compose_box: Replace compose box with a banner when cannot post in a channel

assets/l10n/app_en.arb

@@ -188,6 +188,10 @@
   "@errorBannerDeactivatedDmLabel": {
     "description": "Label text for error banner when sending a message to one or multiple deactivated users."
   },
+  "errorBannerCannotPostInChannelLabel": "You do not have permission to post in this channel.",
+  "@errorBannerCannotPostInChannelLabel": {
+    "description": "Error-banner text replacing the compose box when you do not have permission to send a message to the channel."
+  },
   "composeBoxAttachFilesTooltip": "Attach files",
   "@composeBoxAttachFilesTooltip": {
     "description": "Tooltip for compose box icon to attach a file to the message."

lib/api/model/initial_snapshot.dart

@@ -64,6 +64,14 @@ class InitialSnapshot {
 
   final List<UserTopicItem>? userTopics; // TODO(server-6)
 
+  /// The number of days until a user's account is treated as a full member.
+  ///
+  /// Search for "realm_waiting_period_threshold" in https://zulip.com/api/register-queue.
+  ///
+  /// For how to determine if a user is a full member, see:
+  ///   https://zulip.com/api/roles-and-permissions#determining-if-a-user-is-a-full-member
+  final int realmWaitingPeriodThreshold;
+
   final Map<String, RealmDefaultExternalAccount> realmDefaultExternalAccounts;
 
   final int maxFileUploadSizeMib;
@@ -115,6 +123,7 @@ class InitialSnapshot {
     required this.streams,
     required this.userSettings,
     required this.userTopics,
+    required this.realmWaitingPeriodThreshold,
     required this.realmDefaultExternalAccounts,
     required this.maxFileUploadSizeMib,
     required this.realmUsers,

lib/api/model/model.dart

@@ -263,6 +263,18 @@ class User {
   factory User.fromJson(Map<String, dynamic> json) => _$UserFromJson(json);
 
   Map<String, dynamic> toJson() => _$UserToJson(this);
+
+  /// Whether the user has passed the realm's waiting period to be a full member.
+  ///
+  /// See:
+  ///   https://zulip.com/api/roles-and-permissions#determining-if-a-user-is-a-full-member
+  ///
+  /// To determine if a user is a full member, callers must also check that the
+  /// user's role is at least Role.Member.
+  bool hasPassedWaitingPeriod(DateTime byDate, int realmWaitingPeriodThreshold) {
+    final dateJoined = DateTime.parse(this.dateJoined);
+    return byDate.difference(dateJoined).inDays >= realmWaitingPeriodThreshold;
+  }
 }
 
 /// As in [User.profileData].
@@ -303,6 +315,11 @@ enum UserRole{
   final int? apiValue;
 
   int? toJson() => apiValue;
+
+  bool isAtLeast(UserRole threshold) {
+    // Roles with more privilege have lower [apiValue].
+    return (apiValue ?? 0) <= (threshold.apiValue ?? 0);
+  }
 }
 
 /// As in `streams` in the initial snapshot.
@@ -370,6 +387,19 @@ class ZulipStream {
     _$ZulipStreamFromJson(json);
 
   Map<String, dynamic> toJson() => _$ZulipStreamToJson(this);
+
+  bool hasPostingPermission(User user, {required DateTime byDate, required int realmWaitingPeriodThreshold}) {
+    final role = user.role;
+    return switch (channelPostPolicy) {
+      ChannelPostPolicy.any            => true,
+      ChannelPostPolicy.fullMembers    => role.isAtLeast(UserRole.member) && (role == UserRole.member
+                                            ? user.hasPassedWaitingPeriod(byDate, realmWaitingPeriodThreshold)
+                                            : true),
+      ChannelPostPolicy.moderators     => role.isAtLeast(UserRole.moderator),
+      ChannelPostPolicy.administrators => role.isAtLeast(UserRole.administrator),
+      ChannelPostPolicy.unknown        => true,
+    };
+  }
 }
 
