random.ts

/**
 * Please refer to the terms of the license agreement in the root of the project
 *
 * (c) 2024 Feedzai
 */
import { isBoolean, isUndefined } from "../typed";

/**
 * Produces a random number between the inclusive lower and upper bounds.
 * If only one argument is provided a number between 0 and the given number is returned.
 * If floating is true, or either lower or upper are floats, a floating-point number is returned instead of an integer.
 *
 * @example
 *
 * random(0, 5)
 * // => an integer between 0 and 5
 *
 * random(5)
 * // => also an integer between 0 and 5
 *
 * random(5, true)
 * // => a floating-point number between 0 and 5
 *
 * random(1.2, 5.2)
 * // => a floating-point number between 1.2 and 5.2
 *
 * random()
 * // => 0 or 1
 *
 * random(-1)
 * // => -1 or 0
 *
 * @export
 * @param {number} [lower=0]
 * @param {(number | boolean)} [upper]
 * @param {boolean} [floating]
 * @returns {number} a random number
 */
export function random(lower: number = 0, upper?: number | boolean, floating?: boolean): number {
  if (isBoolean(upper)) {
    floating = upper;
    upper = undefined;
  }

  if (isNaN(upper as number)) {
    upper = lower < 0 ? 0 : 1;
  }

  if (isUndefined(floating)) {
    floating = !Number.isInteger(lower) || !Number.isInteger(upper as number);
  }

  const randomNumber = Math.random() * ((upper as number) - lower) + lower;
  return floating ? randomNumber : Math.round(randomNumber);
}