"""备份保留策略清理。"""
from datetime import datetime, timedelta
from typing import Optional

from sqlalchemy.orm import Session

from app.core.storage.factory import create_storage
from app.models.job import Job
from app.models.run import Run
from app.utils.logging import get_logger

log = get_logger(__name__)


def apply_retention(db: Session, job: Job) -> int:
    """根据 job 的 retention_count / retention_days 清理旧备份。

    返回删除的 run 数。
    """
    # 取该 job 所有成功 runs，按 finished_at 倒序
    runs = (
        db.query(Run)
        .filter(Run.job_id == job.id, Run.status == "success")
        .order_by(Run.finished_at.desc())
        .all()
    )
    if not runs:
        return 0

    keep_count = job.retention_count or 7
    keep_days = job.retention_days

    to_keep_ids: set[int] = set()
    for i, r in enumerate(runs):
        keep_by_count = i < keep_count
        keep_by_days = True
        if keep_days and r.finished_at:
            threshold = datetime.utcnow() - timedelta(days=keep_days)
            if r.finished_at < threshold:
                keep_by_days = False
        if keep_by_count or keep_by_days:
            to_keep_ids.add(r.id)

    to_delete = [r for r in runs if r.id not in to_keep_ids]
    if not to_delete:
        return 0

    storage = create_storage(job.storage)
    removed = 0
    for r in to_delete:
        try:
            if r.artifact_path:
                # 用同步方法简单调用即可（local 是同步包装 async，但这里 aioboto3/aiofiles 都是异步；
                # 实际上 base storage 都是 async 方法，所以这里需要在同步上下文跑 event loop）
                pass
        except Exception:
            log.exception("Failed to delete artifact %s (db row still kept)", r.artifact_path)
        db.delete(r)
        removed += 1

    db.commit()
    log.info("Retention cleanup for job=%s: deleted %s runs", job.name, removed)

    # 真实删除 S3/local 文件（需要在 async 上下文）
    import asyncio
    try:
        loop = asyncio.new_event_loop()
        try:
            for r in to_delete:
                if r.artifact_path:
                    try:
                        loop.run_until_complete(storage.delete(r.artifact_path))
                    except Exception:
                        log.exception("Artifact delete failed: %s", r.artifact_path)
        finally:
            loop.close()
    except Exception:
        log.exception("Artifact cleanup loop error")

    return removed