from fastapi import APIRouter, Depends, Query
from sqlalchemy import and_, or_, select
from sqlalchemy.ext.asyncio import AsyncSession

from ..cursors import decode, encode
from ..db import get_session
from ..models import Check
from ..schemas import ID_PATTERN, ChecksPage, CheckState
from ..timeutil import to_utc

router = APIRouter()


@router.get("/checks", response_model=ChecksPage)
async def list_checks(
    agent_id: str | None = Query(default=None, max_length=128, pattern=ID_PATTERN),
    cursor: str | None = Query(default=None, max_length=512),
    limit: int = Query(default=100, ge=1, le=500),
    session: AsyncSession = Depends(get_session),
) -> ChecksPage:
    stmt = select(Check).order_by(Check.agent_id, Check.check_id)
    if agent_id is not None:
        stmt = stmt.where(Check.agent_id == agent_id)
    if cursor is not None:
        last_agent, last_check = decode(cursor, 2)
        stmt = stmt.where(
            or_(
                Check.agent_id > last_agent,
                and_(Check.agent_id == last_agent, Check.check_id > last_check),
            )
        )
    rows = (await session.execute(stmt.limit(limit + 1))).scalars().all()
    next_cursor = None
    if len(rows) > limit:
        rows = rows[:limit]
        next_cursor = encode(rows[-1].agent_id, rows[-1].check_id)
    items = [
        CheckState(
            agent_id=r.agent_id,
            check_id=r.check_id,
            status=r.status,
            last_observed_at=to_utc(r.last_observed_at),
            exit_code=r.exit_code,
            incident_key=r.incident_key,
            summary=r.summary,
        )
        for r in rows
    ]
    return ChecksPage(items=items, next_cursor=next_cursor)