"""启动时的清理工作。"""
import logging

from sqlalchemy import update

from app.db import SessionLocal
from app.models.job import JobStatus, ProcessingJob

logger = logging.getLogger(__name__)

# 进程重启后不可能再继续的中间状态
_STALE_STATUSES = (
    JobStatus.pending,
    JobStatus.ocr_running,
    JobStatus.ai_running,
)


async def fail_stale_jobs() -> int:
    """把残留的进行中任务标记为失败。

    任务跑在 BackgroundTasks 里，进程重启就没了。不清理的话这些任务会永远
    停在 pending/*_running，前端会一直轮询下去。
    """
    async with SessionLocal() as db:
        result = await db.execute(
            update(ProcessingJob)
            .where(ProcessingJob.status.in_(_STALE_STATUSES))
            .values(
                status=JobStatus.failed,
                error_message="服务重启，任务中断，请重新上传",
            )
        )
        await db.commit()
        count = result.rowcount or 0
    if count:
        logger.info("已清理 %d 个残留任务", count)
    return count