/*
 * Copyright 2012-2014 Red Hat, Inc.
 *
 * This file is part of Thermostat.
 *
 * Thermostat is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published
 * by the Free Software Foundation; either version 2, or (at your
 * option) any later version.
 *
 * Thermostat 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
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with Thermostat; see the file COPYING.  If not see
 * <http://www.gnu.org/licenses/>.
 *
 * Linking this code with other modules is making a combined work
 * based on this code.  Thus, the terms and conditions of the GNU
 * General Public License cover the whole combination.
 *
 * As a special exception, the copyright holders of this code give
 * you permission to link this code with independent modules to
 * produce an executable, regardless of the license terms of these
 * independent modules, and to copy and distribute the resulting
 * executable under terms of your choice, provided that you also
 * meet, for each linked independent module, the terms and conditions
 * of the license of that module.  An independent module is a module
 * which is not derived from or based on this code.  If you modify
 * this code, you may extend this exception to your version of the
 * library, but you are not obligated to do so.  If you do not wish
 * to do so, delete this exception statement from your version.
 */

package com.redhat.thermostat.agent;

import java.util.HashMap;
import java.util.Map;

import org.osgi.framework.BundleContext;
import org.osgi.framework.ServiceRegistration;

/**
 * Registers a {@link VmStatusListener} as an OSGi Service.
 * <p>
 * This is just a convenience wrapper over
 * {@link BundleContext#registerService(String, Object, java.util.Dictionary)}.
 * It does absolutely nothing special.
 *
 * @see VmStatusListener
 */
public class VmStatusListenerRegistrar {

    private final BundleContext context;
    private final Map<VmStatusListener, ServiceRegistration> registrations = new HashMap<>();

    public VmStatusListenerRegistrar(BundleContext context) {
        this.context = context;
    }

    public void register(VmStatusListener listener) {
        registrations.put(listener, context.registerService(VmStatusListener.class.getName(), listener, null));
    }

    public void unregister(VmStatusListener listener) {
        ServiceRegistration registration = registrations.remove(listener);
        if (registration == null) {
            throw new IllegalArgumentException("no listener found");
        }

        registration.unregister();
    }
}