from fastapi import Depends, HTTPException, status
from fastapi.security import OAuth2PasswordBearer
from jose import JWTError
from sqlalchemy.orm import Session
from app.auth.security import decode_token
from app.database import get_db
from app.models.user import User

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

ROLES = {"admin": 4, "accountant": 3, "user": 2, "viewer": 1}


def _get_current_user(token: str, db: Session) -> User:
    credentials_exc = HTTPException(
        status_code=status.HTTP_401_UNAUTHORIZED,
        detail="Could not validate credentials",
        headers={"WWW-Authenticate": "Bearer"},
    )
    try:
        payload = decode_token(token)
        if payload.get("type") != "access":
            raise credentials_exc
        user_id = int(payload["sub"])
    except (JWTError, KeyError, ValueError):
        raise credentials_exc

    user = db.get(User, user_id)
    if not user or not user.is_active:
        raise HTTPException(status_code=status.HTTP_401_UNAUTHORIZED, detail="User inactive or not found")
    return user


def get_current_user(token: str = Depends(oauth2_scheme), db: Session = Depends(get_db)) -> User:
    return _get_current_user(token, db)


def require_role(minimum_role: str):
    """Dependency factory — blocks users whose role rank is below minimum_role."""
    min_rank = ROLES[minimum_role]

    def _check(current_user: User = Depends(get_current_user)) -> User:
        user_rank = ROLES.get(current_user.role.name, 0)
        if user_rank < min_rank:
            raise HTTPException(status_code=status.HTTP_403_FORBIDDEN, detail="Insufficient permissions")
        return current_user

    return _check


require_viewer = Depends(require_role("viewer"))
require_user = Depends(require_role("user"))
require_accountant = Depends(require_role("accountant"))
require_admin = Depends(require_role("admin"))