from collections.abc import Generator

from fastapi import Depends, HTTPException, status
from fastapi.security import HTTPAuthorizationCredentials, HTTPBearer
from sqlalchemy.orm import Session
import jwt

from app.core.database import SessionLocal
from app.core.security import decode_access_token
from app.models.user import User


bearer_scheme = HTTPBearer(auto_error=False)


def get_db() -> Generator[Session, None, None]:
    db = SessionLocal()
    try:
        yield db
    finally:
        db.close()


def get_current_user(
    credentials: HTTPAuthorizationCredentials | None = Depends(bearer_scheme),
    db: Session = Depends(get_db),
) -> User:
    if credentials is None:
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="Not authenticated",
        )

    try:
        payload = decode_access_token(credentials.credentials)
        user_id = int(payload["sub"])
    except (KeyError, ValueError, TypeError, jwt.PyJWTError):
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="Invalid token",
        ) from None

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


def get_current_admin_user(
    current_user: User = Depends(get_current_user),
) -> User:
    if not current_user.is_admin:
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN,
            detail="Admin access required",
        )
    return current_user