user [nfc]: Move proxy boilerplate out to substore file

Author: gnprice

lib/model/store.dart

@@ -441,7 +441,7 @@ class PerAccountStore extends PerAccountStoreBase with
     RealmStore, ProxyRealmStore,
     EmojiStore, ProxyEmojiStore,
     SavedSnippetStore,
-    UserStore,
+    UserStore, ProxyUserStore,
     ChannelStore,
     MessageStore {
   /// Construct a store for the user's data, starting from the given snapshot.
@@ -595,23 +595,9 @@ class PerAccountStore extends PerAccountStoreBase with
   //|//////////////////////////////
   // Users and data about them.
 
+  @protected
   @override
-  User? getUser(int userId) => _users.getUser(userId);
-
-  @override
-  Iterable<User> get allUsers => _users.allUsers;
-
-  @override
-  bool isUserMuted(int userId, {MutedUsersEvent? event}) =>
-    _users.isUserMuted(userId, event: event);
-
-  @override
-  MutedUsersVisibilityEffect mightChangeShouldMuteDmConversation(MutedUsersEvent event) =>
-    _users.mightChangeShouldMuteDmConversation(event);
-
-  @override
-  UserStatus getUserStatus(int userId) => _users.getUserStatus(userId);
-
+  UserStore get userStore => _users;
   final UserStoreImpl _users;
 
   final TypingStatus typingStatus;

lib/model/user.dart

@@ -1,3 +1,5 @@
+import 'package:flutter/foundation.dart';
+
 import '../api/model/events.dart';
 import '../api/model/initial_snapshot.dart';
 import '../api/model/model.dart';
@@ -179,6 +181,28 @@ enum MutedUsersVisibilityEffect {
   mixed;
 }
 
+mixin ProxyUserStore on UserStore {
+  @protected
+  UserStore get userStore;
+
+  @override
+  User? getUser(int userId) => userStore.getUser(userId);
+
+  @override
+  Iterable<User> get allUsers => userStore.allUsers;
+
+  @override
+  bool isUserMuted(int userId, {MutedUsersEvent? event}) =>
+    userStore.isUserMuted(userId, event: event);
+
+  @override
+  MutedUsersVisibilityEffect mightChangeShouldMuteDmConversation(MutedUsersEvent event) =>
+    userStore.mightChangeShouldMuteDmConversation(event);
+
+  @override
+  UserStatus getUserStatus(int userId) => userStore.getUserStatus(userId);
+}
+
 /// The implementation of [UserStore] that does the work.
 ///
 /// Generally the only code that should need this class is [PerAccountStore]