message-list : add a prompt to notify guest(s) when DM

Fixes #798
showDMWarningBanner could be initialized in the initState to shouldShowGuestUserWarningPrompt(store) and Visibility wrapper could have been gotten rid off , but due to unavailability of store beforehand it was not possible.

To create the guests list, I got rid off all the users in the store which are not in the recepients list and role-checked them.

assets/l10n/app_en.arb

@@ -831,5 +831,13 @@
   "zulipAppTitle": "Zulip",
   "@zulipAppTitle": {
     "description": "The name of Zulip. This should be either 'Zulip' or a transliteration."
+  },
+  "bannerText": "{guestCount, plural, =1{{guestNamesList} is a guest in this organization.} other{{guestNamesList} are guests in this organization.}}",
+  "@bannerText": {
+    "description": "Message displaying guest names in the organization.",
+    "placeholders": {
+      "guestCount": {"type": "int", "example": "3"},
+      "guestNamesList": {"type": "String", "example": "Alice, Bob, Charlie"}
+    }
   }
 }

lib/api/model/initial_snapshot.dart

@@ -79,6 +79,8 @@ class InitialSnapshot {
   ///   https://zulip.com/api/roles-and-permissions#determining-if-a-user-is-a-full-member
   final int realmWaitingPeriodThreshold;
 
+  final bool? realmEnableGuestUserDmWarning;
+
   final Map<String, RealmDefaultExternalAccount> realmDefaultExternalAccounts;
 
   final int maxFileUploadSizeMib;
@@ -135,6 +137,7 @@ class InitialSnapshot {
     required this.realmWildcardMentionPolicy,
     required this.realmMandatoryTopics,
     required this.realmWaitingPeriodThreshold,
+    required this.realmEnableGuestUserDmWarning,
     required this.realmDefaultExternalAccounts,
     required this.maxFileUploadSizeMib,
     required this.serverEmojiDataUrl,

lib/generated/l10n/zulip_localizations.dart

@@ -1214,6 +1214,12 @@ abstract class ZulipLocalizations {
   /// In en, this message translates to:
   /// **'Zulip'**
   String get zulipAppTitle;
+
+  /// Message displaying guest names in the organization.
+  ///
+  /// In en, this message translates to:
+  /// **'{guestCount, plural, =1{{guestNamesList} is a guest in this organization.} other{{guestNamesList} are guests in this organization.}}'**
+  String bannerText(int guestCount, String guestNamesList);
 }
 
 class _ZulipLocalizationsDelegate extends LocalizationsDelegate<ZulipLocalizations> {

lib/generated/l10n/zulip_localizations_ar.dart

@@ -648,4 +648,15 @@ class ZulipLocalizationsAr extends ZulipLocalizations {
 
   @override
   String get zulipAppTitle => 'Zulip';
+
+  @override
+  String bannerText(int guestCount, String guestNamesList) {
+    String _temp0 = intl.Intl.pluralLogic(
+      guestCount,
+      locale: localeName,
+      other: '$guestNamesList are guests in this organization.',
+      one: '$guestNamesList is a guest in this organization.',
+    );
+    return '$_temp0';
+  }
 }

lib/generated/l10n/zulip_localizations_en.dart

@@ -648,4 +648,15 @@ class ZulipLocalizationsEn extends ZulipLocalizations {
 
   @override
   String get zulipAppTitle => 'Zulip';
+
+  @override
+  String bannerText(int guestCount, String guestNamesList) {
+    String _temp0 = intl.Intl.pluralLogic(
+      guestCount,
+      locale: localeName,
+      other: '$guestNamesList are guests in this organization.',
+      one: '$guestNamesList is a guest in this organization.',
+    );
+    return '$_temp0';
+  }
 }

