public final class FromUrlHelper {

    public static JSONObject getJSONObject(String url) throws IOException {
        if (Constants.debug) Log.d("API Call", url);
        JSONObject jsonObject = null;
        try {
            jsonObject = new JSONObject(FromUrlHelper.getJSONFromUrl(url));
        } catch (JSONException e) {
            e.printStackTrace();
        }

        return jsonObject;
    }
}

public class AuthService {
    private static AuthService ourInstance = null;

    public static AuthService getInstance() {
        if (ourInstance == null) {
            ourInstance = new AuthService();
        }

        return ourInstance;
    }

    private String currentSession;
    private boolean loggined;

    private AuthService() {
    }

    public boolean login(String email, String password) {

        if (!email.isEmpty() && !password.isEmpty()) {
            try {
                JSONObject result = FromUrlHelper.getJSONObject(Constants.serviceBaseUrl + "login?email=" + email + "&password=" + password);
                try {
                    int errorCode = result.getInt("errorCode");
                    if (errorCode == 0) {
                        this.currentSession = result.getString("sessionId");
                        loggined = true;
                        return true;
                    }
                } catch (JSONException e) {
                    e.printStackTrace();
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }

        return false;
    }

    public boolean logout() {
        loggined = false;
        this.currentSession = null;
        return true;
    }
}

AuthService authService = AuthService.getInstance();

if(authService.login("email","password")) {
    // do something
} else {
    // do something
}

        $customer = $this->entityManager->getRepository(Customer::class)->findOneBy(['email' => $request->get('email'), 'password' => md5($request->get('password')), 'eshop' => $eshop]);
        if ($customer) {
            /** @var Session $session */
            $session = $this->getSessionFromCustomer($customer);
            if(!$session) {
                $sessionId = $this->createSession($customer);
            } else {
                $sessionId = $session->getCode(); 
            }
            $response->errorCode = self::ERR_OK;
        } else {
            $sessionId = null;
            $response->errorCode = self::ERR_AUTH;
        }

        $response->sessionId = $sessionId;

        return new JsonResponse($response);