import java.util.Random;

public class EventGenerator 
{
    int avgInterArrivalTime = 20;
    int avgLoadTime = 10;
    int avgRideTime = 10;
    
    Random prg;
    long seed = 9999;
    
    // set the random seed so that results are the same each time
    // around. this is useful for debuggin
    public EventGenerator()
    {
	prg = new Random();
	prg.setSeed( seed );
    }
    
    // sets the average inter-arrival time and average load time and average
    // ride time for a customer
    public void setParameters( int a, int l, int r )
	throws IllegalTimeValueException
    {
	if ( a <= 0 || l <= 0 || r <= 0 )
	    throw new IllegalTimeValueException();
	avgInterArrivalTime = a;
	avgLoadTime = l;
	avgRideTime = r;
    }

    // given the current time 
    // (which is the arrival time of the last customer),
    // this returns a new arrival event
    public Even getNextArrivalEvent( int currentTime )
    {
	double interArrival, load, ride;
	
	interArrival = - ( Math.log( 1 - prg.nextDouble() ) ) * avgInterArrivalTime;
	load = - ( Math.log( 1 - prg.nextDouble() ) ) * avgLoadTime;
	ride = - ( Math.log( 1 - prg.nextDouble() ) ) * avgRideTime;
	
	// this part is changed [3/08/06]: //****corrected on March 11
        int arrivalTime = (int) interArrival + currentTime;
	Rider newRider = new Rider( arrivalTime, (int)load, (int)ride );
	Event newEvent = new Event( newRider, arrivalTime, Event.arrivalEvent);
	return( newEvent );
    }
}