fix browsing failures when requests return no files or folders

core/src/main/groovy/com/muwire/core/search/BrowseManager.groovy

@@ -123,10 +123,12 @@ class BrowseManager {
         JsonOutput jsonOutput = new JsonOutput()
         def baos = new ByteArrayOutputStream()
         def dos = new DataOutputStream(new GZIPOutputStream(baos))
+        if (count > 0) {
             writeFiles(topLevelItems.files.values(), dos, jsonOutput)
             writeDirs(topLevelItems.dirs, dos, jsonOutput)
             dos.close()
             os.write(baos.toByteArray())
+        }
         os.flush()
         
         InputStream is = endpoint.getInputStream()
@@ -168,19 +170,21 @@ class BrowseManager {
                 def cb = new PathCallback()
                 tempTree.traverse(requestedPath, cb)
                 filesToWrite = cb.files
-                dirsToWrite = Collections.emptySet()
+                dirsToWrite = cb.dirs
             }
             filesToWrite.each {it.hit(browser, System.currentTimeMillis(), "Browse Host")}
             os.write("Files:${filesToWrite.size()}\r\n".getBytes(StandardCharsets.US_ASCII))
             os.write("Dirs:${dirsToWrite.size()}\r\n".getBytes(StandardCharsets.US_ASCII))
             os.write("\r\n".getBytes(StandardCharsets.US_ASCII))
             
+            if (filesToWrite.size() + dirsToWrite.size() > 0) {
                 baos = new ByteArrayOutputStream()
                 dos = new DataOutputStream(new GZIPOutputStream(baos))
                 writeFiles(filesToWrite, dos, jsonOutput)
                 writeDirs(dirsToWrite, dos, jsonOutput)
                 dos.close()
                 os.write(baos.toByteArray())
+            }
             os.flush()
         }
     }
@@ -239,9 +243,14 @@ class BrowseManager {
     private static class PathCallback implements PathTreeCallback<BrowsedFile, BrowsedFolder> {
         
         final Set<SharedFile> files = new HashSet<>()
+        final Set<Path> dirs = new HashSet<>()
 
         @Override
         void onDirectoryEnter(Path path, BrowsedFolder value) {
+            if (!value.sent) {
+                value.sent = true
+                dirs.add(value.path)
+            }
         }
 
         @Override

core/src/main/groovy/com/muwire/core/search/BrowseSession.groovy

@@ -136,6 +136,7 @@ class BrowseSession implements Runnable {
                     if (!headers.containsKey("Dirs"))
                         throw new Exception("Dirs header missing")
                     int dirs = Integer.parseInt(headers['Dirs'])
+                    if (files + dirs > 0) {
                         eventBus.publish(new BrowseStatusEvent(host: event.host, status: BrowseStatus.FETCHING,
                                 totalResults: results, currentItems: (files + dirs), uuid: uuid))
                         log.info("starting to fetch ${files} files and ${dirs} dirs with uuid $uuid")
@@ -176,8 +177,8 @@ class BrowseSession implements Runnable {
                                     path: path.toArray(new String[0]))
                             eventBus.publish(event)
                         }
-                    eventBus.publish(new BrowseStatusEvent(host: event.host, status : BrowseStatus.FINISHED, uuid : uuid))
-                    
+                        eventBus.publish(new BrowseStatusEvent(host: event.host, status: BrowseStatus.FINISHED, uuid: uuid))
+                    }
                     while(true) {
                         Request nextPath = fetchQueue.poll(PING_INTERVAL, TimeUnit.MILLISECONDS)
                         if (nextPath == null) {

gui/src/main/groovy/com/muwire/gui/ResultTreeModel.groovy

@@ -37,6 +37,7 @@ class ResultTreeModel extends DefaultTreeModel {
             node = elementNode
         }
      
+        if (node.getChildCount() == 0)
             node.addDescendant(new PlaceholderNode())
     }