/*
 * Copyright 2012-2017 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.launcher.internal;

import java.util.List;
import java.util.concurrent.CopyOnWriteArrayList;

public class CurrentEnvironment {

    public interface CurrentEnvironmentChangeListener {
        public void enviornmentChanged(Environment oldEnv, Environment newEnv);
    }

    private Environment current;
    private List<CurrentEnvironmentChangeListener> listeners = new CopyOnWriteArrayList<>();

    public CurrentEnvironment(Environment initial) {
        current = initial;
    }

    public Environment getCurrent() {
        return current;
    }

    public void setCurrent(Environment environment) {
        if (environment == current) {
            return;
        }

        Environment old = current;
        current = environment;
        fireEnvironmentChanged(old, current);
    }

    private void fireEnvironmentChanged(Environment oldEnv, Environment newEnv) {
        for (CurrentEnvironmentChangeListener listener : listeners) {
            listener.enviornmentChanged(oldEnv, newEnv);
        }
    }

    public void addListener(CurrentEnvironmentChangeListener listener) {
        listeners.add(listener);
    }

    public void removeListener(CurrentEnvironmentChangeListener listener) {
        listeners.remove(listener);
    }
}