/*
 * 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.flink.types;

import java.io.IOException;
import java.util.Collection;
import java.util.HashMap;
import java.util.Map;
import java.util.Set;

import org.apache.flink.annotation.Public;
import org.apache.flink.core.memory.DataInputView;
import org.apache.flink.core.memory.DataOutputView;
import org.apache.flink.util.ReflectionUtil;

/**
 * Generic map base type for PACT programs that implements the Value and Map interfaces.
 * The {@link MapValue} encapsulates a Java {@link HashMap} object.
 * 
 * @see org.apache.flink.types.Value
 * @see java.util.Map
 * @see java.util.HashMap
 * 
 * @param <K> Type of the map's key element.
 * @param <V> Type of the map's value element.
 * 
 * 
 */
@Public
public abstract class MapValue<K extends Value, V extends Value> implements Value, Map<K, V> {
	private static final long serialVersionUID = 1L;
	
	// type of the map's key
	private final Class<K> keyClass;
	// type of the map's value
	private final Class<V> valueClass;
	// encapsulated map
	private final Map<K, V> map;

	/**
	 * Initializes the encapsulated map with an empty HashMap.
	 */
	public MapValue() {
		this.keyClass = ReflectionUtil.getTemplateType1(this.getClass());
		this.valueClass = ReflectionUtil.getTemplateType2(this.getClass());

		this.map = new HashMap<>();
	}

	/**
	 * Initializes the encapsulated map with a HashMap filled with all entries of the provided map.
	 * 
	 * @param map Map holding all entries with which the new encapsulated map is filled.
	 */
	public MapValue(Map<K, V> map) {
		this.keyClass = ReflectionUtil.getTemplateType1(this.getClass());
		this.valueClass = ReflectionUtil.getTemplateType2(this.getClass());

		this.map = new HashMap<>(map);
	}

	@Override
	public void read(final DataInputView in) throws IOException {
		int size = in.readInt();
		this.map.clear();

		try {
			for (; size > 0; size--) {
				final K key = this.keyClass.newInstance();
				final V val = this.valueClass.newInstance();
				key.read(in);
				val.read(in);
				this.map.put(key, val);
			}
		} catch (final InstantiationException | IllegalAccessException e) {
			throw new RuntimeException(e);
		}
	}

	@Override
	public void write(final DataOutputView out) throws IOException {
		out.writeInt(this.map.size());
		for (final Entry<K, V> entry : this.map.entrySet()) {
			entry.getKey().write(out);
			entry.getValue().write(out);
		}
	}

	/*
	 * (non-Javadoc)
	 * @see java.lang.Object#toString()
	 */
	@Override
	public String toString() {
		return this.map.toString();
	}

	/*
	 * (non-Javadoc)
	 * @see java.lang.Object#hashCode()
	 */
	@Override
	public int hashCode() {
		final int prime = 47;
		int result = 1;
		result = prime * result + this.map.hashCode();
		return result;
	}

	/*
	 * (non-Javadoc)
	 * @see java.lang.Object#equals(java.lang.Object)
	 */
	@Override
	public boolean equals(final Object obj) {
		if (this == obj) {
			return true;
		}
		if (obj == null) {
			return false;
		}
		if (this.getClass() != obj.getClass()) {
			return false;
		}
		final MapValue<?, ?> other = (MapValue<?, ?>) obj;
		if (this.map == null) {
			if (other.map != null) {
				return false;
			}
		} else if (!this.map.equals(other.map)) {
			return false;
		}
		return true;
	}

	/*
	 * (non-Javadoc)
	 * @see java.util.Map#clear()
	 */
	@Override
	public void clear() {
		this.map.clear();
	}

	/*
	 * (non-Javadoc)
	 * @see java.util.Map#containsKey(java.lang.Object)
	 */
	@Override
	public boolean containsKey(final Object key) {
		return this.map.containsKey(key);
	}

	/*
	 * (non-Javadoc)
	 * @see java.util.Map#containsValue(java.lang.Object)
	 */
	@Override
	public boolean containsValue(final Object value) {
		return this.map.containsValue(value);
	}

	/*
	 * (non-Javadoc)
	 * @see java.util.Map#entrySet()
	 */
	@Override
	public Set<Entry<K, V>> entrySet() {
		return this.map.entrySet();
	}

	/*
	 * (non-Javadoc)
	 * @see java.util.Map#get(java.lang.Object)
	 */
	@Override
	public V get(final Object key) {
		return this.map.get(key);
	}

	/*
	 * (non-Javadoc)
	 * @see java.util.Map#isEmpty()
	 */
	@Override
	public boolean isEmpty() {
		return this.map.isEmpty();
	}

	/*
	 * (non-Javadoc)
	 * @see java.util.Map#keySet()
	 */
	@Override
	public Set<K> keySet() {
		return this.map.keySet();
	}

	/*
	 * (non-Javadoc)
	 * @see java.util.Map#put(java.lang.Object, java.lang.Object)
	 */
	@Override
	public V put(final K key, final V value) {
		return this.map.put(key, value);
	}

	/*
	 * (non-Javadoc)
	 * @see java.util.Map#putAll(java.util.Map)
	 */
	@Override
	public void putAll(final Map<? extends K, ? extends V> m) {
		this.map.putAll(m);
	}

	/*
	 * (non-Javadoc)
	 * @see java.util.Map#remove(java.lang.Object)
	 */
	@Override
	public V remove(final Object key) {
		return this.map.remove(key);
	}

	/*
	 * (non-Javadoc)
	 * @see java.util.Map#size()
	 */
	@Override
	public int size() {
		return this.map.size();
	}

	/*
	 * (non-Javadoc)
	 * @see java.util.Map#values()
	 */
	@Override
	public Collection<V> values() {
		return this.map.values();
	}

}