✨ Basic message sending and listing

lib/providers/channel.dart

@@ -28,8 +28,11 @@ class ChatChannelProvider extends ChangeNotifier {
     });
   }
 
-  Future<List<SnChannel>> _fetchChannelsFromServer(
-      {scope = 'global', direct = false}) async {
+  Future<List<SnChannel>> _fetchChannelsFromServer({
+    String scope = 'global',
+    bool direct = false,
+    bool doNotSave = false,
+  }) async {
     final resp = await _sn.client.get(
       '/cgi/im/channels/$scope/me/available',
       queryParameters: {
@@ -39,15 +42,37 @@ class ChatChannelProvider extends ChangeNotifier {
     final out = List<SnChannel>.from(
       resp.data?.map((e) => SnChannel.fromJson(e)) ?? [],
     );
-    _saveChannelToLocal(out);
+    if (!doNotSave) _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.
+  /// The get channel method will return the channel with the given alias.
+  /// It will use the local storage as much as possible.
+  /// The alias should include the scope, formatted as `scope:alias`.
+  Future<SnChannel> getChannel(String key) async {
+    if (_channelBox != null) {
+      final local = _channelBox!.get(key);
+      if (local != null) return local;
+    }
+
+    var resp = await _sn.client.get('/cgi/im/channels/$key');
+    var out = SnChannel.fromJson(resp.data);
+
+    // Preload realm of the channel
+    if (out.realmId != null) {
+      resp = await _sn.client.get('/cgi/id/realms/${out.realmId}');
+      out = out.copyWith(realm: SnRealm.fromJson(resp.data));
+    }
+
+    _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();
 
@@ -55,18 +80,34 @@ class ChatChannelProvider extends ChangeNotifier {
     final realms = List<SnRealm>.from(
       resp.data?.map((e) => SnRealm.fromJson(e)) ?? [],
     );
+    final realmMap = {
+      for (final realm in realms) realm.alias: realm,
+    };
 
     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);
+    final directMessages = await _fetchChannelsFromServer(
+      scope: scopeToFetch.first,
+      direct: true,
+    );
+    result.addAll(directMessages);
 
-    for (final scope in scopeToFetch) {
-      final channel =
-          await _fetchChannelsFromServer(scope: scope, direct: false);
-      result.addAll(channel);
+    final nonBelongsChannels = await _fetchChannelsFromServer(
+      scope: scopeToFetch.first,
+      direct: false,
+    );
+    result.addAll(nonBelongsChannels);
+
+    for (final scope in scopeToFetch.skip(1)) {
+      final channel = await _fetchChannelsFromServer(
+        scope: scope,
+        direct: false,
+        doNotSave: true,
+      );
+      final out = channel.map((ele) => ele.copyWith(realm: realmMap[scope]));
+      _saveChannelToLocal(out);
+      result.addAll(out);
     }
 
     yield result;

lib/providers/user_directory.dart

@@ -0,0 +1,50 @@
+import 'package:flutter/material.dart';
+import 'package:provider/provider.dart';
+import 'package:surface/providers/sn_network.dart';
+import 'package:surface/types/account.dart';
+
+class UserDirectoryProvider {
+  late final SnNetworkProvider _sn;
+
+  UserDirectoryProvider(BuildContext context) {
+    _sn = context.read<SnNetworkProvider>();
+  }
+
+  final Map<String, int> _idCache = {};
+  final Map<int, SnAccount> _cache = {};
+
+  Future<List<SnAccount?>> listAccount(Iterable<dynamic> id) async {
+    final out = await Future.wait(
+      id.map((e) => getAccount(e)),
+    );
+    return out;
+  }
+
+  Future<SnAccount?> getAccount(dynamic id) async {
+    if (id is String && _idCache.containsKey(id)) {
+      id = _idCache[id];
+    }
+    if (_cache.containsKey(id)) {
+      return _cache[id];
+    }
+
+    try {
+      final resp = await _sn.client.get('/cgi/id/users/$id');
+      final account = SnAccount.fromJson(
+        resp.data as Map<String, dynamic>,
+      );
+      _cache[account.id] = account;
+      if (id is String) _idCache[id] = account.id;
+      return account;
+    } catch (err) {
+      return null;
+    }
+  }
+
+  SnAccount? getAccountFromCache(dynamic id) {
+    if (id is String && _idCache.containsKey(id)) {
+      id = _idCache[id];
+    }
+    return _cache[id];
+  }
+}