auth.py

from ast import mod
from datetime import UTC, datetime, timedelta
from unittest import result

import jwt
from fastapi.security import OAuth2PasswordBearer
from pwdlib import PasswordHash
import hashlib
import secrets

from config import settings

from typing import Annotated
from fastapi import Depends, HTTPException, status
from sqlalchemy.ext.asyncio import AsyncSession
from database import get_db
from sqlalchemy import select
import models


password_hash = PasswordHash.recommended()

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


def hash_password(password: str) -> str:
    return password_hash.hash(password)


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

def generate_reset_token() -> str:
    return secrets.token_urlsafe(32)

def hash_reset_token(token: str) -> str:
    return hashlib.sha256(token.encode()).hexdigest()


def create_access_token(data: dict, expires_delta: timedelta | None = None) -> str:
    """Create a JWT access token."""
    to_encode = data.copy()
    if expires_delta:
        expire = datetime.now(UTC) + expires_delta
    else:
        expire = datetime.now(UTC) + timedelta(
            minutes=settings.access_token_expire_minutes,
        )
    to_encode.update({"exp": expire})
    encoded_jwt = jwt.encode(
        to_encode,
        settings.secret_key.get_secret_value(),
        algorithm=settings.algorithm,
    )
    return encoded_jwt


def verify_access_token(token: str) -> str | None:
    """Verify a JWT access token and return the subject (user id) if valid."""
    try:
        payload = jwt.decode(
            token,
            settings.secret_key.get_secret_value(),
            algorithms=[settings.algorithm],
            options={"require": ["exp", "sub"]},
        )
    except jwt.InvalidTokenError:
        return None
    else:
        return payload.get("sub")


async def get_current_user(
    token: Annotated[str, Depends(oauth2_scheme)],
    db: Annotated[AsyncSession, Depends(get_db)]
) -> models.User:
    user_id = verify_access_token(token)
    if user_id is None:
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="Invalid or expired token",
            headers={"WWW-Authenticate": "Bearer"},
        )

    try:
        user_id_int = int(user_id)

    except (TypeError, ValueError):
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="Invalid or expired token",
            headers={"WWW-Authenticate": "Bearer"},
        )

    result = await db.execute(
        select(models.User).where(models.User.id == user_id_int)
    )

    user = result.scalars().first()
    if not user:
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="User not found",
            headers={"WWW-Authenticate": "Bearer"},
        )
    return user

CurrentUser = Annotated[models.User, Depends(get_current_user)]