from fastapi import Depends, HTTPException, Request, status
from itsdangerous import BadSignature, SignatureExpired, URLSafeTimedSerializer
from sqlalchemy.orm import Session

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

_serializer = URLSafeTimedSerializer(settings.secret_key, salt="habit-session")

SESSION_MAX_AGE_SECONDS = 60 * 60 * 24 * 30  # 30일


def create_session_token(user_id: int) -> str:
    return _serializer.dumps({"user_id": user_id})


def get_session_user_id(request: Request) -> int | None:
    token = request.cookies.get(settings.session_cookie_name)
    if not token:
        return None
    try:
        data = _serializer.loads(token, max_age=SESSION_MAX_AGE_SECONDS)
    except (BadSignature, SignatureExpired):
        return None
    return data.get("user_id")


def require_login(request: Request, db: Session = Depends(get_db)) -> User:
    user_id = get_session_user_id(request)
    user = db.get(User, user_id) if user_id is not None else None
    if user is None:
        raise HTTPException(status_code=status.HTTP_401_UNAUTHORIZED, detail="로그인이 필요합니다")
    return user


def get_current_user_optional(request: Request, db: Session) -> User | None:
    user_id = get_session_user_id(request)
    return db.get(User, user_id) if user_id is not None else None


def is_logged_in(request: Request) -> bool:
    return get_session_user_id(request) is not None