from typing import Generator
from fastapi import Depends, HTTPException, status
from fastapi.security import OAuth2PasswordBearer
from jose import jwt, JWTError
from sqlalchemy.orm import Session
from ..core import security
from ..core.config import settings
from ..db.session import SessionLocal
from ..models.user import User
from ..schemas.token import TokenPayload
# Reference: https://fastapi.tiangolo.com/tutorial/security/
oauth2_scheme = OAuth2PasswordBearer(tokenUrl=f"/token")

def get_db() -> Generator:
    try:
        db = SessionLocal()
        yield db
    finally:
        db.close()

async def get_current_user(
    db: Session = Depends(get_db), token: str = Depends(oauth2_scheme)
) -> User:
    credentials_exception = HTTPException(
        status_code=status.HTTP_401_UNAUTHORIZED,
        detail="Could not validate credentials",
        headers={"WWW-Authenticate": "Bearer"},
    )
    try:
        payload = jwt.decode(
            token, settings.SECRET_KEY, algorithms=[settings.ALGORITHM]
        )
        username: str = payload.get("sub")
        if username is None:
            raise credentials_exception
        token_data = TokenPayload(sub=username)
    except JWTError:
        raise credentials_exception
    user = db.query(User).filter(User.email == token_data.sub).first()
    if not user:
        raise credentials_exception
    return user

async def get_current_active_user(
    current_user: User = Depends(get_current_user),
) -> User:
    if not current_user.is_active:
        raise HTTPException(status_code=400, detail="Inactive user")
    return current_user