"""流失风险预警。"""

from datetime import datetime, timezone

from sqlalchemy import select, func
from sqlalchemy.ext.asyncio import AsyncSession

from app.models.company import Company
from app.models.report import MonthlyReport


async def detect_churn_risk(db: AsyncSession, tenant_id: str) -> list[dict]:
    """识别企业活跃度下降/数据共享减少/互动减少的早期信号。"""
    result = await db.execute(
        select(Company).where(Company.tenant_id == tenant_id)
    )
    companies = result.scalars().all()

    risks: list[dict] = []
    for company in companies:
        # 检查最近月报提交情况
        report_result = await db.execute(
            select(func.count(MonthlyReport.id))
            .where(MonthlyReport.company_id == company.id)
        )
        report_count = report_result.scalar_one()

        if report_count == 0:
            risks.append({
                "company_id": str(company.id),
                "company_name": company.name,
                "risk_level": "high",
                "signals": ["从未提交月报"],
                "detected_at": datetime.now(timezone.utc).isoformat(),
            })

    return risks