package lwjglgame;

import org.lwjgl.*;
import org.lwjgl.glfw.*;
import org.lwjgl.opengl.*;
import org.lwjgl.system.*;

import java.nio.*;

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

public class Main {

    // The window handle
    private long window;

    public void run(){
        System.out.println("lwjgl " + Version.getVersion() + "");

        init();
        loop();

        glfwFreeCallbacks(window);
        glfwDestroyWindow(window);

        glfwTerminate();
        glfwSetErrorCallback(null).free();
    }

    private void init(){
        GLFWErrorCallback.createPrint(System.err).set();

        if(!glfwInit())
            throw new IllegalStateException("unable to init glfw");

        glfwSetKeyCallback(window, (window, key, scancode, action, mode) -> {
            if ( key == GLFW_KEY_ESCAPE && action == GLFW_RELEASE )
                glfwSetWindowShouldClose(window, true);
        });

        try(MemoryStack stack = stackPush()){
            IntBuffer pwidth = stack.mallocInt(1);
            IntBuffer pheight = stack.mallocInt(1);

            glfwGetWindowSize(window, pwidth, pheight);
            GLFWVidMode vidmode = glfwGetVideoMode(glfwGetPrimaryMonitor());


            glfwSetWindowPos(
                    window,
                    (vidmode.width() - pwidth.get(0)) / 2,
                    (vidmode.height() - pheight.get(0)) / 2
            );
        }

        glfwMakeContextCurrent(window);
        glfwSwapInterval(1);
        glfwShowWindow(window);
    }

    private void loop(){
        GL.createCapabilities();

        glClearColor(1.0f, 0.0f, 0.0f, 0.0f);

        while(!glfwWindowShouldClose(window)){
            glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

            glfwSwapBuffers(window);

            glfwPollEvents();
        }
    }

    public static void main(String[] args) {
        new Main().run();
    }
}