content: /*******************************************************************************
   * Copyright (c) 2000, 2008 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:
   *   Jesper Kamstrup Linnet (eclipse@kamstrup-linnet.dk) - initial API and implementation 
   * 			(report 36180: Callers/Callees view)
   *******************************************************************************/
  package org.eclipse.wst.jsdt.internal.ui.callhierarchy;
  
  import org.eclipse.jface.viewers.ISelection;
  import org.eclipse.jface.viewers.StructuredViewer;
  import org.eclipse.swt.dnd.DND;
  import org.eclipse.swt.dnd.DropTargetEvent;
  import org.eclipse.wst.jsdt.core.IFunction;
  import org.eclipse.wst.jsdt.internal.ui.packageview.SelectionTransferDropAdapter;
  import org.eclipse.wst.jsdt.internal.ui.util.SelectionUtil;
  
  class CallHierarchyTransferDropAdapter extends SelectionTransferDropAdapter {
  
  	private static final int OPERATION = DND.DROP_LINK;
  	private CallHierarchyViewPart fCallHierarchyViewPart;
  
  	public CallHierarchyTransferDropAdapter(CallHierarchyViewPart viewPart, StructuredViewer viewer) {
  		super(viewer);
  		setFullWidthMatchesItem(false);
  		fCallHierarchyViewPart= viewPart;
  	}
  
  	public void validateDrop(Object target, DropTargetEvent event, int operation) {
  		event.detail= DND.DROP_NONE;
  		initializeSelection();
  		if (target != null){
  			super.validateDrop(target, event, operation);
  			return;
  		}	
  		if (getInputElement(getSelection()) != null) 
  			event.detail= OPERATION;
  	}
  	
  	/* (non-Javadoc)
  	 * @see org.eclipse.wst.jsdt.internal.ui.packageview.SelectionTransferDropAdapter#isEnabled(org.eclipse.swt.dnd.DropTargetEvent)
  	 */
  	public boolean isEnabled(DropTargetEvent event) {
  		return true;
  	}
  
  	public void drop(Object target, DropTargetEvent event) {
  		if (target != null || event.detail != OPERATION){
  			super.drop(target, event);
  			return;
  		}	
  		IFunction input= getInputElement(getSelection());
  		fCallHierarchyViewPart.setMethod(input);
  	}
  	
  	private static IFunction getInputElement(ISelection selection) {
  		Object single= SelectionUtil.getSingleElement(selection);
  		if (single == null)
  			return null;
  		return getCandidate(single);
  	}
      
      /**
       * Converts the input to a possible input candidates
       */ 
      public static IFunction getCandidate(Object input) {
          if (!(input instanceof IFunction)) {
              return null;
          }
          return (IFunction) input;
      }
  }
  