/* 
 * 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;

import java.lang.reflect.Method;

public class SystemInfoGenerator extends AbstractDataGenerator<String> {
	private static final Class INFO_CLASS = Environment.class;

	private static final String METHOD_PREFIX = "get";

	private Method _staticMethod;

	public SystemInfoGenerator(LocalChannel localChannel, int defaultPeriod,
			String[] options) {
		super(localChannel, defaultPeriod, options);

		assert options.length == 3 : "options.length==3";

		if (options[2] != null) {
			try {
				int period = Integer.valueOf(options[2]);
				setPeriod(period);
			} catch (NumberFormatException e) {
				assert false : "Should be ensured by regular expression.";
			}
		}
	}

	/**
	 * {@inheritDoc}
	 */
	@Override
	protected void init(String[] options) {
		String methodName = options[0];

		try {
			_staticMethod = INFO_CLASS.getMethod(METHOD_PREFIX + methodName,
					null);
		} catch (SecurityException e) {
			e.printStackTrace();
		} catch (NoSuchMethodException e) {
			e.printStackTrace();
		}

		try {
			int period = Integer.parseInt(options[1]);
			setPeriod(period);
		} catch (NumberFormatException nfe) {
			// ignore
		}
	}

	/**
	 * {@inheritDoc}
	 */
	@Override
	protected String generateNextValue() {
		Object result = "";

		if (_staticMethod != null) {
			try {
				result = _staticMethod.invoke(null, null);
			} catch (Exception e) {
				result = e.getMessage();
			}
		}

		return result.toString();
	}

}