import { curryN } from "@unboxing/function";
import { indexOf } from "./indexOf";

interface Intersection {
  <T>(list1: ArrayLike<T>, list2: ArrayLike<T>): T[];
  <T>(list1: ArrayLike<T>): (list2: ArrayLike<T>) => T[];
}

/**
 * Combines two array into a set (i.e. no duplicates) composed of those
 * elements common to both arrays.
 */
export const intersection = curryN(2, <T>(a: ArrayLike<T> = [], b: ArrayLike<T> = []) => {
  const result = [];

  for (let i = 0; i < a.length; i++) {
      if (indexOf(a[i], b) >= 0) {
          result.push(a[i]);
      }
  }

  return result;
}) as Intersection