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package net.sf.cuf.model.ui;

import net.sf.cuf.model.ValueModel;

import javax.swing.ButtonModel;
import javax.swing.event.ChangeListener;
import javax.swing.event.ChangeEvent;
import java.util.List;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;


/**
 * A RadioButtonAdapter connects a number of radio button
 * models to a ValueModel holding an Integer with the index
 * for the radio button list.
 * The ValueModel holding the Integer is often the selectionHolder()
 * of a SelectionInList ValueModel.
 * Whenever either the selection of the radio buttons or
 * the index of the ValueModel changes, the other model
 * is adjusted accordingly.
 * A RadioButtonAdapter is not a ValueModel itself, but connects a
 * ValueModel holding an integer to a list of ButtonModels.
 */
public class RadioButtonAdapter implements ActionListener, ChangeListener
{
    /** the value model we are watching, never null */
    private ValueModel          mSelectionHolder;
    /** the list of ButtonModels, never null */
    private List   mButtonModels;
    /** marker if we are in an action performed or state changed callback */
    private boolean             mInCallback;

    /**
     * Creates a new adapter between a ValueModel holding an Integer
     * and a list of ButtonModels
     * Whenever one of the models changes, the other is adjusted accordingly.
     * The initial selected buttonmodel is taken from the value model.
     *
     * @param pSelectionHolder ValueModel holding an Integer
     * @param pButtonModels a list of ButtonModel objects
     * @throws IllegalArgumentException if pSelectionHolder or pButtonModels is null
     */
    public RadioButtonAdapter(final ValueModel pSelectionHolder, final List pButtonModels)
    {
        if (pSelectionHolder==null)
            throw new IllegalArgumentException("selection holder must not be null");
        if (pButtonModels==null)
            throw new IllegalArgumentException("button model list must not be null");

        mSelectionHolder= pSelectionHolder;
        mButtonModels   = pButtonModels;
        mInCallback     = false;

        for (ButtonModel buttonModel : mButtonModels)
        {
            buttonModel.addActionListener(this);
        }
        mSelectionHolder.addChangeListener(this);

        adjustRadiobuttons();
    }

    /**
     * Invoked when an action occurs.
     * @param pEvent  a ActionEvent object
     */
    public void actionPerformed(final ActionEvent pEvent)
    {
        if (mInCallback)
        {
            return;
        }

        ButtonModel model= (ButtonModel)pEvent.getSource();
        Integer     index= mButtonModels.indexOf(model);

        try
        {
            mInCallback= true;
            mSelectionHolder.setValue(index);
        }
        finally
        {
            mInCallback= false;
        }
    }

    /**
     * Invoked when the target of the listener has changed its state.
     * @param pEvent  a ChangeEvent object
     */
    public void stateChanged(final ChangeEvent pEvent)
    {
        if (mInCallback)
        {
            return;
        }

        adjustRadiobuttons();
    }

    /**
     * Helper to adjust the radio buttons to the index.
     */
    private void adjustRadiobuttons()
    {
        Integer index= (Integer)mSelectionHolder.getValue();

        try
        {
            mInCallback= true;

            // null is the magic marker for "nothing selected"
            if (index==null)
            {
                for (ButtonModel model : mButtonModels)
                {
                    model.setSelected(false);
                }
            }
            else
            {
                ButtonModel model= mButtonModels.get(index);
                model.setSelected(true);
            }
        }
        finally
        {
            mInCallback= false;
        }
    }
}