Persist a single set of targets for all streams

 * Split ResultListener and ExceptionListener implementation, the
   methods turns out not to be closely related.
 * Extract CompositeResultListener from Stream, making TweetShell own
   it, this simplifies code and allows you to have targets even if no
   stream is instantiated.

1 files changed, 32 insertions, 31 deletions

diff --git a/src/main/TweetShell.java b/src/main/TweetShell.java
index fa1fb49..6d9edd1 100644
--- a/src/main/TweetShell.java
+++ b/src/main/TweetShell.java
@@ -31,6 +31,16 @@ public class TweetShell implements TwitterApi.PinSupplier {
 
     private TwitterApi api_cached;
     private Stream stream_cached;
+    private final CompositeResultListener resultListeners;
+
+    public TweetShell() {
+        resultListeners = new CompositeResultListener();
+        // by default, store something that counts responses
+        resultListeners.register(new TweetCounter());
+        // and something that prints tweets to console.
+        resultListeners.register(new StreamHandler());
+        // see getPossibleTargets() for more listener types.
+    }
 
     private TwitterApi getApi() throws IOException {
         if (api_cached == null) {
@@ -42,27 +52,23 @@ public class TweetShell implements TwitterApi.PinSupplier {
     private Stream getStream() throws IOException {
         if (stream_cached == null) {
             OAuthRequester requester = (OAuthRequester) getApi().getRequester();
-            StreamHandler handler = new StreamHandler();
             stream_cached = new StreamImpl(requester);
             StreamImpl streamObserver = (StreamImpl) stream_cached;
-            streamObserver.setExceptionListener(handler);
-
-            CompositeResultListener listeners = new CompositeResultListener();
-            streamObserver.setResultListener(listeners);
-            // by default, store something that counts responses
-            listeners.register(new TweetCounter());
-            // and something that prints tweets to console.
-            listeners.register(handler);
+            streamObserver.setExceptionListener(new StreamExceptionHandler());
+            streamObserver.setResultListener(resultListeners);
         }
         return stream_cached;
     }
 
-    private class StreamHandler implements ResultListener, ExceptionListener {
+    private class StreamExceptionHandler implements ExceptionListener {
 
         @Override
         public void exceptionGenerated(Exception ex) {
             System.err.println("Stream closed due to " + ex);
         }
+    }
+
+    private class StreamHandler implements ResultListener {
 
         @Override
         public void tweetGenerated(JSONObject obj) {
@@ -269,13 +275,11 @@ public class TweetShell implements TwitterApi.PinSupplier {
             case exit:
                 throw new NoSuchElementException();
             case target:
-                StreamImpl stream = (StreamImpl) getStream();
-                CompositeResultListener rls;
-                rls = (CompositeResultListener) stream.getResultListener();
                 if (params.length > 0) {
-                    configureTargets(rls, params);
+                    configureTargets(params);
                 } else {
-                    ClassEnabledTracker<ResultListener> targets = getPossibleTargets(rls);
+                    ClassEnabledTracker<ResultListener> targets;
+                    targets = getPossibleTargets();
                     // print the names of all targets that are enabled
                     System.out.print("Enabled targets:");
                     for (String name : targets.getNames()) {
@@ -290,25 +294,24 @@ public class TweetShell implements TwitterApi.PinSupplier {
     }
 
     /**
-     * @param stream An instance for which open targets apply to.
      * @return All targets that can be disabled or enabled.
      */
-    private ClassEnabledTracker<ResultListener> getPossibleTargets(CompositeResultListener rls) {
+    private ClassEnabledTracker<ResultListener> getPossibleTargets() {
         Map<String, Class<? extends ResultListener>> targets = new TreeMap<>();
         targets.put("file", DataWriter.class);
         targets.put("shell", StreamHandler.class);
 
         ClassEnabledTracker<ResultListener> targetFoo = new ClassEnabledTracker<>(targets);
         targetFoo.disableAll();
-        targetFoo.enableClasses(rls.getRegistered());
+        targetFoo.enableClasses(resultListeners.getRegistered());
         return targetFoo;
     }
 
     /**
      * Process enable and disable target parameters.
      */
-    private void configureTargets(CompositeResultListener rls, String[] params) {
-        ClassEnabledTracker<ResultListener> targets = getPossibleTargets(rls);
+    private void configureTargets(String[] params) {
+        ClassEnabledTracker<ResultListener> targets = getPossibleTargets();
 
         for (String type : params) {
             String name;
@@ -333,20 +336,19 @@ public class TweetShell implements TwitterApi.PinSupplier {
             }
         }
         for (String name : targets.getDisabled()) {
-            if (disableTarget(rls, targets.getClassByName(name))) {
+            if (disableTarget(targets.getClassByName(name))) {
                 System.err.println("Disabled " + name);
             }
         }
         for (String name : targets.getEnabled()) {
-            if (enableTarget(rls, targets.getClassByName(name))) {
+            if (enableTarget(targets.getClassByName(name))) {
                 System.err.println("Enabled " + name);
             }
         }
     }
 
-    private boolean enableTarget(CompositeResultListener rls,
-            Class<? extends ResultListener> rlCls) {
-        ResultListener oldListener = rls.findListener(rlCls);
+    private boolean enableTarget(Class<? extends ResultListener> rlCls) {
+        ResultListener oldListener = resultListeners.findListener(rlCls);
 
         // don't add it again if already activated
         if (oldListener != null) {
@@ -359,26 +361,25 @@ public class TweetShell implements TwitterApi.PinSupplier {
             String profilesFilename = config.getProperty(DataWriter.CFG_PROFILE_FILENAME);
             String tweetsFilename = config.getProperty(DataWriter.CFG_TWEETS_FILENAME);
 
-            rls.register(new DataWriter(profilesFilename, tweetsFilename));
+            resultListeners.register(new DataWriter(profilesFilename, tweetsFilename));
 
             // save the changes to the config.
             config.save();
         } else if (rlCls == StreamHandler.class) {
-            rls.register(new StreamHandler());
+            resultListeners.register(new StreamHandler());
         }
         return true;
     }
 
-    private boolean disableTarget(CompositeResultListener rls,
-            Class<? extends ResultListener> rlCls) {
-        ResultListener oldListener = rls.findListener(rlCls);
+    private boolean disableTarget(Class<? extends ResultListener> rlCls) {
+        ResultListener oldListener = resultListeners.findListener(rlCls);
 
         // no need for action if not activated
         if (oldListener == null) {
             return false;
         }
 
-        rls.unregister(oldListener);
+        resultListeners.unregister(oldListener);
         // do we need to cleanup something?
         if (oldListener instanceof DataWriter) {
             ((DataWriter) oldListener).close();