lib/generated/l10n/zulip_localizations_ja.dart

@@ -648,4 +648,15 @@ class ZulipLocalizationsJa extends ZulipLocalizations {
 
   @override
   String get zulipAppTitle => 'Zulip';
+
+  @override
+  String bannerText(int guestCount, String guestNamesList) {
+    String _temp0 = intl.Intl.pluralLogic(
+      guestCount,
+      locale: localeName,
+      other: '$guestNamesList are guests in this organization.',
+      one: '$guestNamesList is a guest in this organization.',
+    );
+    return '$_temp0';
+  }
 }

lib/generated/l10n/zulip_localizations_nb.dart

@@ -648,4 +648,15 @@ class ZulipLocalizationsNb extends ZulipLocalizations {
 
   @override
   String get zulipAppTitle => 'Zulip';
+
+  @override
+  String bannerText(int guestCount, String guestNamesList) {
+    String _temp0 = intl.Intl.pluralLogic(
+      guestCount,
+      locale: localeName,
+      other: '$guestNamesList are guests in this organization.',
+      one: '$guestNamesList is a guest in this organization.',
+    );
+    return '$_temp0';
+  }
 }

lib/generated/l10n/zulip_localizations_pl.dart

@@ -648,4 +648,15 @@ class ZulipLocalizationsPl extends ZulipLocalizations {
 
   @override
   String get zulipAppTitle => 'Zulip';
+
+  @override
+  String bannerText(int guestCount, String guestNamesList) {
+    String _temp0 = intl.Intl.pluralLogic(
+      guestCount,
+      locale: localeName,
+      other: '$guestNamesList are guests in this organization.',
+      one: '$guestNamesList is a guest in this organization.',
+    );
+    return '$_temp0';
+  }
 }

lib/generated/l10n/zulip_localizations_ru.dart

@@ -648,4 +648,15 @@ class ZulipLocalizationsRu extends ZulipLocalizations {
 
   @override
   String get zulipAppTitle => 'Zulip';
+
+  @override
+  String bannerText(int guestCount, String guestNamesList) {
+    String _temp0 = intl.Intl.pluralLogic(
+      guestCount,
+      locale: localeName,
+      other: '$guestNamesList are guests in this organization.',
+      one: '$guestNamesList is a guest in this organization.',
+    );
+    return '$_temp0';
+  }
 }

lib/generated/l10n/zulip_localizations_sk.dart

@@ -648,4 +648,15 @@ class ZulipLocalizationsSk extends ZulipLocalizations {
 
   @override
   String get zulipAppTitle => 'Zulip';
+
+  @override
+  String bannerText(int guestCount, String guestNamesList) {
+    String _temp0 = intl.Intl.pluralLogic(
+      guestCount,
+      locale: localeName,
+      other: '$guestNamesList are guests in this organization.',
+      one: '$guestNamesList is a guest in this organization.',
+    );
+    return '$_temp0';
+  }
 }

lib/model/store.dart

@@ -335,6 +335,7 @@ class PerAccountStore extends ChangeNotifier with EmojiStore, ChannelStore, Mess
       recentDmConversationsView: RecentDmConversationsView(
         initial: initialSnapshot.recentPrivateConversations, selfUserId: account.userId),
       recentSenders: RecentSenders(),
+      realmEnableGuestUserDmWarning: initialSnapshot.realmEnableGuestUserDmWarning,
     );
   }
 
@@ -361,6 +362,7 @@ class PerAccountStore extends ChangeNotifier with EmojiStore, ChannelStore, Mess
     required this.unreads,
     required this.recentDmConversationsView,
     required this.recentSenders,
+    required this.realmEnableGuestUserDmWarning,
   }) : assert(selfUserId == globalStore.getAccount(accountId)!.userId),
        assert(realmUrl == globalStore.getAccount(accountId)!.realmUrl),
        assert(realmUrl == connection.realmUrl),
@@ -567,6 +569,8 @@ class PerAccountStore extends ChangeNotifier with EmojiStore, ChannelStore, Mess
 
   final AutocompleteViewManager autocompleteViewManager = AutocompleteViewManager();
 
