type A = {
  A: 'a'; B: 'b'; C: 'c'; D: 'd'; E: 'e'; F: 'f'; G: 'g'; H: 'h'; I: 'i'; J: 'j';
  K: 'k'; L: 'l'; M: 'm'; N: 'n'; O: 'o'; P: 'p'; Q: 'q'; R: 'r'; S: 's'; T: 't';
  U: 'u'; V: 'v'; W: 'w'; X: 'x'; Y: 'y'; Z: 'z';
};

type KebabCase<S extends string, Acc extends string = ""> =
  S extends `${infer Head}${infer Rest}` ? Head extends "-" | "_" ? KebabCase<Rest, `${Acc}${Head}`> :
  Head extends keyof A ? KebabCase<Rest, `${Acc}${Acc extends '' ? '' : '-'}${A[Head]}`> : 
  KebabCase<Rest, `${Acc}${Head}`> : Acc

import type { Equal, Expect } from '@type-challenges/utils'

type cases = [
  Expect<Equal<KebabCase<'FooBarBaz'>, 'foo-bar-baz'>>,
  Expect<Equal<KebabCase<'fooBarBaz'>, 'foo-bar-baz'>>,
  Expect<Equal<KebabCase<'foo-bar'>, 'foo-bar'>>,
  Expect<Equal<KebabCase<'foo_bar'>, 'foo_bar'>>,
  Expect<Equal<KebabCase<'Foo-Bar'>, 'foo--bar'>>,
  Expect<Equal<KebabCase<'ABC'>, 'a-b-c'>>,
  Expect<Equal<KebabCase<'-'>, '-'>>,
  Expect<Equal<KebabCase<''>, ''>>,
  Expect<Equal<KebabCase<'😎'>, '😎'>>,
]