import java.util.ArrayList;

import java.util.Collections;

import java.util.Comparator;

import java.util.List;

import android.database.DataSetObserver;

import android.widget.BaseAdapter;

public abstract class ObservableTreeMapAdapter<K,V> extends BaseAdapter {

	private boolean sourceChanged = true;

	private List<V> entries = new ArrayList<V>();

	private ObservableTreeMap<K, V> source;

	private DataSetObserver observer = new DataSetObserver() {

		@Override

		public void onChanged() {

			sourceChanged = true;

			notifyDataSetChanged();

		}

		@Override

		public void onInvalidated() {

			invalidate();

		}

	};

	abstract protected Comparator<V> getEntryOrder();

	protected List<V> getEntries() {

		if(sourceChanged) {

			entries.clear();

			entries.addAll(source.getMap().values());

			Collections.sort(entries, getEntryOrder());

			sourceChanged = false;

		}

		return entries;

	}

	public int getCount() {

		return getEntries().size();

	}

	public void setSource(ObservableTreeMap<K,V> source) {

		if(this.source != null) {

			this.source.unregisterObserver(observer);

		}

		this.source = source;

		this.source.registerObserver(observer);

		sourceChanged = true;

		notifyDataSetChanged();

	}

	public void invalidate() {

		if(source != null) {

			source.unregisterObserver(observer);

		}

		source = null;

		notifyDataSetInvalidated();

	}

}