/*
    * Licensed to the Apache Software Foundation (ASF) under one or more
    * contributor license agreements.  See the NOTICE file distributed with
    * this work for additional information regarding copyright ownership.
    * The ASF licenses this file to You 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 org.apache.commons.collections4.bidimap;
  
  import java.io.IOException;
  import java.io.ObjectInputStream;
  import java.io.ObjectOutputStream;
  import java.io.Serializable;
  import java.util.ArrayList;
  import java.util.Comparator;
  import java.util.Iterator;
  import java.util.ListIterator;
  import java.util.Map;
  import java.util.SortedMap;
  import java.util.TreeMap;
  
  import org.apache.commons.collections4.BidiMap;
  import org.apache.commons.collections4.OrderedBidiMap;
  import org.apache.commons.collections4.OrderedMap;
  import org.apache.commons.collections4.OrderedMapIterator;
  import org.apache.commons.collections4.ResettableIterator;
  import org.apache.commons.collections4.SortedBidiMap;
  import org.apache.commons.collections4.map.AbstractSortedMapDecorator;
  
  /**
   * Implements {@link BidiMap} with two {@link TreeMap} instances.
   * <p>
   * The setValue() method on iterators will succeed only if the new value being set is
   * not already in the bidi map.
   * </p>
   * <p>
   * When considering whether to use this class, the {@link TreeBidiMap} class should
   * also be considered. It implements the interface using a dedicated design, and does
   * not store each object twice, which can save on memory use.
   * </p>
   * <p>
   * NOTE: From Commons Collections 3.1, all subclasses will use {@link TreeMap}
   * and the flawed {@code createMap} method is ignored.
   * </p>
   *
   * @param <K> the type of the keys in this map
   * @param <V> the type of the values in this map
   * @since 3.0
   */
  public class DualTreeBidiMap<K, V> extends AbstractDualBidiMap<K, V>
          implements SortedBidiMap<K, V>, Serializable {
  
      /**
       * Inner class MapIterator.
       *
       * @param <K> the type of the keys.
       * @param <V> the type of the values.
       */
      protected static class BidiOrderedMapIterator<K, V> implements OrderedMapIterator<K, V>, ResettableIterator<K> {
  
          /** The parent map */
          private final AbstractDualBidiMap<K, V> parent;
  
          /** The iterator being decorated */
          private ListIterator<Map.Entry<K, V>> iterator;
  
          /** The last returned entry */
          private Map.Entry<K, V> last;
  
          /**
           * Constructs a new instance.
           * @param parent  the parent map
           */
          protected BidiOrderedMapIterator(final AbstractDualBidiMap<K, V> parent) {
              this.parent = parent;
              iterator = new ArrayList<>(parent.entrySet()).listIterator();
          }
  
          @Override
          public K getKey() {
              if (last == null) {
                  throw new IllegalStateException(
                          "Iterator getKey() can only be called after next() and before remove()");
              }
              return last.getKey();
          }
  
          @Override
          public V getValue() {
              if (last == null) {
                 throw new IllegalStateException(
                         "Iterator getValue() can only be called after next() and before remove()");
             }
             return last.getValue();
         }
 
         @Override
         public boolean hasNext() {
             return iterator.hasNext();
         }
 
         @Override
         public boolean hasPrevious() {
             return iterator.hasPrevious();
         }
 
         @Override
         public K next() {
             last = iterator.next();
             return last.getKey();
         }
 
         @Override
         public K previous() {
             last = iterator.previous();
             return last.getKey();
         }
 
         @Override
         public void remove() {
             iterator.remove();
             parent.remove(last.getKey());
             last = null;
         }
 
         @Override
         public void reset() {
             iterator = new ArrayList<>(parent.entrySet()).listIterator();
             last = null;
         }
 
         @Override
         public V setValue(final V value) {
             if (last == null) {
                 throw new IllegalStateException(
                         "Iterator setValue() can only be called after next() and before remove()");
             }
             if (parent.reverseMap.containsKey(value) &&
                 parent.reverseMap.get(value) != last.getKey()) {
                 throw new IllegalArgumentException(
                         "Cannot use setValue() when the object being set is already in the map");
             }
             final V oldValue = parent.put(last.getKey(), value);
             // Map.Entry specifies that the behavior is undefined when the backing map
             // has been modified (as we did with the put), so we also set the value
             last.setValue(value);
             return oldValue;
         }
 
