import 'dart:async';
import 'dart:io';

import '../pipeline/question_pipeline.dart';

/// Runs [QuestionPipeline.runMaintenanceCycle] on a fixed interval.
class QuestionBackgroundWorker {
  QuestionBackgroundWorker({
    required QuestionPipeline pipeline,
    required Duration interval,
  })  : _pipeline = pipeline,
        _interval = interval;

  final QuestionPipeline _pipeline;
  final Duration _interval;
  Timer? _timer;
  bool _running = false;

  void start() {
    if (_timer != null) {
      return;
    }
    stdout.writeln(
      'Question background worker started (interval ${_interval.inSeconds}s)',
    );
    _timer = Timer.periodic(_interval, (_) => _tick());
    unawaited(_tick());
  }

  void stop() {
    _timer?.cancel();
    _timer = null;
    _pipeline.close();
  }

  Future<void> _tick() async {
    if (_running) {
      return;
    }
    _running = true;
    try {
      await _pipeline.runMaintenanceCycle();
    } catch (e, st) {
      stderr.writeln('Question background worker tick failed: $e\n$st');
    } finally {
      _running = false;
    }
  }
}