channel_list: Setup "All channels" page

Fixes parts of zulip#188

Author: Khader-1

Diff for: assets/l10n/app_en.arb

@@ -363,6 +363,13 @@
       "num": {"type": "int", "example": "4"}
     }
   },
+  "browseMoreNChannels": "Browse {num, plural, =0{all channels} =1{1 more channel} other{{num} more channels}}",
+  "@browseMoreNChannels": {
+    "description": "Label showing the number of other channels that user can subscribe to",
+    "placeholders": {
+      "num": {"type": "int", "example": "4"}
+    }
+  },
   "errorInvalidResponse": "The server sent an invalid response",
   "@errorInvalidResponse": {
     "description": "Error message when an API call returned an invalid response."
@@ -480,6 +487,10 @@
   "@mentionsPageTitle": {
     "description": "Title for the page of @-mentions."
   },
+  "channelListPageTitle": "All channels",
+  "@channelListPageTitle": {
+    "description": "Title for the page of all channels."
+  },
   "notifGroupDmConversationLabel": "{senderFullName} to you and {numOthers, plural, =1{1 other} other{{numOthers} others}}",
   "@notifGroupDmConversationLabel": {
     "description": "Label for a group DM conversation notification.",

Diff for: lib/widgets/channel_list.dart

@@ -0,0 +1,74 @@
+import 'package:flutter/material.dart';
+import 'package:flutter_gen/gen_l10n/zulip_localizations.dart';
+
+import '../api/model/model.dart';
+import '../model/narrow.dart';
+import 'icons.dart';
+import 'message_list.dart';
+import 'page.dart';
+import 'store.dart';
+
+class ChannelListPage extends StatelessWidget {
+  const ChannelListPage({super.key});
+
+  static Route<void> buildRoute({int? accountId, BuildContext? context}) {
+    return MaterialAccountWidgetRoute(accountId: accountId, context: context,
+      page: const ChannelListPage());
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    final store = PerAccountStoreWidget.of(context);
+    final zulipLocalizations = ZulipLocalizations.of(context);
+    final streams = store.streams.values.toList();
+    return Scaffold(
+      appBar: AppBar(title: Text(zulipLocalizations.channelListPageTitle)),
+      body: SafeArea(
+        child: ListView.builder(
+          itemCount: streams.length,
+          itemBuilder: (context, index) => ChannelItem(stream: streams[index]))));
+  }
+}
+
+@visibleForTesting
+class ChannelItem extends StatelessWidget {
+  const ChannelItem({super.key, required this.stream});
+
+  final ZulipStream stream;
+
+  @override
+  Widget build(BuildContext context) {
+    return Material(
+      color: Colors.white,
+      child: InkWell(
+        onTap: () => Navigator.push(context, MessageListPage.buildRoute(context: context,
+          narrow: ChannelNarrow(stream.streamId))),
+        child: Padding(
+          padding: const EdgeInsets.symmetric(vertical: 8, horizontal: 16),
+          child: Row(children: [
+            Icon(size: 16, iconDataForStream(stream)),
+            const SizedBox(width: 8),
+            Expanded(child: Column(
+              crossAxisAlignment: CrossAxisAlignment.start,
+              mainAxisAlignment: MainAxisAlignment.spaceBetween,
+              children: [
+                Text(stream.name,
+                style: const TextStyle(
+                  fontSize: 18,
+                  height: (20 / 18),
+                  // TODO(#95) need dark-theme color
+                  color: Color(0xFF262626)),
+                maxLines: 1,
+                overflow: TextOverflow.ellipsis),
+                if (stream.description.isNotEmpty) Text(
+                  stream.description,
+                  style: const TextStyle(
+                    fontSize: 12,
+                    // TODO(#95) need dark-theme color
+                    color: Color(0xCC262626)),
+                  maxLines: 1,
+                  overflow: TextOverflow.ellipsis),
+              ])),
+            ]))));
+  }
+}

Diff for: lib/widgets/subscription_list.dart

@@ -1,4 +1,5 @@
 import 'package:flutter/material.dart';
+import 'package:flutter_gen/gen_l10n/zulip_localizations.dart';
 
 import '../api/model/model.dart';
 import '../model/narrow.dart';
@@ -8,6 +9,7 @@ import 'icons.dart';
 import 'message_list.dart';
 import 'page.dart';
 import 'store.dart';
+import 'channel_list.dart';
 import 'text.dart';
 import 'theme.dart';
 import 'unread_count_badge.dart';
@@ -107,7 +109,7 @@ class _SubscriptionListPageState extends State<SubscriptionListPage> with PerAcc
               _SubscriptionList(unreadsModel: unreadsModel, subscriptions: unpinned),
             ],
 
-            // TODO(#188): add button leading to "All Streams" page with ability to subscribe
+            if (store.streams.isNotEmpty) const _ChannelListLinkItem(),
 
             // This ensures last item in scrollable can settle in an unobstructed area.
             const SliverSafeArea(sliver: SliverToBoxAdapter(child: SizedBox.shrink())),
@@ -199,6 +201,41 @@ class _SubscriptionList extends StatelessWidget {
   }
 }
 
