/*
  The Intersection class contains four queues (streets) and a light,
  it defines how cars cross the intersection
*/
public class Intersection{
    //possible values for the traffic light
    public static final boolean NS_LIGHT = false, EW_LIGHT = true;

    //the cardinal directions
    public static final int NORTH = 0, EAST = 1, SOUTH = 2, WEST = 3;

    //maximum number of time steps
    private int max;

    //the current time step
    private int time;

    //current state of the traffic lights
    private boolean light;

    //a Generator object that adds cars
    private Generator traffic;

    //the 4 streets that meet at the intersection
    private Queue streets[];

    //number of cars crossed from each direction
    private int numcars[];

    //total delay experienced by cars from each direction
    private int cardelay[];

    //constructor, specify the number of time steps
    //and the traffic pattern to use
    //also initializes the instance variables
    public Intersection(int duration, Generator pattern){
	time = 0;
	max = duration;
	light = NS_LIGHT;
	traffic = pattern;

	//each street needs a queue and two counters
	streets = new Queue[4];
	numcars = new int[4];
	cardelay = new int[4];
	for(int i=0;i<4;i++){
	    streets[i] = new Queue();
	    numcars[i] = cardelay[i] = 0;
	}
    }

    //helper function that moves 0, 1, or 2 Cars across the intersection
    private void advance(){

    }

    //helper that flips the lights if needed...
    //you may want to edit this while testing
    private void switchLights(){
	// just flip every 10 times
	if(time%10 == 0)light = !light;
    }

    //run the simulation
    public void run(){
	for(;time<max;time++){
	    advance();
	    traffic.addTraffic(streets, time);
	    switchLights();
	}
    }

    public void printStats(){
	//print out the column headers
	System.out.println("                 N \tE \tS \tW");

	//show the total number of cars and delay for each street
	System.out.println("Cars crossed: \t"+numcars[0]+" \t"+
			   numcars[1]+" \t"+numcars[2]+" \t"+numcars[3]);
	System.out.println("Total delay:   \t"+cardelay[0]+" \t"+
			   cardelay[1]+" \t"+cardelay[2]+" \t"+
			   cardelay[3]);

	//compute the average delay (if possible)
	System.out.print("Average delay: \t");
	for(int i=0;i<4;i++){
	    if(numcars[i]==0)System.out.print("N/A \t");
	    else System.out.print((cardelay[i]/numcars[i])+" \t");
	}
	System.out.println();

	//show how many cars were left in the simulation
	System.out.println("Cars stranded: \t"+streets[0].getLength()+" \t"+
			   streets[1].getLength()+" \t"+
			   streets[2].getLength()+" \t"+
			   streets[3].getLength());
    }
}