/* 
 * Copyright (c) 2008 Stiftung Deutsches Elektronen-Synchrotron, 
 * 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.platform.internal.simpledal.local;

/**
 * Generator for random double values.
 * 
 * @author swende
 * 
 */
public class CountdownGenerator extends AbstractDataGenerator<Double> {
	private double _distance;
	private double _from;
	private double _to;
	private long _countdownPeriod;
	
	private long _startMs=-1;
	
	/**
	 * Constructor.
	 * @param localChannel the local channel
	 * @param defaultPeriod the default period
	 * @param options
	 */
	public CountdownGenerator(LocalChannel localChannel, int defaultPeriod,
			String[] options) {
		super(localChannel, defaultPeriod, options);
	}

	/**
	 * {@inheritDoc}
	 */
	@Override
	protected void init(String[] options) {
		try {
			_from = Double.parseDouble(options[0]);
		} catch (NumberFormatException nfe) {
			_from = 0;
		}

		try {
			_to = Double.parseDouble(options[1]);
		} catch (NumberFormatException nfe) {
			_to = 1;
		}

		try {
			_countdownPeriod = Long.parseLong(options[2]);
		} catch (NumberFormatException nfe) {
			_to = 1000;
		}

		
		try {
			int period = Integer.parseInt(options[3]);
			setPeriod(period);
		} catch (NumberFormatException nfe) {
			// ignore
		}

		if (_from < _to) {
			double tmp = _from;
			_from = _to;
			_to = tmp;
		}
	
		_distance = _from - _to;
	}

	/**
	 * {@inheritDoc}
	 */
	@Override
	protected Double generateNextValue() {
		double result = -1;
		
		if(_startMs < 0) {
			_startMs = System.currentTimeMillis();
		}
		
		long now = System.currentTimeMillis();
		long diff = now-_startMs;
		
		
		if(diff>=_countdownPeriod) {
			_startMs = -1;
			result = _from;
		} else {
			double percent = (double) diff/_countdownPeriod;
			result = _from - (_distance * percent);
		}

		
		return result;
	}

}