feat(Interactions): add autocomplete api types

[suneettipirneni]

Please describe the changes this PR makes and why it should be merged:

Adds very experimental support for autocomplete.

Reference Discord API Docs PRs or commits:

• document autocomplete discord/discord-api-docs#3996

[vladfrangu]

Initial review - don't forget v8 :D

[suneettipirneni]

So unfortunately typescript won't be able to enforce that the command has either a choices array OR a autocomplete boolean, without breaking the existing union. So it's just going to be appended onto the APIApplicationCommandArgumentOptions and will need to be enforced during runtime.

[ckohen]

When sending only typescript can enforce either choices or autocomplete via a discriminated union. On the receiving side there's not much of a benefit to having a discriminated union, but it could still work, just means people have to build type guards

[suneettipirneni]

When sending only typescript can enforce either choices or autocomplete via a discriminated union. On the receiving side there's not much of a benefit to having a discriminated union, but it could still work, just means people have to build type guards

Even on the sending side with a discriminated union it doesn't work properly, it's because TS unions aren't 'exclusive or' unions. That means if multiple types with the same tag (type) in this case are used, the discriminated union will no longer function properly because there's no longer a 1-1 mapping of tags to types.

[suneettipirneni]

Here's a TS playground that shows this:
https://www.typescriptlang.org/play?#code/JYOwLgpgTgZghgYwgAgMoEcCucooN4BQyxyYAngA4QBcyA5AM5Y4R0DcRJANhCAOZgAFrRCYAtgCNoHAL4EC5KsgDCwKAh7IAvMkLFFNZACIEajRCMAaTlDgATYJgYjxUqNbkFQkWIhQBBEAB7IWhVdU09EgNaOlMI1msSZDhg0KgAJXtHZ2RRSWkCTwM0QTglHXDzZAAfZECQwTCzTTqMbFwOAgQgkAYwZDs4MDhaVDKK3U59SkM4lsTplLSmzOynWgBGAAZtpJJbBw3kHb3kAHpz5AAhRuRDnOW7ZcboLKOGFNwUri4ggHcIM9VigpAg4E4UAAVVDITAgYC9T4sEB0AZiTBgbC-MjICAADw0TmAADcIAA6IpAA

[ckohen]

You need a discriminated union explicitly preventing the other property. But I realized there's no identifier for which we would be using without adding a nonexistent prop. How does discord handle it if you send both anyways? Maybe a type generic could work?

[suneettipirneni]

You need a discriminated union explicitly preventing the other property. But I realized there's no identifier for which we would be using without adding a nonexistent prop. How does discord handle it if you send both anyways? Maybe a type generic could work?

Maybe I'm missing something, but I don't know how a generic type would help here, since generics don't change which fields are shown and which ones are not shown. Generics only affect already existing fields. As for how discord handles it I'm not entirely sure since I haven't tested it, but according the docs PR, choices can't be present when autocomplete is true.

[ckohen]

This is what I mean by using generics

[suneettipirneni]

This is what I mean by using generics

I see how this can work, however, how would you integrate this into the APIApplicationCommandOption type union?

[suneettipirneni]

Alright so, somehow I was able to get typescript to typecheck the autocomplete variants. I basically made the autocomplete property of type never on all types except on choice types. When choices are provided, autocomplete is defined as false or undefined. If autocomplete is present choices is defined as never. This results in invalid variants not being allowed by typescript.

[vladfrangu]

More issues, please also port the fixes to v9 :D

Stale