from datetime import datetime, timedelta, timezone
from fastapi import Depends, HTTPException, status
from fastapi.security import OAuth2PasswordBearer
from jose import jwt, JWTError
from config import SECRET_KEY, ALGORITHM, ACCESS_TOKEN_EXPIRE_MINUTES

oauth2_scheme = OAuth2PasswordBearer(tokenUrl="/api/token")

def create_access_token(data: dict, expires_delta: timedelta = None):
    to_encode = data.copy()
    expire = datetime.now(timezone.utc) + (expires_delta or timedelta(minutes=ACCESS_TOKEN_EXPIRE_MINUTES))
    to_encode.update({"exp": expire})
    return jwt.encode(to_encode, SECRET_KEY, algorithm=ALGORITHM)

def get_current_user(token: str = Depends(oauth2_scheme)):
    credentials_exception = HTTPException(
        status_code=status.HTTP_401_UNAUTHORIZED,
        detail="Could not validate credentials",
        headers={"WWW-Authenticate": "Bearer"},
    )
    try:
        payload = jwt.decode(token, SECRET_KEY, algorithms=[ALGORITHM])
        username = payload.get("sub")
        if username is None:
            raise credentials_exception
    except JWTError:
        raise credentials_exception
    return username