import { ExtractNestedArrayType } from "../_internal/types.mjs";

//#region src/array/flat-map.d.ts
/**
 * Maps each element through `iteratee` and flattens the resulting arrays. When
 * the optional `depth` (third argument) is omitted — or explicitly set to
 * `Number.POSITIVE_INFINITY` — the result is *fully* flattened. This deviates
 * from `Array.prototype.flatMap`, whose default depth is `1`. Passing a finite
 * `depth` flattens to exactly that level; omitting it or passing `Infinity`
 * flattens fully.
 *
 * Negative, `NaN`, and non-integer `depth` values follow
 * `Array.prototype.flat` semantics (negative/`NaN` → no flattening, non-integer
 * → floored).
 *
 * For an async iteratee, use `flatMapAsync` instead.
 * @param array - The array to map and flatten.
 * @param iteratee - Produces the new array elements. Receives the item, its index, and the source array.
 * @returns A new array with the mapped, flattened elements.
 * @example
 * // Default — deep flatten
 * flatMap([1, 2, 3], (n) => [[n, n]]);
 * // [1, 1, 2, 2, 3, 3]
 * @example
 * // Explicit depth of 1 — matches `Array.prototype.flatMap`'s default
 * flatMap([1, 2, 3], (n) => [[n, n]], 1);
 * // [[1, 1], [2, 2], [3, 3]]
 * @example
 * // Depth of 2 flattens two levels
 * flatMap([1, 2], (n) => [[[n, n]]], 2);
 * // [[1, 1], [2, 2]]
 * @example
 * // Depth of 0 just maps — no flattening
 * flatMap([1, 2], (n) => [n, n], 0);
 * // [[1, 1], [2, 2]]
 * @example
 * // `Infinity` is equivalent to omitting `depth`
 * flatMap([[1, [2, [3, [4]]]]], (item) => item, Number.POSITIVE_INFINITY);
 * // [1, 2, 3, 4]
 * @example
 * // The iteratee receives (item, index, array)
 * flatMap(['a', 'b'], (item, index) => [item, index]);
 * // ['a', 0, 'b', 1]
 */
declare function flatMap<T, U>(array: readonly T[], iteratee: (item: T, index: number, array: readonly T[]) => U): ExtractNestedArrayType<U>[];
declare function flatMap<T, U, D extends number>(array: readonly T[], iteratee: (item: T, index: number, array: readonly T[]) => U, depth: D): FlatArray<U[], D>[];
//#endregion
export { flatMap };