package com.c2kernel.persistency;
import java.util.HashMap;
import java.util.StringTokenizer;

import com.c2kernel.common.ObjectNotFoundException;
import com.c2kernel.entity.AgentHelper;
import com.c2kernel.entity.C2KLocalObject;
import com.c2kernel.entity.Item;
import com.c2kernel.entity.ItemHelper;
import com.c2kernel.lookup.ItemPath;
import com.c2kernel.lookup.Lookup;
import com.c2kernel.persistency.outcome.Outcome;
import com.c2kernel.process.Gateway;
import com.c2kernel.process.auth.Authenticator;
import com.c2kernel.utils.Logger;

/** Used by proxies to load clusters by queryData from the Entity.
*   Last client storage - only used if not cached elsewhere
*/

public class ProxyLoader extends ClusterStorage {
    HashMap<ItemPath, Item> entities = new HashMap<ItemPath, Item>();
    Lookup lookup;

    @Override
	public void open(Authenticator auth) throws ClusterStorageException {
        lookup = Gateway.getLookup();
    }

    @Override
	public void close() throws ClusterStorageException {
    }
    // introspection
    @Override
	public short queryClusterSupport(String clusterType) {
        return READ;
    }

    @Override
	public String getName() {
        return "Proxy Cluster Loader";
    }

    @Override
	public String getId() {
        return "CORBA";
    }

    // retrieve object by path
    @Override
	public C2KLocalObject get(ItemPath thisItem, String path) throws ClusterStorageException {
        try {
            Item thisEntity = getIOR(thisItem);
            String type = getClusterType(path);

            // fetch the xml from the item
            String queryData = thisEntity.queryData(path);
            if (Logger.doLog(6)) Logger.msg(6, "ProxyLoader - "+thisItem+":"+path+" = "+queryData);

            if (queryData != null) {
                if (type.equals(OUTCOME))
                    return new Outcome(path, queryData);
                else
                    return (C2KLocalObject)Gateway.getMarshaller().unmarshall(queryData);
            }
        } catch (ObjectNotFoundException e) {
        	return null;
        } catch (Exception e) {
            Logger.error(e);
            throw new ClusterStorageException(e.getMessage());
        }
        return null;
    }

    // store object by path
    @Override
	public void put(ItemPath thisItem, C2KLocalObject obj) throws ClusterStorageException {
        // not supported
        throw new ClusterStorageException("Cannot write to items through the ProxyLoader");
    }
    // delete cluster
    @Override
	public void delete(ItemPath thisItem, String path) throws ClusterStorageException {
        // not supported
        throw new ClusterStorageException("Cannot write to items through the ProxyLoader");
    }

    /* navigation */

    // directory listing
    @Override
	public String[] getClusterContents(ItemPath thisItem, String path) throws ClusterStorageException {
        try {
            Item thisEntity = getIOR(thisItem);
            String contents = thisEntity.queryData(path+"/all");
            StringTokenizer tok = new StringTokenizer(contents, ",");
            String[] result = new String[tok.countTokens()];
            for (int i=0; i<result.length; i++)
                result[i] = tok.nextToken();

            return result;
        } catch (Exception e) {
        	Logger.error(e);
            throw new ClusterStorageException(e.getMessage());
        }
    }

    private Item getIOR(ItemPath thisPath) throws ClusterStorageException {
        if (entities.containsKey(thisPath)) {
            // check the cache
            Logger.msg(7, "ProxyLoader.getIOR() - "+thisPath+" cached.");
            return entities.get(thisPath);
        }

        try {
            Logger.msg(7, "ProxyLoader.getIOR() - Resolving "+thisPath+".");
            org.omg.CORBA.Object ior = lookup.resolve(thisPath);

            Item thisItem = null;
            try {
            	thisItem = ItemHelper.narrow(ior);
            } catch (org.omg.CORBA.BAD_PARAM ex) {
                try {
                	thisItem =  AgentHelper.narrow(ior);
                } catch (org.omg.CORBA.BAD_PARAM ex2) {
                    throw new ClusterStorageException ("Could not narrow "+thisItem+" as a known Entity type");
                }
            }

            Logger.msg(7, "ProxyLoader.getIOR() - Found "+thisItem+".");
            entities.put(thisPath, thisItem);
            return thisItem;
        } catch (Exception e) {
            throw new ClusterStorageException("Error narrowing "+thisPath+": "+e.getMessage());
        }
    }
}