/*******************************************************************************
 * Copyright (c) 2000, 2005 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
 * Port to the D programming language:
 *     Frank Benoit <benoit@tionex.de>
 *******************************************************************************/
module org.eclipse.draw2d.ButtonGroup;

import java.lang.all;
import java.util.ArrayList;
import java.util.List;
import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;

import org.eclipse.draw2d.ButtonModel;

/**
 * A ButtonGroup holds a group of {@link Clickable Clickable's} models and provides unique
 * selection in them. There is  capability to add a default selection. Models who want to
 * belong to the group should just add themselves to this group. By doing so they listen
 * to this group for changes.
 * <p>
 * Setting of the default selection results in its being selected any time
 * {@link #setSelected(ButtonModel, bool)} is called. If no default selection is set,
 * the last entry selected is not allowed to deselect.
 */
public class ButtonGroup {

private ButtonModel selectedModel;
private ButtonModel defaultModel;
private List members;
private List listeners;

/**
 * Constructs a ButtonGroup with no default selection.
 *
 * @since 2.0
 */
public this() {
    members = new ArrayList();
    listeners = new ArrayList();
}

/**
 * Adds the passed ButtonModel to the ButtonGroup.
 *
 * @param model  ButtonModel to be added to this group
 * @since 2.0
 */
public void add(ButtonModel model) {
    if (!members.contains(model)) {
        model.setGroup(this);
        members.add(model);
    }
}

/**
 * Adds the passed listener. ButtonGroups use PropertyChangeListeners to react to
 * selection changes in the ButtonGroup.
 *
 * @param listener  Listener to be added to this group
 * @since 2.0
 */
public void addPropertyChangeListener(PropertyChangeListener listener) {
    listeners.add(cast(Object)listener);
}

/**
 * Fires a PropertyChangeEvent to all PropertyChangeListeners added to this ButtonGroup.
 *
 * @param oldValue  Old selection value
 * @param newValue  New selection value
 * @since 2.0
 */
protected void firePropertyChange(Object oldValue, Object newValue) {
    PropertyChangeEvent event = new PropertyChangeEvent(
        this, ButtonModel.SELECTED_PROPERTY, oldValue, newValue);
    for (int i = 0; i < listeners.size(); i++)
        (cast(PropertyChangeListener)listeners.get(i)).propertyChange(event);
}

/**
 * Returns the ButtonModel which is selected by default for this ButtonGroup.
 *
 * @return The default ButtonModel
 * @since 2.0
 */
public ButtonModel getDefault() {
    return defaultModel;
}

/**
 * Returns a List which contains all of the {@link ButtonModel ButtonModels} added to this
 * ButtonGroup.
 *
 * @return The List of ButtonModels in this ButtonGroup
 * @since 2.0
 */
public List getElements() {
    return members;
}

/**
 * Returns the ButtonModel for the currently selected button.
 *
 * @return The ButtonModel for the currently selected button
 * @since 2.0
 */
public ButtonModel getSelected() {
    return selectedModel;
}

/**
 * Determines if the given ButtonModel is selected or not.
 *
 * @param model  Model being tested for selected status
 * @return  Selection state of the given model
 * @since 2.0
 */
public bool isSelected(ButtonModel model) {
    return (model is getSelected());
}

/**
 * Removes the given ButtonModel from this ButtonGroup.
 *
 * @param model  ButtonModel being removed
 * @since 2.0
 */
public void remove(ButtonModel model) {
    if (getSelected() is model)
        setSelected(getDefault(), true);
    if (defaultModel is model)
        defaultModel = null;
    members.remove(model);
}

/**
 * Removes the passed PropertyChangeListener from this ButtonGroup.
 *
 * @param listener  PropertyChangeListener to be removed
 * @since 2.0
 */
public void removePropertyChangeListener(PropertyChangeListener listener) {
    listeners.remove(cast(Object)listener);
}

/**
 * Sets the passed ButtonModel to be the currently selected ButtonModel of this
 * ButtonGroup. Fires a property change.
 *
 * @param model ButtonModel to be selected
 * @since 2.0
 */
protected void selectNewModel(ButtonModel model) {
    ButtonModel oldModel = selectedModel;
    selectedModel = model;
    if (oldModel !is null)
        oldModel.setSelected(false);
    firePropertyChange(oldModel, model);
}

/**
 * Sets the default selection of this ButtonGroup. Does nothing if it is not present in
 * the group. Sets selection to the passed ButtonModel.
 *
 * @param model  ButtonModel which is to be the default selection.
 * @since 2.0
 */
public void setDefault(ButtonModel model) {
    defaultModel = model;
    if (getSelected() is null && defaultModel !is null)
        defaultModel.setSelected(true);
}

/**
 * Sets the button with the given ButtonModel to be selected.
 *
 * @param model The ButtonModel to be selected
 * @since 2.0
 */
public void setSelected(ButtonModel model) {
    if (model is null)
        selectNewModel(null);
    else
        model.setSelected(true);
}

/**
 * Sets model to the passed state.
 * <p>
 * If <i>value</i> is
 * <ul>
 *      <li><code>true</code>:
 *      <ul>
 *          <li>The passed ButtonModel will own selection.
 *      </ul>
 *      <li><code>false</code>:
 *      <ul>
 *          <li>If the passed model owns selection, it will lose selection, and
 *          selection will be given to the default ButonModel. If no default
 *          ButtonModel was set, selection will remain as it was, as one ButtonModel
 *          must own selection at all times.
 *          <li>If the passed model does not own selection, then selection will remain
 *          as it was.
 *      </ul>
 * </ul>
 *
 * @param model The model to be affected
 * @param value The selected state
 * @since 2.0
 */
public void setSelected(ButtonModel model, bool value) {
    if (value) {
        if (model is getSelected())
            return;
        selectNewModel(model);
    } else {
        if (model !is getSelected())
            return;
        if (getDefault() is null)
            return;
        getDefault().setSelected(true);
    }
}

}