autocomplete: Add and test MentionAutocompleteView

Co-authored-by: Greg Price <[email protected]>

Author: chrisbobbe

lib/model/autocomplete.dart

@@ -1,4 +1,176 @@
+import 'package:flutter/foundation.dart';
+
+import '../api/model/events.dart';
 import '../api/model/model.dart';
+import 'narrow.dart';
+import 'store.dart';
+
+/// A per-account manager for the view-models of autocomplete interactions.
+///
+/// There should be exactly one of these per PerAccountStore.
+///
+/// Since this manages a cache of user data, the handleRealmUser…Event functions
+/// must be called as appropriate.
+///
+/// On reassemble, call [reassemble].
+class AutocompleteViewManager {
+  final Set<MentionAutocompleteView> _mentionAutocompleteViews = {};
+
+  AutocompleteDataCache autocompleteDataCache = AutocompleteDataCache();
+
+  void registerMentionAutocomplete(MentionAutocompleteView view) {
+    final added = _mentionAutocompleteViews.add(view);
+    assert(added);
+  }
+
+  void unregisterMentionAutocomplete(MentionAutocompleteView view) {
+    final removed = _mentionAutocompleteViews.remove(view);
+    assert(removed);
+  }
+
+  void handleRealmUserAddEvent(RealmUserAddEvent event) {
+    for (final view in _mentionAutocompleteViews) {
+      view.refreshStaleUserResults();
+    }
+  }
+
+  void handleRealmUserRemoveEvent(RealmUserRemoveEvent event) {
+    for (final view in _mentionAutocompleteViews) {
+      view.refreshStaleUserResults();
+    }
+    autocompleteDataCache.invalidateUser(event.userId);
+  }
+
+  void handleRealmUserUpdateEvent(RealmUserUpdateEvent event) {
+    for (final view in _mentionAutocompleteViews) {
+      view.refreshStaleUserResults();
+    }
+    autocompleteDataCache.invalidateUser(event.userId);
+  }
+
+  /// Called when the app is reassembled during debugging, e.g. for hot reload.
+  ///
+  /// Calls [MentionAutocompleteView.reassemble] for all that are registered.
+  ///
+  void reassemble() {
+    for (final view in _mentionAutocompleteViews) {
+      view.reassemble();
+    }
+  }
+}
+
+/// A view-model for a mention-autocomplete interaction.
+///
+/// The owner of one of these objects must call [dispose] when the object
+/// will no longer be used, in order to free resources on the [PerAccountStore].
+///
+/// Lifecycle:
+///  * Create with [init].
+///  * Add listeners with [addListener].
+///  * Use the [query] setter to start a search for a query.
+///  * On reassemble, call [reassemble].
+///  * When the object will no longer be used, call [dispose] to free
+///    resources on the [PerAccountStore].
+class MentionAutocompleteView extends ChangeNotifier {
+  MentionAutocompleteView._({required this.store, required this.narrow});
+
+  factory MentionAutocompleteView.init({
+    required PerAccountStore store,
+    required Narrow narrow,
+  }) {
+    final view = MentionAutocompleteView._(store: store, narrow: narrow);
+    store.autocompleteViewManager.registerMentionAutocomplete(view);
+    return view;
+  }
+
+  @override
+  void dispose() {
+    store.autocompleteViewManager.unregisterMentionAutocomplete(this);
+    // TODO cancel in-progress computations if possible
+    super.dispose();
+  }
+
+  final PerAccountStore store;
+  final Narrow narrow;
+
+  MentionAutocompleteQuery? _currentQuery;
+  set query(MentionAutocompleteQuery query) {
+    _currentQuery = query;
+    _startSearch(query);
+  }
+
+  /// Recompute user results for the current query, if any.
+  ///
+  /// Called in particular when we get a [RealmUserEvent].
+  void refreshStaleUserResults() {
+    if (_currentQuery != null) {
+      _startSearch(_currentQuery!);
+    }
+  }
+
+  /// Called when the app is reassembled during debugging, e.g. for hot reload.
+  ///
+  /// This will redo the search from scratch for the current query, if any.
+  void reassemble() {
+    if (_currentQuery != null) {
+      _startSearch(_currentQuery!);
+    }
+  }
+
+  Iterable<MentionAutocompleteResult> get results => _results;
+  List<MentionAutocompleteResult> _results = [];
+
+  _startSearch(MentionAutocompleteQuery query) async {
+    List<MentionAutocompleteResult>? newResults;
+
+    while (true) {
+      try {
+        newResults = await _computeResults(query);
+        break;
+      } on ConcurrentModificationError {
+        // Retry
+        // TODO backoff?
+      }
+    }
+
+    if (newResults == null) {
+      // Query was old; new search is in progress.
+      return;
+    }
+
+    _results = newResults;
+    notifyListeners();
+  }
+
+  Future<List<MentionAutocompleteResult>?> _computeResults(MentionAutocompleteQuery query) async {
+    final List<MentionAutocompleteResult> results = [];
+    final Iterable<User> users = store.users.values;
+
+    final iterator = users.iterator;
+    bool isDone = false;
+    while (!isDone) {
+      // CPU perf: End this task; enqueue a new one for resuming this work
+      await Future(() {});
+
+      if (query != _currentQuery) {
+        return null;
+      }
+
+      for (int i = 0; i < 1000; i++) {
+        if (!iterator.moveNext()) { // Can throw ConcurrentModificationError
+          isDone = true;
+          break;
+        }
+
+        final User user = iterator.current;
+        if (query.testUser(user, store.autocompleteViewManager.autocompleteDataCache)) {
+          results.add(UserMentionAutocompleteResult(userId: user.userId));
+        }
+      }
+    }
+    return results;
+  }
+}
 
