from datetime import datetime, timedelta
from typing import Any, Union

from fastapi import HTTPException, status, Depends
from fastapi.security import OAuth2PasswordBearer
from jose import jwt, JWTError
from passlib.context import CryptContext
from sqlalchemy.orm import Session

from config.database import get_db


ACCESS_TOKEN_EXPIRE_MINUTES = 30
SECRET_KEY = "your-secret-key"  # Change this in production
ALGORITHM = "HS256"

pwd_context = CryptContext(schemes=["pbkdf2_sha256"], deprecated="auto")

oauth2_scheme = OAuth2PasswordBearer(tokenUrl="users/login")


def create_access_token(
    subject: Union[str, Any], expires_delta: Union[timedelta, None] = None
) -> str:
    if expires_delta:
        expire = datetime.utcnow() + expires_delta
    else:
        expire = datetime.utcnow() + timedelta(minutes=ACCESS_TOKEN_EXPIRE_MINUTES)
    to_encode = {"exp": expire, "sub": str(subject)}
    encoded_jwt = jwt.encode(to_encode, SECRET_KEY, algorithm=ALGORITHM)
    return encoded_jwt


def verify_password(plain_password: str, hashed_password: str) -> bool:
    return pwd_context.verify(plain_password, hashed_password)


def get_password_hash(password: str) -> str:
    return pwd_context.hash(password)


async def get_current_user(token: str = Depends(oauth2_scheme), db: Session = Depends(get_db)):
    from models.user import User
    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
    user = db.query(User).filter(User.username == username).first()
    if user is None:
        raise credentials_exception
    return user