"""
Planification des jobs de scraping via RQ Scheduler.
"""

from __future__ import annotations

from dataclasses import dataclass
from datetime import datetime, timedelta, timezone
from typing import Optional

import redis
from redis.exceptions import ConnectionError as RedisConnectionError
from redis.exceptions import RedisError, TimeoutError as RedisTimeoutError
from rq import Queue
from rq_scheduler import Scheduler

from pricewatch.app.core.config import AppConfig, get_config
from pricewatch.app.core.logging import get_logger
from pricewatch.app.tasks.scrape import scrape_product

logger = get_logger("tasks.scheduler")


class RedisUnavailableError(Exception):
    """Exception levee quand Redis n'est pas disponible."""

    def __init__(self, message: str = "Redis non disponible", cause: Optional[Exception] = None):
        self.message = message
        self.cause = cause
        super().__init__(self.message)


@dataclass
class ScheduledJobInfo:
    """Infos de retour pour un job planifie."""

    job_id: str
    next_run: datetime


def check_redis_connection(redis_url: str) -> bool:
    """
    Verifie si Redis est accessible.

    Returns:
        True si Redis repond, False sinon.
    """
    try:
        conn = redis.from_url(redis_url)
        conn.ping()
        return True
    except (RedisConnectionError, RedisTimeoutError, RedisError) as e:
        logger.debug(f"Redis ping echoue: {e}")
        return False


class ScrapingScheduler:
    """Scheduler pour les jobs de scraping avec RQ."""

    def __init__(self, config: Optional[AppConfig] = None, queue_name: str = "default") -> None:
        self.config = config or get_config()
        self._queue_name = queue_name
        self._redis: Optional[redis.Redis] = None
        self._queue: Optional[Queue] = None
        self._scheduler: Optional[Scheduler] = None

    def _ensure_connected(self) -> None:
        """Etablit la connexion Redis si necessaire, leve RedisUnavailableError si echec."""
        if self._redis is not None:
            return

        try:
            self._redis = redis.from_url(self.config.redis.url)
            # Ping pour verifier la connexion
            self._redis.ping()
            self._queue = Queue(self._queue_name, connection=self._redis)
            self._scheduler = Scheduler(queue=self._queue, connection=self._redis)
            logger.debug(f"Connexion Redis etablie: {self.config.redis.url}")
        except (RedisConnectionError, RedisTimeoutError) as e:
            self._redis = None
            msg = f"Impossible de se connecter a Redis ({self.config.redis.url}): {e}"
            logger.error(msg)
            raise RedisUnavailableError(msg, cause=e) from e
        except RedisError as e:
            self._redis = None
            msg = f"Erreur Redis: {e}"
            logger.error(msg)
            raise RedisUnavailableError(msg, cause=e) from e

    @property
    def redis(self) -> redis.Redis:
        """Acces a la connexion Redis (lazy)."""
        self._ensure_connected()
        return self._redis  # type: ignore

    @property
    def queue(self) -> Queue:
        """Acces a la queue RQ (lazy)."""
        self._ensure_connected()
        return self._queue  # type: ignore

    @property
    def scheduler(self) -> Scheduler:
        """Acces au scheduler RQ (lazy)."""
        self._ensure_connected()
        return self._scheduler  # type: ignore

    def enqueue_immediate(
        self,
        url: str,
        use_playwright: Optional[bool] = None,
        save_db: bool = True,
    ):
        """Enqueue un job immediat."""
        job = self.queue.enqueue(
            scrape_product,
            url,
            use_playwright=use_playwright,
            save_db=save_db,
        )
        logger.info(f"Job enqueued: {job.id}")
        return job

    def schedule_product(
        self,
        url: str,
        interval_hours: int = 24,
        use_playwright: Optional[bool] = None,
        save_db: bool = True,
    ) -> ScheduledJobInfo:
        """Planifie un scraping recurrent (intervalle en heures)."""
        interval_seconds = int(timedelta(hours=interval_hours).total_seconds())
        next_run = datetime.now(timezone.utc) + timedelta(seconds=interval_seconds)

        job = self.scheduler.schedule(
            scheduled_time=next_run,
            func=scrape_product,
            args=[url],
            kwargs={"use_playwright": use_playwright, "save_db": save_db},
            interval=interval_seconds,
            repeat=None,
        )
        logger.info(f"Job planifie: {job.id}, prochaine execution: {next_run.isoformat()}")
        return ScheduledJobInfo(job_id=job.id, next_run=next_run)