import 'dart:async';
import 'dart:typed_data';

import 'package:halkyon_learn_flutter/src/feature/settings/data/settings_gateway.dart';

/// A [SettingsGateway] in memory: ids are `settings-001`, `settings-002`, …,
/// in the order of creation as UUID v7s are, and [receiveRemoteRow] plays a
/// sync that brought a row.
class FakeSettingsGateway() implements SettingsGateway {
  final _rows = <String, ByteData>{};
  final _remoteChanges = StreamController<void>.broadcast();
  var _next = 1;

  /// Every payload written, in order, as (id, payload).
  final writes = <(String, ByteData)>[];

  /// The ids of the deleted rows, in order.
  final deleted = <String>[];

  /// Stores the row [id] as if another device had written it and a sync had
  /// brought it here.
  void receiveRemoteRow(String id, ByteData payload) {
    _rows[id] = payload;
    _remoteChanges.add(null);
  }

  @override
  Future<List<SettingsRow>> rows() async => [
    for (final MapEntry(key: id, value: payload) in _rows.entries)
      (id: id, payload: payload),
  ];

  @override
  Future<String> insert(ByteData payload) async {
    final id = 'settings-${'${_next++}'.padLeft(3, '0')}';
    _rows[id] = payload;
    writes.add((id, payload));
    return id;
  }

  @override
  Future<void> updatePayload(String id, ByteData payload) async {
    if (_rows.containsKey(id)) {
      _rows[id] = payload;
      writes.add((id, payload));
    }
  }

  @override
  Future<void> delete(String id) async {
    _rows.remove(id);
    deleted.add(id);
  }

  @override
  Stream<void> get remoteChanges => _remoteChanges.stream;
}