Confusion

using System;
using UnityEngine;
using Facebook.Unity;
using GameSparks.Api.Requests;

public class AuthManagerFB {
    static bool loggedIn;

    /// <summary>
    /// Pass all actions that require authenticated user as a callback.
    /// </summary>
    /// <param name="onSuccess">Called if/once user has authenticated</param>
    /// <param name="onError">Called on failure</param>
    /// <param name="showDialog">Whether or not to show the Facebook-login dialog if user has not authenticated</param>
    /// <example>
    /// <code>
    /// ifAuthenticated(() => { /* User authenticated, do something */ },
    ///   onError: msg => Debug.Log("Error: " + msg),
    ///   showDialog: true);
    /// </code>
    /// </example>
    public void ifAuthenticated(Action onSuccess, Action<string> onError = null, bool showDialog = false) {
        if (loggedIn) {
            onSuccess();
            return;
        }
        if (onError == null) onError = s => {};

        Action doGameSparksLogin = () => {
            new FacebookConnectRequest().SetAccessToken(AccessToken.CurrentAccessToken.TokenString).Send(response => {
                if (response.HasErrors) {
                    onError("GameSpark login failed");
                } else {
                    Debug.Log("Logged in as " + response.UserId);
                    loggedIn = true;

                    onSuccess();
                }
            });
        };

        InitDelegate doFacebookLogin = () => {
            if (FB.IsLoggedIn)
                doGameSparksLogin();
            else if (showDialog) {
                FB.LogInWithReadPermissions(new string[] { "public_profile", "email", "user_friends" }, loginResult => {
                    if (FB.IsLoggedIn)
                        doGameSparksLogin();
                    else {
                        Debug.Log("Facebook login error: " + loginResult.Error);
                        onError("Facebook login failed");
                    }
                });
            } else
                onError("Not logged in");
        };

        if (FB.IsInitialized)
            doFacebookLogin();
        else {
            try {
                FB.Init(doFacebookLogin);
            } catch (Exception e) {
                Debug.LogWarning("Facebook ERROR: " + e.Message);
                onError("Facebook login failed");
            }
        }
    }
}