/**
 * QueueClass.java
 * Perry Holloway 
 * 
 */

// Declaration of QueueClass
class QueueClass
{
    int MAX_QUEUE = 100; // Global variable -- max array size
    
    // QueueClass Constructor
    public QueueClass()
    {
	Front = null;
	Rear = null;
	Count = 0;
   	Previous = null;
    }// end of  constructor

    // Boolean method if the Queue is Empty
    public boolean QueueIsEmpty()
    {
    	return (Count == 0);
    }
  
    // This is a method that was added to return the length of the Queue
    public int length()
    {
  	return Count;
    }

    //Redoing the QueueAdd to make it work as a priority queue
    public void QueueAdd(Event event)
    {
        // This is the case when the queue is empty and nothing to compare it to
        if(Front == null)
        {
            Front = event;
            Rear  = event;
            ++Count;
        }// end of the if
        
        //  this is the case where there is already stuff in the queue
	//  and the new event has a lower time then the front
        else if(Front.get_arrival_time() >= event.get_arrival_time())
        {
            event.next = Front;
            Front = event;
            ++Count;
	} // end of the case where you replace the front with new event
	   
	// This is the case where the new event is has a greater arrival time
	// than everything in the Queue
	else if(Rear.get_arrival_time() <= event.get_arrival_time())
	{
            event.next = null;
            Rear.next  = event;
            Rear       = event;
            ++Count;
	} // end of the case
	   
	// The case where it will have to place event in the correct position
	else
	{
            Previous = Front;
            while(Previous != null)
            {
		if(event.get_arrival_time() > Previous.next.get_arrival_time())
		{
                    Previous = Previous.next;
		}
                else
		{
                    break;// to end the loop
		}
            } // End of the While loop
            event.next = Previous.next;
            Previous.next = event;
            ++Count;
	 } // End of the Else
    }// end QueueAdd
    
    // This is a method to Remove an Event from the Queue
    public void QueueRemove()
    {
   	// queue is not empty; remove front
        if (Front != null)
   	{
            Front = Front.next;
            if(Front == null)
            {
                Rear = null;
            }
            --Count;
        }// end if
    }// end QueueRemove

    public Event GetQueueFront()
    {
        boolean Success = (!QueueIsEmpty());
        //System.out.println("Count = " + Count);
        if (Success)
        {
            // queue is not empty; retrieve front
            return Front;
        }
        else
        {
            //System.out.println("Count is suppose to be 0 but is = " + Count);
            //System.out.println("Failure in GetQueueFront ");
            Event Event_Null = new Event();
            Event_Null = null;
            return Event_Null;
        }
    }  // end GetQueueFront

    //Event[] Items = new Event[MAX_QUEUE];
    private Event  Front;
    private Event  Rear;
    private Event  Previous;
    int            Count;

} // end QueueClass