/*
    * $Source: /usr/cvsroot/melati/melati-example-odmg/src/main/java/org/melati/poem/odmg/PoemTableAsDCollection.java,v $
    * $Revision: 1.14 $
    *
    * Copyright (C) 2000 Chris Kimpton
    * 
    * Part of Melati (http://melati.org), a framework for the rapid
    * development of clean, maintainable web applications.
    *
   * Melati is free software; Permission is granted to copy, distribute
   * and/or modify this software under the terms either:
   *
   * a) the GNU General Public License as published by the Free Software
   *    Foundation; either version 2 of the License, or (at your option)
   *    any later version,
   *
   *    or
   *
   * b) any version of the Melati Software License, as published
   *    at http://melati.org
   *
   * You should have received a copy of the GNU General Public License and
   * the Melati Software License along with this program;
   * if not, write to the Free Software Foundation, Inc.,
   * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA to obtain the
   * GNU General Public License and visit http://melati.org to obtain the
   * Melati Software License.
   *
   * Feel free to contact the Developers of Melati (http://melati.org),
   * if you would like to work out a different arrangement than the options
   * outlined here.  It is our intention to allow Melati to be used by as
   * wide an audience as possible.
   *
   * This program is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU General Public License for more details.
   *
   * Contact details for copyright holder:
   *
   *     Chris Kimpton (kimtoc@techie.com)
   *
   */
  package org.melati.poem.odmg;
  
  import java.util.Iterator;
  import java.util.Collection;
  import java.util.Enumeration;
  
  import org.melati.poem.Persistent;
  import org.melati.poem.Table;
  
  /**
   * Wrapper class to present a Poem Table as a Collection.
   */
  
  class PoemTableAsDCollection implements org.odmg.DCollection {
  
    private Table _wrappedTable = null;
  
    PoemTableAsDCollection(Table aTable) {
      _wrappedTable = aTable;
    }
  
    public boolean isEmpty() { return size() == 0; }
    public int size() { return _wrappedTable.count(""); }
  
    public boolean add(Object obj) { 
      _wrappedTable.create((Persistent)obj);
      return true;
    }
  
    public boolean removeAll(Collection coll) {  
      Iterator iter = coll.iterator();
      while (iter.hasNext()) {
         if (!remove(iter.next()))
           return false;
      }
      return true;
    }
  
   /** 
    * removes the specified object from the collection.
    *
    * WARNING - this removes and commits it immediately!
    * WARNING2 - it also deletes entries from tables that reference this object 
    * - this means you CANNOT have circular references
    */
    public boolean remove(Object obj) {  
      Persistent p = (Persistent)obj;
      // delete all references first
       Enumeration refs = _wrappedTable.getDatabase().referencesTo(p);
        while (refs.hasMoreElements()) {
          Persistent q = (Persistent)refs.nextElement();
          q.deleteAndCommit();
        }
  
      p.deleteAndCommit();
      return true;
   }
 
   public Iterator iterator() { 
     return new EnumerationIterator(_wrappedTable.selection());
   }
 
  /** 
   * returns all objects that match the query.
   * NOTE: The query string is split into the where-clause and 
   * the order-by-clause and passed to poem.
   */
   public Iterator select(String queryString) {
     String lowerCaseQueryString = queryString.toLowerCase();
     int whereStart = lowerCaseQueryString.indexOf("where ");
     if (whereStart<0) 
       whereStart = 0;
     else
       whereStart += 6;
 
     int orderByStart = lowerCaseQueryString.indexOf("order by ");
     int whereEnd = 0;
     if (orderByStart<0)
       whereEnd = queryString.length();
     else if (orderByStart==0) {
       whereStart = -1; // no where clause
       orderByStart += 9;
     }
     else {
       whereEnd = orderByStart;
       orderByStart += 9;
     }
     
     String whereClause = "";
     String orderByClause = "";
     if (whereStart>=0)
       whereClause = queryString.substring(whereStart,whereEnd);
     if (orderByStart>=0)
       orderByClause = queryString.substring(orderByStart,queryString.length());
 
 /*
     System.err.println("[poem-odmg]query string="+queryString);
     System.err.println("[poem-odmg]where start="+whereStart);
     System.err.println("[poem-odmg]where end="+whereEnd);
     System.err.println("[poem-odmg]order by start="+orderByStart);
     System.err.println("[poem-odmg]where clause="+whereClause);
     System.err.println("[poem-odmg]order by clause="+orderByClause);
 */
     return new EnumerationIterator(
         _wrappedTable.selection(whereClause,orderByClause,true));
   }
 
   public Object selectElement(String queryString) {
     Iterator iter = select(queryString);
     if (iter.hasNext())
       return iter.next();
     return null;
   }
 
 // the following have not been implemented - yet...
   public org.odmg.DCollection query(String queryString) { 
     throw new org.odmg.NotImplementedException(); 
   }
   public Object[] toArray(Object[] obj) { 
     throw new org.odmg.NotImplementedException(); 
   }
   public Object[] toArray() { 
     throw new org.odmg.NotImplementedException(); 
   }
   public boolean existsElement(String obj) { 
     throw new org.odmg.NotImplementedException(); 
   }
   public boolean contains(Object obj) { 
     throw new org.odmg.NotImplementedException(); 
   }
   public boolean addAll(Collection coll) { 
     throw new org.odmg.NotImplementedException(); 
   }
   public boolean containsAll(Collection coll) { 
     throw new org.odmg.NotImplementedException(); 
   }
   public boolean retainAll(Collection coll) { 
     throw new org.odmg.NotImplementedException(); 
   }
   public void clear() { 
     throw new org.odmg.NotImplementedException(); 
   }
 
 /** utility class for converting enumerations into iterators */
 private class EnumerationIterator implements Iterator {
   private Enumeration _enum = null;
   EnumerationIterator(Enumeration en) {
     _enum = en;
   }
 
   public boolean hasNext() { return _enum.hasMoreElements(); }
   public Object next() { return _enum.nextElement(); }
   public void remove() { throw new org.odmg.NotImplementedException(); }
 }
 
 
 }