Add beatmap characteristic

[peddermaster2]

Feature request

It would be helpful to get selected beatmap characteristic where we have the difficulty.

Motivation

This is helpful for displaying if it is not "Standard", e.g. "Lawless".

I also use it to log the result of the played beatmap to a local database for analysis. And for levels with multiple characteristics it is currently impossible to know which one was selected.

[peddermaster2]

I have made a try in https://github.com/peddermaster2/beatsaber-http-status/tree/add-characteristic .
Should I create a PR?

[peddermaster2]

@opl- I have also noticed while coding this, that the map characteristic are encoded in the "mode" field. The documentation lists the possible values but all combinations with Lightshow and Lawless (or any other modded characteristic) are missing.

[opl-]

Indeed, this is already part of game.mode. As a comment in the code states, // This was an awful idea. It exists for historical purposes, as back in Beat Saber 0.11.1 that's the string the game had in the setup data (link to line in 1.0.0).

Lightshow and Lawless can both already appear in there, as can 90/360. The documentation just hasn't been updated to include them.

I think the best solution here is to add beatmap.characteristic as per your suggestion (linking to BSMG wiki in protocol.md for current list of characteristics), and update the documentation to explain that game.mode starts with the current mode followed by the characteristic, and that if the characteristic is wanted beatmap.characteristic should be used instead.

This keeps backwards compatibility, allows people to easily find out what the mode is by checking the beginning of the string (or getting a substring using length of beatmap.characteristic if exact value is really needed), and of course makes the characteristic trivial to retrieve. I don't think anyone has much of a use for the mode (solo/party/multiplayer) anyway, other than knowing if it's multiplayer or not.

If no one has any objections I'll implement these changes over the weekend.

[opl-]

So, that was a very long weekend... Won't get published until #82 either gets fixed or tires me out.