/*
   * The contents of this file are subject to the BT "ZEUS" Open Source 
   * Licence (L77741), Version 1.0 (the "Licence"); you may not use this file 
   * except in compliance with the Licence. You may obtain a copy of the Licence
   * from $ZEUS_INSTALL/licence.html or alternatively from
   * http://www.labs.bt.com/projects/agents/zeus/licence.htm
   * 
   * Except as stated in Clause 7 of the Licence, software distributed under the
   * Licence is distributed WITHOUT WARRANTY OF ANY KIND, either express or 
  * implied. See the Licence for the specific language governing rights and 
  * limitations under the Licence.
  * 
  * The Original Code is within the package zeus.*.
  * The Initial Developer of the Original Code is British Telecommunications
  * public limited company, whose registered office is at 81 Newgate Street, 
  * London, EC1A 7AJ, England. Portions created by British Telecommunications 
  * public limited company are Copyright 1996-9. All Rights Reserved.
  * 
  * THIS NOTICE MUST BE INCLUDED ON ANY COPY OF THIS FILE
  */
  
  
  
  package zeus.concepts;
  
  import java.util.*;
  import zeus.util.*;
  
  public class ResourceItem extends Observable {
     public static final String ALLOCATED = "Reserved";
     public static final String UNALLOCATED = "Free";
  
     public static final int UNCHANGED = 0;
     public static final int MODIFY    = 1;
     public static final int DELETE    = 2;
  
     protected Fact fact = null;
     protected Hashtable reservations = new Hashtable();
  
     public ResourceItem(Fact fact) {
        Assert.notNull(fact);
        this.fact = fact;
     }
  
     public Fact getFact() { return fact; }
  
     public synchronized boolean isReserved() {
        return !reservations.isEmpty();
     }
  
     public synchronized boolean reservationOK(int start, boolean consumed,
                                               int amount) {
        return unreservedAmount(start,consumed) >= amount;
     }
     public synchronized int unreservedAmount(int start, boolean consumed) {
        return fact.getNumber() - reservedAmount(start,consumed);
     }
     public synchronized int reservedAmount(int start, boolean consumed) {
        Enumeration enum = reservations.elements();
        int reserved = 0;
        Entry e;
        while( enum.hasMoreElements() ) {
           e = (Entry)enum.nextElement();
           if ( consumed ) {
              if ( e.consumed || e.start > start )
                 reserved += e.amount;
           }
           else {
              if ( e.consumed && e.start <= start )
                 reserved += e.amount;
           }
        }
        return reserved;
     }
  
     public int getReservedAmount(Observer observer) {
        Entry e = (Entry) reservations.get(observer);
        return (e == null) ? 0 : e.amount;
     }
     public synchronized void changeReservedAmount(Observer o, int amount) {
        Entry e = (Entry) reservations.get(o);
        Assert.notNull(e);
        Assert.notFalse(e.amount >= amount);
        e.amount = amount;
     }
     public synchronized void cancelReservation(Observer observer) {
        deleteObserver(observer);
        Entry e = (Entry) reservations.remove(observer);
     }
     public synchronized boolean executeNow(Observer observer, int now) {
        boolean execute_now = true;
        Entry e = (Entry) reservations.get(observer);
        if ( !e.consumed )
           return true;
        else {
           reservations.remove(observer);
           boolean status = reservationOK(now,e.consumed,e.amount);
           reservations.put(observer,e);
           return status;
       }
    }
    public synchronized boolean newStartTime(Observer observer, int start) {
       Entry e = (Entry) reservations.remove(observer);
       if ( reserve(observer,start,e.consumed,e.amount) )
          return true;
       else {
          reservations.put(observer,e);
          return false;
       }
    }
 
    public synchronized boolean reserve(Observer observer, int start,
                                        boolean consumed, int amount) {
 
       if ( !reservationOK(start,consumed,amount) ) return false;
 
       Entry e = new Entry(start,consumed,amount);
       // Assert.notFalse(reservations.put(observer,e) == null);
       Entry xe = (Entry) reservations.put(observer,e);
       if ( xe != null ) {
          System.err.println("ResourceItem reserve: multiple entries " +
                             "for same observer " + observer);
          System.err.println("Previous = " + xe);
          System.err.println("Current = " + e);
       }
 
       addObserver(observer);
       return true;
    }
 
    public void deleted() {
       Core.DEBUG(3,"Notifying observers of deletion...\n" + fact.pprint());
       setChanged();
       notifyObservers("deleted");
    }
 
    public int consumed(Observer observer) {
       deleteObserver(observer);
       int no = fact.getNumber();
       Entry e = (Entry) reservations.remove(observer);
       int status;
       if ( !e.consumed )         status = UNCHANGED;
       else if ( e.amount < no )  status = MODIFY;
       else                       status = DELETE;
 
       if ( status == MODIFY ) fact.setNumber(no-e.amount);
 
       return status;
    }
    protected class Entry {
       public int start;
       public boolean consumed;
       public int amount;
 
       public Entry(int start, boolean consumed, int amount) {
          this.start = start;
          this.consumed = consumed;
          this.amount = amount;
       }
       public String toString() {
          return( "(" +
                   ":start " + start + " " +
                   ":consumed " + consumed + " " +
                   ":amount " + amount +
                  ")"
                );
       }
    }
 }