"""日志自动清理服务 — 基于 APScheduler cron job。

每天定时清理过期记录:
- 数据变更工单 (tickets + ticket_approvals)
- 审计日志 (audit_logs)
- 查询历史 (query_histories)
- 定时任务日志 (scheduled_task_logs)

清理规则:
- 只清理已完成/已拒绝的工单（status in ['success', 'failed', 'rejected']）
- 每项保留天数由 system_settings 中对应 key 控制
- 0 天 = 不清理
- 清理结果记录到 audit_logs
"""
import logging
from datetime import datetime, timedelta, timezone
from typing import Optional

from sqlalchemy import select, delete, func

from app.core.database import async_session
from app.models.system_setting import SystemSetting
from app.models.ticket import Ticket
from app.models.audit_log import AuditLog
from app.models.query_history import QueryHistory
from app.models.scheduled_task import ScheduledTaskLog

logger = logging.getLogger(__name__)


async def _get_setting(db, key: str) -> Optional[str]:
    """获取系统设置值。"""
    result = await db.execute(select(SystemSetting).where(SystemSetting.key == key))
    s = result.scalar_one_or_none()
    return s.value if s else None


async def _cleanup_tickets(db, days: int) -> int:
    """清理过期工单及其审批记录。"""
    if days <= 0:
        return 0
    cutoff = datetime.now(timezone.utc) - timedelta(days=days)

    # 先找要删除的工单 ID
    result = await db.execute(
        select(Ticket.id).where(
            Ticket.status.in_(['success', 'failed', 'rejected']),
            Ticket.create_time < cutoff,
        )
    )
    ticket_ids = [row[0] for row in result.all()]
    if not ticket_ids:
        return 0

    # 删除审批记录
    from app.models.ticket import TicketApproval
    for tid in ticket_ids:
        await db.execute(delete(TicketApproval).where(TicketApproval.ticket_id == tid))

    # 删除工单
    await db.execute(delete(Ticket).where(Ticket.id.in_(ticket_ids)))
    await db.commit()
    return len(ticket_ids)


async def _cleanup_audit_logs(db, days: int) -> int:
    """清理过期审计日志。"""
    if days <= 0:
        return 0
    cutoff = datetime.now(timezone.utc) - timedelta(days=days)
    result = await db.execute(delete(AuditLog).where(AuditLog.created_at < cutoff))
    await db.commit()
    return result.rowcount


async def _cleanup_query_histories(db, days: int) -> int:
    """清理过期查询历史。"""
    if days <= 0:
        return 0
    cutoff = datetime.now(timezone.utc) - timedelta(days=days)
    result = await db.execute(delete(QueryHistory).where(QueryHistory.created_at < cutoff))
    await db.commit()
    return result.rowcount


async def _cleanup_scheduled_task_logs(db, days: int) -> int:
    """清理过期定时任务日志。"""
    if days <= 0:
        return 0
    cutoff = datetime.now(timezone.utc) - timedelta(days=days)
    result = await db.execute(delete(ScheduledTaskLog).where(ScheduledTaskLog.started_at < cutoff))
    await db.commit()
    return result.rowcount


async def run_cleanup() -> dict:
    """执行一次完整清理，返回各项统计。"""
    stats = {
        'tickets': 0,
        'audit_logs': 0,
        'query_histories': 0,
        'scheduled_task_logs': 0,
    }

    try:
        async with async_session() as db:
            enabled = await _get_setting(db, 'cleanup_enabled')
            if enabled != 'true':
                logger.info('自动清理已禁用，跳过')
                return stats

            ticket_days = int(await _get_setting(db, 'cleanup_ticket_days') or '0')
            audit_days = int(await _get_setting(db, 'cleanup_audit_log_days') or '0')
            query_days = int(await _get_setting(db, 'cleanup_query_history_days') or '0')
            task_log_days = int(await _get_setting(db, 'cleanup_scheduled_task_log_days') or '0')

            stats['tickets'] = await _cleanup_tickets(db, ticket_days)
            stats['audit_logs'] = await _cleanup_audit_logs(db, audit_days)
            stats['query_histories'] = await _cleanup_query_histories(db, query_days)
            stats['scheduled_task_logs'] = await _cleanup_scheduled_task_logs(db, task_log_days)

            logger.info(f'自动清理完成: {stats}')
    except Exception as e:
        logger.error(f'自动清理失败: {e}')

    return stats


async def run_cleanup_sync():
    """sync wrapper for APScheduler job."""
    return await run_cleanup()