         @Override
         public String toString() {
             if (last != null) {
                 return "MapIterator[" + getKey() + "=" + getValue() + "]";
             }
             return "MapIterator[]";
         }
     }
 
     /**
      * Internal sorted map view.
      *
      * @param <K> the type of the keys.
      * @param <V> the type of the values.
      */
     protected static class ViewMap<K, V> extends AbstractSortedMapDecorator<K, V> {
         /**
          * Constructs a new instance.
          * @param bidi  the parent bidi map
          * @param sm  the subMap sorted map
          */
         protected ViewMap(final DualTreeBidiMap<K, V> bidi, final SortedMap<K, V> sm) {
             // the implementation is not great here...
             // use the normalMap as the filtered map, but reverseMap as the full map
             // this forces containsValue and clear to be overridden
             super(new DualTreeBidiMap<>(sm, bidi.reverseMap, bidi.inverseBidiMap));
         }
 
         @Override
         public void clear() {
             // override as default implementation uses reverseMap
             for (final Iterator<K> it = keySet().iterator(); it.hasNext();) {
                 it.next();
                 it.remove();
             }
         }
 
         @Override
         public boolean containsValue(final Object value) {
             // override as default implementation uses reverseMap
             return decorated().normalMap.containsValue(value);
         }
 
         @Override
         protected DualTreeBidiMap<K, V> decorated() {
             return (DualTreeBidiMap<K, V>) super.decorated();
         }
 
         @Override
         public SortedMap<K, V> headMap(final K toKey) {
             return new ViewMap<>(decorated(), super.headMap(toKey));
         }
 
         @Override
         public K nextKey(final K key) {
             return decorated().nextKey(key);
         }
 
         @Override
         public K previousKey(final K key) {
             return decorated().previousKey(key);
         }
 
         @Override
         public SortedMap<K, V> subMap(final K fromKey, final K toKey) {
             return new ViewMap<>(decorated(), super.subMap(fromKey, toKey));
         }
 
         @Override
         public SortedMap<K, V> tailMap(final K fromKey) {
             return new ViewMap<>(decorated(), super.tailMap(fromKey));
         }
     }
 
     /** Ensure serialization compatibility */
     private static final long serialVersionUID = 721969328361809L;
 
     /** The key comparator to use */
     private final Comparator<? super K> comparator;
 
     /** The value comparator to use */
     private final Comparator<? super V> valueComparator;
 
     /**
      * Creates an empty {@link DualTreeBidiMap}.
      */
     public DualTreeBidiMap() {
         super(new TreeMap<>(), new TreeMap<>());
         this.comparator = null;
         this.valueComparator = null;
     }
 
     /**
      * Constructs a {@link DualTreeBidiMap} using the specified {@link Comparator}.
      *
      * @param keyComparator  the comparator
      * @param valueComparator  the values comparator to use
      */
     public DualTreeBidiMap(final Comparator<? super K> keyComparator, final Comparator<? super V> valueComparator) {
         super(new TreeMap<>(keyComparator), new TreeMap<>(valueComparator));
         this.comparator = keyComparator;
         this.valueComparator = valueComparator;
     }
 
     /**
      * Constructs a {@link DualTreeBidiMap} and copies the mappings from
      * specified {@link Map}.
      *
      * @param map  the map whose mappings are to be placed in this map
      */
     public DualTreeBidiMap(final Map<? extends K, ? extends V> map) {
         super(new TreeMap<>(), new TreeMap<>());
         putAll(map);
         this.comparator = null;
         this.valueComparator = null;
     }
 
     /**
      * Constructs a {@link DualTreeBidiMap} that decorates the specified maps.
      *
      * @param normalMap  the normal direction map
      * @param reverseMap  the reverse direction map
      * @param inverseBidiMap  the inverse BidiMap
      */
     protected DualTreeBidiMap(final Map<K, V> normalMap, final Map<V, K> reverseMap,
                               final BidiMap<V, K> inverseBidiMap) {
         super(normalMap, reverseMap, inverseBidiMap);
         this.comparator = ((SortedMap<K, V>) normalMap).comparator();
         this.valueComparator = ((SortedMap<V, K>) reverseMap).comparator();
     }
 
     @Override
     public Comparator<? super K> comparator() {
         return ((SortedMap<K, V>) normalMap).comparator();
     }
 
