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package net.sf.cuf.state.ui;

import javax.swing.JTree;
import javax.swing.event.TreeSelectionEvent;
import javax.swing.event.TreeSelectionListener;
import javax.swing.tree.TreePath;
import javax.swing.tree.TreeSelectionModel;

/**
 * The SwingTreeSelectionState class models a State with a TreeSelectionModel
 * of a JTree as the state source. The value of the state is determined by
 * comparing the TreeSelectionsModels's selection with a user-defined TreePath.
 * If the user-defined TreePath is contained in the TreeSelectionModel's
 * selection, the state is true.
 */
public class SwingTreeSelectionState extends AbstractSwingState implements TreeSelectionListener
{
    /** the selection we monitor, never null */
    private TreeSelectionModel mTreeSelectionModel;
    /** user provided path we check, default is null */
    private TreePath           mTreePath;

    /**
     * Creates a new state, using the selection model of the handed tree
     * as its state source.
     * If the selection contains null, then the
     * state is true.
     * @param pTree tree we take the selection model from, must not be null
     */
    public SwingTreeSelectionState(final JTree pTree)
    {
        this(pTree, null);
    }

    /**
     * Creates a new state, using the selection model of the handed tree
     * as its state source.
     * If the selection contains pTreePath, then the state is true.
     * @param pTree tree we take the selection model from, must not be null
     * @param pTreePath user-provided TreePath we check the selection against, may be null
     */
    public SwingTreeSelectionState(final JTree pTree, final TreePath pTreePath)
    {
        super();
        if (pTree== null)
        {
            throw new IllegalArgumentException("JTree must not be null");
        }
        init(pTree.getSelectionModel(), pTreePath);
    }

    /**
     * Creates a new state, using the handed selection model as its state source.
     * If the selection contains pTreePath, then the state is true.
     * @param pSelectionModel the selection we monitor, must not be null
     * @param pTreePath user-provided TreePath we check the selection against, may be null
     */
    public SwingTreeSelectionState(final TreeSelectionModel pSelectionModel, final TreePath pTreePath)
    {
        super();
        init(pSelectionModel, pTreePath);
    }
    /**
     * Common init stuff of the constructors.
     * @param pSelectionModel the selection we monitor, must not be null
     * @param pTreePath TreePath we check the selection against, may be null
     */
    private void init(final TreeSelectionModel pSelectionModel, final TreePath pTreePath)
    {
        if (pSelectionModel == null)
        {
            throw new IllegalArgumentException("tree selection model must not be null");
        }
        mTreePath          = pTreePath;
        mTreeSelectionModel= pSelectionModel;

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

        mTreeSelectionModel.addTreeSelectionListener(this);
    }

    /**
     * Sets the TreePath we try to find in the tree selection.
     * @param pTreePath user-provided TreePath we check the selection against
     */
    public void setCompareContent(final TreePath pTreePath)
    {
        mTreePath = pTreePath;
        checkStateChange();
    }

    /**
     * Called whenever the value of the selection changes.
     * @param pEvent the event that characterizes the change.
     */
    public void valueChanged(final TreeSelectionEvent pEvent)
    {
        checkStateChange();
    }

    /**
     * Check if mListIndex is selected, if mListIndex is NO_SELECTION, check if there is no selection.
     * @return the state, true if the user provided index is contained in the list selection
     */
    protected boolean getInternalState()
    {
        if ((mTreePath == null) && mTreeSelectionModel.isSelectionEmpty())
        {
            return true;
        }
        else
        {
            return mTreeSelectionModel.isPathSelected(mTreePath);
        }
    }

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