#include "simul.h"
/*
 * member functions for event queue
 */
eventQClass::eventQClass()
// constructor
{
   head = NULL;
   tail = NULL;
   count = 0;
}

boolean eventQClass::Empty()
// check if empty
{
   if (head == NULL)
     return TRUE;
   else
     return FALSE;
}

void eventQClass::Enqueue(eventClass event)
// this queue is maintained as a priority queue
{
   eventClass *temp, *search;

   count ++;

   temp = new eventClass;     // create a new node
   (*temp) = event;
   temp->next = NULL;
   temp->prev = NULL;

   if (Empty() == TRUE)    // only one node
   {
     head = temp;
     tail = temp;
   }
   else if ((head->eventtime > temp->eventtime))  // insert before
   {
      temp->next = head;
      temp->prev = head->prev;
      head->prev = temp;
      head = temp;
   }
   else                    // find a proper place (according to time)
   {
      search = head;
      while ((search != NULL) && (search->eventtime <= temp->eventtime))
         search = search->next;

      if (search != NULL)
      {
         temp->next = search;
         temp->prev = search->prev;
         search->prev->next = temp;
         search->prev = temp;
      }
      else     // insert after the end
      {
         tail->next = temp;
         temp->prev = tail;
         tail = temp;
      }
   }
}

eventClass eventQClass::Front()
// this if for event queue
{
   if (Empty() == TRUE)
   {
      cerr << "event queue empty when front \n";
      exit(1);
   }
   return *(head);
}

void eventQClass::Dequeue()
// delete one element from queue
{
   eventClass *temp;

   if (Empty() == TRUE)
   {
     cerr << "event queue empty when dequeue \n";
     exit(1);
   }
   else
   {
     temp = head;
     head = head->next;
     delete temp;
   }
}

int eventQClass::Length()
// print the length of the event queue
// used for debug only
{
    return count;
}