'use strict';
import type { NestedArray } from './commonTypes';

export function flattenArray<T>(array: NestedArray<T>): T[] {
  if (!Array.isArray(array)) {
    return [array];
  }
  const resultArr: T[] = [];

  const _flattenArray = (arr: NestedArray<T>[]): void => {
    arr.forEach((item) => {
      if (Array.isArray(item)) {
        _flattenArray(item);
      } else {
        resultArr.push(item);
      }
    });
  };
  _flattenArray(array);
  return resultArr;
}

export const has = <K extends string>(
  key: K,
  x: unknown
): x is typeof x & { [key in K]: unknown } => {
  if (typeof x === 'function' || typeof x === 'object') {
    if (x === null || x === undefined) {
      return false;
    } else {
      return key in x;
    }
  }
  return false;
};