API Suggestion: Add TownPreDeleteCmdEvent and NationPreDeleteCmdEvent

[galacticwarrior9]

Please explain your feature request to the best of your abilities:

Follows the same principle as the existing TownPreUnclaimEvent. The new events would be called in /t delete and /n delete respectively.

PreDeleteTownEvent and PreNationDeleteEvent are called in the database handler, which means players are not sent the cancellation message. This can leave players confused (see #6178 for a similar problem). Some may also only want to prevent players from deleting via command, without interfering with deletions triggered elsewhere in the plugin.

[Warriorrrr]

Instead of a new event, why not just add the deleter to it so that the message can be sent?

[galacticwarrior9]

Sure, that would help. However, there is still the problem of the existing events being called by Towny when it deletes a town/nation internally. I would prefer not to interfere with these deletions as it isn't necessary for my use-case and can lead to odd issues.

[Warriorrrr]

Having a deletion cause exposed would help with that

[galacticwarrior9]

I agree, that would be great

[LlmDl]

I'm kinda thinking this one is going to have a fairly big refactor behind it. The issue I ran into before was that the removeTown and removeNation methods don't return anything for the other methods to work off of.

We could change those (and other things) over to booleans so some of the methods could deal with failures.

The other thing that's a bit of an issue is that towny can send a town/nation to be deleted for very good reasons (like having no residents or no towns,) and another plugin can currently stop that object being deleted.

We could also create removeTown(Town, new DeleteCause(Player, DeleteReason.TOWN_DELETE_COMMAND) and simply pass in a new DeleteCause object. DeleteCause would need to support a Player being nullable, and probably have a enum of actual reasons backing it. Then removeTown(Town, Boolean, DeleteCause) could send back an error message when the event is cancelled when DeleteCause.getPlayer() isn't null. It could also skip throwing the event entirely when the DeleteCause.getDeleteReason() is something critical where the TownyObject really shouldn't exist.