package lift;

public class Monitor {
	private int here;
	private int next;
	private int[] waitEntry;
	private int[] waitExit;
	private int load;
	private boolean dirUp;

	public synchronized void enterLift(int personLoc, int target){
		try {
			while(here != personLoc){ wait(); }
		} catch (InterruptedException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}

		if(load <= 4) {
			load++;
			waitExit[target]++;
			waitEntry[personLoc]--;
		} else {
			waitEntry[personLoc]++;
		}

		notifyAll();
	}

	public synchronized void leaveLift(int target){
		try {
			while(here != target) { wait(); }
		} catch (InterruptedException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}

		load--;
		waitExit[here]--;

		notifyAll();
	}

	public synchronized void moveLift(){
		try {
			while((waitEntry[here] > 0 && load <= 4) || waitExit[here] > 0) { wait(); } // (waitQ > 0 && load < 4) eller liftQ > 0
		} catch (InterruptedException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}

		liftMovement();

		notifyAll();
	}

	private void liftMovement() {
		if(next > 6) {
			dirUp = false;
		} else if (next < 0){
			dirUp = true;
		}

		if(dirUp){
			if(next <= -1) {
				next = 1;
				here = 0;
			} else {
				next++;
				here++;
			}
		} else {
			if(next >= 7){
				next = 5;
				here = 6;
			} else {
				next--;
				here--;
			}
		}
	}
}