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);
    }
  }
}