Refactor game validity checks

[Askaholic]

When I added the coop validity checks initially, I added them all on the base Game class with a switch that checked the featured mod. However in hindsight, I should have made use of the existing object oriented design and put the coop checks in the CoopGame subclass. This would have the added benefit of decoupling the coop validity checks from the featured mod. We should also do a similar refactor for the "faf validity checks" as well.

Related code:

server/server/games/game.py

Line 587 in e4ca993

elif self.game_mode == FeaturedModType.COOP:

[46bit]

@Askaholic Hey. I had a look into this one and want to check the approach I'm thinking of.

The default Game.game_mode is FeaturedModType.FAF. But https://github.com/FAForever/server/blob/e4ca993/server/game_service.py#L155 instantiates a CustomGame for that game mode. As far as I can tell, Game isn't an abstract class but may as well be.

The logic in validate_game_settings is shared for all game modes, so it doesn't make sense to duplicate that. I think we're better off adding a validate_game_mode_settings method:

• The existing logic in Game._validate_coop_game_settings would move to CoopGame.validate_game_mode_settings.
• The existing logic in Game._validate_faf_game_settings would move to Game.validate_game_mode_settings or CustomGame.validate_game_mode_settings.

Remaining question is whether Game can practically be made abstract or not. Do you have any opinions on that?

[Askaholic]

Yea that sounds like what I had in mind, checks that happen for all games (like for unrated maps or mods etc) should happen on the base class, and checks that are specific to some other type of game like a coop game or a ladder game should happen on those classes. Right now there is a direct mapping between featured mod and game class, but that's going to change with TMM.

With the addition of TMM, we are going to (eventually) get rid of the ladder1v1 featured mod altogether, and just use the faf featured mod, but we will still use the LadderGame class for handling the matchmaker specific game logic. And there are also plans to generalize the logic regarding coop, so that we can more easily support coop games that are played using other featured mods, like nomads coop for example.