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/*
 * H2GIS is a library that brings spatial support to the H2 Database Engine
 * http://www.h2database.com. H2GIS is developed by CNRS
 * http://www.cnrs.fr/.
 *
 * This code is part of the H2GIS project. H2GIS is free software; 
 * you can redistribute it and/or modify it under the terms of the GNU
 * Lesser General Public License as published by the Free Software Foundation;
 * version 3.0 of the License.
 *
 * H2GIS is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License
 * for more details .
 *
 *
 * For more information, please consult: http://www.h2gis.org/
 * or contact directly: info_at_h2gis.org
 */

package org.h2gis.functions.osgi;

import org.h2gis.utilities.JDBCUtilities;
import org.h2gis.utilities.dbtypes.DBTypes;
import org.osgi.framework.BundleContext;
import org.osgi.framework.ServiceReference;
import org.osgi.util.tracker.ServiceTrackerCustomizer;

import javax.sql.DataSource;
import java.sql.Connection;
import java.sql.DatabaseMetaData;
import java.sql.SQLException;
import org.h2gis.utilities.TableLocation;

/**
 * When a new data source is registered this tracker add spatial features to the linked database.
 *
 * @author Nicolas Fortin
 */
public class DataSourceTracker implements ServiceTrackerCustomizer {

    /** BundleContext instance */
    private BundleContext bundleContext;

    /**
     * Constructor
     * @param bundleContext BundleContext instance
     */
    public DataSourceTracker(BundleContext bundleContext) {
        this.bundleContext = bundleContext;
    }

    @Override
    public FunctionTracker addingService(ServiceReference dataSourceServiceReference) {
        DataSource dataSource = bundleContext.getService(dataSourceServiceReference);
        try {
            try (Connection connection = dataSource.getConnection()) {
                DatabaseMetaData meta = connection.getMetaData();
                // If not H2 or in client mode, does not register H2 spatial functions.
                if (!JDBCUtilities.H2_DRIVER_NAME.equals(meta.getDriverName())
                        || (meta.getURL() != null && meta.getURL().toLowerCase().startsWith("jdbc:h2:tcp://"))) {
                    return null;
                }
                // Check if the database has been properly initialised by the DataSource service provider
                if (!JDBCUtilities.tableExists(connection, TableLocation.parse("PUBLIC.GEOMETRY_COLUMNS", DBTypes.H2))) {
                    return null;
                }
            }
        } catch (SQLException ex) {
            System.err.print(ex.toString());
        }
        FunctionTracker functionTracker = new FunctionTracker(dataSource,bundleContext);
        functionTracker.open();
        return functionTracker;
    }

    @Override
    public void modifiedService(ServiceReference dataSourceServiceReference,
                                FunctionTracker functionTracker) {

    }

    @Override
    public void removedService(ServiceReference dataSourceServiceReference,
                               FunctionTracker functionTracker) {
        if(functionTracker!=null) {
            functionTracker.close();
        }
    }
}