Type-level UUID

uuid.ts

type VersionChar =
    | '1' | '2' | '3' | '4' | '5';

type Char =
    | '0' | '1' | '2' | '3'
    | '4' | '5' | '6' | '7'
    | '8' | '9' | 'a' | 'b'
    | 'c' | 'd' | 'e' | 'f';

type Prev<X extends number> =
    [never, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, ...never[]][X];

type HasLength<S extends string, Len extends number> = [Len] extends [0]
    ? (S extends '' ? true : never)
    : (S extends `${infer C}${infer Rest}`
        ? (Lowercase<C> extends Char ? HasLength<Rest, Prev<Len>> : never)
        : never);

type Char4<S extends string> = true extends HasLength<S, 4> ? S : never;
type Char8<S extends string> = true extends HasLength<S, 8> ? S : never;
type Char12<S extends string> = true extends HasLength<S, 12> ? S : never;

type VersionGroup<S extends string> = S extends `${infer Version}${infer Rest}`
    ? (Version extends VersionChar
        ? (true extends HasLength<Rest, 3> ? S : never)
        : never)
    : never;

type NilUUID = '00000000-0000-0000-0000-000000000000';

type UUID<S extends string> = S extends NilUUID
    ? S
    : (S extends `${infer S8}-${infer S4_1}-${infer S4_2}-${infer S4_3}-${infer S12}`
        ? (S8 extends Char8<S8>
            ? (S4_1 extends Char4<S4_1>
                ? (S4_2 extends VersionGroup<S4_2>
                    ? (S4_3 extends Char4<S4_3>
                        ? (S12 extends Char12<S12>
                            ? S
                            : never)
                        : never)
                    : never)
                : never)
            : never)
        : never);

const getUser = <S extends string>(id: UUID<S>): void => console.log(id);

getUser('00000000-0000-0000-0000-000000000000'); // ✅ special Nil UUID
getUser('11111111-1111-0111-1111-111111111111'); // ✅ zero is a special case
getUser('11111111-1111-1111-1111-111111111111'); // ✅ version 1
getUser('11111111-1111-2111-1111-111111111111'); // ✅ version 2
getUser('11111111-1111-3111-1111-111111111111'); // ✅ version 3
getUser('11111111-1111-4111-1111-111111111111'); // ✅ version 4
getUser('11111111-1111-5111-1111-111111111111'); // ✅ version 5
getUser('11111111-1111-6111-1111-111111111111'); // ✅ version 6 doesn't exist