from datetime import datetime, timedelta

from apscheduler.triggers.cron import CronTrigger


# 重写Cron定时
class VbCronTrigger(CronTrigger):
		@classmethod
		def from_crontab(cls, expr: str, timezone=None):
				values = expr.split()
				if len(values) != 6 and len(values) != 7:
						raise ValueError('Wrong number of fields; got {}, expected 6 or 7'.format(len(values)))
				
				second = values[0]
				minute = values[1]
				hour = values[2]
				if '?' in values[3]:
						day = None
				elif 'L' in values[5]:
						day = f"last {values[5].replace('L', '')}"
				elif 'W' in values[3]:
						day = cls.__find_recent_workday(int(values[3].split('W')[0]))
				else:
						day = values[3].replace('L', 'last')
				month = values[4]
				if '?' in values[5] or 'L' in values[5]:
						week = None
				elif '#' in values[5]:
						week = int(values[5].split('#')[1])
				else:
						week = values[5]
				if '#' in values[5]:
						day_of_week = int(values[5].split('#')[0]) - 1
				else:
						day_of_week = None
				year = values[6] if len(values) == 7 else None
				return cls(
						second=second,
						minute=minute,
						hour=hour,
						day=day,
						month=month,
						week=week,
						day_of_week=day_of_week,
						year=year,
						timezone=timezone,
				)
		
		@classmethod
		def __find_recent_workday(cls, day: int):
				now = datetime.now()
				date = datetime(now.year, now.month, day)
				if date.weekday() < 5:
						return date.day
				else:
						diff = 1
						while True:
								previous_day = date - timedelta(days=diff)
								if previous_day.weekday() < 5:
										return previous_day.day
								else:
										diff += 1