channel_list: All channels screen

assets/l10n/app_en.arb

@@ -396,6 +396,24 @@
   "@topicValidationErrorMandatoryButEmpty": {
     "description": "Topic validation error when topic is required but was empty."
   },
+  "subscribedToNChannels": "Subscribed to {num, plural, =0{no channels} =1{1 channel} other{{num} channels}}",
+  "@subscribedToNChannels": {
+    "description": "Test page label showing number of channels user is subscribed to.",
+    "placeholders": {
+      "num": {"type": "int", "example": "4"}
+    }
+  },
+  "browseNMoreChannels": "Browse {num, plural, =1{1 more channel} other{{num} more channels}}",
+  "@browseNMoreChannels": {
+    "description": "Label showing the number of other channels that user can subscribe to",
+    "placeholders": {
+      "num": {"type": "int", "example": "4"}
+    }
+  },
+  "browseAllChannels": "Browse all channels",
+  "@browseAllChannels": {
+    "description": "Label for the option to show all channels, this is only shown if user is already subscribed to all visible channels"
+  },
   "errorInvalidResponse": "The server sent an invalid response",
   "@errorInvalidResponse": {
     "description": "Error message when an API call returned an invalid response."
@@ -532,6 +550,14 @@
   "@starredMessagesPageTitle": {
     "description": "Title for the page of starred messages."
   },
+  "channelListPageTitle": "All channels",
+  "@channelListPageTitle": {
+    "description": "Title for the page of all channels."
+  },
+  "noChannelsFound": "There are no channels you can view in this organization.",
+  "@noChannelsFound": {
+    "description": "Message when no channels are found"
+  },
   "notifGroupDmConversationLabel": "{senderFullName} to you and {numOthers, plural, =1{1 other} other{{numOthers} others}}",
   "@notifGroupDmConversationLabel": {
     "description": "Label for a group DM conversation notification.",
@@ -586,5 +612,25 @@
   "errorNotificationOpenAccountMissing": "The account associated with this notification no longer exists.",
   "@errorNotificationOpenAccountMissing": {
     "description": "Error message when the account associated with the notification is not found"
+  },
+  "messageSubscribedToChannel": "You've just subscribed to ",
+  "@messageSubscribedToChannel": {
+    "description": "A message shown to inform user that subscription is successful"
+  },
+  "messageAlreadySubscribedToChannel": "You're already subscribed to ",
+  "@messageAlreadySubscribedToChannel": {
+    "description": "A message shown to inform user that subscription is already made"
+  },
+  "errorFailedToSubscribeToChannel": "Failed to subscribe to ",
+  "@errorFailedToSubscribeToChannel": {
+    "description": "An error message when subscribe action fails"
+  },
+  "messageUnsubscribedFromChannel": "You've unsubscribed from ",
+  "@messageUnsubscribedFromChannel": {
+    "description": "A message shown to inform user that unsubscribe action passes"
+  },
+  "errorFailedToUnsubscribeFromChannel": "Failed to unsubscribe to ",
+  "@errorFailedToUnsubscribeFromChannel": {
+    "description": "An error message when unsubscribe action fails"
   }
 }

lib/api/model/model.dart

@@ -495,6 +495,24 @@ class Subscription extends ZulipStream {
 
   @override
   Map<String, dynamic> toJson() => _$SubscriptionToJson(this);
+
+  /// Returns a plain `ZulipStream` with same values as `this`
+  ///
+  /// This is helpful when unsubscribing from a stream.
+  ZulipStream toStream() => ZulipStream(
+    streamId: streamId,
+    name: name,
+    description: description,
+    renderedDescription: renderedDescription,
+    dateCreated: dateCreated,
+    firstMessageId: firstMessageId,
+    inviteOnly: inviteOnly,
+    isWebPublic: isWebPublic,
+    historyPublicToSubscribers: historyPublicToSubscribers,
+    messageRetentionDays: messageRetentionDays,
+    channelPostPolicy: channelPostPolicy,
+    canRemoveSubscribersGroup: canRemoveSubscribersGroup,
+    streamWeeklyTraffic: streamWeeklyTraffic);
 }
 
 @JsonEnum(fieldRename: FieldRename.snake, valueField: "apiValue")

lib/api/route/channels.dart

@@ -1,6 +1,7 @@
 import 'package:json_annotation/json_annotation.dart';
 
 import '../core.dart';
+import '../model/model.dart';
 part 'channels.g.dart';
 
 /// https://zulip.com/api/get-stream-topics
@@ -38,3 +39,49 @@ class GetStreamTopicsEntry {
 
   Map<String, dynamic> toJson() => _$GetStreamTopicsEntryToJson(this);
 }
+
+/// https://zulip.com/api/subscribe
+Future<SubscribeToChannelsResult> subscribeToChannels(ApiConnection connection, List<ZulipStream> streams) {
+  return connection.post('subscribe', SubscribeToChannelsResult.fromJson,
+    'users/me/subscriptions', {'subscriptions': streams.map((e) => {'name': e.name}).toList()});
+}
+
+@JsonSerializable(fieldRename: FieldRename.snake)
+class SubscribeToChannelsResult {
+  final Map<String, List<String>> subscribed;
+  final Map<String, List<String>> alreadySubscribed;
+  final List<String>? unauthorized;
+
+  SubscribeToChannelsResult({
+    required this.subscribed,
+    required this.alreadySubscribed,
+    this.unauthorized,
+  });
+
+  factory SubscribeToChannelsResult.fromJson(Map<String, dynamic> json) =>
+    _$SubscribeToChannelsResultFromJson(json);
+
+  Map<String, dynamic> toJson() => _$SubscribeToChannelsResultToJson(this);
+}
+
+/// https://zulip.com/api/usubscribe
+Future<UnsubscribeFromChannelsResult> unsubscribeFromChannels(ApiConnection connection, List<ZulipStream> streams) {
+  return connection.delete('unsubscribe', UnsubscribeFromChannelsResult.fromJson,
+    'users/me/subscriptions', {'subscriptions': streams.map((e) => e.name).toList()});
+}
+
+@JsonSerializable(fieldRename: FieldRename.snake)
+class UnsubscribeFromChannelsResult {
+  final List<String> removed;
+  final List<String> notRemoved;
+
+  UnsubscribeFromChannelsResult({
+    required this.removed,
+    required this.notRemoved,
+  });
+
+  factory UnsubscribeFromChannelsResult.fromJson(Map<String, dynamic> json) =>
+    _$UnsubscribeFromChannelsResultFromJson(json);
+
+  Map<String, dynamic> toJson() => _$UnsubscribeFromChannelsResultToJson(this);
+}

lib/model/channel.dart

@@ -304,6 +304,15 @@ class ChannelStoreImpl with ChannelStore {
 
       case SubscriptionRemoveEvent():
         for (final streamId in event.streamIds) {
+          final subscription = streams[streamId];
+          if (subscription == null || subscription is! Subscription) { // TODO(log)
+            continue;
+          }
+          assert(streamsByName[subscription.name] is Subscription);
+          assert(subscriptions.containsKey(streamId));
+          final unsubscribedStream = subscription.toStream();
+          streams[streamId] = unsubscribedStream;
+          streamsByName[subscription.name] = unsubscribedStream;
           subscriptions.remove(streamId);
         }