     /**
      * Creates a new instance of this object.
      *
      * @param normalMap  the normal direction map
      * @param reverseMap  the reverse direction map
      * @param inverseMap  the inverse BidiMap
      * @return new bidi map
      */
     @Override
     protected DualTreeBidiMap<V, K> createBidiMap(final Map<V, K> normalMap, final Map<K, V> reverseMap,
                                                   final BidiMap<K, V> inverseMap) {
         return new DualTreeBidiMap<>(normalMap, reverseMap, inverseMap);
     }
 
     @Override
     public K firstKey() {
         return ((SortedMap<K, V>) normalMap).firstKey();
     }
 
     @Override
     public SortedMap<K, V> headMap(final K toKey) {
         final SortedMap<K, V> sub = ((SortedMap<K, V>) normalMap).headMap(toKey);
         return new ViewMap<>(this, sub);
     }
 
     @Override
     public SortedBidiMap<V, K> inverseBidiMap() {
         return (SortedBidiMap<V, K>) super.inverseBidiMap();
     }
 
     /**
      * Defaults to {@link #inverseBidiMap()}.
      *
      * @return Defaults to {@link #inverseBidiMap()}.
      */
     public OrderedBidiMap<V, K> inverseOrderedBidiMap() {
         return inverseBidiMap();
     }
 
     /**
      * Defaults to {@link #inverseBidiMap()}.
      *
      * @return Defaults to {@link #inverseBidiMap()}.
      */
     public SortedBidiMap<V, K> inverseSortedBidiMap() {
         return inverseBidiMap();
     }
 
     @Override
     public K lastKey() {
         return ((SortedMap<K, V>) normalMap).lastKey();
     }
 
     /**
      * Obtains an ordered map iterator.
      * <p>
      * This implementation copies the elements to an ArrayList in order to
      * provide the forward/backward behavior.
      * </p>
      *
      * @return a new ordered map iterator
      */
     @Override
     public OrderedMapIterator<K, V> mapIterator() {
         return new BidiOrderedMapIterator<>(this);
     }
 
     @Override
     public K nextKey(final K key) {
         if (isEmpty()) {
             return null;
         }
         if (normalMap instanceof OrderedMap) {
             return ((OrderedMap<K, ?>) normalMap).nextKey(key);
         }
         final SortedMap<K, V> sm = (SortedMap<K, V>) normalMap;
         final Iterator<K> it = sm.tailMap(key).keySet().iterator();
         it.next();
         if (it.hasNext()) {
             return it.next();
         }
         return null;
     }
 
     @Override
     public K previousKey(final K key) {
         if (isEmpty()) {
             return null;
         }
         if (normalMap instanceof OrderedMap) {
             return ((OrderedMap<K, V>) normalMap).previousKey(key);
         }
         final SortedMap<K, V> sm = (SortedMap<K, V>) normalMap;
         final SortedMap<K, V> hm = sm.headMap(key);
         if (hm.isEmpty()) {
             return null;
         }
         return hm.lastKey();
     }
 
     /**
      * Deserializes an instance from an ObjectInputStream.
      *
      * @param in The source ObjectInputStream.
      * @throws IOException            Any of the usual Input/Output related exceptions.
      * @throws ClassNotFoundException A class of a serialized object cannot be found.
      */
     private void readObject(final ObjectInputStream in) throws IOException, ClassNotFoundException {
         in.defaultReadObject();
         normalMap = new TreeMap<>(comparator);
         reverseMap = new TreeMap<>(valueComparator);
         @SuppressWarnings("unchecked") // will fail at runtime if the stream is incorrect
         final Map<K, V> map = (Map<K, V>) in.readObject();
         putAll(map);
     }
 
     @Override
     public SortedMap<K, V> subMap(final K fromKey, final K toKey) {
         final SortedMap<K, V> sub = ((SortedMap<K, V>) normalMap).subMap(fromKey, toKey);
         return new ViewMap<>(this, sub);
     }
 
     @Override
     public SortedMap<K, V> tailMap(final K fromKey) {
         final SortedMap<K, V> sub = ((SortedMap<K, V>) normalMap).tailMap(fromKey);
         return new ViewMap<>(this, sub);
     }
 
     @Override
     public Comparator<? super V> valueComparator() {
         return ((SortedMap<V, K>) reverseMap).comparator();
     }
 
     /**
      * Serializes this object to an ObjectOutputStream.
      *
      * @param out the target ObjectOutputStream.
      * @throws IOException thrown when an I/O errors occur writing to the target stream.
      */
     private void writeObject(final ObjectOutputStream out) throws IOException {
         out.defaultWriteObject();
         out.writeObject(normalMap);
     }
 
 }