/* 
 * Copyright (c) 2006 Stiftung Deutsches Elektronen-Synchroton, 
 * Member of the Helmholtz Association, (DESY), HAMBURG, GERMANY.
 *
 * THIS SOFTWARE IS PROVIDED UNDER THIS LICENSE ON AN "../AS IS" BASIS. 
 * WITHOUT WARRANTY OF ANY KIND, EXPRESSED OR IMPLIED, INCLUDING BUT NOT LIMITED 
 * TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR PARTICULAR PURPOSE AND 
 * NON-INFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE 
 * FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, 
 * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR 
 * THE USE OR OTHER DEALINGS IN THE SOFTWARE. SHOULD THE SOFTWARE PROVE DEFECTIVE 
 * IN ANY RESPECT, THE USER ASSUMES THE COST OF ANY NECESSARY SERVICING, REPAIR OR 
 * CORRECTION. THIS DISCLAIMER OF WARRANTY CONSTITUTES AN ESSENTIAL PART OF THIS LICENSE. 
 * NO USE OF ANY SOFTWARE IS AUTHORIZED HEREUNDER EXCEPT UNDER THIS DISCLAIMER.
 * DESY HAS NO OBLIGATION TO PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, 
 * OR MODIFICATIONS.
 * THE FULL LICENSE SPECIFYING FOR THE SOFTWARE THE REDISTRIBUTION, MODIFICATION, 
 * USAGE AND OTHER RIGHTS AND OBLIGATIONS IS INCLUDED WITH THE DISTRIBUTION OF THIS 
 * PROJECT IN THE FILE LICENSE.HTML. IF THE LICENSE IS NOT INCLUDED YOU MAY FIND A COPY 
 * AT HTTP://WWW.DESY.DE/LEGAL/LICENSE.HTM
 */
package org.csstudio.sds.internal.model.logic;

import java.util.HashMap;

import org.csstudio.sds.internal.rules.ParameterDescriptor;

/**
 * RuleState information for the <code>RuleEngine</code>.
 * 
 * @author Alexander Will & Sven Wende
 * @version $Revision: 1.4 $
 * 
 */
final class RuleState {
	/**
	 * References to all input channels.
	 */
	private ParameterDescriptor[] _parameters;

	/**
	 * Contains the latest values for the input channels.
	 */
	private HashMap<ParameterDescriptor, Object> _cachedValues;

	/**
	 * Standard constructor.
	 * 
	 * @param parameters
	 *            Parameter descriptions for the inialisation of this state
	 *            object.
	 */
	public RuleState(final ParameterDescriptor[] parameters) {
		_parameters = parameters;

		// prepare cache
		_cachedValues = new HashMap<ParameterDescriptor, Object>();

		for(ParameterDescriptor p : parameters) {
			_cachedValues.put(p, p.getValue());
		}
	}

	/**
	 * Cache the latest value for a given channel name in this state.
	 * 
	 * @param parameter
	 *            A channel name.
	 * @param value
	 *            The latest value from the given channel.
	 */
	public synchronized void cacheParameterValue(final ParameterDescriptor parameter,
			final Object value) {
		if (_cachedValues.containsKey(parameter)) {
			_cachedValues.put(parameter, value);
		}
	}

	/**
	 * Return the most recent parameter values of this state.
	 * 
	 * @return The most recent parameter values of this state.
	 */
	public Object[] getRecentParameterValues() {
		Object[] result = new Object[_parameters.length];
		for (int i = 0; i < _parameters.length; i++) {
			result[i] = _cachedValues.get(_parameters[i]);
		}

		return result;
	}
}