import { Inc } from "./math";

export type Head<T extends any[], D = never> = T extends [infer X, ...any[]] ? X : D;

export type Tail<T extends any[]> = ((...x: T) => void) extends ((x: any, ...xs: infer XS) => void) ? XS : never

export type Last<T extends any[], D = never> = {

0: D,

1: Head<T>,

2: Last<Tail<T>>,

}[T extends [] ? 0 : T extends [any] ? 1 : 2];

export type Cons<X, XS extends any[]> = ((h: X, ...args: XS) => void) extends ((...args: infer R) => void) ? R : [];

export type Reverse<L extends any[], X extends any[] = []> = {

0: X,

1: Reverse<Tail<L>, Cons<Head<L>, X>>

}[L extends [] ? 0 : 1]

export type Concat<A extends any[], B extends any[], R extends any[] = []> = {

0: Reverse<R>,

1: Concat<Tail<A>, B, Cons<Head<A>, R>>

2: Concat<A, Tail<B>, Cons<Head<B>, R>>

}[A extends [] ? B extends [] ? 0 : 2 : 1];

export type Zip<A extends any[], B extends any[], R extends any[] = []> = {

0: Reverse<R>,

1: Zip<Tail<A>, Tail<B>, Cons<[Head<A>, Head<B>], R>>

}[A extends [] ? 0 : B extends [] ? 0 : 1];

export type Take<N extends number, T extends any[], R extends any[] = []> = {

0: Reverse<R>,

1: Take<N, Tail<T>, Cons<Head<T>, R>>

}[T extends [] ? 0 : R["length"] extends N ? 0 : 1];

export type Group<N extends number, T extends any[], R1 extends any[] = [], R2 extends any[] = []> = {

0: Reverse<R2>,

1: Group<N, T, [], Cons<Reverse<R1>, R2>>,

2: Group<N, Tail<T>, Cons<Head<T>, R1>, R2>

}[T extends [] ? R1 extends [] ? 0 : 1 : (R1["length"] extends N ? 1 : 2)];

export type Drop<N extends number, T extends any[], R extends any[] = []> = {

0: T,

1: Drop<N, Tail<T>, Cons<Head<T>, R>>

}[T extends [] ? 0 : R["length"] extends N ? 0 : 1];

export type Flat<T extends any[][], R1 extends any[] = [], R2 extends any[] = []> = {

0: Reverse<R2>,

1: Flat<Tail<T>, Head<T, []>, R2>,

2: Flat<T, Tail<R1>, Cons<Head<R1>, R2>>

}[T extends [] ? R1 extends [] ? 0 : 2 : (R1 extends [] ? 1 : 2)];

export type Repeat<T, N extends number, R extends any[] = []> = {

0: R,

1: Repeat<T, N, Cons<T, R>>

}[R["length"] extends N ? 0 : 1];

export type Range<A extends number, B extends number, R extends any[] = []> = {

0: Reverse<Cons<A, R>>,

1: Range<Inc<A>, B, Cons<A, R>>

}[A extends B ? 0 : 1];