package org.hedgewars.hedgeroid.netplay;

import java.util.Collection;

import java.util.Collections;

import java.util.LinkedHashMap;

import java.util.LinkedList;

import java.util.List;

import java.util.Map;

/**

 * A map of items, sorted by time of insertion (earliest first). 

 * Observers can be notified about insertions, deletions and changes (which don't change the order).

 * This is useful for e.g. the lists of current rooms and players, because it allows easy addition

 * and removal of entries on the one side, as well as reaction to these events by UI elements.

 */

public class ObservableLinkedHashMap<K,V> {

	private LinkedHashMap<K,V> map = new LinkedHashMap<K,V>();

	private List<Observer<K,V>> observers = new LinkedList<Observer<K,V>>();

	public Collection<V> getValues() {

		return Collections.unmodifiableCollection(map.values());

	}

	public Map<K,V> getMap() {

		return Collections.unmodifiableMap(map);

	}

	public void observe(Observer<K,V> observer) {

		observers.add(observer);

	}

	public void unobserve(Observer<K,V> observer) {

		observers.remove(observer);

	}

	// TODO ugh

	public void clear() {

		while(!map.isEmpty()) {

			remove(map.keySet().iterator().next());

		}

	}

	public void put(K key, V value) {

		V oldValue = map.put(key, value);

		Map<K,V> unmodifiableMap = Collections.unmodifiableMap(map);

		if(oldValue != null) {

			for(Observer<K,V> o : observers) {

				o.itemReplaced(unmodifiableMap, key, oldValue, value);

			}

		} else {

			for(Observer<K,V> o : observers) {

				o.itemAdded(unmodifiableMap, key, value);

			}

		}

	}

	public void remove(K key) {

		V oldValue = map.remove(key);

		if(oldValue != null) {

			Map<K,V> unmodifiableMap = Collections.unmodifiableMap(map);

			for(Observer<K,V> o : observers) {

				o.itemRemoved(unmodifiableMap, key, oldValue);

			}

		}

	}

	public static interface Observer<K,V> {

		void itemAdded(Map<K,V> map, K key, V value);

		void itemRemoved(Map<K,V> map, K key, V oldValue);

		void itemReplaced(Map<K,V> map, K key, V oldValue, V newValue);

	}

}