class ScheduleWeekdayOption {
  final int backendValue;
  final String shortLabel;
  final String fullLabel;

  const ScheduleWeekdayOption({
    required this.backendValue,
    required this.shortLabel,
    required this.fullLabel,
  });
}

const scheduleWeekdayOptions = <ScheduleWeekdayOption>[
  ScheduleWeekdayOption(
    backendValue: 1,
    shortLabel: 'Пн',
    fullLabel: 'понедельник',
  ),
  ScheduleWeekdayOption(
    backendValue: 2,
    shortLabel: 'Вт',
    fullLabel: 'вторник',
  ),
  ScheduleWeekdayOption(backendValue: 3, shortLabel: 'Ср', fullLabel: 'среда'),
  ScheduleWeekdayOption(
    backendValue: 4,
    shortLabel: 'Чт',
    fullLabel: 'четверг',
  ),
  ScheduleWeekdayOption(
    backendValue: 5,
    shortLabel: 'Пт',
    fullLabel: 'пятница',
  ),
  ScheduleWeekdayOption(
    backendValue: 6,
    shortLabel: 'Сб',
    fullLabel: 'суббота',
  ),
  ScheduleWeekdayOption(
    backendValue: 0,
    shortLabel: 'Вс',
    fullLabel: 'воскресенье',
  ),
];

DateTime defaultOnceScheduleTime({DateTime? now}) {
  final base = now ?? DateTime.now();
  final candidate = base.add(const Duration(hours: 4));
  final roundedMinute = ((candidate.minute + 4) ~/ 5) * 5;
  final normalized = DateTime(
    candidate.year,
    candidate.month,
    candidate.day,
    candidate.hour,
    roundedMinute,
  );
  return normalized.isAfter(base)
      ? normalized
      : normalized.add(const Duration(minutes: 5));
}

String? validateOnceSchedule(DateTime? scheduledAt, {DateTime? now}) {
  if (scheduledAt == null) {
    return 'Выберите дату и время';
  }
  final threshold = (now ?? DateTime.now()).add(const Duration(minutes: 1));
  if (!scheduledAt.isAfter(threshold)) {
    return 'Нужна дата хотя бы на минуту вперёд';
  }
  return null;
}

String? validateCronSchedule({
  required int? hour,
  required int? minute,
  required Set<int> weekdays,
}) {
  if (hour == null || hour < 0 || hour > 23) {
    return 'Час должен быть от 0 до 23';
  }
  if (minute == null || minute < 0 || minute > 59) {
    return 'Минута должна быть от 0 до 59';
  }
  if (weekdays.isEmpty) {
    return 'Выберите хотя бы один день недели';
  }
  return null;
}

String serializeCronWeekdays(Set<int> weekdays) {
  if (weekdays.length == scheduleWeekdayOptions.length) {
    return '*';
  }
  final sorted = weekdays.toList()..sort();
  return sorted.join(',');
}

String describeCronWeekdays(Set<int> weekdays) {
  if (weekdays.isEmpty) {
    return 'дни не выбраны';
  }
  if (weekdays.length == scheduleWeekdayOptions.length) {
    return 'каждый день';
  }
  final weekdaySet = weekdays.toSet();
  final selected = scheduleWeekdayOptions
      .where((option) => weekdaySet.contains(option.backendValue))
      .map((option) => option.shortLabel)
      .toList();
  return selected.join(', ');
}

String describeCronWeekdaysExpression(String? value) {
  if (value == null || value.isEmpty || value == '*') {
    return 'каждый день';
  }

  final weekdays = value
      .split(',')
      .map((item) => int.tryParse(item.trim()))
      .whereType<int>()
      .toSet();
  if (weekdays.isEmpty) {
    return value;
  }

  return describeCronWeekdays(weekdays);
}

String formatLocalScheduleDateTime(DateTime value) {
  String pad(int number) => number.toString().padLeft(2, '0');
  return '${pad(value.day)}.${pad(value.month)}.${value.year} ${pad(value.hour)}:${pad(value.minute)}';
}

String formatRunAtLabel(String? value) {
  if (value == null || value.isEmpty) {
    return 'время не указано';
  }

  final parsed = DateTime.tryParse(value);
  if (parsed == null) {
    return value;
  }

  return formatLocalScheduleDateTime(parsed.toLocal());
}