word_search: add function for retrieving single entry by id

lib/search.dart

@@ -41,6 +41,10 @@ extension JaDBConnection on DatabaseExecutor {
         pageSize,
       );
 
+  ///
+  Future<WordSearchResult?> jadbGetWordById(int id) =>
+      getWordByIdWithDbConnection(this, id);
+
   /// Search for a word in the database, and return the count of results.
   Future<int?> jadbSearchWordCount(
     String word, {

lib/search/word_search/word_search.dart

@@ -10,6 +10,7 @@ import 'package:jadb/models/word_search/word_search_result.dart';
 import 'package:jadb/search/word_search/data_query.dart';
 import 'package:jadb/search/word_search/entry_id_query.dart';
 import 'package:jadb/search/word_search/regrouping.dart';
+import 'package:jadb/table_names/jmdict.dart';
 import 'package:sqflite_common/sqlite_api.dart';
 
 enum SearchMode {
@@ -95,3 +96,58 @@ Future<int?> searchWordCountWithDbConnection(
 
   return entryIdCount;
 }
+
+Future<WordSearchResult?> getWordByIdWithDbConnection(
+  DatabaseExecutor connection,
+  int id,
+) async {
+  if (id <= 0) {
+    return null;
+  }
+
+  final exists = await connection.rawQuery(
+    'SELECT EXISTS(SELECT 1 FROM "${JMdictTableNames.entry}" WHERE "entryId" = ?)',
+    [id],
+  ).then((value) => value.isNotEmpty && value.first.values.first == 1);
+
+  if (!exists) {
+    return null;
+  }
+
+  final LinearWordQueryData linearWordQueryData =
+      await fetchLinearWordQueryData(
+    connection,
+    [id],
+  );
+
+  final result = regroupWordSearchResults(
+    entryIds: [ScoredEntryId(id, 0)],
+    readingElements: linearWordQueryData.readingElements,
+    kanjiElements: linearWordQueryData.kanjiElements,
+    jlptTags: linearWordQueryData.jlptTags,
+    commonEntries: linearWordQueryData.commonEntries,
+    senses: linearWordQueryData.senses,
+    senseAntonyms: linearWordQueryData.senseAntonyms,
+    senseDialects: linearWordQueryData.senseDialects,
+    senseFields: linearWordQueryData.senseFields,
+    senseGlossaries: linearWordQueryData.senseGlossaries,
+    senseInfos: linearWordQueryData.senseInfos,
+    senseLanguageSources: linearWordQueryData.senseLanguageSources,
+    senseMiscs: linearWordQueryData.senseMiscs,
+    sensePOSs: linearWordQueryData.sensePOSs,
+    senseRestrictedToKanjis: linearWordQueryData.senseRestrictedToKanjis,
+    senseRestrictedToReadings: linearWordQueryData.senseRestrictedToReadings,
+    senseSeeAlsos: linearWordQueryData.senseSeeAlsos,
+    exampleSentences: linearWordQueryData.exampleSentences,
+    readingElementInfos: linearWordQueryData.readingElementInfos,
+    readingElementRestrictions: linearWordQueryData.readingElementRestrictions,
+    kanjiElementInfos: linearWordQueryData.kanjiElementInfos,
+  );
+
+  assert(
+    result.length == 1,
+    'Expected exactly one result for entryId $id, but got ${result.length}',
+  );
+
+  return result.firstOrNull;
+}

test/search/word_search_test.dart

@@ -6,11 +6,16 @@ import 'setup_database_connection.dart';
 void main() {
   test("Search a word", () async {
     final connection = await setup_database_connection();
-
     final result = await connection.jadbSearchWord("kana");
     expect(result, isNotNull);
   });
 
+  test("Get a word by id", () async {
+    final connection = await setup_database_connection();
+    final result = await connection.jadbGetWordById(1577090);
+    expect(result, isNotNull);
+  });
+
   test(
     "Serialize all words",
     () async {