import 'package:postgres/postgres.dart';

/// Per-question link between a user, quiz row, and shared spelling item.
class SpellingQuestionLinksDb {
  SpellingQuestionLinksDb(this._connection);

  final Pool _connection;

  /// Creates a link when the spelling tile loads; idempotent per [questionId].
  Future<void> linkQuestion({
    required String questionId,
    required String firebaseUid,
    required String spellingItemId,
  }) async {
    await _connection.execute(
      Sql.named(
        '''
        INSERT INTO spelling_question_links (
          question_id, firebase_uid, spelling_item_id
        ) VALUES (
          @question_id::uuid, @uid, @item_id::uuid
        )
        ON CONFLICT (question_id) DO NOTHING
        ''',
      ),
      parameters: <String, dynamic>{
        'question_id': questionId,
        'uid': firebaseUid,
        'item_id': spellingItemId,
      },
    );
  }

  /// Removes every quiz-to-item link for [firebaseUid].
  Future<void> deleteAllForUser(String firebaseUid) async {
    await _connection.execute(
      Sql.named(
        '''
        DELETE FROM spelling_question_links
        WHERE firebase_uid = @uid
        ''',
      ),
      parameters: <String, dynamic>{'uid': firebaseUid},
    );
  }

  Future<bool> hasLink(String questionId) async {
    final Result result = await _connection.execute(
      Sql.named(
        '''
        SELECT 1
        FROM spelling_question_links
        WHERE question_id = @question_id::uuid
        LIMIT 1
        ''',
      ),
      parameters: <String, dynamic>{'question_id': questionId},
    );
    return result.isNotEmpty;
  }
}