emoji: Add view-model for autocomplete, EmojiAutocompleteView

As of this commit, it's not yet possible in the app to initiate an
emoji autocomplete interaction.  So in the widgets code that would
consume the results of such an interaction, we just throw for now,
leaving that to be implemented in a later commit.

Author: gnprice

lib/model/autocomplete.dart

@@ -7,6 +7,7 @@ import '../api/model/events.dart';
 import '../api/model/model.dart';
 import '../api/route/channels.dart';
 import '../widgets/compose_box.dart';
+import 'emoji.dart';
 import 'narrow.dart';
 import 'store.dart';
 
@@ -142,6 +143,7 @@ class AutocompleteIntent<QueryT extends AutocompleteQuery> {
 class AutocompleteViewManager {
   final Set<MentionAutocompleteView> _mentionAutocompleteViews = {};
   final Set<TopicAutocompleteView> _topicAutocompleteViews = {};
+  final Set<EmojiAutocompleteView> _emojiAutocompleteViews = {};
 
   AutocompleteDataCache autocompleteDataCache = AutocompleteDataCache();
 
@@ -165,6 +167,16 @@ class AutocompleteViewManager {
     assert(removed);
   }
 
+  void registerEmojiAutocomplete(EmojiAutocompleteView view) {
+    final added = _emojiAutocompleteViews.add(view);
+    assert(added);
+  }
+
+  void unregisterEmojiAutocomplete(EmojiAutocompleteView view) {
+    final removed = _emojiAutocompleteViews.remove(view);
+    assert(removed);
+  }
+
   void handleRealmUserRemoveEvent(RealmUserRemoveEvent event) {
     autocompleteDataCache.invalidateUser(event.userId);
   }
@@ -683,6 +695,13 @@ class AutocompleteResult {}
 /// and managed by some [ComposeAutocompleteView].
 sealed class ComposeAutocompleteResult extends AutocompleteResult {}
 
+/// An emoji chosen in an autocomplete interaction, via [EmojiAutocompleteView].
+class EmojiAutocompleteResult extends ComposeAutocompleteResult {
+  EmojiAutocompleteResult(this.candidate);
+
+  final EmojiCandidate candidate;
+}
+
 /// A result from an @-mention autocomplete interaction,
 /// managed by a [MentionAutocompleteView].
 ///

lib/model/emoji.dart

@@ -268,6 +268,34 @@ class EmojiStoreImpl with EmojiStore {
   }
 }
 
+class EmojiAutocompleteView extends AutocompleteView<EmojiAutocompleteQuery, EmojiAutocompleteResult> {
+  EmojiAutocompleteView._({required super.store, required super.query});
+
+  factory EmojiAutocompleteView.init({
+    required PerAccountStore store,
+    required EmojiAutocompleteQuery query,
+  }) {
+    final view = EmojiAutocompleteView._(store: store, query: query);
+    store.autocompleteViewManager.registerEmojiAutocomplete(view);
+    return view;
+  }
+
+  @override
+  Future<List<EmojiAutocompleteResult>?> computeResults() async {
+    // TODO(#1068): rank emoji results (popular, realm, other; exact match, prefix, other)
+    final results = <EmojiAutocompleteResult>[];
+    if (await filterCandidates(filter: _testCandidate,
+          candidates: store.allEmojiCandidates(), results: results)) {
+      return null;
+    }
+    return results;
+  }
+
+  EmojiAutocompleteResult? _testCandidate(EmojiAutocompleteQuery query, EmojiCandidate candidate) {
+    return query.matches(candidate) ? EmojiAutocompleteResult(candidate) : null;
+  }
+}
+
 class EmojiAutocompleteQuery extends ComposeAutocompleteQuery {
   EmojiAutocompleteQuery(super.raw)
     : _adjusted = _adjustQuery(raw);

lib/widgets/autocomplete.dart

@@ -187,6 +187,8 @@ class ComposeAutocomplete extends AutocompleteField<ComposeAutocompleteQuery, Co
     final store = PerAccountStoreWidget.of(context);
     final String replacementString;
     switch (option) {
+      case EmojiAutocompleteResult():
+        throw UnimplementedError(); // TODO(#670)
       case UserMentionAutocompleteResult(:var userId):
         if (query is! MentionAutocompleteQuery) {
           return; // Shrug; similar to `intent == null` case above.
@@ -208,6 +210,7 @@ class ComposeAutocomplete extends AutocompleteField<ComposeAutocompleteQuery, Co
   Widget buildItem(BuildContext context, int index, ComposeAutocompleteResult option) {
     final child = switch (option) {
       MentionAutocompleteResult() => _MentionAutocompleteItem(option: option),
+      EmojiAutocompleteResult() => throw UnimplementedError(), // TODO(#670)
     };
     return InkWell(
       onTap: () {

