package umontreal.iro.lecuyer.util;

import java.util.AbstractList;
import java.util.List;
import java.util.Iterator;
import java.util.ListIterator;


/**
 * Represents a list that dynamically transforms the elements 
 * of another list.
 * This abstract class defines a list
 * containing an inner list of elements of a certain type,
 * and provides facilities to convert these
 * inner elements to outer elements of another
 * type.
 * A concrete subclass simply needs to provide
 * methods for converting between the inner
 * and the outer types.@param <IE> the inner type of the elements.
 * 
 *    @param <OE> the type of the outer elements.
 * 
 */
public abstract class TransformingList extends AbstractList {
   private List fromList;


   /**
    * Creates a new transforming list wrapping
    *  the inner list fromList.
    * 
    * @param fromList the inner list.
    * 
    * 
    */
   public TransformingList (List fromList) {
      this.fromList = fromList;
   }


   public List getInnerList() {
      return fromList;
   }

   /**
    * Converts an element in the inner list to
    *  an element of the outer type.
    * 
    * @param e the inner element.
    * 
    *    @return the outer element.
    * 
    */
   public abstract OE convertFromInnerType (IE e);


   /**
    * Converts an element of the outer type to
    *  an element for the inner list.
    * 
    * @param e the outer element.
    * 
    *    @return the inner element.
    * 
    */
   public abstract IE convertToInnerType (OE e);


   public void add (int index, OE element) {
      IE fe = convertToInnerType (element);
      fromList.add (fe);
   }

   @Override
   public void clear () {
      fromList.clear();
   }

   @Override
   public OE get (int index) {
      return convertFromInnerType (fromList.get (index));
   }
   
   public Iterator iterator() {
      return new MyIterator (fromList.iterator());
   }

   public ListIterator listIterator() {
      return new MyListIterator (fromList.listIterator());
   }

   public ListIterator listIterator (int index) {
      return new MyListIterator (fromList.listIterator (index));
   }

   @Override
   public OE remove (int index) {
      return convertFromInnerType (fromList.remove (index));
   }

   @Override
   public OE set (int index, OE element) {
      IE from = convertToInnerType (element);
      from = fromList.set (index, from);
      return convertFromInnerType (from);
   }

   @Override
   public int size () {
      return fromList.size();
   }

   private class MyIterator implements Iterator {
      private Iterator itr;

      public MyIterator (Iterator itr) {
         this.itr = itr;
      }

      public boolean hasNext() {
         return itr.hasNext();
      }

      public OE next() {
         return convertFromInnerType (itr.next());
      }
      
      public void remove() {
         itr.remove();
      }
   }

   private class MyListIterator implements ListIterator {
      private ListIterator itr;
   
      public MyListIterator (ListIterator itr) {
         this.itr = itr;
      }

      public void add (OE o) {
         IE fe = convertToInnerType (o);
         itr.add (fe);
      }

      public boolean hasNext() {
         return itr.hasNext();
      }

      public boolean hasPrevious() {
         return itr.hasPrevious();
      }

      public OE next() {
         return convertFromInnerType (itr.next());
      }

      public int nextIndex() {
         return itr.nextIndex();
      }

      public OE previous() {
         return convertFromInnerType (itr.previous());
      }

      public int previousIndex() {
         return itr.previousIndex();
      }

      public void remove() {
         itr.remove();
      }

      public void set (OE o) {
         IE fe = convertToInnerType (o);
         itr.set (fe);
      }
   }



}