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 *    Please make sure that third-party modules and libraries are used
 *    according to their respective licenses.
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 *     Copyright (C) 2004-2011 Open-Xchange, Inc.
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 *     This program is free software; you can redistribute it and/or modify it
 *     under the terms of the GNU General Public License, Version 2 as published
 *     by the Free Software Foundation.
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 *     WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 *     or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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 *     You should have received a copy of the GNU General Public License along
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 */

package com.openexchange.folderstorage.osgi;

import org.osgi.framework.BundleContext;
import org.osgi.framework.ServiceReference;
import org.osgi.util.tracker.ServiceTrackerCustomizer;
import com.openexchange.folderstorage.FolderStorage;
import com.openexchange.folderstorage.internal.FolderStorageRegistry;

/**
 * {@link FolderStorageTracker} - The tracker for folder storages.
 * 
 * @author <a href="mailto:thorben.betten@open-xchange.com">Thorben Betten</a>
 */
public final class FolderStorageTracker implements ServiceTrackerCustomizer {

    private static final org.apache.commons.logging.Log LOG = org.apache.commons.logging.LogFactory.getLog(FolderStorageTracker.class);

    private final BundleContext context;

    /**
     * Initializes a new {@link FolderStorageTracker}.
     */
    public FolderStorageTracker(final BundleContext context) {
        super();
        this.context = context;
    }

    public Object addingService(final ServiceReference reference) {
        final Object addedService = context.getService(reference);
        // Get tree identifier
        final String treeId;
        {
            final Object obj = reference.getProperty("tree");
            if (null == obj) {
                LOG.error(new StringBuilder(32).append("Missing tree identifier property \"tree\" for ").append(
                    addedService.getClass().getName()).toString());
                // Nothing to track, return null
                context.ungetService(reference);
                return null;
            }
            treeId = obj.toString();
        }
        // Add to registry
        if (FolderStorageRegistry.getInstance().addFolderStorage(treeId, (FolderStorage) addedService)) {
            return addedService;
        }
        LOG.error(new StringBuilder(32).append("Failed registration to tree identifier \"").append(treeId).append("\" for ").append(
            addedService.getClass().getName()).toString());
        // Nothing to track, return null
        context.ungetService(reference);
        return null;
    }

    public void modifiedService(final ServiceReference reference, final Object service) {
        // Nothing to do
    }

    public void removedService(final ServiceReference reference, final Object service) {
        if (null != service) {
            try {
                // Get tree identifier
                final String treeId;
                {
                    final Object obj = reference.getProperty("tree");
                    if (null == obj) {
                        LOG.error(new StringBuilder(32).append("Missing tree identifier property \"tree\" for ").append(
                            service.getClass().getName()).toString());
                        return;
                    }
                    treeId = obj.toString();
                }
                FolderStorageRegistry.getInstance().removeFolderStorage(treeId, (FolderStorage) service);
            } finally {
                context.ungetService(reference);
            }
        }
    }

}