test/model/emoji_test.dart

@@ -3,6 +3,7 @@ import 'package:test/scaffolding.dart';
 import 'package:zulip/api/model/events.dart';
 import 'package:zulip/api/model/model.dart';
 import 'package:zulip/api/route/realm.dart';
+import 'package:zulip/model/autocomplete.dart';
 import 'package:zulip/model/emoji.dart';
 import 'package:zulip/model/store.dart';
 
@@ -203,6 +204,74 @@ void main() {
     });
   });
 
+  group('EmojiAutocompleteView', () {
+    Condition<Object?> isUnicodeResult({String? emojiCode, List<String>? names}) {
+      return (it) => it.isA<EmojiAutocompleteResult>().candidate.which(
+        isUnicodeCandidate(emojiCode, names));
+    }
+
+    Condition<Object?> isRealmResult({String? emojiCode, String? emojiName}) {
+      return (it) => it.isA<EmojiAutocompleteResult>().candidate.which(
+        isRealmCandidate(emojiCode: emojiCode, emojiName: emojiName));
+    }
+
+    Condition<Object?> isZulipResult() {
+      return (it) => it.isA<EmojiAutocompleteResult>().candidate.which(
+        isZulipCandidate());
+    }
+
+    PerAccountStore prepare({
+      Map<String, String> realmEmoji = const {},
+      Map<String, List<String>>? unicodeEmoji,
+    }) {
+      final store = eg.store(
+        initialSnapshot: eg.initialSnapshot(realmEmoji: {
+          for (final MapEntry(:key, :value) in realmEmoji.entries)
+            key: eg.realmEmojiItem(emojiCode: key, emojiName: value),
+        }));
+      if (unicodeEmoji != null) {
+        store.setServerEmojiData(ServerEmojiData(codeToNames: unicodeEmoji));
+      }
+      return store;
+    }
+
+    test('results can include all three emoji types', () async {
+      final store = prepare(
+        realmEmoji: {'1': 'happy'}, unicodeEmoji: {'1f642': ['smile']});
+      final view = EmojiAutocompleteView.init(store: store,
+        query: EmojiAutocompleteQuery(''));
+      bool done = false;
+      view.addListener(() { done = true; });
+      await Future(() {});
+      check(done).isTrue();
+      check(view.results).deepEquals([
+        isUnicodeResult(names: ['smile']),
+        isRealmResult(emojiName: 'happy'),
+        isZulipResult(),
+      ]);
+    });
+
+    test('results update after query change', () async {
+      final store = prepare(
+        realmEmoji: {'1': 'happy'}, unicodeEmoji: {'1f642': ['smile']});
+      final view = EmojiAutocompleteView.init(store: store,
+        query: EmojiAutocompleteQuery('h'));
+      bool done = false;
+      view.addListener(() { done = true; });
+      await Future(() {});
+      check(done).isTrue();
+      check(view.results).single.which(
+        isRealmResult(emojiName: 'happy'));
+
+      done = false;
+      view.query = EmojiAutocompleteQuery('s');
+      await Future(() {});
+      check(done).isTrue();
+      check(view.results).single.which(
+        isUnicodeResult(names: ['smile']));
+    });
+  });
+
   group('EmojiAutocompleteQuery.matches', () {
     EmojiCandidate unicode(List<String> names, {String? emojiCode}) {
       emojiCode ??= '10ffff';
@@ -369,3 +438,7 @@ extension EmojiCandidateChecks on Subject<EmojiCandidate> {
   Subject<Iterable<String>> get aliases => has((x) => x.aliases, 'aliases');
   Subject<EmojiDisplay> get emojiDisplay => has((x) => x.emojiDisplay, 'emojiDisplay');
 }
+
+extension EmojiAutocompleteResultChecks on Subject<EmojiAutocompleteResult> {
+  Subject<EmojiCandidate> get candidate => has((x) => x.candidate, 'candidate');
+}