/*
 * #!
 * Ontopia Engine
 * #-
 * Copyright (C) 2001 - 2013 The Ontopia Project
 * #-
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 * !#
 */

package net.ontopia.utils;

import java.util.Collection;
import java.util.Comparator;
import java.util.HashSet;
import java.util.TreeMap;

/**
 * INTERNAL: A sorted map which stores entries containing Collection
 * values. Any object can be used as key. The add(key,value) and
 * remove(key,value) makes sure that the Collection values are updated
 * correctly.<p>
 *
 * The maintained index must only contain values implementing the
 * Collection interface. The data structure looks like this:
 * <code>{key: [value, value, ...], key: [value, ...]}</code><p>
 *
 * Empty entries are removed by default.<p>
 */

public class CollectionSortedMap<K, V> extends TreeMap<K, Collection<V>> {

  protected boolean drop_empty = true;

  public CollectionSortedMap() {
  }

  public CollectionSortedMap(Comparator<K> c) {
    super(c);
  }

  // ----------------------------------------------------------------------------
  // Collection index values
  // ----------------------------------------------------------------------------

  protected Collection<V> createCollection() {
    return new HashSet<V>();
  }

  public void add(K key, V value) {

    // Get collection value
    Collection<V> coll = get(key);

    // Add to collection
    if (coll != null) {
      // Add new value
      coll.add(value);
    } else {
      // Create new collection
      coll = createCollection();
      coll.add(value);
      // Add new entry to index
      put(key, coll);
    }
  }

  //@Override disabled for java 7 backward compatibility
  public boolean remove(Object key, Object value) {

    // Get collection value
    Collection<V> coll = get(key);

    // Remove from collection
    if (coll != null) {
      // Remove value
      boolean removed = coll.remove(value);
      // Remove key
      if (drop_empty && coll.size() == 0) remove(key);
      
      return removed;
    }
    return false;
  }

  public void move(V value, K old_key, K new_key) {
    remove(old_key, value);
    add(new_key, value);
  }


  // public void replace(Object key, Object old_value, Object new_value) {
  //
  //   // Get collection value
  //   Collection coll = (Collection)get(key);
  //
  //   // Remove from collection
  //   if (coll != null) {
  //     // Remove value
  //     coll.remove(old_value);
  //     coll.add(new_value);
  //   } else {
  //     // Create new collection
  //     coll = createCollection();
  //     coll.add(new_value);
  //     // Add new entry to index
  //     put(key, coll);
  //   }
  //
  // }

  // public void replaceAll(Object key, Object old_value, Object new_value) {
  // }

}