 class MentionAutocompleteQuery {
   MentionAutocompleteQuery(this.raw)
@@ -51,3 +223,30 @@ class AutocompleteDataCache {
     _nameWordsByUser.remove(userId);
   }
 }
+
+abstract class MentionAutocompleteResult {}
+
+class UserMentionAutocompleteResult extends MentionAutocompleteResult {
+  UserMentionAutocompleteResult({required this.userId});
+
+  final int userId;
+}
+
+enum WildcardMentionType {
+  all,
+  everyone,
+  stream,
+}
+
+class WildcardMentionAutocompleteResult extends MentionAutocompleteResult {
+  WildcardMentionAutocompleteResult({required this.type});
+
+  final WildcardMentionType type;
+}
+
+
+class UserGroupMentionAutocompleteResult extends MentionAutocompleteResult {
+  UserGroupMentionAutocompleteResult({required this.userGroupId});
+
+  final int userGroupId;
+}

lib/model/store.dart

@@ -13,6 +13,7 @@ import '../api/model/model.dart';
 import '../api/route/events.dart';
 import '../api/route/messages.dart';
 import '../log.dart';
+import 'autocomplete.dart';
 import 'database.dart';
 import 'message_list.dart';
 
@@ -178,6 +179,8 @@ class PerAccountStore extends ChangeNotifier {
     assert(removed);
   }
 
+  final AutocompleteViewManager autocompleteViewManager = AutocompleteViewManager();
+
   /// Called when the app is reassembled during debugging, e.g. for hot reload.
   ///
   /// This will redo from scratch any computations we can, such as parsing
@@ -186,6 +189,7 @@ class PerAccountStore extends ChangeNotifier {
     for (final view in _messageListViews) {
       view.reassemble();
     }
+    autocompleteViewManager.reassemble();
   }
 
   void handleEvent(Event event) {
@@ -197,10 +201,12 @@ class PerAccountStore extends ChangeNotifier {
     } else if (event is RealmUserAddEvent) {
       assert(debugLog("server event: realm_user/add"));
       users[event.person.userId] = event.person;
+      autocompleteViewManager.handleRealmUserAddEvent(event);
       notifyListeners();
     } else if (event is RealmUserRemoveEvent) {
       assert(debugLog("server event: realm_user/remove"));
       users.remove(event.userId);
+      autocompleteViewManager.handleRealmUserRemoveEvent(event);
       notifyListeners();
     } else if (event is RealmUserUpdateEvent) {
       assert(debugLog("server event: realm_user/update"));
@@ -226,6 +232,7 @@ class PerAccountStore extends ChangeNotifier {
           profileData.remove(update.id);
         }
       }
+      autocompleteViewManager.handleRealmUserUpdateEvent(event);
       notifyListeners();
     } else if (event is MessageEvent) {
       assert(debugLog("server event: message ${jsonEncode(event.message.toJson())}"));

test/model/autocomplete_checks.dart

@@ -0,0 +1,6 @@
+import 'package:checks/checks.dart';
+import 'package:zulip/model/autocomplete.dart';
+
+extension UserMentionAutocompleteResultChecks on Subject<UserMentionAutocompleteResult> {
+  Subject<int> get userId => has((r) => r.userId, 'userId');
+}