import java.util.Hashtable;

import java.util.Iterator;

    /**

     *  

     * This method will attempt to return an IContainer common to all selected resources.

     * If there is no common IContainer, it will return a null

     * 

     * @param selection the current resource selection

     */

    protected IResource getCommonIResource(IStructuredSelection selection) {

    	IResource commonIResource = null;

    	IResource someIResource = null;

    	ArrayList resources = new ArrayList();

        Object selected = null;

        Object resource = null;

        boolean resourcesResideInSameProject = false;

        Hashtable uniqueProjects = new Hashtable();

        String projectName = null;

        if ( (selection != null) && (selection.size() > 1) ) {

	     try {

	    	  //First, get the IResource for this selection; if it exists

	    	  //Second, if the IResource is an IFile, get its container instead

	    	  //Third, determine if these IResources have a common project

	    	  Iterator it = selection.iterator();

	    	  while(it.hasNext()) {

	    		  selected = it.next();

		          if (selected instanceof IAdaptable) {

		              resource = ((IAdaptable) selected).getAdapter(IResource.class);

		              if (resource != null) {

		                  someIResource = (IResource) resource;

		                  if (someIResource.getType() == IResource.FILE){

		                	  resources.add(someIResource.getParent());

		                  }//if

		                  else {

		                	  resources.add(someIResource);

		                  }//endif

		                  //keep track of unique project names

		                  projectName = someIResource.getProject().getName();

		                  if (!uniqueProjects.containsKey( projectName )) {

		                	  uniqueProjects.put(projectName, projectName);

		                  }//if

		              }//if

		          }//if

	    	  }//while

	    	  if (resources.size() > 1) {

		    	  //

		    	  //figure out if resources all reside in same project

		    	  //

		    	  resourcesResideInSameProject = (uniqueProjects.size() == 1);

		    	  uniqueProjects.clear();

		    	  if (!resourcesResideInSameProject) {

		    		  //resources do reside in the same project, therefore no common IContainer resource is possible 

	    			  //so return null

	    			  commonIResource = null;

		    	  }//if

		    	  else {

		    		  //all the resources reside in the same project

		    		  //now find the longest common path

		    		  IResource[] theResources = (IResource[])resources.toArray(new IResource[0]);

		    		  resources.clear();

		    		  int i = 0;

		    		  int j =0;

		    		  IPath currentPath = null;

		    		  boolean pathSame = true;

		    		  int iSmallestSegmentCount = -1;

		    		  int segmentCount = 0;

	    			   //

	    			   //trim the IResource  paths to the smallest segment size before the main comparison starts

	    			   //

	    			   //

	    			   // if the resources already have the same segment count then the following code won't affect

	    			   // the resource array elements at all. However, if the segment counts are not identical, then

	    			   // this step is necessary.

	    				iSmallestSegmentCount = Integer.MAX_VALUE;

	    				//determine the smallest path segment count among all resources

		    			for(i=0;i<theResources.length;i++){

		    				segmentCount = theResources[i].getFullPath().segmentCount();

		    				if (segmentCount < iSmallestSegmentCount) {

		    					iSmallestSegmentCount = segmentCount;

		    				}//if

		    			}//for

		    		   //reduce all resources to the smallest segment size

		    		   for(i=0;i<theResources.length;i++){

		    			   segmentCount = theResources[i].getFullPath().segmentCount();

		    			   if (segmentCount > iSmallestSegmentCount) {

		    				   for(j=0;j<(segmentCount-iSmallestSegmentCount);j++){

		    					   //modifying array of resources to get parent of this

		    					   //resource and store it in the old position of the child resource

		    					   theResources[i] = theResources[i].getParent();

		    				   }//for

		    			   }//if

		    		   }//for

		    		   //

		    		   // Begin main comparison loop

		    		   //

			    	   boolean commonContainerPathAchieved = false;

			    	   while(!commonContainerPathAchieved) {

		    			   //

		    			   // path segment counts are all the same at this point for all the resources

		    			   //

	 		    		    //get the path of the first element to use for comparison  

	 		    		    currentPath = theResources[0].getFullPath();

				    		//determine if the resources' paths are the same

				    		pathSame = true;

				    		for(i=0;i<theResources.length;i++){

				    				if (!currentPath.equals(theResources[i].getFullPath())) {

				    					pathSame = false;

				    					break;

				    				}//if

				    		}//for

			    			if (pathSame == false) {					    		

			    				   //

			    				   // get the parents of all the resources and store them in resource array

			    				   //

			    				   for(i=0;i<theResources.length;i++){

			    					   //modifying array of resources to get parent of this

			    					   //resource and store it in the old position of the child resource

			    					   theResources[i] = theResources[i].getParent();

			    				   }//for

			    			}//if

			    			else {

			    				//path is finally common across all resources

			    				//break out of loop

			    				commonContainerPathAchieved = true;

			    			}//endif

			    		}//while

		    		  //

		    		  // At this point, all the IContainer elements in the array have the same path

		    		  //

    				  //set the commonIResource

	    			  commonIResource = theResources[0];

		    	  }//endif

	    	  }//if

	    	}//try

	    	catch(Exception e){

	    		e.printStackTrace();

	    	}//catch

        }//if

    	return commonIResource;

    }