"""Celery app + beat schedule."""

import logging

from celery import Celery
from celery.schedules import crontab
from celery.signals import worker_ready

from app.core.config import settings

logger = logging.getLogger(__name__)


def _parse_cron(spec: str) -> crontab:
    """Parse 'M H DoM Mon DoW' crontab string into Celery crontab. Empty fields default to '*'."""
    parts = spec.strip().split()
    if len(parts) != 5:
        raise ValueError(f"crontab spec must have 5 fields, got: {spec!r}")
    minute, hour, dom, month, dow = parts
    return crontab(
        minute=minute,
        hour=hour,
        day_of_month=dom,
        month_of_year=month,
        day_of_week=dow,
    )


def _default_regions() -> list[int]:
    return [int(x.strip()) for x in settings.scrape_kn_default_regions.split(",") if x.strip()]


celery_app = Celery(
    "gendesign",
    broker=settings.redis_url,
    backend=settings.redis_url,
    include=["app.workers.tasks.scrape_kn"],
)
celery_app.conf.timezone = "Europe/Moscow"

# Расписание задаётся через SCRAPE_KN_CRON env var (см. app.core.config).
# Каждый региональный sweep оборачивается случайной задержкой 0..SCRAPE_KN_JITTER_SECONDS
# внутри самой задачи (см. tasks.scrape_kn) — чтобы не бить ровно в одну минуту.
celery_app.conf.beat_schedule = {
    f"kn-region-{rc}": {
        "task": "tasks.scrape_kn.scrape_kn_region",
        "schedule": _parse_cron(settings.scrape_kn_cron),
        "args": [rc, None],
    }
    for rc in _default_regions()
}


@worker_ready.connect
def _resume_zombie_runs(sender=None, **_kwargs) -> None:
    """When a worker finishes booting (after redeploy/restart), find any sweep
    that was 'running' with a stale heartbeat (>5 min) and re-enqueue a resume
    task. Each resume creates a fresh run_id linked via resumed_from_run_id;
    the original row is marked 'zombie' so the audit trail is preserved.
    """
    from sqlalchemy import text

    from app.core.db import SessionLocal

    db = SessionLocal()
    try:
        rows = (
            db.execute(
                text(
                    """
                    SELECT run_id
                      FROM kn_scrape_runs
                     WHERE status = 'running'
                       AND objects_snapshot IS NOT NULL
                       AND COALESCE(heartbeat_at, started_at)
                           < NOW() - INTERVAL '5 minutes'
                     ORDER BY started_at ASC
                     LIMIT 20
                    """
                )
            )
            .mappings()
            .all()
        )
        if not rows:
            logger.info("worker_ready: нет stale runs для resume")
            return

        ids = [int(r["run_id"]) for r in rows]
        # Помечаем найденные как 'zombie' одним апдейтом — resume создаст новые
        # run_id со ссылкой resumed_from_run_id.
        db.execute(
            text(
                """
                UPDATE kn_scrape_runs
                   SET status = 'zombie',
                       finished_at = NOW(),
                       error = COALESCE(error,
                           'auto-zombie at worker_ready, resume scheduled')
                 WHERE run_id = ANY(:ids)
                """
            ),
            {"ids": ids},
        )
        db.commit()
    except Exception as e:
        logger.exception("worker_ready resume scan failed: %s", e)
        try:
            db.rollback()
        except Exception:
            pass
        return
    finally:
        db.close()

    # Enqueue resume tasks. Late import to avoid circular at module load.
    from app.workers.tasks.scrape_kn import resume_kn_run

    for rid in ids:
        try:
            resume_kn_run.apply_async(args=[rid])
            logger.info("worker_ready: resume_kn_run enqueued for run=%s", rid)
        except Exception as e:
            logger.warning("worker_ready: failed to enqueue resume for run=%s: %s", rid, e)