+  final bool? realmEnableGuestUserDmWarning;
+
   // End of data.
   ////////////////////////////////////////////////////////////////
 

lib/widgets/message_list.dart

@@ -183,6 +183,8 @@ abstract class MessageListPageState {
   ///
   /// This is null if [MessageList] has not mounted yet.
   MessageListView? get model;
+
+  bool showDMWarningBanner = true;
 }
 
 class MessageListPage extends StatefulWidget {
@@ -224,10 +226,14 @@ class _MessageListPageState extends State<MessageListPage> implements MessageLis
   MessageListView? get model => _messageListKey.currentState?.model;
   final GlobalKey<_MessageListState> _messageListKey = GlobalKey();
 
+  @override
+  late bool showDMWarningBanner;
+
   @override
   void initState() {
     super.initState();
     narrow = widget.initNarrow;
+    showDMWarningBanner = narrow is DmNarrow;
   }
 
   void _narrowChanged(Narrow newNarrow) {
@@ -241,6 +247,7 @@ class _MessageListPageState extends State<MessageListPage> implements MessageLis
     final store = PerAccountStoreWidget.of(context);
     final messageListTheme = MessageListTheme.of(context);
     final zulipLocalizations = ZulipLocalizations.of(context);
+    final designVariables= DesignVariables.of(context);
 
     final Color? appBarBackgroundColor;
     bool removeAppBarBottomBorder = false;
@@ -318,10 +325,72 @@ class _MessageListPageState extends State<MessageListPage> implements MessageLis
                   narrow: narrow,
                   onNarrowChanged: _narrowChanged,
                 ))),
+            if(shouldShowGuestUserWarningPrompt(store))
+              showGuestUserWarningPrompt(narrow as DmNarrow, store, designVariables, zulipLocalizations),
             if (ComposeBox.hasComposeBox(narrow))
               ComposeBox(key: _composeBoxKey, narrow: narrow)
           ]))));
   }
+
+  bool shouldShowGuestUserWarningPrompt(PerAccountStore store) =>
+  store.connection.zulipFeatureLevel! >= 348 &&
+   narrow is DmNarrow && (store.realmEnableGuestUserDmWarning ?? false);
+
+  Widget showGuestUserWarningPrompt(
+    DmNarrow narrow,
+    PerAccountStore store,
+    DesignVariables designVariables,
+    ZulipLocalizations zulipLocalizations,
+  ) {
+    final recipients = narrow.otherRecipientIds;
+    final allUsersInStore = Map<int, User>.from(store.users);
+    allUsersInStore.removeWhere((userId, user) => !recipients.contains(userId));
+    final guestNames =
+        allUsersInStore.values
+            .where((user) => user.role == UserRole.guest)
+            .map((e) => e.fullName)
+            .toList();
+
+    if(guestNames.isEmpty){
+      return SizedBox();
+    }
+
+    return Visibility(
+      visible: showDMWarningBanner,
+      child: Align(
+        alignment: Alignment.centerLeft,
+        child: Container(
+          width: MediaQuery.of(context).size.width,
+          decoration: BoxDecoration(
+            borderRadius: BorderRadius.circular(4),
+            border: Border.all(color: designVariables.dmUserWarningBannerBorder,),
+            color: designVariables.dmUserWarningBanner,
+          ),
+          margin: EdgeInsets.all(4),
+          padding: EdgeInsets.symmetric(horizontal: 10, vertical: 8),
+          child: Row(
+            mainAxisAlignment: MainAxisAlignment.spaceBetween,
+            children: [
+              Flexible(
+                child: Text(
+                  zulipLocalizations.bannerText(guestNames.length, guestNames.join(', ')),
+                  style: TextStyle(color: Colors.white),
+                ),
+              ),
+              GestureDetector(
+                onTap: () {
+                 setState(() {
+                   showDMWarningBanner= false;
+                 });
+                },
+                child: Icon(Icons.close, color: Colors.white),
+              ),
+            ],
+          ),
+        ),
+      ),
+    );
+  }
 }
 
