfwCreateWindow(width, height, "Boulevard Combattant", NULL, NULL);
        assert this.window != NULL;

        // On récupère les informations du moniteur principal
        GLFWVidMode vidmode = glfwGetVideoMode(glfwGetPrimaryMonitor());
        assert vidmode != null;

        // On met la fenêtre au centre de l'écran principale
        glfwSetWindowPos(this.window, (vidmode.width() - width)/2, (vidmode.height() - height)/2);

        glfwSetKeyCallback(window, new Input());
        glfwSetInputMode(window, GLFW_STICKY_KEYS, GLFW_TRUE);

        // Contexte = zone cible des rendus
        glfwMakeContextCurrent(this.window);
        glfwShowWindow(this.window);
        GL.createCapabilities();

        glfwSetFramebufferSizeCallback(window, resizeWindow);

        glEnable(GL_DEPTH_TEST); // Z-Buffer
        glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
        System.out.println("OpenGL: " + glGetString(GL_VERSION));
    }

    /**
     *
     */
    private void update(){
        glfwPollEvents();
    }

    /**
     *
     */
    private void render(){

        glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

        for (ObjectGl objectGl : objectsGl) {
            objectGl.render();
        }

        int error = glGetError();
        if (error != GL_NO_ERROR) System.out.println(error);
        glfwSwapBuffers(window); //Envoie le buffer vers le moniteur
    }

    /**
     * TODO la boucle de rendu doit être inscrite dans la boucle de gameplay: cette methode doit disparaitre
     */
    public void run(){
        while(running){
            update();
            render();
            if(glfwWindowShouldClose(window)) running = false;
        }
    }

    public void add_objectGl(ObjectGl obj){
        objectsGl.add(obj);
    }

    public void remove_objectGl(ObjectGl obj){
        objectsGl.remove(obj);
    }

    /**
     * Est appelé à chaque modification de la taille de la fenêtre, et modifie la taille de la zone de rendu
     * pour quelle corresponde à la taille de la fenêtre
     */
    private static final GLFWFramebufferSizeCallback resizeWindow = new GLFWFramebufferSizeCallback(){
        @Override
        public void invoke(long window, int width, int height){
            glViewport(0,0,width,height);
        }
    };

    public static void main(String[] args) {
        Engine engine = new Engine();
        engine.init();
        // Add objects to render
        ObjectGl cube = new ObjectGl(-0.2f,-0.2f,0.0f,1.0f,1.0f);
        engine.add_objectGl(cube);
//        engine.remove_objectGl(cube);

        engine.run();
    }

}