"use strict";

/*
 * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
 * or more contributor license agreements. Licensed under the Elastic License
 * 2.0 and the Server Side Public License, v 1; you may not use this file except
 * in compliance with, at your election, the Elastic License 2.0 or the Server
 * Side Public License, v 1.
 */

/**
 * Subtracts two numbers. If at least one array of numbers is passed into the function, the function will be applied index-wise to each element.
 * @param {(number|number[])} a a number or an array of numbers
 * @param {(number|number[])} b a number or an array of numbers
 * @return {(number|number[])} The difference of `a` and `b` if both are numbers or an array of differences applied index-wise to each element.
 * @throws `'Array length mismatch'` if `a` and `b` are arrays with different lengths
 * @example
 * subtract(6, 3) // returns 3
 * subtract([10, 20, 30, 40], 10) // returns [0, 10, 20, 30]
 * subtract(10, [1, 2, 5, 10]) // returns [9, 8, 5, 0]
 * subtract([14, 42, 65, 108], [2, 7, 5, 12]) // returns [12, 35, 52, 96]
 */

function subtract(a, b) {
  if (Array.isArray(a) && Array.isArray(b)) {
    if (a.length !== b.length) throw new Error('Array length mismatch');
    return a.map((val, i) => val - b[i]);
  }
  if (Array.isArray(a)) return a.map(a => a - b);
  if (Array.isArray(b)) return b.map(b => a - b);
  return a - b;
}
module.exports = {
  subtract
};