from datetime import UTC, datetime

from fastapi import APIRouter, Depends
from sqlalchemy import func, select
from sqlalchemy.ext.asyncio import AsyncSession

from ..db import get_session
from ..models import Agent, Check, Incident
from ..schemas import SystemSummaryResponse

router = APIRouter()


@router.get("/system-summary", response_model=SystemSummaryResponse)
async def system_summary(session: AsyncSession = Depends(get_session)) -> SystemSummaryResponse:
    agents_rows = (
        await session.execute(
            select(Agent.status, func.count())
            .where(Agent.accepted_key_hash.is_not(None))
            .group_by(Agent.status)
        )
    ).all()
    checks_rows = (
        await session.execute(select(Check.status, func.count()).group_by(Check.status))
    ).all()
    open_incidents = (
        await session.execute(
            select(func.count()).select_from(Incident).where(Incident.state == "open")
        )
    ).scalar_one()

    agents = {status: count for status, count in agents_rows}
    checks = {status: count for status, count in checks_rows}
    return SystemSummaryResponse(
        agents_online=agents.get("alive", 0),
        agents_offline=agents.get("stale", 0) + agents.get("dead", 0),
        checks_ok=checks.get("ok", 0),
        checks_warning=checks.get("warning", 0),
        checks_critical=checks.get("critical", 0),
        checks_unknown=checks.get("unknown", 0),
        open_incidents=open_incidents,
        generated_at=datetime.now(UTC),
    )