/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

// Takes "<number>:<jitter>" (jitter as absolute value or percentage,
// e.g. "1000:20%") and returns a randomized number around the base
// value. Anything else is returned unchanged.
export function jitter(sApprox: string | number): string | number {
  if (!sApprox) {
    return sApprox;
  }

  if (typeof sApprox !== 'string') {
    return sApprox;
  }

  if (sApprox.indexOf(':') < 0) {
    return sApprox;
  }

  const inputs = sApprox.split(':');
  const nb = parseInt(inputs[0], 10);
  const approxPercent = parseInt(inputs[1], 10);

  let approx = approxPercent;
  if (inputs[1].indexOf('%') >= 0) {
    approx = (nb * approxPercent) / 100;
  }

  return Math.max(0, nb - approx + Math.random() * 2 * approx);
}