/*
 * 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.map;

import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;
import java.util.Map;

import org.apache.commons.collections4.Transformer;

Decorates another Map to transform objects that are added.

The Map put methods and Map.Entry setValue method are affected by this class.
Thus objects must be removed or searched for using their transformed form.
For example, if the transformation converts Strings to Integers, you must
use the Integer form to remove objects.


Note that TransformedMap is not synchronized and is not thread-safe. If you wish to use this map from multiple threads concurrently, you must use appropriate synchronization. The simplest approach is to wrap this map using Collections.synchronizedMap(Map<Object,Object>). This class may throw exceptions when accessed by concurrent threads without synchronization. 

This class is Serializable from Commons Collections 3.1.

Type parameters:
<K> – the type of the keys in this map
<V> – the type of the values in this map
See Also:
TransformedSplitMap
Since:
3.0/**
 * Decorates another <code>Map</code> to transform objects that are added.
 * <p>
 * The Map put methods and Map.Entry setValue method are affected by this class.
 * Thus objects must be removed or searched for using their transformed form.
 * For example, if the transformation converts Strings to Integers, you must
 * use the Integer form to remove objects.
 * </p>
 * <p>
 * <strong>Note that TransformedMap is not synchronized and is not thread-safe.</strong>
 * If you wish to use this map from multiple threads concurrently, you must use
 * appropriate synchronization. The simplest approach is to wrap this map
 * using {@link java.util.Collections#synchronizedMap(Map)}. This class may throw
 * exceptions when accessed by concurrent threads without synchronization.
 * </p>
 * <p>
 * This class is Serializable from Commons Collections 3.1.
 * </p>
 *
 * @param <K> the type of the keys in this map
 * @param <V> the type of the values in this map
 *
 * @see org.apache.commons.collections4.splitmap.TransformedSplitMap
 * @since 3.0
 */
public class TransformedMap<K, V>
        extends AbstractInputCheckedMapDecorator<K, V>
        implements Serializable {

    
Serialization version /** Serialization version */
    private static final long serialVersionUID = 7023152376788900464L;

    
The transformer to use for the key /** The transformer to use for the key */
    protected final Transformer<? super K, ? extends K> keyTransformer;
    
The transformer to use for the value /** The transformer to use for the value */
    protected final Transformer<? super V, ? extends V> valueTransformer;

    
Factory method to create a transforming map.
 If there are any elements already in the map being decorated, they are NOT transformed. Contrast this with transformedMap(Map<Object,Object>, Transformer<? super Object,? extends Object>, Transformer<? super Object,? extends Object>). 
Params:
map –  the map to decorate, must not be null
keyTransformer –  the transformer to use for key conversion, null means no transformation
valueTransformer –  the transformer to use for value conversion, null means no transformation
Type parameters:
<K> –  the key type
<V> –  the value type
Throws:
NullPointerException – if map is null
Returns:
a new transformed map
Since:
4.0/**
     * Factory method to create a transforming map.
     * <p>
     * If there are any elements already in the map being decorated, they
     * are NOT transformed.
     * Contrast this with {@link #transformedMap(Map, Transformer, Transformer)}.
     *
     * @param <K>  the key type
     * @param <V>  the value type
     * @param map  the map to decorate, must not be null
     * @param keyTransformer  the transformer to use for key conversion, null means no transformation
     * @param valueTransformer  the transformer to use for value conversion, null means no transformation
     * @return a new transformed map
     * @throws NullPointerException if map is null
     * @since 4.0
     */
    public static <K, V> TransformedMap<K, V> transformingMap(final Map<K, V> map,
            final Transformer<? super K, ? extends K> keyTransformer,
            final Transformer<? super V, ? extends V> valueTransformer) {
        return new TransformedMap<>(map, keyTransformer, valueTransformer);
    }

    
Factory method to create a transforming map that will transform
existing contents of the specified map.
 If there are any elements already in the map being decorated, they will be transformed by this method. Contrast this with transformingMap(Map<Object,Object>, Transformer<? super Object,? extends Object>, Transformer<? super Object,? extends Object>). 
Params:
map –  the map to decorate, must not be null
keyTransformer –  the transformer to use for key conversion, null means no transformation
valueTransformer –  the transformer to use for value conversion, null means no transformation
Type parameters:
<K> –  the key type
<V> –  the value type
Throws:
NullPointerException – if map is null
Returns:
a new transformed map
Since:
4.0/**
     * Factory method to create a transforming map that will transform
     * existing contents of the specified map.
     * <p>
     * If there are any elements already in the map being decorated, they
     * will be transformed by this method.
     * Contrast this with {@link #transformingMap(Map, Transformer, Transformer)}.
     *
     * @param <K>  the key type
     * @param <V>  the value type
     * @param map  the map to decorate, must not be null
     * @param keyTransformer  the transformer to use for key conversion, null means no transformation
     * @param valueTransformer  the transformer to use for value conversion, null means no transformation
     * @return a new transformed map
     * @throws NullPointerException if map is null
     * @since 4.0
     */
    public static <K, V> TransformedMap<K, V> transformedMap(final Map<K, V> map,
            final Transformer<? super K, ? extends K> keyTransformer,
            final Transformer<? super V, ? extends V> valueTransformer) {
        final TransformedMap<K, V> decorated = new TransformedMap<>(map, keyTransformer, valueTransformer);
        if (map.size() > 0) {
            final Map<K, V> transformed = decorated.transformMap(map);
            decorated.clear();
            decorated.decorated().putAll(transformed);  // avoids double transformation
        }
        return decorated;
    }

    //-----------------------------------------------------------------------
    
Constructor that wraps (not copies).

