package jaxe;

import javax.swing.undo.CannotRedoException;
import javax.swing.undo.CannotUndoException;
import javax.swing.undo.UndoManager;
import javax.swing.undo.UndoableEdit;

/**
 * UndoManager to recognise a modified document
 * @author Kykal
 */
public class JaxeUndoManager extends UndoManager {

    /**
     * Creates the UndoManager
     *
     */
	public JaxeUndoManager() {
		_count = 0;
		_edited = false;
	}

    /**
     * Adds an edit and increases the counter
     * @see javax.swing.undo.UndoManager#addEdit(javax.swing.undo.UndoableEdit)
     */
	public synchronized boolean addEdit(UndoableEdit anEdit) {
		_count++;
		return super.addEdit(anEdit);
	}

    /**
     * Does an undo and decreases the counter
     * @see javax.swing.undo.UndoManager#undo()
     */
	public synchronized void undo() throws CannotUndoException {
		super.undo();
        _count--;
	}

    /**
     * Does a redo and increases the counter again
     * @see javax.swing.undo.UndoManager#redo()
     */
	public synchronized void redo() throws CannotRedoException {
		super.redo();
        _count++;
	}
    
    /**
     * Sets the edited flag
     */
    public void setEdited() {
        _edited = true;
    }

    /**
     * Is document edited?
     * @return true, if any edit has added to UndoManager or edit flag is set
     */
	public boolean isEdited() {
		return _edited || _count > 0;
	}

    /**
     * Edit flag
     */
	private boolean _edited;
	/**
     * Edit counter
	 */
	private int _count;
}