compose: Implement guest user DM warning banner

Author: chimnayajith

assets/l10n/app_en.arb

@@ -415,6 +415,21 @@
       "others": {"type": "String", "example": "Alice, Bob"}
     }
   },
+  "guestUserDmWarningOne": "{guestUser} is a guest in this organization.",
+  "@guestUserDmWarningOne": {
+    "description": "Warning shown when composing a DM to one guest user",
+    "placeholders": {
+      "guestUser": {"type": "String", "example": "Alice"}
+    }
+  },
+
+  "guestUserDmWarningMany": "{guestUsers} are guests in this organization.",
+  "@guestUserDmWarningMany": {
+    "description": "Warning shown when composing DMs to multiple guest users",
+    "placeholders": {
+      "guestUsers": {"type": "String", "example": "Alice, Bob, and Charlie"}
+    }
+  },
   "messageListGroupYouWithYourself": "Messages with yourself",
   "@messageListGroupYouWithYourself": {
     "description": "Message list recipient header for a DM group that only includes yourself."

lib/generated/l10n/zulip_localizations.dart

@@ -647,6 +647,18 @@ abstract class ZulipLocalizations {
   /// **'DMs with {others}'**
   String dmsWithOthersPageTitle(String others);
 
+  /// Warning shown when composing a DM to one guest user
+  ///
+  /// In en, this message translates to:
+  /// **'{guestUser} is a guest in this organization.'**
+  String guestUserDmWarningOne(String guestUser);
+
+  /// Warning shown when composing DMs to multiple guest users
+  ///
+  /// In en, this message translates to:
+  /// **'{guestUsers} are guests in this organization.'**
+  String guestUserDmWarningMany(String guestUsers);
+
   /// Message list recipient header for a DM group that only includes yourself.
   ///
   /// In en, this message translates to:

lib/generated/l10n/zulip_localizations_ar.dart

@@ -324,6 +324,16 @@ class ZulipLocalizationsAr extends ZulipLocalizations {
     return 'DMs with $others';
   }
 
+  @override
+  String guestUserDmWarningOne(String guestUser) {
+    return '$guestUser is a guest in this organization.';
+  }
+
+  @override
+  String guestUserDmWarningMany(String guestUsers) {
+    return '$guestUsers are guests in this organization.';
+  }
+
   @override
   String get messageListGroupYouWithYourself => 'Messages with yourself';
 

lib/generated/l10n/zulip_localizations_en.dart

@@ -324,6 +324,16 @@ class ZulipLocalizationsEn extends ZulipLocalizations {
     return 'DMs with $others';
   }
 
+  @override
+  String guestUserDmWarningOne(String guestUser) {
+    return '$guestUser is a guest in this organization.';
+  }
+
+  @override
+  String guestUserDmWarningMany(String guestUsers) {
+    return '$guestUsers are guests in this organization.';
+  }
+
   @override
   String get messageListGroupYouWithYourself => 'Messages with yourself';
 

lib/generated/l10n/zulip_localizations_ja.dart

@@ -324,6 +324,16 @@ class ZulipLocalizationsJa extends ZulipLocalizations {
     return 'DMs with $others';
   }
 
+  @override
+  String guestUserDmWarningOne(String guestUser) {
+    return '$guestUser is a guest in this organization.';
+  }
+
+  @override
+  String guestUserDmWarningMany(String guestUsers) {
+    return '$guestUsers are guests in this organization.';
+  }
+
   @override
   String get messageListGroupYouWithYourself => 'Messages with yourself';
 

lib/generated/l10n/zulip_localizations_nb.dart

@@ -324,6 +324,16 @@ class ZulipLocalizationsNb extends ZulipLocalizations {
     return 'DMs with $others';
   }
 
+  @override
+  String guestUserDmWarningOne(String guestUser) {
+    return '$guestUser is a guest in this organization.';
+  }
+
+  @override
+  String guestUserDmWarningMany(String guestUsers) {
+    return '$guestUsers are guests in this organization.';
+  }
+
   @override
   String get messageListGroupYouWithYourself => 'Messages with yourself';
 

lib/generated/l10n/zulip_localizations_pl.dart

@@ -324,6 +324,16 @@ class ZulipLocalizationsPl extends ZulipLocalizations {
     return 'DM z $others';
   }
 
+  @override
+  String guestUserDmWarningOne(String guestUser) {
+    return '$guestUser is a guest in this organization.';
+  }
+
+  @override
+  String guestUserDmWarningMany(String guestUsers) {
+    return '$guestUsers are guests in this organization.';
+  }
+
   @override
   String get messageListGroupYouWithYourself => 'Zapiski na własne konto';
 

lib/generated/l10n/zulip_localizations_ru.dart

@@ -324,6 +324,16 @@ class ZulipLocalizationsRu extends ZulipLocalizations {
     return 'ЛС с $others';
   }
 
+  @override
+  String guestUserDmWarningOne(String guestUser) {
+    return '$guestUser is a guest in this organization.';
+  }
+
+  @override
+  String guestUserDmWarningMany(String guestUsers) {
+    return '$guestUsers are guests in this organization.';
+  }
+
   @override
   String get messageListGroupYouWithYourself => 'Сообщения с собой';
 

lib/generated/l10n/zulip_localizations_sk.dart

@@ -324,6 +324,16 @@ class ZulipLocalizationsSk extends ZulipLocalizations {
     return 'DMs with $others';
   }
 