 /// The name of a property of [ZulipStream] that gets updated

lib/model/store.dart

@@ -235,6 +235,7 @@ class PerAccountStore extends ChangeNotifier with EmojiStore, ChannelStore, Mess
       connection: connection,
       realmUrl: realmUrl,
       maxFileUploadSizeMib: initialSnapshot.maxFileUploadSizeMib,
+      realmWaitingPeriodThreshold: initialSnapshot.realmWaitingPeriodThreshold,
       realmDefaultExternalAccounts: initialSnapshot.realmDefaultExternalAccounts,
       customProfileFields: _sortCustomProfileFields(initialSnapshot.customProfileFields),
       emailAddressVisibility: initialSnapshot.emailAddressVisibility,
@@ -270,6 +271,7 @@ class PerAccountStore extends ChangeNotifier with EmojiStore, ChannelStore, Mess
     required this.connection,
     required this.realmUrl,
     required this.maxFileUploadSizeMib,
+    required this.realmWaitingPeriodThreshold,
     required this.realmDefaultExternalAccounts,
     required this.customProfileFields,
     required this.emailAddressVisibility,
@@ -324,6 +326,8 @@ class PerAccountStore extends ChangeNotifier with EmojiStore, ChannelStore, Mess
 
   String get zulipVersion => account.zulipVersion;
   final int maxFileUploadSizeMib; // No event for this.
+  /// For docs, please see [InitialSnapshot.realmWaitingPeriodThreshold].
+  final int realmWaitingPeriodThreshold;  // TODO(#668): update this realm setting
   final Map<String, RealmDefaultExternalAccount> realmDefaultExternalAccounts;
   List<CustomProfileField> customProfileFields;
   /// For docs, please see [InitialSnapshot.emailAddressVisibility].

lib/widgets/compose_box.dart

@@ -1071,26 +1071,8 @@ class _FixedDestinationComposeBoxState extends State<_FixedDestinationComposeBox
     super.dispose();
   }
 
-  Widget? _errorBanner(BuildContext context) {
-    if (widget.narrow case DmNarrow(:final otherRecipientIds)) {
-      final store = PerAccountStoreWidget.of(context);
-      final hasDeactivatedUser = otherRecipientIds.any((id) =>
-        !(store.users[id]?.isActive ?? true));
-      if (hasDeactivatedUser) {
-        return _ErrorBanner(label: ZulipLocalizations.of(context)
-          .errorBannerDeactivatedDmLabel);
-      }
-    }
-    return null;
-  }
-
   @override
   Widget build(BuildContext context) {
-    final errorBanner = _errorBanner(context);
-    if (errorBanner != null) {
-      return _ComposeBoxContainer(child: errorBanner);
-    }
-
     return _ComposeBoxLayout(
       contentController: _contentController,
       contentFocusNode: _contentFocusNode,
@@ -1128,8 +1110,37 @@ class ComposeBox extends StatelessWidget {
     }
   }
 
+  Widget? _errorBanner(BuildContext context) {
+    final store = PerAccountStoreWidget.of(context);
+    final selfUser = store.users[store.selfUserId]!;
+    switch (narrow) {
+      case ChannelNarrow narrow:
+        final channel = store.streams[narrow.streamId]!;
+        return channel.hasPostingPermission(selfUser, byDate: DateTime.now(), realmWaitingPeriodThreshold: store.realmWaitingPeriodThreshold)
+          ? null : _ErrorBanner(label: ZulipLocalizations.of(context).errorBannerCannotPostInChannelLabel);
+      case TopicNarrow narrow:
+        final channel = store.streams[narrow.streamId]!;
+        return channel.hasPostingPermission(selfUser, byDate: DateTime.now(), realmWaitingPeriodThreshold: store.realmWaitingPeriodThreshold)
+          ? null : _ErrorBanner(label: ZulipLocalizations.of(context).errorBannerCannotPostInChannelLabel);
+      case DmNarrow(:final otherRecipientIds):
+        final hasDeactivatedUser = otherRecipientIds.any((id) =>
+          !(store.users[id]?.isActive ?? true));
+        return hasDeactivatedUser ? _ErrorBanner(label: ZulipLocalizations.of(context)
+          .errorBannerDeactivatedDmLabel) : null;
+      case CombinedFeedNarrow():
+      case MentionsNarrow():
+      case StarredMessagesNarrow():
+        return null;
+    }
+  }
+
   @override
   Widget build(BuildContext context) {
+    final errorBanner = _errorBanner(context);
+    if (errorBanner != null) {
+      return _ComposeBoxContainer(child: errorBanner);
+    }
+
     final narrow = this.narrow;
     switch (narrow) {
       case ChannelNarrow():

