/*
    * 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.multimap;
  
  import java.util.Collection;
  import java.util.Collections;
  import java.util.List;
  import java.util.ListIterator;
  import java.util.Map;
  
  import org.apache.commons.collections4.ListUtils;
  import org.apache.commons.collections4.ListValuedMap;
  
  /**
   * Abstract implementation of the {@link ListValuedMap} interface to simplify
   * the creation of subclass implementations.
   * <p>
   * Subclasses specify a Map implementation to use as the internal storage and
   * the List implementation to use as values.
   * </p>
   *
   * @param <K> the type of the keys in this map
   * @param <V> the type of the values in this map
   * @since 4.1
   */
  public abstract class AbstractListValuedMap<K, V> extends AbstractMultiValuedMap<K, V>
          implements ListValuedMap<K, V> {
  
      /** Values ListIterator */
      private final class ValuesListIterator implements ListIterator<V> {
  
          private final K key;
          private List<V> values;
          private ListIterator<V> iterator;
  
          ValuesListIterator(final K key) {
              this.key = key;
              this.values = ListUtils.emptyIfNull(getMap().get(key));
              this.iterator = values.listIterator();
          }
  
          ValuesListIterator(final K key, final int index) {
              this.key = key;
              this.values = ListUtils.emptyIfNull(getMap().get(key));
              this.iterator = values.listIterator(index);
          }
  
          @Override
          public void add(final V value) {
              if (getMap().get(key) == null) {
                  final List<V> list = createCollection();
                  getMap().put(key, list);
                  this.values = list;
                  this.iterator = list.listIterator();
              }
              this.iterator.add(value);
          }
  
          @Override
          public boolean hasNext() {
              return iterator.hasNext();
          }
  
          @Override
          public boolean hasPrevious() {
              return iterator.hasPrevious();
          }
  
          @Override
          public V next() {
              return iterator.next();
          }
  
          @Override
          public int nextIndex() {
              return iterator.nextIndex();
          }
  
          @Override
          public V previous() {
              return iterator.previous();
          }
  
          @Override
          public int previousIndex() {
             return iterator.previousIndex();
         }
 
         @Override
         public void remove() {
             iterator.remove();
             if (values.isEmpty()) {
                 getMap().remove(key);
             }
         }
 
         @Override
         public void set(final V value) {
             iterator.set(value);
         }
 
     }
 
     /**
      * Wrapped list to handle add and remove on the list returned by get(object)
      */
     private final class WrappedList extends WrappedCollection implements List<V> {
 
         WrappedList(final K key) {
             super(key);
         }
 
         @Override
         public void add(final int index, final V value) {
             List<V> list = getMapping();
             if (list == null) {
                 list = createCollection();
                 getMap().put(key, list);
             }
             list.add(index, value);
         }
 
         @Override
         public boolean addAll(final int index, final Collection<? extends V> c) {
             List<V> list = getMapping();
             if (list == null) {
                 list = createCollection();
                 final boolean changed = list.addAll(index, c);
                 if (changed) {
                     getMap().put(key, list);
                 }
                 return changed;
             }
             return list.addAll(index, c);
         }
 
         @Override
         public boolean equals(final Object other) {
             final List<V> list = getMapping();
             if (list == null) {
                 return Collections.emptyList().equals(other);
             }
             if (!(other instanceof List)) {
                 return false;
             }
             final List<?> otherList = (List<?>) other;
             return ListUtils.isEqualList(list, otherList);
         }
 
         @Override
         public V get(final int index) {
             final List<V> list = ListUtils.emptyIfNull(getMapping());
             return list.get(index);
         }
 
         @Override
         protected List<V> getMapping() {
             return getMap().get(key);
         }
 
         @Override
         public int hashCode() {
             final List<V> list = getMapping();
             return ListUtils.hashCodeForList(list);
         }
 
         @Override
         public int indexOf(final Object o) {
             final List<V> list = ListUtils.emptyIfNull(getMapping());
             return list.indexOf(o);
         }
 
         @Override
         public int lastIndexOf(final Object o) {
             final List<V> list = ListUtils.emptyIfNull(getMapping());
             return list.lastIndexOf(o);
         }
 
         @Override
         public ListIterator<V> listIterator() {
             return new ValuesListIterator(key);
         }
 
         @Override
         public ListIterator<V> listIterator(final int index) {
             return new ValuesListIterator(key, index);
         }
 
         @Override
         public V remove(final int index) {
             final List<V> list = ListUtils.emptyIfNull(getMapping());
             final V value = list.remove(index);
             if (list.isEmpty()) {
                 AbstractListValuedMap.this.remove(key);
             }
             return value;
         }
 
         @Override
         public V set(final int index, final V value) {
             final List<V> list = ListUtils.emptyIfNull(getMapping());
             return list.set(index, value);
         }
 
         @Override
         public List<V> subList(final int fromIndex, final int toIndex) {
             final List<V> list = ListUtils.emptyIfNull(getMapping());
             return list.subList(fromIndex, toIndex);
         }
 
     }
 
     /**
      * Constructor needed for subclass serialisation.
      */
     protected AbstractListValuedMap() {
     }
 
     /**
      * A constructor that wraps, not copies
      *
      * @param map  the map to wrap, must not be null
      * @throws NullPointerException if the map is null
      */
     protected AbstractListValuedMap(final Map<K, ? extends List<V>> map) {
         super(map);
     }
 
     /**
      * Creates a new value collection using the provided factory.
      * @return a new list
      */
     @Override
     protected abstract List<V> createCollection();
 
     /**
      * Gets the list of values associated with the specified key. This would
      * return an empty list in case the mapping is not present
      *
      * @param key  the key to retrieve
      * @return the {@code List} of values, will return an empty {@link List} for no mapping
      */
     @Override
     public List<V> get(final K key) {
         return wrappedCollection(key);
     }
 
     @Override
     @SuppressWarnings("unchecked")
     protected Map<K, List<V>> getMap() {
         return (Map<K, List<V>>) super.getMap();
     }
 
     /**
      * Removes all values associated with the specified key.
      * <p>
      * A subsequent {@code get(Object)} would return an empty list.
      *
      * @param key  the key to remove values from
      * @return the {@code List} of values removed, will return an empty,
      *   unmodifiable list for no mapping found.
      */
     @Override
     public List<V> remove(final Object key) {
         return ListUtils.emptyIfNull(getMap().remove(key));
     }
 
     @Override
     List<V> wrappedCollection(final K key) {
         return new WrappedList(key);
     }
 
 }