/*******************************************************************************
 * This file is part of logisim-evolution.
 *
 *   logisim-evolution 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 3 of the License, or
 *   (at your option) any later version.
 *
 *   logisim-evolution 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 logisim-evolution.  If not, see <http://www.gnu.org/licenses/>.
 *
 *   Original code by Carl Burch (http://www.cburch.com), 2011.
 *   Subsequent modifications by :
 *     + Haute École Spécialisée Bernoise
 *       http://www.bfh.ch
 *     + Haute École du paysage, d'ingénierie et d'architecture de Genève
 *       http://hepia.hesge.ch/
 *     + Haute École d'Ingénierie et de Gestion du Canton de Vaud
 *       http://www.heig-vd.ch/
 *   The project is currently maintained by :
 *     + REDS Institute - HEIG-VD
 *       Yverdon-les-Bains, Switzerland
 *       http://reds.heig-vd.ch
 *******************************************************************************/

package com.cburch.logisim.prefs;

import java.util.prefs.PreferenceChangeEvent;
import java.util.prefs.Preferences;

class PrefMonitorString extends AbstractPrefMonitor<String> {
	private static boolean isSame(String a, String b) {
		return a == null ? b == null : a.equals(b);
	}

	private String dflt;

	private String value;

	PrefMonitorString(String name, String dflt) {
		super(name);
		this.dflt = dflt;
		Preferences prefs = AppPreferences.getPrefs();
		this.value = prefs.get(name, dflt);
		prefs.addPreferenceChangeListener(this);
	}

	public String get() {
		return value;
	}

	public void preferenceChange(PreferenceChangeEvent event) {
		Preferences prefs = event.getNode();
		String prop = event.getKey();
		String name = getIdentifier();
		if (prop.equals(name)) {
			String oldValue = value;
			String newValue = prefs.get(name, dflt);
			if (!isSame(oldValue, newValue)) {
				value = newValue;
				AppPreferences.firePropertyChange(name, oldValue, newValue);
			}
		}
	}

	public void set(String newValue) {
		String oldValue = value;
		if (!isSame(oldValue, newValue)) {
			value = newValue;
			AppPreferences.getPrefs().put(getIdentifier(), newValue);
		}
	}
}