/*
 * Copyright (c) 2012, grossmann
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 * * Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * * Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 * * Neither the name of the jo-widgets.org nor the
 *   names of its contributors may be used to endorse or promote products
 *   derived from this software without specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL jo-widgets.org BE LIABLE FOR ANY
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
 * DAMAGE.
 */

package org.jowidgets.util;

import java.util.LinkedHashSet;
import java.util.LinkedList;
import java.util.Set;

/**
 * Implements the mutable value interface.
 * Remark: This class is not thread save.
 * 
 * @param <VALUE_TYPE> The type of the mutable value
 */
public final class MutableValue<VALUE_TYPE> implements IMutableValue<VALUE_TYPE> {

    private final Set<IMutableValueListener<VALUE_TYPE>> valueListeners;

    private VALUE_TYPE value;

    public MutableValue() {
        this(null);
    }

    public MutableValue(final VALUE_TYPE value) {
        this.valueListeners = new LinkedHashSet<IMutableValueListener<VALUE_TYPE>>();
        this.value = value;
    }

    @Override
    public void addMutableValueListener(final IMutableValueListener<VALUE_TYPE> listener) {
        Assert.paramNotNull(valueListeners, "valueListeners");
        this.valueListeners.add(listener);
    }

    @Override
    public void removeMutableValueListener(final IMutableValueListener<VALUE_TYPE> listener) {
        Assert.paramNotNull(valueListeners, "valueListeners");
        this.valueListeners.remove(listener);
    }

    @Override
    public VALUE_TYPE getValue() {
        return value;
    }

    public void setValue(final VALUE_TYPE value) {
        final VALUE_TYPE oldValue = this.value;
        if (!NullCompatibleEquivalence.equals(oldValue, value)) {
            this.value = value;
            fireChangedEvent(oldValue, value);
        }
    }

    private void fireChangedEvent(final VALUE_TYPE oldValue, final VALUE_TYPE newValue) {
        final IValueChangedEvent<VALUE_TYPE> event = new ValueChangedEventImpl<VALUE_TYPE>(oldValue, value, this);
        for (final IMutableValueListener<VALUE_TYPE> listener : new LinkedList<IMutableValueListener<VALUE_TYPE>>(valueListeners)) {
            listener.changed(event);
        }
    }

}