/*
    * 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;
  
  import java.util.Collection;
  import java.util.Map;
  import java.util.Objects;
  import java.util.Set;
  
  import org.apache.commons.collections4.collection.UnmodifiableCollection;
  import org.apache.commons.collections4.iterators.UnmodifiableMapIterator;
  import org.apache.commons.collections4.map.EntrySetToMapIteratorAdapter;
  import org.apache.commons.collections4.map.UnmodifiableEntrySet;
  import org.apache.commons.collections4.set.UnmodifiableSet;
  
  /**
   * Utilities for working with "split maps:" objects that implement {@link Put}
   * and/or {@link Get} but not {@link Map}.
   *
   * @since 4.0
   * @see Get
   * @see Put
   */
  public class SplitMapUtils {
  
      private static final class WrappedGet<K, V> implements IterableMap<K, V>, Unmodifiable {
          private final Get<K, V> get;
  
          private WrappedGet(final Get<K, V> get) {
              this.get = get;
          }
  
          @Override
          public void clear() {
              throw new UnsupportedOperationException();
          }
  
          @Override
          public boolean containsKey(final Object key) {
              return get.containsKey(key);
          }
  
          @Override
          public boolean containsValue(final Object value) {
              return get.containsValue(value);
          }
  
          @Override
          public Set<Map.Entry<K, V>> entrySet() {
              return UnmodifiableEntrySet.unmodifiableEntrySet(get.entrySet());
          }
  
          @Override
          public boolean equals(final Object arg0) {
              if (arg0 == this) {
                  return true;
              }
              return arg0 instanceof WrappedGet && ((WrappedGet<?, ?>) arg0).get.equals(get);
          }
  
          @Override
          public V get(final Object key) {
              return get.get(key);
          }
  
          @Override
          public int hashCode() {
              return "WrappedGet".hashCode() << 4 | get.hashCode();
          }
  
          @Override
          public boolean isEmpty() {
              return get.isEmpty();
          }
  
          @Override
          public Set<K> keySet() {
              return UnmodifiableSet.unmodifiableSet(get.keySet());
          }
  
          @Override
          public MapIterator<K, V> mapIterator() {
              final MapIterator<K, V> it;
              if (get instanceof IterableGet) {
                  it = ((IterableGet<K, V>) get).mapIterator();
             } else {
                 it = new EntrySetToMapIteratorAdapter<>(get.entrySet());
             }
             return UnmodifiableMapIterator.unmodifiableMapIterator(it);
         }
 
         @Override
         public V put(final K key, final V value) {
             throw new UnsupportedOperationException();
         }
 
         @Override
         public void putAll(final Map<? extends K, ? extends V> t) {
             throw new UnsupportedOperationException();
         }
 
         @Override
         public V remove(final Object key) {
             return get.remove(key);
         }
 
         @Override
         public int size() {
             return get.size();
         }
 
         @Override
         public Collection<V> values() {
             return UnmodifiableCollection.unmodifiableCollection(get.values());
         }
     }
 
     private static final class WrappedPut<K, V> implements Map<K, V>, Put<K, V> {
         private final Put<K, V> put;
 
         private WrappedPut(final Put<K, V> put) {
             this.put = put;
         }
 
         @Override
         public void clear() {
             put.clear();
         }
 
         @Override
         public boolean containsKey(final Object key) {
             throw new UnsupportedOperationException();
         }
 
         @Override
         public boolean containsValue(final Object value) {
             throw new UnsupportedOperationException();
         }
 
         @Override
         public Set<Map.Entry<K, V>> entrySet() {
             throw new UnsupportedOperationException();
         }
 
         @Override
         public boolean equals(final Object obj) {
             if (obj == this) {
                 return true;
             }
             return obj instanceof WrappedPut && ((WrappedPut<?, ?>) obj).put.equals(put);
         }
 
         @Override
         public V get(final Object key) {
             throw new UnsupportedOperationException();
         }
 
         @Override
         public int hashCode() {
             return "WrappedPut".hashCode() << 4 | put.hashCode();
         }
 
         @Override
         public boolean isEmpty() {
             throw new UnsupportedOperationException();
         }
 
         @Override
         public Set<K> keySet() {
             throw new UnsupportedOperationException();
         }
 
         @Override
         @SuppressWarnings("unchecked")
         public V put(final K key, final V value) {
             return (V) put.put(key, value);
         }
 
         @Override
         public void putAll(final Map<? extends K, ? extends V> t) {
             put.putAll(t);
         }
 
         @Override
         public V remove(final Object key) {
             throw new UnsupportedOperationException();
         }
 
         @Override
         public int size() {
             throw new UnsupportedOperationException();
         }
 
         @Override
         public Collection<V> values() {
             throw new UnsupportedOperationException();
         }
     }
 
     /**
      * Gets the specified {@link Get} as an instance of {@link IterableMap}.
      * If {@code get} implements {@link IterableMap} directly, no conversion will take place.
      * If {@code get} implements {@link Map} but not {@link IterableMap} it will be decorated.
      * Otherwise, an {@link Unmodifiable} {@link IterableMap} will be returned.
      *
      * @param <K> the key type
      * @param <V> the value type
      * @param get to wrap, must not be null
      * @return {@link IterableMap}
      * @throws NullPointerException if the argument is null
      */
     @SuppressWarnings("unchecked")
     public static <K, V> IterableMap<K, V> readableMap(final Get<K, V> get) {
         Objects.requireNonNull(get, "get");
         if (get instanceof Map) {
             return get instanceof IterableMap ?
                     (IterableMap<K, V>) get :
                     MapUtils.iterableMap((Map<K, V>) get);
         }
         return new WrappedGet<>(get);
     }
 
     /**
      * Gets the specified {@link Put} as an instanceof {@link Map}.
      * If {@code put} implements {@link Map} directly, no conversion will take place.
      * Otherwise, a <em>write-only</em> {@link Map} will be returned.  On such a {@link Map}
      * it is recommended that the result of #put(K, V) be discarded as it likely will not
      * match {@code V} at runtime.
      *
      * @param <K> the key type
      * @param <V> the element type
      * @param put to wrap, must not be null
      * @return {@link Map}
      * @throws NullPointerException if the argument is null
      */
     @SuppressWarnings("unchecked")
     public static <K, V> Map<K, V> writableMap(final Put<K, V> put) {
         Objects.requireNonNull(put, "put");
         if (put instanceof Map) {
             return (Map<K, V>) put;
         }
         return new WrappedPut<>(put);
     }
 
     /**
      * Don't allow instances.
      */
     private SplitMapUtils() {
         // empty
     }
 
 }