package algs13;
import stdlib.*;

public class XMM1Queue {
	public static void main(String[] args) {
		int SIZE = 60;
		args = new String[] { ".2", ".333" }; SIZE = 60;
		//args = new String[] { ".2", ".25" };  SIZE = 120;
		//args = new String[] { ".2", ".21" };  SIZE = 240;

		double lambda = Double.parseDouble(args[0]);  // arrival rate
		double mu     = Double.parseDouble(args[1]);  // service rate

		Queue<Double> q = new Queue<>();            // arrival times of customers
		double nextArrival   = StdRandom.exp(lambda);     // time of next arrival
		double nextDeparture = Double.POSITIVE_INFINITY;  // time of next departure

		// histogram object
		XHistogram hist = new XHistogram(SIZE);

		// simulate an M/M/1 queue
		while (true) {

			// it's an arrival
			if (nextArrival <= nextDeparture) {
				if (q.isEmpty()) nextDeparture = nextArrival + StdRandom.exp(mu);
				q.enqueue(nextArrival);
				nextArrival += StdRandom.exp(lambda);
			}

			// it's a departure
			else {
				double wait = nextDeparture - q.dequeue();
				StdOut.format("Wait = %6.2f, queue size = %d\n", wait, q.size());
				hist.addDataPoint(Math.min(SIZE-1,  (int) (Math.round(wait))));
				StdDraw.clear ();
				hist.draw ();
				StdDraw.show (1);
				if (q.isEmpty()) nextDeparture = Double.POSITIVE_INFINITY;
				else             nextDeparture += StdRandom.exp(mu);

			}
		}

	}

}