/* -------------------------------------------------------- *
 * Aaron Morris                                             *
 * CS522                                                    *
 * Object-Oriented Event-Driven Simulation                  *
 *                                                          *
 * Class representing Event List.  Queue of events.         *
 * Events are added in sorted order                         *
 * -------------------------------------------------------- */
//package datasend;
import java.awt.*;

public class EventQueue {

        protected SimEvent eventList;     // Start of Event List
        protected SimEvent tail;          // End of list
        protected int numQueued;          // Number of Items in List


	/* Basic Object Constructor, creating Queue to store events */
 	public EventQueue()
    	{
                this.eventList = null;
                this.tail = null;
                this.numQueued = 0;
    	}

        // Method to return number of Queued objects
	public int getNumQueued() { return this.numQueued; }

        // Method to remove and return first event in Queue
	public SimEvent deQueue()
	{
            SimEvent temp;
            temp = eventList;

            // If there are queued members
            if (numQueued > 0)
            {
              eventList = eventList.getNext();
              if (eventList == null) tail = null;
              temp.setNext(null);
              numQueued--;
            }
            else { System.out.println("Tried to DeQueue when Q Empty"); }

            //System.out.println("DEQUEUED " + temp.getStringRep());
            //PrintQueue();

            return temp;
	}


        // Method to add an Event to the list in sorted order
	public void enQueue(SimEvent ev)
	{
            SimEvent temp,temp2;

            // If will be first event in list
            if (numQueued == 0)
            {
                eventList = ev;
                tail = ev;
            }

            // If adding to beginning
            else if (ev.getSortVal() < eventList.getSortVal())
            {
                ev.setNext(eventList);
                eventList = ev;
            }

            // If adding at end
            else if (ev.getSortVal() >= tail.getSortVal())
            {
                tail.setNext(ev);
                tail = ev;
                ev.setNext(null);
            }

            // Else somewhere in the middle, have to traverse list
            else
            {
                temp = eventList;
                while ((temp.getNext() != null)&&
                       (ev.getSortVal() > temp.getNext().getSortVal()))
                {
                    temp = temp.getNext();
                }
                temp2 = temp.getNext();
                temp.setNext(ev);
                ev.setNext(temp2);
            }
            numQueued++;

            //System.out.println("ENQUEUED " + ev.getStringRep());
            //PrintQueue();
        }

        // For Testing purposes, print out current eventList
        public void PrintQueue()
        {
            SimEvent temp = eventList;
            System.out.print("EventList[" + numQueued + "]: ");
            while (temp != null)
            {
                System.out.print(" ");
                System.out.print(temp.getStringRep());
                temp = temp.getNext();
            }
            System.out.println ("   END OF LIST");
        }
}