StateFilter.java

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/*
    Calimero - A library for KNX network access
    Copyright (C) 2006-2008 B. Malinowsky

    This program is free software; you can redistribute it and/or 
    modify it under the terms of the GNU General Public License 
    as published by the Free Software Foundation; either version 2 
    of the License, or at your option any later version. 
 
    This program is distributed in the hope that it will be useful, 
    but WITHOUT ANY WARRANTY; without even the implied warranty of 
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the 
    GNU General Public License for more details. 
 
    You should have received a copy of the GNU General Public License 
    along with this program; if not, write to the Free Software 
    Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA. 
 
    Linking this library statically or dynamically with other modules is 
    making a combined work based on this library. Thus, the terms and 
    conditions of the GNU General Public License cover the whole 
    combination. 
 
    As a special exception, the copyright holders of this library give you 
    permission to link this library with independent modules to produce an 
    executable, regardless of the license terms of these independent 
    modules, and to copy and distribute the resulting executable under terms 
    of your choice, provided that you also meet, for each linked independent 
    module, the terms and conditions of the license of that module. An 
    independent module is a module which is not derived from or based on 
    this library. If you modify this library, you may extend this exception 
    to your version of the library, but you are not obligated to do so. If 
    you do not wish to do so, delete this exception statement from your 
    version. 
*/

package tuwien.auto.calimero.buffer;

import java.util.ArrayList;
import java.util.Collection;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;

import tuwien.auto.calimero.GroupAddress;
import tuwien.auto.calimero.KNXAddress;
import tuwien.auto.calimero.buffer.Configuration.NetworkFilter;
import tuwien.auto.calimero.buffer.Configuration.RequestFilter;
import tuwien.auto.calimero.buffer.cache.Cache;
import tuwien.auto.calimero.buffer.cache.CacheObject;
import tuwien.auto.calimero.cemi.CEMI;
import tuwien.auto.calimero.cemi.CEMIFactory;
import tuwien.auto.calimero.cemi.CEMILData;
import tuwien.auto.calimero.datapoint.Datapoint;
import tuwien.auto.calimero.datapoint.DatapointMap;
import tuwien.auto.calimero.datapoint.DatapointModel;
import tuwien.auto.calimero.datapoint.StateDP;
import tuwien.auto.calimero.exception.KNXFormatException;

/**
 * Predefined filter for filtering KNX messages of datapoints with state semantic into the
 * associated network buffer configuration.
 * <p>
 * This filter might be used in a configuration to build up and maintain a process image
 * of the KNX network the used network link communicates with. The buffer will keep the
 * most up to date state to a KNX group address / datapoint.<br>
 * KNX messages are buffered using a {@link LDataObject} (an object of this
 * type is also expected when the request method is invoked).
 * <p>
 * If a datapoint model is available in the {@link Configuration}, the filter uses that
 * model in its {@link #init(Configuration)} method. It initializes its local lookup
 * references with necessary updating / invalidating information of other datapoints
 * stored in that model. Thus, the filter will update or invalidate all other associated
 * datapoint state values in the network buffer configuration when receiving a new KNX
 * message.<br>
 * To reflect subsequent changes of the datapoint model in the filter, the filter has to
 * be reinitialized (using {@link #init(Configuration)}.
 * 
 * @author B. Malinowsky
 */
public class StateFilter implements NetworkFilter, RequestFilter
{
	// TODO: provide an automated way to detect and react
	// on changes in the datapoint model
	
	// contains cross references of datapoints: which datapoint (key, of
	// type KNXAddress) invalidates/updates which datapoints (value,
	// of type List with GroupAddress entries)
	private Map invalidate;
	private Map update;
	
	/**
	 * Creates a new state based filter.
	 * <p>
	 */
	public StateFilter()
	{}

	/* (non-Javadoc)
	 * @see tuwien.auto.calimero.buffer.Configuration.NetworkFilter#init
	 * (tuwien.auto.calimero.buffer.Configuration)
	 */
	public void init(Configuration c)
	{
		final DatapointModel m = c.getDatapointModel();
		if (m != null)
			createReferences(m);
	}
	
