team-9/backend/auth/session.py

import base64
import datetime
import os
import requests

SPOTIFY_CLIENT_ID = os.getenv("SPOTIFY_CLIENT_ID")
SPOTIFY_CLIENT_SECRET = os.getenv("SPOTIFY_CLIENT_SECRET")

class SessionData():
    __access_token: str
    __refresh_token: str
    __expires_in: int 
    __creation_date: datetime.datetime

    def __init__(self, __access_token, __refresh_token, __expires_in, __creation_date = None):
        self.__access_token = __access_token
        self.__refresh_token = __refresh_token
        self.__expires_in = __expires_in
        self.__creation_date = __creation_date or datetime.datetime.now()

    def nearly_expired(self, before=30):
        delta_time = datetime.datetime.now() -  self.__creation_date
        return delta_time.seconds > self.__expires_in - before
    
    def is_expired(self):
        return self.nearly_expired(0)

    def refresh(self):
        token_url = "https://accounts.spotify.com/api/token"
        headers = {
            "Authorization": "Basic " + base64.encode(SPOTIFY_CLIENT_ID + ":" + SPOTIFY_CLIENT_SECRET),
            "Content-Type": "application/json"
        }
        data = {
            "refresh_token": self.__refresh_token,
            "grant_type": "refresh_token"
        }

        try:
            response = requests.post(token_url, json=data, headers=headers)
            response.raise_for_status()
            result = response.json()

            # Assumendo che la risposta contenga questi campi
            self.__access_token = result["access_token"]
            self.__refresh_token = result.get("refresh_token", self.__refresh_token)
            self.__expires_in = result["expires_in"]
            self.__creation_date = datetime.datetime.now()

        except requests.exceptions.RequestException as e:
            print(f"Errore durante il refresh del token: {e}")
            raise e
    
    @property
    def access_tokens(self):
        if self.nearly_expired():
            self.refresh()

        return self.__access_token

    def __eq__(self, other):
        if not isinstance(other, SessionData):
            return False

        return (self.__access_token == other.__access_token and
                self.__refresh_token == other.__refresh_token and
                self.__expires_in == other.__expires_in)


class SessionManager():
    __current_session: SessionData
    __instance: "SessionManager" = None

    def __new__(cls, *args, **kwargs):
        if cls.__instance is None:
            cls.__instance = super(SessionManager, cls).__new__(cls)
        return cls.__instance
    
    def __init__(self):
        self.__current_session = None

    @classmethod
    def instance(cls):
        if cls.__instance is None:
            cls.__instance = SessionManager()
        
        return cls.__instance
    
    def set_session(self, __current_session):
        if self.__current_session is not None:
            return
        
        self.__current_session = __current_session

    def get_current_session(self):
        return self.__current_session