Disable verify button if no message was exchanged

Fixes #5878
Closes #5951
// FREEBIE

res/values/strings.xml

@@ -451,6 +451,7 @@
     <string name="RecipientPreferenceActivity_unblock">Unblock</string>
     <string name="RecipientPreferenceActivity_enabled">Enabled</string>
     <string name="RecipientPreferenceActivity_disabled">Disabled</string>
+    <string name="RecipientPreferenceActivity_available_once_a_message_has_been_sent_or_received">Available once a message has been sent or received.</string>
 
     <!-- RedPhone -->
     <string name="RedPhone_answering">Answering</string>

src/org/thoughtcrime/securesms/ConversationActivity.java

@@ -1026,6 +1026,8 @@ public class ConversationActivity extends PassphraseRequiredActionBarActivity
       public void onClick(View v) {
         Intent intent = new Intent(ConversationActivity.this, RecipientPreferenceActivity.class);
         intent.putExtra(RecipientPreferenceActivity.RECIPIENTS_EXTRA, recipients.getIds());
+        intent.putExtra(RecipientPreferenceActivity.CAN_HAVE_SAFETY_NUMBER_EXTRA,
+                        isSecureText && !isSelfConversation());
 
         startActivitySceneTransition(intent, titleView.findViewById(R.id.title), "recipient_name");
       }

src/org/thoughtcrime/securesms/RecipientPreferenceActivity.java

@@ -56,6 +56,7 @@ public class RecipientPreferenceActivity extends PassphraseRequiredActionBarActi
   private static final String TAG = RecipientPreferenceActivity.class.getSimpleName();
 
   public static final String RECIPIENTS_EXTRA             = "recipient_ids";
+  public static final String CAN_HAVE_SAFETY_NUMBER_EXTRA = "can_have_safety_number";
 
   private static final String PREFERENCE_MUTED    = "pref_key_recipient_mute";
   private static final String PREFERENCE_TONE     = "pref_key_recipient_ringtone";
@@ -192,6 +193,7 @@ public class RecipientPreferenceActivity extends PassphraseRequiredActionBarActi
     private Recipients        recipients;
     private BroadcastReceiver staleReceiver;
     private MasterSecret      masterSecret;
+    private boolean           canHaveSafetyNumber;
 
     @Override
     public void onCreate(Bundle icicle) {
@@ -201,6 +203,8 @@ public class RecipientPreferenceActivity extends PassphraseRequiredActionBarActi
       initializeRecipients();
 
       this.masterSecret        = getArguments().getParcelable("master_secret");
+      this.canHaveSafetyNumber = getActivity().getIntent()
+                                 .getBooleanExtra(RecipientPreferenceActivity.CAN_HAVE_SAFETY_NUMBER_EXTRA, false);
 
       this.findPreference(PREFERENCE_TONE)
           .setOnPreferenceChangeListener(new RingtoneChangeListener());
@@ -299,6 +303,9 @@ public class RecipientPreferenceActivity extends PassphraseRequiredActionBarActi
             if (result.isPresent()) {
               if (identityPreference != null) identityPreference.setOnPreferenceClickListener(new IdentityClickedListener(result.get()));
               if (identityPreference != null) identityPreference.setEnabled(true);
+            } else if (canHaveSafetyNumber) {
+              if (identityPreference != null) identityPreference.setSummary(R.string.RecipientPreferenceActivity_available_once_a_message_has_been_sent_or_received);
+              if (identityPreference != null) identityPreference.setEnabled(false);
             } else {
               if (identityPreference != null) getPreferenceScreen().removePreference(identityPreference);
             }