content: package tim.prune.undo;
  
  import java.awt.FlowLayout;
  import java.awt.event.KeyAdapter;
  import java.awt.event.KeyEvent;
  import java.awt.BorderLayout;
  import javax.swing.BorderFactory;
  import javax.swing.JButton;
  import javax.swing.JDialog;
  import javax.swing.JFrame;
  import javax.swing.JLabel;
  import javax.swing.JList;
  import javax.swing.JPanel;
  import javax.swing.JScrollPane;
  import javax.swing.ListSelectionModel;
  
  import tim.prune.App;
  import tim.prune.I18nManager;
  
  /**
   * Class to manage the selection of actions to undo or redo
   */
  public abstract class UndoRedoManager
  {
  	private final App _app;
  	private final JFrame _parentFrame;
  	private JDialog _dialog = null;
  	private JList<String> _actionList = null;
  	private final String _tokenPrefix;
  
  
  	/**
  	 * Constructor
  	 * @param inApp App object
  	 * @param inFrame parent frame
  	 * @param inUndo true for undo, false for redo
  	 */
  	protected UndoRedoManager(App inApp, JFrame inFrame, boolean inUndo)
  	{
  		_app = inApp;
  		_parentFrame = inFrame;
  		_tokenPrefix = "dialog." + (inUndo ? "undo" : "redo") + ".";
  	}
  
  	/**
  	 * Show the dialog to select which actions to undo or redo
  	 */
  	public void show(UndoStack inStack)
  	{
  		_dialog = new JDialog(_parentFrame, getText("title"), true);
  		_dialog.setLocationRelativeTo(_parentFrame);
  		JPanel mainPanel = new JPanel();
  		mainPanel.setLayout(new BorderLayout(3, 3));
  		mainPanel.setBorder(BorderFactory.createEmptyBorder(5, 5, 5, 5));
  		mainPanel.add(new JLabel(getText("pretext") + ":"), BorderLayout.NORTH);
  
  		String[] actions = inStack.getDescriptions().toArray(new String[0]);
  		_actionList = new JList<String>(actions);
  		_actionList.setSelectionMode(ListSelectionModel.SINGLE_INTERVAL_SELECTION);
  		_actionList.setSelectedIndex(0);
  		_actionList.addListSelectionListener(e -> {
  			if (_actionList.getMinSelectionIndex() > 0) {
  				_actionList.setSelectionInterval(0, _actionList.getMaxSelectionIndex());
  			}
  		});
  		_actionList.addKeyListener(new KeyAdapter() {
  			public void keyReleased(KeyEvent e)
  			{
  				// close dialog if escape pressed
  				if (e.getKeyCode() == KeyEvent.VK_ESCAPE) {
  					_dialog.dispose();
  				}
  			}
  		});
  
  		mainPanel.add(new JScrollPane(_actionList), BorderLayout.CENTER);
  		// Buttons
  		JPanel buttonPanel = new JPanel();
  		buttonPanel.setLayout(new FlowLayout(FlowLayout.RIGHT));
  		JButton okButton = new JButton(I18nManager.getText("button.ok"));
  		okButton.addActionListener(e -> {
  			undoRedoActions(_app, _actionList.getMaxSelectionIndex() + 1);
  			_dialog.dispose();
  		});
  		buttonPanel.add(okButton);
  		JButton cancelButton = new JButton(I18nManager.getText("button.cancel"));
  		cancelButton.addActionListener(e -> _dialog.dispose());
  		buttonPanel.add(cancelButton);
  		mainPanel.add(buttonPanel, BorderLayout.SOUTH);
  		_dialog.getContentPane().add(mainPanel);
  		_dialog.pack();
  		_dialog.setVisible(true);
  	}
  
  	/** To be overridden by subclasses */
  	protected abstract void undoRedoActions(App inApp, int inNumActions);
  
  	/** @return text for the given key */
  	private String getText(String inKey) {
  		return I18nManager.getText(_tokenPrefix + inKey);
  	}
  }
  