search: add jadbFilterWordIds

lib/search.dart

@@ -44,7 +44,11 @@ extension JaDBConnection on DatabaseExecutor {
     pageSize: pageSize,
   );
 
-  ///
+  /// Filter a list of word IDs, and return the ones that are listed in the word dictionary.
+  Future<Set<int>> jadbFilterWordIds(Iterable<int> ids) =>
+      filterWordIdsWithDbConnection(this, ids);
+
+  /// Get a word by its ID. Returns null if no result is found for the given ID.
   Future<WordSearchResult?> jadbGetWordById(int id) =>
       getWordByIdWithDbConnection(this, id);
 

lib/search/word_search/word_search.dart

@@ -96,6 +96,24 @@ Future<int?> searchWordCountWithDbConnection(
   return entryIdCount;
 }
 
+Future<Set<int>> filterWordIdsWithDbConnection(
+  DatabaseExecutor connection,
+  Iterable<int> ids,
+) async {
+  if (ids.isEmpty) {
+    return {};
+  }
+
+  final Set<int> filteredIds = await connection
+      .rawQuery(
+        'SELECT "entryId" FROM "${JMdictTableNames.entry}" WHERE "entryId" IN (${ids.map((_) => '?').join(',')})',
+        ids.toList(),
+      )
+      .then((rows) => rows.map((row) => row['entryId'] as int).toSet());
+
+  return filteredIds;
+}
+
 /// Fetches a single word by its entry ID, returning null if not found.
 Future<WordSearchResult?> getWordByIdWithDbConnection(
   DatabaseExecutor connection,