/*******************************************************************************
 * Copyright (c) 2005, 2008 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *     Brad Reynolds - bug 164653
 *******************************************************************************/
module org.eclipse.jface.internal.databinding.swt.SingleSelectionObservableValue;

import java.lang.all;

import org.eclipse.core.databinding.observable.Diffs;
import org.eclipse.core.databinding.observable.Realm;
import org.eclipse.jface.internal.databinding.provisional.swt.AbstractSWTObservableValue;
import org.eclipse.swt.widgets.Control;

/**
 * @since 1.0
 * 
 */
abstract public class SingleSelectionObservableValue :
        AbstractSWTObservableValue {

    private bool updating = false;

    private int currentSelection;

    /**
     * @param control
     *            the control
     */
    public this(Control control) {
        super(control);
        init();
    }
    
    /**
     * @param realm
     * @param control
     */
    public this(Realm realm, Control control) {
        super(realm, control);
        init();
    }
    
    private void init() {       
        currentSelection = doGetSelectionIndex();
        doAddSelectionListener(new class() Runnable{
            public void run() {
                if (!updating) {
                    int newSelection = doGetSelectionIndex();
                    notifyIfChanged(currentSelection, newSelection);
                    currentSelection = newSelection;
                }
            }
        });
    }

    /**
     * @param runnable
     */
    protected abstract void doAddSelectionListener(Runnable runnable);

    public void doSetValue(Object value) {
        try {
            updating = true;
            int intValue = (cast(Integer) value).intValue();
            doSetSelectionIndex(intValue);
            notifyIfChanged(currentSelection, intValue);
            currentSelection = intValue;
        } finally {
            updating = false;
        }
    }

    /**
     * @param intValue
     *            the selection index
     */
    protected abstract void doSetSelectionIndex(int intValue);

    public Object doGetValue() {
        return new Integer(doGetSelectionIndex());
    }

    /**
     * @return the selection index
     */
    protected abstract int doGetSelectionIndex();

    public Object getValueType() {
        return Integer.TYPE;
    }

    private void notifyIfChanged(int oldValue, int newValue) {
        if (oldValue !is newValue) {
            fireValueChange(Diffs.createValueDiff(new Integer(
                    oldValue), new Integer(newValue)));
        }
    }
}