"""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 datetime import datetime, timezone

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.models import CrawlLog, TaskLock
from app.services.cleaner import cleanup_tmp
from app.services.crawler import crawl_daily
from app.services.summarizer import summarize_batch

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
    )

    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。

    使用 task_locks 表防止重入：同一天的 pipeline 任务只有一个能运行。
    """
    tz = ZoneInfo(settings.APP_TIMEZONE)
    today = datetime.now(tz).strftime("%Y-%m-%d")
    now = datetime.now(timezone.utc)
    lock_key = f"pipeline-{today}"

    db: Session = SessionLocal()
    try:
        # 尝试获取锁
        lock = TaskLock(
            task="scheduler",
            lock_key=lock_key,
            status="running",
            owner="daily_pipeline",
            acquired_at=now,
        )
        try:
            db.add(lock)
            db.commit()
        except Exception:
            db.rollback()
            logger.warning("Daily pipeline already running for %s, skipping", today)
            return

        # 写调度日志
        log_entry = CrawlLog(
            task="scheduler",
            status="running",
            date=datetime.now(tz).date(),
            started_at=now,
        )
        db.add(log_entry)
        db.commit()

        error_msg = None
        try:
            # Step 1: 抓取
            logger.info("Scheduler pipeline: crawl %s", today)
            crawl_result = await crawl_daily(db, today)
            logger.info("Scheduler pipeline: crawl done, found=%d new=%d",
                        crawl_result.get("found", 0), crawl_result.get("new", 0))

            # Step 2: 总结 pending 论文
            logger.info("Scheduler pipeline: summarize batch")
            summarize_result = await summarize_batch(db)
            logger.info("Scheduler pipeline: summarize done, result=%s", summarize_result)

            # Step 3: 清理临时文件
            logger.info("Scheduler pipeline: cleanup tmp")
            cleanup_result = cleanup_tmp()
            logger.info("Scheduler pipeline: cleanup done, removed=%d", cleanup_result.get("removed", 0))

            log_entry.status = "success"

        except Exception as exc:
            logger.exception("Scheduler pipeline failed for %s", today)
            log_entry.status = "failed"
            error_msg = str(exc)[:2000]

        finally:
            log_entry.completed_at = datetime.now(timezone.utc)
            if error_msg:
                log_entry.error = error_msg
            db.commit()

            # 释放锁
            lock.status = "finished"
            lock.released_at = datetime.now(timezone.utc)
            db.commit()

    except Exception:
        logger.exception("Unexpected error in daily pipeline")
    finally:
        db.close()