package com.lapissea.amaze;

import java.util.ArrayList;

public class MultiTasking{

	private static class TaskedThread extends Thread{

		Runnable task;

		public TaskedThread(int id){
			super("TaskExecutor-"+id);
		}

		@Override
		public void run(){
			while(true){
				if(hasWork()){
					task.run();
					task=null;
					ask();
				}else ask();
			}
		}

		private void ask(){
			if(askOverlord(this))try{
				synchronized(this){
					wait();
				}
			}catch(InterruptedException e){
				throw new RuntimeException(e);
			}
		}

		boolean hasWork(){
			return task!=null;
		}

	}

	public static boolean							USE_MULTITHREADING=true;
	public static final int							THREAD_CAP	=8;
	private static final ArrayList<TaskedThread>	FREE_THREADS=new ArrayList<>();
	private static final ArrayList<Runnable>		QUEUE		=new ArrayList<>();
	static{
		for(int i=0;i<THREAD_CAP;i++){
			TaskedThread thread=new TaskedThread(i);
			thread.start();
			FREE_THREADS.add(thread);
		}
	}

	public synchronized static void run(Runnable task){
		if(!USE_MULTITHREADING)task.run();
		else if(!FREE_THREADS.isEmpty()){
			TaskedThread thread=FREE_THREADS.remove(0);
			thread.task=task;
			synchronized(thread){
				thread.notifyAll();
			}
		}else QUEUE.add(task);
	}
	public static boolean hasWork(){
		return !QUEUE.isEmpty();
	}
	private synchronized static boolean askOverlord(TaskedThread taskedThread){
		if(QUEUE.isEmpty()){
			FREE_THREADS.add(taskedThread);
			return true;
		}
		taskedThread.task=QUEUE.remove(0);
		return false;
	}

}