/*
 * 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.dal;

import org.csstudio.dal.context.AbstractApplicationContext;
import org.csstudio.dal.simple.SimpleDALBroker;
import org.csstudio.dal.spi.DefaultPropertyFactoryService;
import org.csstudio.dal.spi.LinkPolicy;
import org.csstudio.dal.spi.Plugs;
import org.csstudio.dal.spi.PropertyFactory;
import org.csstudio.dal.spi.PropertyFactoryService;
import org.eclipse.core.runtime.Plugin;
import org.osgi.framework.BundleContext;

/**
 * The activator class controls the plug-in life cycle
 */
public class DalPlugin extends Plugin implements PropertyFactoryService {

	{
		CharacteristicInfo.registerCharacteristicInfo(CharacteristicInfo.C_SEVERITY);
		CharacteristicInfo.registerCharacteristicInfo(CharacteristicInfo.C_TIMESTAMP);
		CharacteristicInfo.registerCharacteristicInfo(CharacteristicInfo.C_STATUS);
	}

	/**
	 * The ID of this plugin.
	 */
	public static final String ID = "org.csstudio.dal"; //$NON-NLS-1$

	/**
	 * The ID of the <code>plugs</code> extension point.
	 */
	public static final String EXTPOINT_PLUGS = ID + ".plugs"; //$NON-NLS-1$

	/**
	 * The shared instance.
	 */
	private static DalPlugin plugin;

	private AbstractApplicationContext applicationContext;

	private SimpleDALBroker broker;

	/**
	 * The constructor
	 */
	public DalPlugin() {
		plugin = this;
	}

	/**
	 * Returns the shared instance
	 *
	 * @return the shared instance
	 */
	public static DalPlugin getDefault() {
		if (plugin == null) {
			plugin = new DalPlugin();
		}
		return plugin;
	}

	/**
	 * Returns the simple dal broker to be used with this DAL plugin.
	 * The broker is configured to use all available property factories
	 * registered with this plugin.
	 *
	 * @return the simple dal broker
	 */
	public synchronized SimpleDALBroker getSimpleDALBroker() {
		if (broker == null) {
			broker = SimpleDALBroker.newInstance(getApplicationContext(),this);
		}
		return broker;
	}

	/* (non-Javadoc)
	 * @see org.eclipse.core.runtime.Plugin#stop(org.osgi.framework.BundleContext)
	 */
	@Override
	public void stop(final BundleContext context) throws Exception {
		if (applicationContext!=null) {
			applicationContext.destroy();
		}
		super.stop(context);
	}

	/**
	 * Returns the application context.
	 *
	 * @return the context
	 */
	public synchronized AbstractApplicationContext getApplicationContext() {
		if (applicationContext==null) {
			applicationContext = new CssApplicationContext("CSS");
		}
		return applicationContext;
	}

	/**
	 * Creates factory for default plug by further calling {@link DalPlugin#getPropertyFactory(AbstractApplicationContext, LinkPolicy, String)}.
	 *
	 */
	@Override
    public PropertyFactory getPropertyFactory(final AbstractApplicationContext ctx,
			final LinkPolicy linkPolicy) {

		// find default
		final String plug= Plugs.getDefaultPlug(ctx.getConfiguration());

		return getPropertyFactory(ctx, linkPolicy, plug);
	}

	/**
	 * Creates factory in following order:
	 * <ul>
	 * <li>first tries to lookup delegate service defined by RCP extension point, this is done trough {@link PlugRegistry}. If this fails, then...</li>
	 * <li>tries to load factory by calling {@link DefaultPropertyFactoryService}, this is fallback procedure, it does no use extension points.</li>
	 * </ul>
	 */
	@Override
    public PropertyFactory getPropertyFactory(final AbstractApplicationContext ctx, final LinkPolicy linkPolicy, final String plugName) {
		final PropertyFactoryService pfs= PlugRegistry.getInstance().getPropertyFactoryService(plugName);
		if (pfs!=null)
			return pfs.getPropertyFactory(ctx, linkPolicy);
		return DefaultPropertyFactoryService.getPropertyFactoryService().getPropertyFactory(ctx, linkPolicy, plugName);
	}

}