Can respond to group membership invitations

lib/ui/widgets/group_membership_widget.dart

@@ -43,8 +43,8 @@ class _GroupMembershipWidgetState extends SafeState<GroupMembershipWidget> {
         return Text(tr("Member"));
 
       case GroupMembershipLevel.INVITED:
-        // TODO: Handle this case.
-        break;
+        return _buildInvitedState();
+
       case GroupMembershipLevel.PENDING:
         return _buildPendingState();
 
@@ -53,6 +53,49 @@ class _GroupMembershipWidgetState extends SafeState<GroupMembershipWidget> {
     }
   }
 
+  /// Build invited state
+  Widget _buildInvitedState() {
+    return RichText(
+      text: TextSpan(children: [
+        WidgetSpan(
+            child: Icon(Icons.info_outline, size: 12),
+            alignment: PlaceholderAlignment.middle),
+        TextSpan(text: " " + tr("Invited") + " "),
+        TextSpan(
+            text: tr("Accept"),
+            style: TextStyle(color: Colors.green),
+            recognizer: TapGestureRecognizer()
+              ..onTap = () => _respondInvitation(true)),
+        TextSpan(text: "  "),
+        TextSpan(
+            text: tr("Reject"),
+            style: TextStyle(color: Colors.red),
+            recognizer: TapGestureRecognizer()
+              ..onTap = () => _respondInvitation(false)),
+      ]),
+    );
+  }
+
+  /// Respond to an invitation
+  void _respondInvitation(bool accept) async {
+    if (!accept &&
+        !await showConfirmDialog(
+            context: context,
+            message: tr("Do you really want to reject this invitation?")))
+      return;
+
+    if (!await GroupsHelper().respondInvitation(_id, accept))
+      showSimpleSnack(context, tr("Could not respond to your invitation!"));
+    else {
+      // Refresh state
+      group.membershipLevel =
+          accept ? GroupMembershipLevel.MEMBER : GroupMembershipLevel.VISITOR;
+      this.setState(() {});
+
+      if (this.widget.onUpdated != null) this.widget.onUpdated();
+    }
+  }
+
   /// Build pending state
   Widget _buildPendingState() {
     return RichText(