import random
from datetime import timedelta

from module.config.utils import get_server_next_update
from module.logger import logger
from module.smart_mgmt.downtime_fetcher import DowntimeFetcher, FetchError


class DowntimeFetch:
    def __init__(self, config):
        self.config = config

    def _set_downtime(self, window, title):
        self.config.modified['DowntimeMgmt.Downtime.Window'] = window
        self.config.modified['DowntimeMgmt.Downtime.Title'] = title
        self.config.update()

    def _update_downtime(self) -> bool:
        """Fetch downtime via fetcher and write cross-task config."""
        try:
            payload = DowntimeFetcher().run()
        except FetchError as e:
            # Expected operational failure (API error, collection missing, no cache);
            # degrade gracefully and let the caller reschedule
            logger.warning(f'Fetch downtime failed: {e}')
            return False
        except Exception:
            # Unexpected programming error; full traceback for diagnosis
            logger.exception('Unexpected error during downtime fetch')
            return False
        self._set_downtime(payload.get('window', ''), payload.get('title', ''))
        return True

    def run(self):
        success = False
        if self.config.SERVER != 'cn':
            # Downtime fetch targets CN Bilibili notices only; skip on other servers
            logger.warning('Downtime fetch is only available for CN server, skip')
        else:
            success = self._update_downtime()
        if success:
            # Stagger execution across instances within 5 minutes after server update
            next_update = get_server_next_update(self.config.Scheduler_ServerUpdate)
            target = next_update + timedelta(seconds=random.randint(0, 300))
            self.config.task_delay(target=target)
        else:
            self.config.task_delay(success=False)