✨ Chat listing

lib/providers/channel.dart

@@ -0,0 +1,80 @@
+import 'package:flutter/material.dart';
+import 'package:hive_flutter/hive_flutter.dart';
+import 'package:provider/provider.dart';
+import 'package:surface/providers/sn_network.dart';
+import 'package:surface/types/chat.dart';
+import 'package:surface/types/realm.dart';
+
+class ChatChannelProvider extends ChangeNotifier {
+  static const kChatChannelBoxName = 'nex_chat_channels';
+
+  late final SnNetworkProvider _sn;
+
+  Box<SnChannel>? get _channelBox => Hive.box<SnChannel>(kChatChannelBoxName);
+
+  ChatChannelProvider(BuildContext context) {
+    _sn = context.read<SnNetworkProvider>();
+    _initializeLocalData();
+  }
+
+  Future<void> _initializeLocalData() async {
+    await Hive.openBox<SnChannel>(kChatChannelBoxName);
+  }
+
+  Future<void> _saveChannelToLocal(Iterable<SnChannel> channels) async {
+    if (_channelBox == null) return;
+    await _channelBox!.putAll({
+      for (final channel in channels) channel.key: channel,
+    });
+  }
+
+  Future<List<SnChannel>> _fetchChannelsFromServer(
+      {scope = 'global', direct = false}) async {
+    final resp = await _sn.client.get(
+      '/cgi/im/channels/$scope/me/available',
+      queryParameters: {
+        'direct': direct,
+      },
+    );
+    final out = List<SnChannel>.from(
+      resp.data?.map((e) => SnChannel.fromJson(e)) ?? [],
+    );
+    _saveChannelToLocal(out);
+    return out;
+  }
+
+  // The fetch channel method return a stream, which will emit twice.
+  // The first time is when the data was fetched from the local storage.
+  // And the second time is when the data was fetched from the server.
+  // But there is some exception that will only cause one of them to be emitted.
+  // Like the local storage is broken or the server is down.
+  Stream<List<SnChannel>> fetchChannels() async* {
+    if (_channelBox != null) yield _channelBox!.values.toList();
+
+    var resp = await _sn.client.get('/cgi/id/realms/me/available');
+    final realms = List<SnRealm>.from(
+      resp.data?.map((e) => SnRealm.fromJson(e)) ?? [],
+    );
+
+    final scopeToFetch = {'global', ...realms.map((e) => e.alias)};
+
+    final List<SnChannel> result = List.empty(growable: true);
+    final dm =
+        await _fetchChannelsFromServer(scope: scopeToFetch.first, direct: true);
+    result.addAll(dm);
+
+    for (final scope in scopeToFetch) {
+      final channel =
+          await _fetchChannelsFromServer(scope: scope, direct: false);
+      result.addAll(channel);
+    }
+
+    yield result;
+  }
+
+  @override
+  void dispose() {
+    _channelBox?.close();
+    super.dispose();
+  }
+}