import type { Subtract } from './math/subtract';
/**
 * ? HELPER
 *
 * @internal
 */
type _Internal_Flat_Fork<Tuple, Depth extends number> = Tuple extends any[] ? _Internal_Flat<Tuple, Subtract<Depth, 1>> : readonly [Tuple];
/**
 * ? MUTABLE
 *
 * @internal
 */
type _Internal_Flat<Tuple extends any[], Depth extends number> = Depth extends 0 ? [...Tuple] : Tuple extends [infer A, ...infer B] ? [..._Internal_Flat_Fork<A, Depth>, ..._Internal_Flat<B, Depth>] : [...Tuple];
/**
 * ? READONLY
 *
 * @internal
 */
type _Internal_FlatReadonly<Tuple extends readonly any[], Depth extends number> = Depth extends 0 ? readonly [...Tuple] : Tuple extends readonly [infer A, ...infer B] ? readonly [
    ..._Internal_Flat_Fork<A, Depth>,
    ..._Internal_FlatReadonly<B, Depth>
] : readonly [...Tuple];
/**
 * Recursively flatten an array up to a given depth.
 *
 * @param Tuple - The array to flatten.
 * @param Depth - The maximum recursion depth.
 * @defaultValue 1
 * @example
 * ```
 * type Foo = ['a0', [0, 1], 'a1', [0, ['b0']], 'a2']
 * type FooFlatDepth1 = Flat<Foo> // ["a0", 0, 1, "a1", 0, ["b0"], "a2"]
 * type FooFlatDepth2 = Flat<Foo, 2> // ["a0", 0, 1, "a1", 0, "b0", "a2"]
 * ```
 */
export type Flat<Tuple extends any[] | readonly any[], Depth extends number = 1> = Tuple extends any[] ? _Internal_Flat<Tuple, Depth> : _Internal_FlatReadonly<Tuple, Depth>;
export {};