Fix crash when signal messages disabled in group conversation

Fixes #6419
Closes #6803

res/layout/conversation_activity.xml

@@ -56,6 +56,13 @@
 
         <include layout="@layout/conversation_input_panel"/>
 
+        <Button android:id="@+id/register_button"
+                android:layout_width="fill_parent"
+                android:layout_height="wrap_content"
+                android:padding="20dp"
+                android:text="@string/conversation_activity__enable_signal_messages"
+                android:visibility="gone"/>
+
         <Button android:id="@+id/unblock_button"
                 android:layout_width="fill_parent"
                 android:layout_height="wrap_content"

res/values/strings.xml

@@ -1316,6 +1316,7 @@
     <string name="Permissions_continue">Continue</string>
     <string name="Permissions_not_now">Not now</string>
     <string name="ConversationListActivity_signal_needs_contacts_permission_in_order_to_search_your_contacts_but_it_has_been_permanently_denied">Signal needs Contacts permission in order to search your contacts, but it has been permanently denied. Please continue to app settings, select \"Permissions\", and enable \"Contacts\".</string>
+    <string name="conversation_activity__enable_signal_messages">ENABLE SIGNAL MESSAGES</string>
 
 
     <!-- EOF -->

src/org/thoughtcrime/securesms/ConversationActivity.java

@@ -225,6 +225,7 @@ public class ConversationActivity extends PassphraseRequiredActionBarActivity
   private   ConversationFragment        fragment;
   private   Button                      unblockButton;
   private   Button                      makeDefaultSmsButton;
+  private   Button                      registerButton;
   private   InputAwareLayout            container;
   private   View                        composePanel;
   protected Stub<ReminderView>          reminderView;
@@ -677,6 +678,13 @@ public class ConversationActivity extends PassphraseRequiredActionBarActivity
     startActivityForResult(intent, SMS_DEFAULT);
   }
 
+  private void handleRegisterForSignal() {
+    Intent intent = new Intent(this, RegistrationActivity.class);
+    intent.putExtra("cancel_button", true);
+    intent.putExtra("master_secret", masterSecret);
+    startActivity(intent);
+  }
+
   private void handleInviteLink() {
     try {
       String inviteText;
@@ -959,11 +967,11 @@ public class ConversationActivity extends PassphraseRequiredActionBarActivity
 
     sendButton.resetAvailableTransports(isMediaMessage);
 
-    if (!isSecureText)                    sendButton.disableTransport(Type.TEXTSECURE);
-    if (recipient.isPushGroupRecipient()) sendButton.disableTransport(Type.SMS);
+    if (!isSecureText && !isPushGroupConversation()) sendButton.disableTransport(Type.TEXTSECURE);
+    if (recipient.isPushGroupRecipient())            sendButton.disableTransport(Type.SMS);
 
-    if (isSecureText) sendButton.setDefaultTransport(Type.TEXTSECURE);
-    else              sendButton.setDefaultTransport(Type.SMS);
+    if (isSecureText || isPushGroupConversation()) sendButton.setDefaultTransport(Type.TEXTSECURE);
+    else                                           sendButton.setDefaultTransport(Type.SMS);
 
     calculateCharactersRemaining();
     supportInvalidateOptionsMenu();
@@ -1213,6 +1221,7 @@ public class ConversationActivity extends PassphraseRequiredActionBarActivity
     emojiDrawerStub       = ViewUtil.findStubById(this, R.id.emoji_drawer_stub);
     unblockButton         = ViewUtil.findById(this, R.id.unblock_button);
     makeDefaultSmsButton  = ViewUtil.findById(this, R.id.make_default_sms_button);
+    registerButton        = ViewUtil.findById(this, R.id.register_button);
     composePanel          = ViewUtil.findById(this, R.id.bottom_panel);
     container             = ViewUtil.findById(this, R.id.layout_container);
     reminderView          = ViewUtil.findStubById(this, R.id.reminder_stub);
@@ -1260,6 +1269,7 @@ public class ConversationActivity extends PassphraseRequiredActionBarActivity
     titleView.setOnBackClickedListener(view -> super.onBackPressed());
     unblockButton.setOnClickListener(v -> handleUnblock());
     makeDefaultSmsButton.setOnClickListener(v -> handleMakeDefaultSms());
+    registerButton.setOnClickListener(v -> handleRegisterForSignal());
 
     composeText.setOnKeyListener(composeKeyPressedListener);
     composeText.addTextChangedListener(composeKeyPressedListener);
@@ -1476,14 +1486,22 @@ public class ConversationActivity extends PassphraseRequiredActionBarActivity
       unblockButton.setVisibility(View.VISIBLE);
       composePanel.setVisibility(View.GONE);
       makeDefaultSmsButton.setVisibility(View.GONE);
+      registerButton.setVisibility(View.GONE);
+    } else if (!isSecureText && isPushGroupConversation()) {
+      unblockButton.setVisibility(View.GONE);
+      composePanel.setVisibility(View.GONE);
+      makeDefaultSmsButton.setVisibility(View.GONE);
+      registerButton.setVisibility(View.VISIBLE);
     } else if (!isSecureText && !isDefaultSms) {
       unblockButton.setVisibility(View.GONE);
       composePanel.setVisibility(View.GONE);
       makeDefaultSmsButton.setVisibility(View.VISIBLE);
+      registerButton.setVisibility(View.GONE);
     } else {
       composePanel.setVisibility(View.VISIBLE);
       unblockButton.setVisibility(View.GONE);
       makeDefaultSmsButton.setVisibility(View.GONE);
+      registerButton.setVisibility(View.GONE);
     }
   }