"""调度服务 — APScheduler 每日自动抓取、总结、清理流水线。"""

from __future__ import annotations

import logging

from apscheduler.schedulers.asyncio import AsyncIOScheduler
from apscheduler.triggers.cron import CronTrigger
from sqlalchemy.orm import Session
from zoneinfo import ZoneInfo

from app.config import settings
from app.database import SessionLocal
from app.services.pipeline import run_pipeline
from app.services.crawler import refresh_upvotes
from app.utils import today_str

logger = logging.getLogger(__name__)

# 模块级 scheduler 实例，保证单例
_scheduler: AsyncIOScheduler | None = None


def get_scheduler() -> AsyncIOScheduler | None:
    """返回当前 scheduler 实例（供测试和外部检查用）。"""
    return _scheduler


def start_scheduler() -> AsyncIOScheduler | None:
    """创建并启动 APScheduler。

    约束：
    - SCHEDULER_ENABLED=true 才启动。
    - APP_WORKERS > 1 时只打印警告（多 worker 下调度器可能重复触发）。
    - 使用 task_locks 表防重入。
    - 调度时间按 APP_TIMEZONE 时区。
    """
    global _scheduler

    if not settings.SCHEDULER_ENABLED:
        logger.info("Scheduler disabled (SCHEDULER_ENABLED=false)")
        return None

    if settings.APP_WORKERS > 1:
        logger.warning(
            "⚠️  APP_WORKERS=%d > 1, scheduler may trigger duplicate tasks. "
            "Set APP_WORKERS=1 or SCHEDULER_ENABLED=false.",
            settings.APP_WORKERS,
        )

    tz = ZoneInfo(settings.APP_TIMEZONE)
    scheduler = AsyncIOScheduler(timezone=tz)

    # 每日流水线：抓取 → 总结 → 清理
    trigger = CronTrigger(
        hour=settings.SCHEDULE_HOUR,
        minute=settings.SCHEDULE_MINUTE,
        timezone=tz,
    )
    scheduler.add_job(
        _daily_pipeline,
        trigger=trigger,
        id="daily_pipeline",
        name="daily_pipeline",
        replace_existing=True,
        max_instances=1,
        misfire_grace_time=3600,  # 允许迟到 1 小时内补执行
    )

    # upvote 刷新：每天流水线之后 30 分钟执行，刷新最近 7 天论文的投票数
    upvote_trigger = CronTrigger(
        hour=settings.SCHEDULE_HOUR,
        minute=settings.SCHEDULE_MINUTE + 30,
        timezone=tz,
    )
    scheduler.add_job(
        _upvote_refresh,
        trigger=upvote_trigger,
        id="upvote_refresh",
        name="upvote_refresh",
        replace_existing=True,
        max_instances=1,
        misfire_grace_time=3600,
    )

    scheduler.start()
    _scheduler = scheduler
    logger.info(
        "Scheduler started: %02d:%02d %s",
        settings.SCHEDULE_HOUR,
        settings.SCHEDULE_MINUTE,
        settings.APP_TIMEZONE,
    )
    return scheduler


def stop_scheduler() -> None:
    """停止调度器。"""
    global _scheduler
    if _scheduler:
        _scheduler.shutdown(wait=False)
        _scheduler = None
        logger.info("Scheduler stopped")


async def _daily_pipeline() -> None:
    """每日流水线：抓取 → 总结 → 清理。

    委托给 pipeline.run_pipeline 执行，使用 task_locks 防重入。
    """
    today = today_str()

    db: Session = SessionLocal()
    try:
        await run_pipeline(db, today, owner="daily_pipeline")
    except RuntimeError:
        logger.warning("Daily pipeline already running for %s, skipping", today)
    except Exception:
        logger.exception("Unexpected error in daily pipeline")
    finally:
        db.close()


async def _upvote_refresh() -> None:
    """刷新最近 N 天论文的 upvotes。"""
    db: Session = SessionLocal()
    try:
        result = await refresh_upvotes(db)
        logger.info(
            "Upvote refresh completed: status=%s updated=%d",
            result.get("status"),
            result.get("updated", 0),
        )
    except Exception:
        logger.exception("Unexpected error in upvote refresh")
    finally:
        db.close()