+class _ChannelListLinkItem extends StatelessWidget {
+  const _ChannelListLinkItem();
+
+  @override
+  Widget build(BuildContext context) {
+    final store = PerAccountStoreWidget.of(context);
+    final notShownStreams = store.streams.length - store.subscriptions.length;
+    final zulipLocalizations = ZulipLocalizations.of(context);
+
+    return SliverToBoxAdapter(
+      child: Material(
+        // TODO(#95) need dark-theme color
+        color: Colors.white,
+        child: InkWell(
+          onTap: () => Navigator.push(context,
+            ChannelListPage.buildRoute(context: context)),
+          child: Padding(
+            padding: const EdgeInsets.symmetric(vertical: 10, horizontal: 16),
+            child: Row(
+              crossAxisAlignment: CrossAxisAlignment.center,
+              mainAxisAlignment: MainAxisAlignment.spaceBetween,
+              children: [
+                Text(
+                  style: const TextStyle(
+                    fontSize: 18,
+                    height: (20 / 18),
+                    // TODO(#95) need dark-theme color
+                    color: Color(0xFF262626),
+                  ).merge(weightVariableTextStyle(context, wght: 600)),
+                  zulipLocalizations.browseMoreNChannels(notShownStreams)),
+                const Icon(Icons.arrow_forward_ios, size: 18),
+              ])))));
+  }
+}
+
 @visibleForTesting
 class SubscriptionItem extends StatelessWidget {
   const SubscriptionItem({

Diff for: test/widgets/channel_list_test.dart

@@ -0,0 +1,42 @@
+import 'package:checks/checks.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:zulip/api/model/model.dart';
+import 'package:zulip/widgets/channel_list.dart';
+
+import '../model/binding.dart';
+import '../example_data.dart' as eg;
+import 'test_app.dart';
+
+void main() {
+  TestZulipBinding.ensureInitialized();
+
+  Future<void> setupChannelListPage(WidgetTester tester, {
+    required List<ZulipStream> streams, required List<Subscription> subscriptions}) async {
+    addTearDown(testBinding.reset);
+    final initialSnapshot = eg.initialSnapshot(
+      subscriptions: subscriptions,
+      streams: streams.toList(),
+    );
+    await testBinding.globalStore.add(eg.selfAccount, initialSnapshot);
+
+    await tester.pumpWidget(TestZulipApp(accountId: eg.selfAccount.id, child: const ChannelListPage()));
+
+    // global store, per-account store
+    await tester.pumpAndSettle();
+  }
+
+  int getItemCount() {
+    return find.byType(ChannelItem).evaluate().length;
+  }
+
+  testWidgets('smoke', (tester) async {
+    await setupChannelListPage(tester, streams: [], subscriptions: []);
+    check(getItemCount()).equals(0);
+  });
+
+  testWidgets('basic list', (tester) async {
+    final streams = List.generate(3, (index) => eg.stream());
+    await setupChannelListPage(tester, streams: streams, subscriptions: []);
+    check(getItemCount()).equals(3);
+  });
+}

Diff for: test/widgets/subscription_list_test.dart

@@ -3,6 +3,7 @@ import 'package:flutter/material.dart';
 import 'package:flutter_test/flutter_test.dart';
 import 'package:zulip/api/model/initial_snapshot.dart';
 import 'package:zulip/api/model/model.dart';
+import 'package:zulip/model/localizations.dart';
 import 'package:zulip/widgets/icons.dart';
 import 'package:zulip/widgets/channel_colors.dart';
 import 'package:zulip/widgets/subscription_list.dart';
@@ -21,11 +22,12 @@ void main() {
     required List<Subscription> subscriptions,
     List<UserTopicItem> userTopics = const [],
     UnreadMessagesSnapshot? unreadMsgs,
+    List<ZulipStream>? streams,
   }) async {
     addTearDown(testBinding.reset);
     final initialSnapshot = eg.initialSnapshot(
       subscriptions: subscriptions,
-      streams: subscriptions,
+      streams: streams ?? subscriptions,
       userTopics: userTopics,
       unreadMsgs: unreadMsgs,
     );
@@ -57,6 +59,23 @@ void main() {
     check(isUnpinnedHeaderInTree()).isFalse();
   });
 
+  testWidgets('link to other channels is shown', (tester) async {
+    final zulipLocalizations = GlobalLocalizations.zulipLocalizations;
+    final streams = List.generate(5, (index) => eg.stream());
+    await setupStreamListPage(tester,
+      streams: streams,
+      subscriptions: [eg.subscription(streams[1])]);
+
+    check(find.text(zulipLocalizations.browseMoreNChannels(4)).evaluate()).isNotEmpty();
+  });
+
+  testWidgets('link to other channels is not shown if server has no visible channels', (tester) async {
+    final zulipLocalizations = GlobalLocalizations.zulipLocalizations;
+    await setupStreamListPage(tester, streams: [], subscriptions: []);
+
+    check(find.text(zulipLocalizations.browseMoreNChannels(0)).evaluate()).isEmpty();
+  });
+
   testWidgets('basic subscriptions', (tester) async {
     await setupStreamListPage(tester, subscriptions: [
       eg.subscription(eg.stream(streamId: 1), pinToTop: true),