/*
 * Copyright 2013 Robert von Burg <eitch@eitchnet.ch>
 * 
 * Licensed 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 li.strolch.utils.collections;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;

/**
 * <p>
 * Collection to store a tree with a depth of 3 elements. This solves having to always write the declaration:
 * </p>
 * 
 * <pre>
 * Map<String, Map&lgt;String, MyObject>> mapOfMaps = new HashMap<>;
 * </pre>
 * 
 * <p>
 * As an example to persist a map of MyObject where the branches are String one would write it as follows:
 * </p>
 * 
 * <pre>
 * MapOfMaps<String, String, MyObject> mapOfMaps = new MapOfMaps<>();
 * </pre>
 * 
 * 
 * @author Robert von Burg <eitch@eitchnet.ch>
 * 
 * @param <T>
 *            The key to a map with U as the key and V as the value
 * @param <U>
 *            The key to get a value (leaf)
 * @param <V>
 *            The value stored in the tree (leaf)
 */
public class MapOfMaps<T, U, V> {

	private Map<T, Map<U, V>> mapOfMaps;

	public MapOfMaps() {
		this.mapOfMaps = new HashMap<>();
	}

	public Set<T> keySet() {
		return this.mapOfMaps.keySet();
	}

	public Map<U, V> getMap(T t) {
		return this.mapOfMaps.get(t);
	}

	public V getElement(T t, U u) {
		Map<U, V> map = this.mapOfMaps.get(t);
		if (map == null)
			return null;
		return map.get(u);
	}

	public V addElement(T t, U u, V v) {
		Map<U, V> map = this.mapOfMaps.get(t);
		if (map == null) {
			map = new HashMap<>();
			this.mapOfMaps.put(t, map);
		}
		return map.put(u, v);
	}

	public List<V> getAllElements() {
		List<V> all = new ArrayList<>();
		for (Map<U, V> u : this.mapOfMaps.values()) {
			all.addAll(u.values());
		}
		return all;
	}

	public List<V> getAllElements(T t) {
		List<V> all = new ArrayList<>();
		Map<U, V> map = this.mapOfMaps.get(t);
		if (map != null) {
			all.addAll(map.values());
		}
		return all;
	}

	public void addMap(T t, Map<U, V> u) {
		Map<U, V> map = this.mapOfMaps.get(t);
		if (map == null) {
			map = new HashMap<>();
			this.mapOfMaps.put(t, map);
		}
		map.putAll(u);
	}

	public V removeElement(T t, U u) {
		Map<U, V> map = this.mapOfMaps.get(t);
		if (map == null) {
			return null;
		}
		V v = map.remove(u);
		if (map.isEmpty()) {
			this.mapOfMaps.remove(t);
		}

		return v;
	}

	public Map<U, V> removeMap(T t) {
		return this.mapOfMaps.remove(t);
	}

	public void clear() {
		Set<Entry<T, Map<U, V>>> entrySet = this.mapOfMaps.entrySet();
		Iterator<Entry<T, Map<U, V>>> iter = entrySet.iterator();
		while (iter.hasNext()) {
			iter.next().getValue().clear();
			iter.remove();
		}
	}

	public boolean containsMap(T t) {
		return this.mapOfMaps.containsKey(t);
	}

	public boolean containsElement(T t, U u) {
		Map<U, V> map = this.mapOfMaps.get(t);
		if (map == null)
			return false;
		return map.containsKey(u);
	}

	public int sizeKeys() {
		return this.mapOfMaps.size();
	}

	public int size() {
		int size = 0;
		Set<Entry<T, Map<U, V>>> entrySet = this.mapOfMaps.entrySet();
		Iterator<Entry<T, Map<U, V>>> iter = entrySet.iterator();
		while (iter.hasNext()) {
			size += iter.next().getValue().size();
		}
		return size;
	}

	public int size(T t) {
		Map<U, V> map = this.mapOfMaps.get(t);
		if (map == null)
			return 0;
		return map.size();
	}

	public boolean isEmpty() {
		return this.mapOfMaps.isEmpty();
	}
}