Limiting Login attempt in Flutter?

Question

I was wondering to find a way to limit login attempt in flutter/firebase. I want the user to be able attempt login post 5 minutes of waiting. I had searched through the internet and could not find any resources to help me out. Do you have any sample code for my references ?

Answer 1

You can stored the time in local storage and when user login again match the stored time with current time if it's less then current time then show error.

Answer 2

You can use SharedPreferences to store the last attempt of the user. Before the user can login you have to check if got a login restriction and have to pass 5 minutes.

In checkLogin you check if the user has a restriction, in this case if a login attempt time was stored. If not then he has no restriction and can login as usual. Else you check if 5 minutes have passed.

static const int fiveMinutes = 5 * 60 * 1000;
static const String lastAttemptKey = 'lastAttempt';

Future<void> checkLogin() async {
    // Initialize SharedPreferences
    SharedPreferences prefs = await SharedPreferences.getInstance();

    // Get last login attempt
    final int lastAttempt = prefs.getInt(lastAttemptKey);

    // Check if is not null
    if (lastAttempt != null) {
      // Get time now
      final int now = DateTime.now().millisecondsSinceEpoch;

      // Get the difference from last login attempt
      final int difference = now - lastAttempt;

      // Check if 5 minutes passed since last login attempt
      if (difference >= fiveMinutes) {
        // User can try to login again
        prefs.remove(lastAttemptKey);
        await login();
      } else {
        // Still in limit, show error
        print('You have to wait 5 minutes');
      }
    } else {
      // First try of user login
      await login();
    }
  }

Here the user can try to login. If it is succesfull navigate to the HomePage. Else you set the time of the login attempt to the local storage.

Future<void> login() async {
    if (login.success) {
      // Navigate to HomePage
    } else {
      // Initialize SharedPreferences
      SharedPreferences prefs = await SharedPreferences.getInstance();

      // Store attempt time
      prefs.setInt(lastAttemptKey, DateTime.now().millisecondsSinceEpoch);
    }
  }