feat(transcription): Adds additional languages via metadata.

src/main/java/org/jitsi/jigasi/JvbConference.java

@@ -1358,7 +1358,8 @@ else if (ChatRoomMemberPresenceChangeEvent.MEMBER_UPDATED
                             + " " + member.getContactAddress());
 
             CallPeer peer;
-            if (jvbCall != null && (peer = jvbCall.getCallPeers().next()) instanceof MediaAwareCallPeer)
+            if (jvbCall != null && jvbCall.getCallPeerCount() > 0
+                    && (peer = jvbCall.getCallPeers().next()) instanceof MediaAwareCallPeer)
             {
                 MediaAwareCallPeer<?, ?, ?> peerMedia = (MediaAwareCallPeer<?, ?, ?>) peer;
                 peerMedia.getConferenceMembers().forEach(confMember ->
@@ -2212,10 +2213,21 @@ private void processRoomMetadataJson(String json)
 
                 if (data.get("type").equals("room_metadata"))
                 {
+                    TranscriptionGatewaySession transcriptionSession = (TranscriptionGatewaySession)this.gatewaySession;
+
                     JSONObject metadataObj = (JSONObject)data.getOrDefault("metadata", new JSONObject());
                     JSONObject recordingObj = (JSONObject)metadataObj.getOrDefault("recording", new JSONObject());
-                    ((TranscriptionGatewaySession)this.gatewaySession).setBackendTranscribingEnabled(
+                    transcriptionSession.setBackendTranscribingEnabled(
                         (boolean)recordingObj.getOrDefault("isTranscribingEnabled", false));
+
+                    JSONObject visitorsObj = (JSONObject)metadataObj.getOrDefault("visitors", new JSONObject());
+                    String languages = (String)visitorsObj.get("transcribingLanguages");
+                    if (StringUtils.isNotEmpty(languages))
+                    {
+                        transcriptionSession.updateTranslateLanguages(languages.split(","));
+                    }
+                    transcriptionSession.setVisitorsCountRequestingTranscription(
+                        Integer.parseInt((String)visitorsObj.get("transcribingCount")));
                 }
             }
         }

src/main/java/org/jitsi/jigasi/Main.java

@@ -152,7 +152,6 @@ public class Main
             "org.jivesoftware.smackx.si",
             "org.jivesoftware.smackx.vcardtemp",
             "org.jivesoftware.smackx.xhtmlim",
-            "org.jivesoftware.smackx.xdata",
             "org.jivesoftware.smackx.eme",
             "org.jivesoftware.smackx.iqprivate",
             "org.jivesoftware.smackx.bookmarks",

src/main/java/org/jitsi/jigasi/TranscriptionGatewaySession.java

@@ -126,6 +126,17 @@ public class TranscriptionGatewaySession
      */
     private int numberOfScheduledParticipantsLeaving = 0;
 
+    /**
+     * The currently used additional languages for translation.
+     * Used for visitors to announce the languages used by visitors.
+     */
+    private List<String> additionalLanguages = new ArrayList<>();
+
+    /**
+     * The number of visitors that are requesting transcriptions.
+     */
+    private int numberOfVisitorsRequestingTranscription = 0;
+
     /**
      * Create a TranscriptionGatewaySession which can handle the transcription
      * of a JVB conference
@@ -359,7 +370,9 @@ void notifyChatRoomMemberUpdated(ChatRoomMember chatMember, Presence presence)
 
     private boolean isTranscriptionRequested()
     {
-        return transcriber.isAnyParticipantRequestingTranscription() || isBackendTranscribingEnabled;
+        return transcriber.isAnyParticipantRequestingTranscription()
+                || isBackendTranscribingEnabled
+                || this.numberOfVisitorsRequestingTranscription > 0;
     }
 
     private void maybeStopTranscription()
@@ -753,4 +766,32 @@ public void setBackendTranscribingEnabled(boolean backendTranscribingEnabled)
 
         this.maybeStopTranscription();
     }
+
+    /**
+     * @param count The count of visitors that are requesting transcriptions.
+     */
+    public void setVisitorsCountRequestingTranscription(int count)
+    {
+        this.numberOfVisitorsRequestingTranscription = count;
+
+        this.maybeStopTranscription();
+    }
+
+    /**
+     * To update all participant languages with the additional that are provided.
+     * @param additionalLanguages languages to add to those from the participants.
+     */
+    void updateTranslateLanguages(String[] additionalLanguages)
+    {
+        List<String> oldLangs = this.additionalLanguages;
+        this.additionalLanguages = Arrays.asList(additionalLanguages);
+
+        // remove unused streams
+        oldLangs.stream().filter(s -> !this.additionalLanguages.contains(s))
+            .forEach(lang -> this.transcriber.getTranslationManager().removeLanguage(lang));
+
+        // add new languages
+        this.additionalLanguages.stream().filter(s -> !oldLangs.contains(s))
+            .forEach(lang -> this.transcriber.getTranslationManager().addLanguage(lang));
+    }
 }

src/main/java/org/jitsi/jigasi/transcription/Transcriber.java

@@ -834,6 +834,14 @@ public TranscriptionService getTranscriptionService()
         return transcriptionService;
     }
 
+    /**
+     * @return the {@link TranslationManager}.
+     */
+    public TranslationManager getTranslationManager()
+    {
+        return this.translationManager;
+    }
+
     /**
      * Notifies all of the listeners of this {@link Transcriber} of a new
      * {@link TranscriptionResult} which was received.

src/main/java/org/jitsi/jigasi/transcription/TranslationManager.java

@@ -140,9 +140,15 @@ private List<TranslationResult> getTranslations(
         {
             for (String targetLanguage : translationLanguages)
             {
+                String sourceLang = result.getParticipant().getSourceLanguage();
+                if (sourceLang != null && sourceLang.equals(targetLanguage))
+                {
+                    continue;
+                }
+
                 String translatedText = translationService.translate(
                     alternatives.iterator().next().getTranscription(),
-                    result.getParticipant().getSourceLanguage(),
+                    sourceLang,
                     targetLanguage);
 
                 translatedResults.add(new TranslationResult(