package dk.thoerup.traininfo.util;

import java.util.HashMap;
import java.util.Iterator;
import java.util.Set;

import android.util.Log;


public class AndroidTimeoutCache<K,V> {

	class CacheItem<T> {
		
		public CacheItem(T v) {
			value = v;
			lastupdate = android.os.SystemClock.elapsedRealtime();
		}
		
		public boolean isExpired(long now) {
			return ( (lastupdate+timeout) < now);
		}
		
		public long lastupdate;
		public T value;
	}
	
	private HashMap<K,CacheItem<V>> cache = new HashMap<K,CacheItem<V>>();
	private long timeout;
	
	public AndroidTimeoutCache(int timeout) {
		this.timeout = timeout; 
	}
	
	public void purgeOldEntries() {
		
		long now = android.os.SystemClock.elapsedRealtime();
		//Log.e("Purge","Purge");
		
		Set<K> keyset = cache.keySet();
		
		for ( Iterator<K> it = keyset.iterator(); it.hasNext() ;) {
			K key = it.next();
			
			CacheItem<V> item = cache.get(key);
			if ( item.isExpired(now)) { //item too old
				it.remove();
				//Log.e("Purge", "removing");
			}			
		}	
		
	}
	
	public void put(K k, V v) {
		CacheItem<V> item= new CacheItem<V>(v);
		cache.put(k, item);
	}
	
	public V get(K k) {
		long now = android.os.SystemClock.elapsedRealtime();
		
		CacheItem<V> item = cache.get(k);
				
		
		if (item != null) {
			if ( item.isExpired(now) ) { //item too old
				return null;
			} else {
				return item.value; //item still good
			}
		} else {
			return null; // no item found
		}
		
	}
	
}