package arc.backend.headless;

import arc.*;
import arc.func.*;
import arc.mock.*;
import arc.struct.*;
import arc.util.*;

/**
 * a headless implementation of an application primarily intended to be used in servers
 * @author Jon Renner
 */
public class HeadlessApplication implements Application{
    protected final MockGraphics graphics;
    protected final Seq<ApplicationListener> listeners = new Seq<>();
    protected final TaskQueue runnables = new TaskQueue();
    protected final Cons<Throwable> exceptionHandler;
    protected long renderInterval;
    protected Thread mainLoopThread;
    protected boolean running = true;

    public HeadlessApplication(ApplicationListener listener){
        this(listener, 1f / 60f, t -> { throw new RuntimeException(t); });
    }

    public HeadlessApplication(ApplicationListener listener, Cons<Throwable> exceptionHandler){
        this(listener, 1f / 60f, exceptionHandler);
    }

    public HeadlessApplication(ApplicationListener listener, float renderIntervalSec, Cons<Throwable> exceptionHandler){

        addListener(listener);
        this.exceptionHandler = exceptionHandler;
        
        Core.settings = new Settings();
        Core.app = this;
        Core.files = new MockFiles();
        Core.audio = new MockAudio();
        Core.graphics = this.graphics = new MockGraphics();
        Core.input = new MockInput();

        renderInterval = renderIntervalSec > 0 ? (long)(renderIntervalSec * 1000000000f) : (renderIntervalSec < 0 ? -1 : 0);

        initialize();
    }

    protected void initialize(){
        mainLoopThread = new Thread("HeadlessApplication"){
            @Override
            public void run(){
                try{
                    HeadlessApplication.this.mainLoop();
                }catch(Throwable t){
                    exceptionHandler.get(t);
                }
            }
        };
        mainLoopThread.start();
    }

    void mainLoop(){
        synchronized(listeners){
            for(ApplicationListener listener : listeners){
                listener.init();
            }
        }

        long t = Time.nanos() + renderInterval;
        if(renderInterval >= 0f){
            while(running){
                final long n = Time.nanos();
                if(t > n){
                    long sleep = t - n;
                    Threads.sleep(sleep / 1000000, (int)(sleep % 1000000));

                    t += renderInterval;
                }else{
                    t = n + renderInterval;
                }

                runnables.run();
                graphics.incrementFrameId();
                defaultUpdate();

                synchronized(listeners){
                    for(ApplicationListener listener : listeners){
                        listener.update();
                    }
                }
                graphics.updateTime();

                // If one of the runnables set running to false, for example after an exit().
                if(!running) break;
            }
        }

        synchronized(listeners){
            for(ApplicationListener listener : listeners){
                listener.pause();
                listener.dispose();
            }
            dispose();
        }
    }

    @Override
    public ApplicationType getType(){
        return ApplicationType.headless;
    }

    @Override
    public String getClipboardText(){
        return null;
    }

    @Override
    public void setClipboardText(String text){

    }

    @Override
    public Seq<ApplicationListener> getListeners(){
        return listeners;
    }

    @Override
    public void post(Runnable runnable){
        runnables.post(runnable);
    }

    @Override
    public void exit(){
        post(() -> running = false);
    }

}
