"""Wiederverwendbare FastAPI-Dependencies."""

from typing import Annotated

from fastapi import Depends, Request
from sqlalchemy.ext.asyncio import AsyncSession

from app.core.cookies import ACCESS_COOKIE
from app.core.errors import AppError, AuthError
from app.core.security import decode_token
from app.db.session import get_session
from app.models import AppUser
from app.services.auth import get_user
from app.services.settings import month_start_day

DbSession = Annotated[AsyncSession, Depends(get_session)]


class PasswordChangeRequiredError(AppError):
    """Der Zugriff ist erst nach dem erzwungenen Passwortwechsel möglich."""

    status_code = 403
    code = "password_change_required"


async def get_current_user(request: Request, session: DbSession) -> AppUser:
    """Liest das Access-Token aus dem Cookie und lädt den Benutzer."""
    token = request.cookies.get(ACCESS_COOKIE)
    if not token:
        raise AuthError("Nicht angemeldet.", code="not_authenticated")

    payload = decode_token(token, "access")
    try:
        user_id = int(payload["sub"])
    except (KeyError, TypeError, ValueError) as exc:
        raise AuthError("Ungültiges Token.", code="invalid_token") from exc

    user = await get_user(session, user_id)
    if user is None:
        raise AuthError("Der Benutzer existiert nicht mehr.", code="invalid_token")
    return user


CurrentUser = Annotated[AppUser, Depends(get_current_user)]


async def get_active_user(user: CurrentUser) -> AppUser:
    """Wie `get_current_user`, verlangt aber einen abgeschlossenen Passwortwechsel."""
    if user.must_change_password:
        raise PasswordChangeRequiredError(
            "Das Passwort muss zuerst geändert werden.",
        )
    return user


ActiveUser = Annotated[AppUser, Depends(get_active_user)]


async def get_month_start_day(session: DbSession) -> int:
    """Der eingestellte Monatsbeginn – jede monatsbezogene Auswertung richtet sich danach."""
    return await month_start_day(session)


MonthStartDay = Annotated[int, Depends(get_month_start_day)]