If there are any elements already in the collection being decorated, they
are NOT transformed.
Params:
map –  the map to decorate, must not be null
keyTransformer –  the transformer to use for key conversion, null means no conversion
valueTransformer –  the transformer to use for value conversion, null means no conversion
Throws:
NullPointerException – if map is null/**
     * Constructor that wraps (not copies).
     * <p>
     * If there are any elements already in the collection being decorated, they
     * are NOT transformed.
     *
     * @param map  the map to decorate, must not be null
     * @param keyTransformer  the transformer to use for key conversion, null means no conversion
     * @param valueTransformer  the transformer to use for value conversion, null means no conversion
     * @throws NullPointerException if map is null
     */
    protected TransformedMap(final Map<K, V> map, final Transformer<? super K, ? extends K> keyTransformer,
            final Transformer<? super V, ? extends V> valueTransformer) {
        super(map);
        this.keyTransformer = keyTransformer;
        this.valueTransformer = valueTransformer;
    }

    //-----------------------------------------------------------------------
    
Write the map out using a custom routine.
Params:
out –  the output stream
Throws:
IOException – if an error occurs while writing to the stream
Since:
3.1/**
     * Write the map out using a custom routine.
     *
     * @param out  the output stream
     * @throws IOException if an error occurs while writing to the stream
     * @since 3.1
     */
    private void writeObject(final ObjectOutputStream out) throws IOException {
        out.defaultWriteObject();
        out.writeObject(map);
    }

    
Read the map in using a custom routine.
Params:
in –  the input stream
Throws:
IOException – if an error occurs while reading from the stream
ClassNotFoundException – if an object read from the stream can not be loaded
Since:
3.1/**
     * Read the map in using a custom routine.
     *
     * @param in  the input stream
     * @throws IOException if an error occurs while reading from the stream
     * @throws ClassNotFoundException if an object read from the stream can not be loaded
     * @since 3.1
     */
    @SuppressWarnings("unchecked") // (1) should only fail if input stream is incorrect
    private void readObject(final ObjectInputStream in) throws IOException, ClassNotFoundException {
        in.defaultReadObject();
        map = (Map<K, V>) in.readObject(); // (1)
    }

    //-----------------------------------------------------------------------
    
Transforms a key.

The transformer itself may throw an exception if necessary.
Params:
object –  the object to transform
Returns:
the transformed object/**
     * Transforms a key.
     * <p>
     * The transformer itself may throw an exception if necessary.
     *
     * @param object  the object to transform
     * @return the transformed object
     */
    protected K transformKey(final K object) {
        if (keyTransformer == null) {
            return object;
        }
        return keyTransformer.transform(object);
    }

    
Transforms a value.

The transformer itself may throw an exception if necessary.
Params:
object –  the object to transform
Returns:
the transformed object/**
     * Transforms a value.
     * <p>
     * The transformer itself may throw an exception if necessary.
     *
     * @param object  the object to transform
     * @return the transformed object
     */
    protected V transformValue(final V object) {
        if (valueTransformer == null) {
            return object;
        }
        return valueTransformer.transform(object);
    }

    
Transforms a map.

The transformer itself may throw an exception if necessary.
Params:
map –  the map to transform
Returns:
the transformed object/**
     * Transforms a map.
     * <p>
     * The transformer itself may throw an exception if necessary.
     *
     * @param map  the map to transform
     * @return the transformed object
     */
    @SuppressWarnings("unchecked")
    protected Map<K, V> transformMap(final Map<? extends K, ? extends V> map) {
        if (map.isEmpty()) {
            return (Map<K, V>) map;
        }
        final Map<K, V> result = new LinkedMap<>(map.size());

        for (final Map.Entry<? extends K, ? extends V> entry : map.entrySet()) {
            result.put(transformKey(entry.getKey()), transformValue(entry.getValue()));
        }
        return result;
    }

    
Override to transform the value when using setValue.
Params:
value –  the value to transform
Returns:
the transformed value
Since:
3.1/**
     * Override to transform the value when using <code>setValue</code>.
     *
     * @param value  the value to transform
     * @return the transformed value
     * @since 3.1
     */
    @Override
    protected V checkSetValue(final V value) {
        return valueTransformer.transform(value);
    }

    
Override to only return true when there is a value transformer.
Returns:
true if a value transformer is in use
Since:
3.1/**
     * Override to only return true when there is a value transformer.
     *
     * @return true if a value transformer is in use
     * @since 3.1
     */
    @Override
    protected boolean isSetValueChecking() {
        return valueTransformer != null;
    }

    //-----------------------------------------------------------------------
    @Override
    public V put(K key, V value) {
        key = transformKey(key);
        value = transformValue(value);
        return decorated().put(key, value);
    }

    @Override
    public void putAll(Map<? extends K, ? extends V> mapToCopy) {
        mapToCopy = transformMap(mapToCopy);
        decorated().putAll(mapToCopy);
    }

}