test/example_data.dart

@@ -109,8 +109,10 @@ User user({
   String? deliveryEmail,
   String? email,
   String? fullName,
+  String? dateJoined,
   bool? isActive,
   bool? isBot,
+  UserRole? role,
   String? avatarUrl,
   Map<int, ProfileFieldUserData>? profileData,
 }) {
@@ -121,13 +123,13 @@ User user({
     deliveryEmail: effectiveDeliveryEmail,
     email: email ?? effectiveDeliveryEmail,
     fullName: fullName ?? 'A user', // TODO generate example names
-    dateJoined: '2023-04-28',
+    dateJoined: dateJoined ?? '2023-04-28',
     isActive: isActive ?? true,
     isBillingAdmin: false,
     isBot: isBot ?? false,
     botType: null,
     botOwnerId: null,
-    role: UserRole.member,
+    role: role ?? UserRole.member,
     timezone: 'UTC',
     avatarUrl: avatarUrl,
     avatarVersion: 0,
@@ -789,6 +791,7 @@ InitialSnapshot initialSnapshot({
   List<ZulipStream>? streams,
   UserSettings? userSettings,
   List<UserTopicItem>? userTopics,
+  int? realmWaitingPeriodThreshold,
   Map<String, RealmDefaultExternalAccount>? realmDefaultExternalAccounts,
   int? maxFileUploadSizeMib,
   List<User>? realmUsers,
@@ -821,6 +824,7 @@ InitialSnapshot initialSnapshot({
       emojiset: Emojiset.google,
     ),
     userTopics: userTopics,
+    realmWaitingPeriodThreshold: realmWaitingPeriodThreshold ?? 0,
     realmDefaultExternalAccounts: realmDefaultExternalAccounts ?? {},
     maxFileUploadSizeMib: maxFileUploadSizeMib ?? 25,
     realmUsers: realmUsers ?? [],

test/widgets/action_sheet_test.dart

@@ -43,7 +43,7 @@ Future<void> setupToMessageActionSheet(WidgetTester tester, {
 
   await testBinding.globalStore.add(eg.selfAccount, eg.initialSnapshot());
   final store = await testBinding.globalStore.perAccount(eg.selfAccount.id);
-  await store.addUser(eg.user(userId: message.senderId));
+  await store.addUsers([eg.selfUser, eg.user(userId: message.senderId)]);
   if (message is StreamMessage) {
     final stream = eg.stream(streamId: message.streamId);
     await store.addStream(stream);

test/widgets/autocomplete_test.dart

@@ -76,10 +76,12 @@ Future<Finder> setupToTopicInput(WidgetTester tester, {
   addTearDown(testBinding.reset);
   await testBinding.globalStore.add(eg.selfAccount, eg.initialSnapshot());
   final store = await testBinding.globalStore.perAccount(eg.selfAccount.id);
+  await store.addUser(eg.selfUser);
   final connection = store.connection as FakeApiConnection;
 
   // prepare message list data
   final stream = eg.stream();
+  await store.addStream(stream);
   final message = eg.streamMessage(stream: stream, sender: eg.selfUser);
   connection.prepare(json: GetMessagesResult(
     anchor: message.id,