 class MessageListAppBarTitle extends StatelessWidget {

lib/widgets/theme.dart

@@ -167,6 +167,8 @@ class DesignVariables extends ThemeExtension<DesignVariables> {
     subscriptionListHeaderLine: const HSLColor.fromAHSL(0.2, 240, 0.1, 0.5).toColor(),
     subscriptionListHeaderText: const HSLColor.fromAHSL(1.0, 240, 0.1, 0.5).toColor(),
     unreadCountBadgeTextForChannel: Colors.black.withValues(alpha: 0.9),
+    dmUserWarningBanner: Color.fromARGB(255, 133, 118, 71),
+    dmUserWarningBannerBorder: Color.fromARGB(255, 127, 111, 60),
   );
 
   static final dark = DesignVariables._(
@@ -224,6 +226,8 @@ class DesignVariables extends ThemeExtension<DesignVariables> {
     // TODO(design-dark) need proper dark-theme color (this is ad hoc)
     subscriptionListHeaderText: const HSLColor.fromAHSL(1.0, 240, 0.1, 0.75).toColor(),
     unreadCountBadgeTextForChannel: Colors.white.withValues(alpha: 0.9),
+    dmUserWarningBanner: Color.fromARGB(255, 133, 118, 71),
+    dmUserWarningBannerBorder: Color.fromARGB(255, 127, 111, 60),
   );
 
   DesignVariables._({
@@ -273,6 +277,8 @@ class DesignVariables extends ThemeExtension<DesignVariables> {
     required this.subscriptionListHeaderLine,
     required this.subscriptionListHeaderText,
     required this.unreadCountBadgeTextForChannel,
+    required this.dmUserWarningBanner,
+    required this.dmUserWarningBannerBorder,
   });
 
   /// The [DesignVariables] from the context's active theme.
@@ -335,6 +341,8 @@ class DesignVariables extends ThemeExtension<DesignVariables> {
   final Color subscriptionListHeaderLine;
   final Color subscriptionListHeaderText;
   final Color unreadCountBadgeTextForChannel;
+  final Color dmUserWarningBanner;
+  final Color dmUserWarningBannerBorder;
 
   @override
   DesignVariables copyWith({
@@ -384,6 +392,8 @@ class DesignVariables extends ThemeExtension<DesignVariables> {
     Color? subscriptionListHeaderLine,
     Color? subscriptionListHeaderText,
     Color? unreadCountBadgeTextForChannel,
+    Color? dmUserWarningBanner,
+    Color? dmUserWarningBannerBorder,
   }) {
     return DesignVariables._(
       background: background ?? this.background,
@@ -432,6 +442,8 @@ class DesignVariables extends ThemeExtension<DesignVariables> {
       subscriptionListHeaderLine: subscriptionListHeaderLine ?? this.subscriptionListHeaderLine,
       subscriptionListHeaderText: subscriptionListHeaderText ?? this.subscriptionListHeaderText,
       unreadCountBadgeTextForChannel: unreadCountBadgeTextForChannel ?? this.unreadCountBadgeTextForChannel,
+      dmUserWarningBanner: dmUserWarningBanner ?? this.dmUserWarningBanner,
+      dmUserWarningBannerBorder: dmUserWarningBannerBorder ?? this.dmUserWarningBannerBorder,
     );
   }
 
@@ -487,6 +499,8 @@ class DesignVariables extends ThemeExtension<DesignVariables> {
       subscriptionListHeaderLine: Color.lerp(subscriptionListHeaderLine, other.subscriptionListHeaderLine, t)!,
       subscriptionListHeaderText: Color.lerp(subscriptionListHeaderText, other.subscriptionListHeaderText, t)!,
       unreadCountBadgeTextForChannel: Color.lerp(unreadCountBadgeTextForChannel, other.unreadCountBadgeTextForChannel, t)!,
+      dmUserWarningBanner: Color.lerp(dmUserWarningBanner, other.dmUserWarningBanner, t)!,
+      dmUserWarningBannerBorder: Color.lerp(dmUserWarningBannerBorder, other.dmUserWarningBannerBorder, t)!,
     );
   }
 }