/reminder list fails if no reminders

[Zabuzard]

Issue

When using the command /reminder list to show all current pending reminders for the user, the command throws an exception when the user has no pending reminders at the moment.

StackTrace

java.lang.IllegalArgumentException: 1 > 0
  at java.base/java.lang.Math.clamp(Math.java:2221)
  at org.togetherjava.tjbot.features.reminder.ReminderCommand.createPendingRemindersPage(ReminderCommand.java:223)
  at org.togetherjava.tjbot.features.reminder.ReminderCommand.handleListCommand(ReminderCommand.java:207)
  at org.togetherjava.tjbot.features.reminder.ReminderCommand.onSlashCommand(ReminderCommand.java:119)
  at org.togetherjava.tjbot.features.system.BotCore.lambda$onSlashCommandInteraction$0(BotCore.java:260)
  at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1090)
  at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:614)
  at java.base/java.lang.Thread.run(Thread.java:1474)

Reproduce

Start the bot locally, do not use /reminder create. Instead, use /reminder list right away. Thats all, the exception should be thrown now.

Bug

The issue is that this code section in ReminderCommand.java:223

calls Math.clamp(x, 1, 0), i.e. min = 1 and max = 0. That makes little sense, hence the crash.

Fix

Funnily enough the code is already prepared to handle the case correctly, just a few lines later it has

if (pendingReminders.isEmpty()) {
  remindersEmbed.setDescription("No pending reminders");

We just have to make sure that totalPages is at least 1. That can also be justified logically as even with nothing to show, we at least want to show a single page. So we just change

int totalPages = Math.ceilDiv(pendingReminders.size(), REMINDERS_PER_PAGE);

into

int totalPages = Math.ceilDiv(pendingReminders.size(), REMINDERS_PER_PAGE);
totalPages = Math.max(1, totalPages);

which ensures it is at least 1. The rest of the code should then work out of the box already.

[suryatejess]

I’d like to work on this.

[Zabuzard]

awesome, enjoy :)

[Zabuzard]

@suryatejess looks like @Zachdehooge went ahead and just made a PR for it.
What is your current progress, did you start already?