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package net.sf.cuf.state.ui;

import net.sf.cuf.state.State;

import javax.swing.JList;
import javax.swing.ListModel;
import javax.swing.event.ListDataEvent;
import javax.swing.event.ListDataListener;

/**
 * The SwingListModelFillState class models a State with the ListModel
 * of a Swing JList as the state source. The value of the state is
 * determined by examining the ListModel's content.
 * If the ListModel's content contains at least a provided number
 * of elements (default: one element), the state is true.
 */
public class SwingListModelFillState extends AbstractSwingState implements State, ListDataListener
{
    /** the selection we monitor, never null */
    private ListModel mListModel;
    /** the number of items we take as fill threshold */
    private int       mThreshold;

    /**
     * Creates a new state, using the model of the handed list as its state source.
     * If the model contains at least one element, then the state is true.
     * @param pList list we take the model from, must not be null
     */
    public SwingListModelFillState(final JList pList)
    {
        this(pList, 1);
    }

    /**
     * Creates a new state, using the model of the handed list as its state source.
     * If the model contains at least pThreshold elements, then the state is true.
     * @param pList list we take the model from, must not be null
     * @param pThreshold threshold of items in the list
     */
    public SwingListModelFillState(final JList pList, final int pThreshold)
    {
        super();
        if (pList == null)
        {
            throw new IllegalArgumentException("JList must not be null");
        }
        init(pList.getModel(), pThreshold);
    }

    /**
     * Creates a new state, using the handed model as its state source.
     * If the model contains at least pThreshold elements, then the state is true.
     * @param pThreshold threshold of items in the list
     * @param pModel the model we monitor, must not be null
     */
    public SwingListModelFillState(final ListModel pModel, final int pThreshold)
    {
        super();
        init(pModel, pThreshold);
    }

    /**
     * Common init stuff of the constructors.
     * @param pModel the model we monitor, must not be null
     * @param pThreshold threshold of items in the list
     */
    private void init(final ListModel pModel, final int pThreshold)
    {
        if (pModel == null)
        {
            throw new IllegalArgumentException("list model must not be null");
        }
        mListModel= pModel;
        mThreshold= pThreshold;

        // initially set the state according to model content
        mIsEnabled= getInternalState();

        mListModel.addListDataListener(this);
    }

    /**
     * Sets the threshold we compare again.
     * @param pThreshold threshold of items in the list
     */
    public void setCompareContent(final int pThreshold)
    {
        mThreshold = pThreshold;
        checkStateChange();
    }

    /**
     * Callback method for our list model.
     * @param pEvent not used
     */
    public void contentsChanged(final ListDataEvent pEvent)
    {
        checkStateChange();
    }

    /**
     * Callback method for our list model.
     * @param pEvent not used
     */
    public void intervalAdded(final ListDataEvent pEvent)
    {
        checkStateChange();
    }

    /**
     * Callback method for our list model.
     * @param pEvent not used
     */
    public void intervalRemoved(final ListDataEvent pEvent)
    {
        checkStateChange();
    }

    /**
     * Check if our model contains at least our threshold number of items.
     * @return the state, true if the model contains enough items
     */
    protected boolean getInternalState()
    {
        return (mListModel.getSize() >= mThreshold);
    }

    /**
     * Set the source of the state as the reason for a change.
     */
    protected void setReason()
    {
        mReason = mListModel;
    }
}