/**
 * Adds a random offset to a number within a certain percentage
 * @example
 * // Returns between 95-105
 * addOffset(100, 5);
 * @example
 * // Returns between 63-77
 * addOffSet(70, 10);
 * @param midpoint The number to be the midpoint of the offset range
 * @param percentage The percentage (in a range of 0-100) to offset
 */
export function addOffset(midpoint: number, percentage: number): number {
  const maxPercent = 100;
  if (percentage < 0 || percentage > maxPercent) {
    return midpoint;
  }

  const offset: number = midpoint * (percentage / maxPercent);

  // Double the range to account for both sides of the midpoint.
  // tslint:disable-next-line:no-magic-numbers
  return midpoint + (Math.random() * (offset * 2) - offset);
}