+  @override
+  String guestUserDmWarningOne(String guestUser) {
+    return '$guestUser is a guest in this organization.';
+  }
+
+  @override
+  String guestUserDmWarningMany(String guestUsers) {
+    return '$guestUsers are guests in this organization.';
+  }
+
   @override
   String get messageListGroupYouWithYourself => 'Messages with yourself';
 

lib/widgets/compose_box.dart

@@ -1484,6 +1484,42 @@ class _ErrorBanner extends _Banner {
   }
 }
 
+class _WarningBanner extends _Banner {
+  const _WarningBanner({
+    required this.label,
+    required this.onDismiss,
+  });
+
+  final String label;
+  final VoidCallback? onDismiss;
+
+  @override
+  String getLabel(ZulipLocalizations zulipLocalizations) => label;
+
+  @override
+  Color getLabelColor(DesignVariables designVariables) =>
+    designVariables.btnLabelAttMediumIntWarning;
+
+  @override
+  Color getBackgroundColor(DesignVariables designVariables) =>
+    designVariables.bannerBgIntWarning;
+
+  @override
+  bool get padEnd => false;
+
+  @override
+  Widget? buildTrailing(BuildContext context) {
+    final designVariables = DesignVariables.of(context);
+    return InkWell(
+      splashFactory: NoSplash.splashFactory,
+      onTap: onDismiss,
+      child: Padding(
+        padding: const EdgeInsets.all(8.0),
+        child: Icon(ZulipIcons.remove,
+          size: 24, color: designVariables.btnLabelAttLowIntWarning)));
+  }
+}
+
 /// The compose box.
 ///
 /// Takes the full screen width, covering the horizontal insets with its surface.
@@ -1521,6 +1557,8 @@ class _ComposeBoxState extends State<ComposeBox> with PerAccountStoreAwareStateM
   @override ComposeBoxController get controller => _controller!;
   ComposeBoxController? _controller;
 
+  bool _isWarningBannerDismissed = false;
+
   @override
   void onNewStore() {
     switch (widget.narrow) {
@@ -1547,6 +1585,12 @@ class _ComposeBoxState extends State<ComposeBox> with PerAccountStoreAwareStateM
     super.dispose();
   }
 
+  void _dismissWarningBanner() {
+    setState(() {
+      _isWarningBannerDismissed = true;
+    });
+  }
+
   /// An [_ErrorBanner] that replaces the compose box's text inputs.
   Widget? _errorBannerComposingNotAllowed(BuildContext context) {
     final store = PerAccountStoreWidget.of(context);
@@ -1576,11 +1620,62 @@ class _ComposeBoxState extends State<ComposeBox> with PerAccountStoreAwareStateM
     return null;
   }
 
+  /// A [_WarningBanner] that goes at the top of the compose box.
+  Widget? _warningBanner(BuildContext context) {
+    if (_isWarningBannerDismissed) return null;
+
+    final store = PerAccountStoreWidget.of(context);
+    final zulipLocalizations = ZulipLocalizations.of(context);
+
+    if (store.connection.zulipFeatureLevel! < 348 ||
+        !store.realmEnableGuestUserDmWarning) {
+      return null;
+    }
+
+    switch (widget.narrow) {
+      case DmNarrow(:final otherRecipientIds):
+        final guestUsers = otherRecipientIds
+          .map((id) => store.getUser(id))
+          .where((user) => user?.role == UserRole.guest)
+          .toList();
+
+        if (guestUsers.isEmpty) return null;
+
+        final guestNames = guestUsers
+          .map((user) => user != null
+            ? store.userDisplayName(user.userId)
+            : zulipLocalizations.unknownUserName)
+          .toList();
+
+        final String formattedNames;
+        if (guestUsers.length == 1) {
+          formattedNames = guestNames[0];
+        } else {
+          final allButLast =
+            guestNames.sublist(0, guestNames.length - 1).join(', ');
+          formattedNames =
+            "$allButLast${guestUsers.length > 2 ? ',' : ''} and ${guestNames.last}";
+        }
+
+        final bannerText = guestUsers.length == 1
+          ? zulipLocalizations.guestUserDmWarningOne(guestNames.first)
+          : zulipLocalizations.guestUserDmWarningMany(formattedNames);
+
+        return _WarningBanner(label: bannerText,
+          onDismiss: _dismissWarningBanner);
+
+      default:
+        return null;
+    }
+  }
+
   @override
   Widget build(BuildContext context) {
     final Widget? body;
 
     final errorBanner = _errorBannerComposingNotAllowed(context);
+    final warningBanner = _warningBanner(context);
+
     if (errorBanner != null) {
       return _ComposeBoxContainer(body: null, banner: errorBanner);
     }
@@ -1603,6 +1698,6 @@ class _ComposeBoxState extends State<ComposeBox> with PerAccountStoreAwareStateM
     //       errorBanner = _ErrorBanner(label:
     //         ZulipLocalizations.of(context).errorSendMessageTimeout);
     //     }
-    return _ComposeBoxContainer(body: body, banner: null);
+    return _ComposeBoxContainer(body: body, banner: warningBanner);
   }
 }