from datetime import datetime, timedelta
from typing import Optional

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

from .config import settings
from .database import get_db
from .models import User

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


def verify_password(plain: str, hashed: str) -> bool:
    return bcrypt.checkpw(plain.encode(), hashed.encode())


def hash_password(plain: str) -> str:
    return bcrypt.hashpw(plain.encode(), bcrypt.gensalt()).decode()


def create_access_token(data: dict, expires_delta: Optional[timedelta] = None) -> str:
    to_encode = data.copy()
    expire = datetime.utcnow() + (expires_delta or timedelta(minutes=settings.access_token_expire_minutes))
    to_encode["exp"] = expire
    return jwt.encode(to_encode, settings.secret_key, algorithm=settings.algorithm)


def get_current_user(token: str = Depends(oauth2_scheme), db: Session = Depends(get_db)) -> 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])
        user_id: int = payload.get("sub")
        if user_id is None:
            raise credentials_exception
    except JWTError:
        raise credentials_exception

    user = db.query(User).filter(User.id == int(user_id)).first()
    if user is None:
        raise credentials_exception
    return user