# fastapi_crud/app/auth.py

from fastapi import Depends, HTTPException, status
from jose import JWTError, jwt
from sqlalchemy.orm import Session
from fastapi.security import OAuth2PasswordBearer, OAuth2PasswordRequestForm
from passlib.context import CryptContext
from datetime import timedelta, datetime
from . import crud, models, schemas, database

# Generate your secret key using the script above and replace it here
SECRET_KEY = "a12f6578e42b1e1e4f48d4d4c8482e92f00a1de8eb5290a4f7a6b42a51220b29"
ALGORITHM = "HS256"
# Set a very long expiration time, e.g., 365 days
ACCESS_TOKEN_EXPIRE_MINUTES = 60 * 24 * 365

pwd_context = CryptContext(schemes=["bcrypt"], deprecated="auto")
oauth2_scheme = OAuth2PasswordBearer(tokenUrl="token")

def authenticate_user(db: Session, username: str, password: str):
    user = crud.get_user_by_username(db, username)
    if not user:
        return False
    if not pwd_context.verify(password, user.hashed_password):
        return False
    return user

def create_access_token(data: dict, expires_delta: timedelta = None):
    to_encode = data.copy()
    if expires_delta:
        to_encode.update({"exp": datetime.utcnow() + expires_delta})
    else:
        to_encode.update({"exp": datetime.utcnow() + timedelta(minutes=ACCESS_TOKEN_EXPIRE_MINUTES)})
    encoded_jwt = jwt.encode(to_encode, SECRET_KEY, algorithm=ALGORITHM)
    return encoded_jwt

async def get_current_user(token: str = Depends(oauth2_scheme), db: Session = Depends(database.get_db)):
    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: str = payload.get("sub")
        if username is None:
            raise credentials_exception
    except JWTError:
        raise credentials_exception
    user = crud.get_user_by_username(db, username=username)
    if user is None:
        raise credentials_exception
    return user