/*******************************************************************************
 * Copyright (c) 2006 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 * Port to the D programming language:
 *     Frank Benoit <benoit@tionex.de>
 *******************************************************************************/
module dwtx.text.undo.IDocumentUndoManager;

// import dwtx.text.undo.DocumentUndoManager; // packageimport
// import dwtx.text.undo.DocumentUndoManagerRegistry; // packageimport
import dwtx.text.undo.DocumentUndoEvent; // packageimport
import dwtx.text.undo.IDocumentUndoListener; // packageimport
// import dwtx.text.undo.UndoMessages; // packageimport


import dwt.dwthelper.utils;

import dwtx.core.commands.ExecutionException;
import dwtx.core.commands.operations.IUndoContext;

/**
 * Interface for a document undo manager. Tracks changes in a document and
 * builds a history of text commands that describe the undoable changes to the
 * document.
 * <p>
 * Clients must explicitly connect to the undo manager to express their interest
 * in the undo history. Clients should disconnect from the undo manager when
 * they are no longer interested in tracking the undo history. If there are no
 * clients connected to the undo manager, it will not track the document's
 * changes and will dispose of any history that was previously kept.</p>
 * <p>
 * Clients may also listen to the undo manager for notifications before and
 * after undo or redo events are performed. Clients must connect to the undo
 * manager in addition to registering listeners.</p>
 * <p>
 * Clients may implement this interface.
 * </p>
 *
 * @see DocumentUndoManagerRegistry
 * @see IDocumentUndoListener
 * @see dwtx.jface.text.IDocument
 * @since 3.2
 */
public interface IDocumentUndoManager {

    /**
     * Adds the specified listener to the list of document undo listeners that
     * are notified before and after changes are undone or redone in the
     * document. This method has no effect if the instance being added is
     * already in the list.
     * <p>
     * Notifications will not be received if there are no clients connected to
     * the receiver. Registering a document undo listener does not implicitly
     * connect the listener to the receiver.</p>
     * <p>
     * Document undo listeners must be prepared to receive notifications from a
     * background thread. Any UI access occurring inside the implementation must
     * be properly synchronized using the techniques specified by the client's
     * widget library.</p>
     *
     * @param listener the document undo listener to be added as a listener
     */
    void addDocumentUndoListener(IDocumentUndoListener listener);

    /**
     * Removes the specified listener from the list of document undo listeners.
     * <p>
     * Removing a listener which is not registered has no effect
     * </p>
     *
     * @param listener the document undo listener to be removed
     */
    void removeDocumentUndoListener(IDocumentUndoListener listener);

    /**
     * Returns the undo context registered for this document
     *
     * @return the undo context registered for this document
     */
    IUndoContext getUndoContext();

    /**
     * Closes the currently open text edit and open a new one.
     */
    void commit();

    /**
     * Connects to the undo manager. Used to signify that a client is monitoring
     * the history kept by the undo manager. This message has no effect if the
     * client is already connected.
     *
     * @param client the object connecting to the undo manager
     */
    void connect(Object client);

    /**
     * Disconnects from the undo manager. Used to signify that a client is no
     * longer monitoring the history kept by the undo manager. If all clients
     * have disconnected from the undo manager, the undo history will be
     * deleted.
     *
     * @param client the object disconnecting from the undo manager
     */
    void disconnect(Object client);

    /**
     * Signals the undo manager that all subsequent changes until
     * <code>endCompoundChange</code> is called are to be undone in one piece.
     */
    void beginCompoundChange();

    /**
     * Signals the undo manager that the sequence of changes which started with
     * <code>beginCompoundChange</code> has been finished. All subsequent
     * changes are considered to be individually undo-able.
     */
    void endCompoundChange();

    /**
     * Sets the limit of the undo history to the specified value. The provided
     * limit will supersede any previously set limit.
     *
     * @param undoLimit the length of this undo manager's history
     */
    void setMaximalUndoLevel(int undoLimit);

    /**
     * Resets the history of the undo manager. After that call,
     * there aren't any undo-able or redo-able text changes.
     */
    void reset();

    /**
     * Returns whether at least one text change can be rolled back.
     *
     * @return <code>true</code> if at least one text change can be rolled back
     */
    bool undoable();

    /**
     * Returns whether at least one text change can be repeated. A text change
     * can be repeated only if it was executed and rolled back.
     *
     * @return <code>true</code> if at least on text change can be repeated
     */
    bool redoable();

    /**
     * Rolls back the most recently executed text change.
     *
     * @throws ExecutionException if an exception occurred during undo
     */
    void undo() ;

    /**
     * Repeats the most recently rolled back text change.
     *
     * @throws ExecutionException if an exception occurred during redo
     */
    void redo() ;

    /**
     * Transfers the undo history from the specified document undo manager to
     * this undo manager.  This message should only be used when it is known
     * that the content of the document of the original undo manager when the
     * last undo operation was recorded is the same as this undo manager's
     * current document content, since the undo history is based on document
     * indexes.  It is the responsibility of the caller
     * to ensure that this call is used correctly.
     *
     * @param manager the document undo manger whose history is to be transferred to the receiver
     */
    public void transferUndoHistory(IDocumentUndoManager manager);

}