social-app/apps/lib/features/calendar/reminders/reminder_cold_start_queue.dart

import 'dart:async';
import 'dart:collection';

typedef ReminderColdStartReplayTask = Future<void> Function();
typedef ReminderColdStartTaskErrorHandler =
    void Function(Object error, StackTrace stackTrace);

class ReminderColdStartQueue {
  final Queue<ReminderColdStartReplayTask> _tasks =
      Queue<ReminderColdStartReplayTask>();
  final ReminderColdStartTaskErrorHandler? _onTaskError;
  Future<void>? _inFlightReplay;

  ReminderColdStartQueue({ReminderColdStartTaskErrorHandler? onTaskError})
    : _onTaskError = onTaskError;

  void enqueue(ReminderColdStartReplayTask task) {
    _tasks.add(task);
  }

  Future<void> replay() {
    final inFlightReplay = _inFlightReplay;
    if (inFlightReplay != null) {
      return inFlightReplay;
    }

    final replayCompleter = Completer<void>();
    final replayFuture = replayCompleter.future;
    _inFlightReplay = replayFuture;

    scheduleMicrotask(() async {
      try {
        await _replayInternal();
        replayCompleter.complete();
      } catch (error, stackTrace) {
        replayCompleter.completeError(error, stackTrace);
      } finally {
        if (identical(_inFlightReplay, replayFuture)) {
          _inFlightReplay = null;
        }
      }
    });

    return replayFuture;
  }

  Future<void> _replayInternal() async {
    while (_tasks.isNotEmpty) {
      final task = _tasks.removeFirst();
      try {
        await task();
      } catch (error, stackTrace) {
        _onTaskError?.call(error, stackTrace);
      }
    }
  }
}