import { curryN } from "@unboxing/function";
import { isArray,isArrayLike } from "@unboxing/is";
import { sliceArray } from "./slice";

interface Concat {
  (list1: string, list2: string): string;
  <U, V>(list1: ArrayLike<U>, list2: ArrayLike<V>): (U | V)[];
  (list1: string): (list2: string) => string;
  <U>(list1: ArrayLike<U>): <V>(list2: ArrayLike<V>) => (U | V)[];
}

/**
 * Returns the result of concatenating the given arrays or strings.
 */
export const concat = curryN(2, <U, V>(a: ArrayLike<U> = [], b: ArrayLike<V> = []) => {
  if (isArray(a)) {
      return a.concat(b);
  }

  if (isArrayLike(a)) {
      const resultArr: (U | V)[] = sliceArray(0, a.length, a);

      for (let i = 0; i < b.length; i++) {
          resultArr.push(b[i]);
      }

      return resultArr;
  }

  return (a as string) + b;
}) as Concat