from datetime import datetime, timezone

from fastapi import Cookie, Depends, HTTPException, status
from sqlalchemy import select
from sqlalchemy.ext.asyncio import AsyncSession

from app.db import get_db
from app.models.auth_session import AuthSession, hash_token
from app.models.user import User

SESSION_COOKIE_NAME = "qm_session"


async def get_current_user(
    qm_session: str | None = Cookie(default=None, alias=SESSION_COOKIE_NAME),
    db: AsyncSession = Depends(get_db),
) -> User:
    if qm_session is None:
        raise HTTPException(status.HTTP_401_UNAUTHORIZED, "not authenticated")

    token_hash = hash_token(qm_session)
    result = await db.execute(select(AuthSession).where(AuthSession.token_hash == token_hash))
    session = result.scalar_one_or_none()
    if session is None or session.expires_at < datetime.now(timezone.utc):
        raise HTTPException(status.HTTP_401_UNAUTHORIZED, "session expired")

    user = await db.get(User, session.user_id)
    if user is None:
        raise HTTPException(status.HTTP_401_UNAUTHORIZED, "user not found")
    return user