/*
 * Jalview - A Sequence Alignment Editor and Viewer (Version 2.4)
 * Copyright (C) 2008 AM Waterhouse, J Procter, G Barton, M Clamp, S Searle
 * 
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 * 
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA
 */
package jalview.io.vamsas;

import uk.ac.vamsas.client.Vobject;

/**
 * Implement the basic logic for synchronising changes to or from the Vamsas
 * Document
 * 
 * @author JimP
 */
public abstract class LocalDocSyncObject extends DatastoreItem
{
  /**
   * 
   * @return null or the local object that is being worked on.
   */
  public abstract Object getLObject();

  /**
   * 
   * @return null or the document object that is being worked on
   */
  public abstract Vobject getVObject();

  /**
   * endpoint for synchronize when all opreations are finished.
   */
  public abstract void nextObject();

  /**
   * called if the local object can be safely updated from the bound document
   * object.
   */
  public abstract void updateFromDoc();

  /**
   * called if the associated document object can be safely updated with the
   * local changes
   */
  public abstract void updateToDoc();

  /**
   * @return true if the local object is modified
   */
  public abstract boolean locallyModified();

  /**
   * 
   * @return true if the bound document object is modified
   */
  public abstract boolean documentModified();

  /**
   * 
   * @return true if the document object is locked w.r.t. this object's update.
   */
  public abstract boolean documentObjectLocked();

  /**
   * 
   * @return a new datastore item instance which binds the local object to a new
   *         document object
   */
  public abstract LocalDocSyncObject newDocumentObject(); // could make this
                                                          // constructor(Lobject)

  /**
   * 
   * @return a new datastore item instance which binds the document object to a
   *         new local object.
   */
  public abstract LocalDocSyncObject newLocalObject(); // make this
                                                        // constructor(Vobject)

  /**
   * apply the update/commit logic as defined in the vamsas paper
   * 
   * @param documentIsUpdated
   *                true if a document update event is being handled
   */
  public void synchronize(boolean documentIsUpdated)
  {
    Object Lobject = getLObject();
    Vobject Vobject = getVObject();
    if (Lobject == null)
    {
      // no local binding for document object
      newLocalObject().synchronize(documentIsUpdated);
      return;
    }
    if (Vobject == null)
    {
      // no document binding for local object
      newDocumentObject().synchronize(documentIsUpdated);
    }
    // Check binding is valid
    if (getjv2vObj(Lobject) != Vobject)
    {
      // no local binding for document object
      newLocalObject().synchronize(documentIsUpdated);
      // no document binding for local object
      newDocumentObject().synchronize(documentIsUpdated);
    }
  }
}