# scheduler_manager.py
from __future__ import annotations
import logging
from dataclasses import asdict
from typing import Callable, List, Optional
from zoneinfo import ZoneInfo

from apscheduler.schedulers.background import BackgroundScheduler
from apscheduler.triggers.cron import CronTrigger

from utils.scan_config_loader import ScanConfigFile

logger = logging.getLogger(__name__)

class ScanScheduler:
    """
    Owns an APScheduler and schedules one job per ScanConfigFile that has scan_options.cron set.
    """

    def __init__(self, timezone: str = "America/Chicago") -> None:
        self.tz = ZoneInfo(timezone)
        self.scheduler = BackgroundScheduler(timezone=self.tz)

    def start(self) -> None:
        """
        Start the underlying scheduler thread.
        """
        if not self.scheduler.running:
            self.scheduler.start()
            logger.info("APScheduler started (tz=%s).", self.tz)

    def shutdown(self) -> None:
        """
        Gracefully stop the scheduler.
        """
        if self.scheduler.running:
            self.scheduler.shutdown(wait=False)
            logger.info("APScheduler stopped.")

    def schedule_configs(
        self,
        configs: List[ScanConfigFile],
        run_scan_fn: Callable[[ScanConfigFile], None],
        replace_existing: bool = True,
    ) -> int:
        """
        Create/replace jobs for all configs with a valid cron.
        Returns number of scheduled jobs.
        """
        count = 0
        for cfg in configs:
            cron = (cfg.scan_options.cron or "").strip() if cfg.scan_options else ""
            if not cron:
                logger.info("Skipping schedule (no cron): %s", cfg.name)
                continue

            job_id = f"scan::{cfg.name}"
            trigger = CronTrigger.from_crontab(cron, timezone=self.tz)

            self.scheduler.add_job(
                func=run_scan_fn,
                trigger=trigger,
                id=job_id,
                args=[cfg],
                max_instances=1,
                replace_existing=replace_existing,
                misfire_grace_time=300,
                coalesce=True,
            )
            logger.info("Scheduled '%s' with cron '%s' (next run: %s)",
                        cfg.name, cron, self._next_run_time(job_id))
            count += 1
        return count

    def _next_run_time(self, job_id: str):
        j = self.scheduler.get_job(job_id)
        if j and hasattr(j, "next_run_time"):
            return j.next_run_time.isoformat() if j.next_run_time else None
        return None