import 'dart:convert';

import 'package:postgres/postgres.dart';

import 'question_source_preferences.dart';

class QuestionSourcePreferencesDb {
  QuestionSourcePreferencesDb(this._connection);

  final Connection _connection;

  Future<List<ResolvedQuestionSourcePreference>> getResolved(
    String firebaseUid,
  ) async {
    final List<Map<String, dynamic>>? stored = await _readStored(firebaseUid);
    return QuestionSourcePreferences.mergeStored(stored);
  }

  Future<bool> isSourceEnabled(String firebaseUid, String sourceId) async {
    final List<ResolvedQuestionSourcePreference> resolved =
        await getResolved(firebaseUid);
    return QuestionSourcePreferences.isEnabled(resolved, sourceId);
  }

  Future<List<ResolvedQuestionSourcePreference>> save(
    String firebaseUid,
    List<Map<String, dynamic>> stored,
  ) async {
    final DateTime updatedAt = DateTime.now().toUtc();
    await _connection.execute(
      Sql.named(
        '''
        INSERT INTO users (firebase_uid, question_source_preferences, updated_at)
        VALUES (@uid, @preferences::jsonb, @updated_at)
        ON CONFLICT (firebase_uid) DO UPDATE SET
          question_source_preferences = EXCLUDED.question_source_preferences,
          updated_at = EXCLUDED.updated_at
        ''',
      ),
      parameters: <String, dynamic>{
        'uid': firebaseUid,
        'preferences': jsonEncode(stored),
        'updated_at': updatedAt,
      },
    );
    return QuestionSourcePreferences.mergeStored(stored);
  }

  Future<List<Map<String, dynamic>>?> _readStored(String firebaseUid) async {
    final Result result = await _connection.execute(
      Sql.named(
        '''
        SELECT question_source_preferences
        FROM users
        WHERE firebase_uid = @uid
        ''',
      ),
      parameters: <String, dynamic>{'uid': firebaseUid},
    );
    if (result.isEmpty) {
      return null;
    }
    final Object? value = result.first[0];
    if (value == null) {
      return null;
    }
    if (value is List<dynamic>) {
      return value.cast<Map<String, dynamic>>();
    }
    if (value is String) {
      final Object? decoded = jsonDecode(value);
      if (decoded is List<dynamic>) {
        return decoded.cast<Map<String, dynamic>>();
      }
    }
    return null;
  }
}