from __future__ import annotations

from dataclasses import dataclass
from datetime import datetime, time
from typing import Awaitable, Callable, Optional

from .models import Schedule


def _parse_hhmm(value: str) -> time:
  hh, mm = value.split(":")
  return time(hour=int(hh), minute=int(mm))


def should_record_now(now: datetime, schedule: Schedule) -> bool:
  if not schedule.enabled:
    return False

  weekday = now.weekday()
  if weekday in (5, 6) and schedule.weekend_all_day:
    return True

  start = _parse_hhmm(schedule.weekdays_from)
  end = _parse_hhmm(schedule.weekdays_to)
  now_t = now.time().replace(second=0, microsecond=0)

  if start == end:
    return True

  if start < end:
    return start <= now_t < end
  return now_t >= start or now_t < end


@dataclass
class Scheduler:
  apply: Callable[[bool], Awaitable[None]]
  _last_state: Optional[bool] = None

  async def tick(self, schedule: Schedule) -> None:
    now = datetime.now()
    state = should_record_now(now, schedule)
    # Always enforce desired state to recover from external/manual drift.
    await self.apply(state)
    self._last_state = state