"""FastAPI dependency functions for auth and role checks."""

from __future__ import annotations

from fastapi import Depends, HTTPException, status
from fastapi.security import OAuth2PasswordBearer
from sqlalchemy import select
from sqlalchemy.ext.asyncio import AsyncSession

from app.core.db import get_db
from app.core.security import decode_access_token
from app.models.user import User, UserRole

oauth2_scheme = OAuth2PasswordBearer(tokenUrl="/api/v1/auth/login")


async def get_current_user(
    token: str = Depends(oauth2_scheme),
    db: AsyncSession = Depends(get_db),
) -> User:
    """Resolve the current authenticated user from the JWT in the Authorization header.

    Raises 401 on invalid/expired token, missing user, or soft-deleted user.
    """
    credentials_exc = HTTPException(
        status_code=status.HTTP_401_UNAUTHORIZED,
        detail="Could not validate credentials",
        headers={"WWW-Authenticate": "Bearer"},
    )

    payload = decode_access_token(token)
    if payload is None:
        raise credentials_exc

    sub = payload.get("sub")
    if sub is None:
        raise credentials_exc

    try:
        user_id = int(sub)
    except (ValueError, TypeError):
        raise credentials_exc from None

    # Load user fresh from DB to honor soft-delete and role changes
    result = await db.execute(select(User).where(User.id == user_id, User.deleted_at.is_(None)))
    user = result.scalar_one_or_none()

    if user is None:
        raise credentials_exc

    return user


async def get_current_admin_user(
    user: User = Depends(get_current_user),
) -> User:
    """Require the current user to have the admin role."""
    user_role = user.role.value if hasattr(user.role, "value") else str(user.role)
    if user_role != UserRole.admin.value:
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN,
            detail="Admin role required",
        )
    return user