/**
 *
 */
package com.c2kernel.utils;

import com.c2kernel.common.InvalidDataException;
import com.c2kernel.common.ObjectNotFoundException;
import com.c2kernel.entity.proxy.ProxyObserver;
import com.c2kernel.entity.proxy.ItemProxy;
import com.c2kernel.entity.proxy.MemberSubscription;
import com.c2kernel.persistency.ClusterStorage;
import com.c2kernel.persistency.outcome.Viewpoint;

public abstract class DescriptionObjectCache<D extends DescriptionObject> {

	SoftCache<String, CacheEntry<D>> cache = new SoftCache<String, CacheEntry<D>>();

	public D get(String name, int version) throws ObjectNotFoundException, InvalidDataException {
		D thisDef;
		synchronized(cache) {
			CacheEntry<D> thisDefEntry = cache.get(name+"_"+version);
			if (thisDefEntry == null) {
				Logger.msg(6, name+" v"+version+" not found in cache. Retrieving.");
		        ItemProxy defItem = LocalObjectLoader.loadLocalObjectDef(getDefRoot(), name);
		        thisDef = loadObject(name, version, defItem);
		        cache.put(name+"_"+version, new CacheEntry<D>(thisDef, defItem, this));
			}
			else {
				Logger.msg(6, name+" v"+version+" found in cache.");
				thisDef = thisDefEntry.def;
			}
		}
        return thisDef;
	}
	
	public abstract String getDefRoot();
	
	public abstract D loadObject(String name, int version, ItemProxy proxy) throws ObjectNotFoundException, InvalidDataException;

	public void removeAct(String id) {
		synchronized(cache) {
		if (cache.keySet().contains(id)) {
			Logger.msg(7, "ActDefCache: Removing activity def "+id+" from cache");
			cache.remove(id);
			}
		}
	}

	public class CacheEntry<E extends DescriptionObject> implements ProxyObserver<Viewpoint> {
		public String id;
		public ItemProxy proxy;
		public E def;
		public DescriptionObjectCache<E> parent;
		public CacheEntry(E def, ItemProxy proxy, DescriptionObjectCache<E> parent) {
			this.id = def.getName()+"_"+def.getVersion();
			this.def = def;
			this.parent = parent;
			this.proxy = proxy;
			proxy.subscribe(new MemberSubscription<Viewpoint>(this, ClusterStorage.VIEWPOINT, false));
		}
		@Override
		public void finalize() {
			parent.removeAct(id);
			proxy.unsubscribe(this);
		}
		@Override
		public void add(Viewpoint contents) {
			parent.removeAct(id);
		}

		@Override
		public void remove(String oldId) {
			parent.removeAct(oldId);
		}

		@Override
		public String toString() {
			return "Cache entry: "+id;
		}
		@Override
		public void control(String control, String msg) {
		}
	}
}