"""API balance / consumption endpoints."""
from __future__ import annotations

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

from app.core.deps import require_readonly, require_support
from app.database import get_db
from app.models.balance import BalanceSnapshot
from app.models.user import User
from app.schemas import BalanceOut
from app.services import balance as balance_service

router = APIRouter(prefix="/api/balance", tags=["balance"])


async def _latest_snapshot(db: AsyncSession, provider: str) -> BalanceSnapshot | None:
    """Prefer the newest successful snapshot; fall back to latest error row."""
    res = await db.execute(
        select(BalanceSnapshot)
        .where(BalanceSnapshot.provider == provider)
        .where(BalanceSnapshot.error.is_(None))
        .where(BalanceSnapshot.remaining.is_not(None))
        .order_by(BalanceSnapshot.created_at.desc())
        .limit(1)
    )
    snap = res.scalar_one_or_none()
    if snap:
        return snap
    res = await db.execute(
        select(BalanceSnapshot)
        .where(BalanceSnapshot.provider == provider)
        .order_by(BalanceSnapshot.created_at.desc())
        .limit(1)
    )
    return res.scalar_one_or_none()


@router.get("", response_model=list[BalanceOut])
async def latest_balances(db: AsyncSession = Depends(get_db), _: User = Depends(require_readonly)):
    """Latest snapshot per provider."""
    out: list[BalanceSnapshot] = []
    for provider in ("openrouter", "deepseek"):
        snap = await _latest_snapshot(db, provider)
        if snap:
            out.append(snap)
    return out


@router.post("/refresh", response_model=list[BalanceOut])
async def refresh_balances(db: AsyncSession = Depends(get_db), _: User = Depends(require_support)):
    await balance_service.poll_once()
    return await latest_balances(db)  # type: ignore[arg-type]