from __future__ import annotations

from dataclasses import dataclass

import jwt
from app.config import settings
from fastapi import Depends, HTTPException, status
from fastapi.security import HTTPAuthorizationCredentials, HTTPBearer
from jwt import ExpiredSignatureError, InvalidTokenError

from packages.domain.entities import User
from packages.ports.user_repository import UserRepository

from .dependencies import get_user_repository

bearer_scheme = HTTPBearer(auto_error=False)


@dataclass(frozen=True, slots=True)
class AuthenticatedUser:
    user: User
    session_id: str | None = None
    token_type: str | None = None


async def get_current_user(
    credentials: HTTPAuthorizationCredentials | None = Depends(bearer_scheme),
    user_repository: UserRepository = Depends(get_user_repository),
) -> AuthenticatedUser:
    if credentials is None or credentials.scheme.lower() != "bearer":
        raise _unauthorized("Missing bearer token")

    payload = _decode_user_token(credentials.credentials)
    user_id = payload.get("sub")
    if not isinstance(user_id, str) or not user_id:
        raise _unauthorized("Invalid token subject")

    user = user_repository.find_by_id(user_id)
    if user is None:
        raise _unauthorized("User no longer exists")

    return AuthenticatedUser(
        user=user,
        session_id=payload.get("sid"),
        token_type=payload.get("type"),
    )


def _decode_user_token(token: str) -> dict:
    try:
        payload = jwt.decode(token, settings.JWT_SECRET_KEY, algorithms=["HS256"])
    except ExpiredSignatureError:
        raise _unauthorized("Token expired") from None
    except InvalidTokenError:
        raise _unauthorized("Invalid token") from None

    if payload.get("type") not in {"user_auth", "access"}:
        raise _unauthorized("Invalid token type")
    return payload


def _unauthorized(detail: str) -> HTTPException:
    return HTTPException(
        status_code=status.HTTP_401_UNAUTHORIZED,
        detail=detail,
        headers={"WWW-Authenticate": "Bearer"},
    )