	/**
	 * Applies state based filter rules on frame.
	 * <p>
	 * Criteria for accept:
	 * <ul>
	 * <li>the KNX message destination address is a group address</li>
	 * <li>there is <b>no</b> datapoint model available in the configuration, or</li>
	 * <li>there is a datapoint model available with a datapoint identified by the
	 * destination address <b>and</b> the datapoint is state based</li>
	 * <li>the message is an application layer group write or group response</li>
	 * </ul>
	 * On acceptance, the frame is stored into the configuration cache using a
	 * {@link LDataObject}. For easier handling of subsequent read requests on such a
	 * buffered frame, all frames are converted to L-data indications with application
	 * layer group response service code before getting stored.
	 * <p>
	 * If update and invalidation information is available, other dependent datapoint
	 * state values will be updated or invalidated appropriately.
	 * 
	 * @param frame {@inheritDoc}
	 * @param c {@inheritDoc}
	 */
	public void accept(CEMI frame, Configuration c)
	{
		final Cache cache = c.getCache();
		if (cache == null || !(frame instanceof CEMILData))
			return;
	
		final CEMILData f = (CEMILData) frame;
		if (!(f.getDestination() instanceof GroupAddress))
			return;
		final GroupAddress dst = (GroupAddress) f.getDestination();
		final DatapointModel m = c.getDatapointModel();
		Datapoint dp = null;
		if (m != null && ((dp = m.get(dst)) == null || !dp.isStateBased()))
			return;
		final byte[] d = f.getPayload();
		// filter for A-Group write (0x80) and read.res (0x40) services
		final int svc = d[0] & 0x03 | d[1] & 0xC0;
		CEMILData copy;
		if (svc == 0x40)
			// actually, read.res could be in a L-Data.con, too... ignore for now
			copy = f;
		else if (svc == 0x80) {
			// adjust to response frame
			d[1] = (byte) (d[1] & 0x3f | 0x40);
			try {
				copy = (CEMILData) CEMIFactory.create(CEMILData.MC_LDATA_IND, d, f);
			}
			catch (final KNXFormatException e) {
				NetworkBuffer.logger.error("preparing message for buffer failed", e);
				return;
			}
		}
		else
			return;
		// put into cache object
		final CacheObject co = cache.get(dst);
		if (co != null) {
			((LDataObject) co).setFrame(copy);
			c.getCache().put(co);
		}
		else
			cache.put(new LDataObject(copy));
		
		// do invalidation/update of other datapoints
		// a write updates and invalidates, read.res only updates
		update(copy, cache);
		if (svc == 0x80)
			invalidate(copy, cache);
	}
	
	/* (non-Javadoc)
	 * @see tuwien.auto.calimero.buffer.Configuration.RequestFilter#request(
	 * tuwien.auto.calimero.KNXAddress, tuwien.auto.calimero.buffer.Configuration)
	 */
	public CEMILData request(KNXAddress dst, Configuration c)
	{
		final Cache cache = c.getCache();
		if (cache == null || !(dst instanceof GroupAddress))
			return null;
		final LDataObject o = (LDataObject) cache.get(dst);
		if (o == null)
			return null;
		// check if there is an expiration timeout for a state based value
		final Datapoint dp;
		final DatapointModel m = c.getDatapointModel();
		if (m != null && (dp = m.get((GroupAddress) dst)) != null && dp.isStateBased()) {
			final int t = ((StateDP) dp).getExpirationTimeout() * 1000;
			if (t != 0 && System.currentTimeMillis() > o.getTimestamp() + t)
				return null;
		}
		return o.getFrame();
	}
	
	private void update(CEMILData f, Cache c)
	{
		if (update != null) {
			final List upd = (List) update.get(f.getDestination());
			if (upd != null)
				for (final Iterator i = upd.iterator(); i.hasNext();) {
					final CacheObject co = c.get(i.next());
					if (co != null)
						((LDataObject) co).setFrame((CEMILData) CEMIFactory.create(null,
							(KNXAddress) co.getKey(), f, false));
				}
		}
	}
	
	private void invalidate(CEMILData f, Cache c)
	{
		if (invalidate != null) {
			final List inv = (List) invalidate.get(f.getDestination());
			if (inv != null)
				for (final Iterator i = inv.iterator(); i.hasNext();)
					c.remove(i.next());
		}
	}
	
	private void createReferences(DatapointModel model)
	{
		invalidate = new HashMap();
		update = new HashMap();
		final Collection c = ((DatapointMap) model).getDatapoints();
		synchronized (c) {
			for (final Iterator i = c.iterator(); i.hasNext();) {
				try {
					final StateDP dp = (StateDP) i.next();
					createReferences(invalidate, dp.getAddresses(false), dp
						.getMainAddress());
					createReferences(update, dp.getAddresses(true), dp.getMainAddress());
				}
				catch (final ClassCastException ignore) {}
			}
		}
	}

	private void createReferences(Map map, Collection forAddr, GroupAddress toAddr)
	{
		for (final Iterator i = forAddr.iterator(); i.hasNext();) {
			final Object o = i.next();
			List l = (List) map.get(o);
			if (l == null)
				map.put(o, l = new ArrayList());
			l.add(toAddr);
		}
	}
}