import java.util.Collection;
import java.util.Comparator;
import java.util.PriorityQueue;
import java.util.SortedSet;

/**
 * The CrusherQueue is a Queue base on the PriorityQueue class to be consumed by the Crusher.
 * This class is Thread safe.
 * 
 * @author Ahmed Messaoud
 * @see Crusher#q
 * @see PriorityQueue
 */
public class CrusherQueue extends PriorityQueue<Truck> {
	private boolean available = true;

	/* (non-Javadoc)
	 * @see java.util.PriorityQueue#add(java.lang.Object)
	 * @see Truck
	 */
	public synchronized boolean add(Truck t){
		if( !available ){
			try{
				wait();
			}catch( Exception e ){}
		}
		available = false;
		//check size, if there is waiting, then advise truck to idle
		if( size() > 0){
			try{
				t.startIdleling();
			}catch(AlreadyIdlelingException e){}
		}
		available = true;
		notify();
		return super.add(t);
	}

	/* (non-Javadoc)
	 * @see java.util.PriorityQueue#poll()
	 * @see Truck
	 */
	public synchronized Truck poll(){
		if( !available ){
			try{
				wait();
			}catch( Exception e ){}
		}
		available = false;
		//check if truck was idleling, if it was, stop the idleling
		if( super.peek() != null ){
			if( super.peek().isIdleling() ){
				try{
					super.peek().stopIdleling();
				}catch(NotIdlelingException e){}
			}
		}
		available = true;
		notify();
		return super.poll();
	}

}