var parse = require('../parse/index.js')

/**
 * @category Common Helpers
 * @summary Compare the two dates reverse chronologically and return -1, 0 or 1.
 *
 * @description
 * Compare the two dates and return -1 if the first date is after the second,
 * 1 if the first date is before the second or 0 if dates are equal.
 *
 * @param {Date|String|Number} dateLeft - the first date to compare
 * @param {Date|String|Number} dateRight - the second date to compare
 * @returns {Number} the result of the comparison
 *
 * @example
 * // Compare 11 February 1987 and 10 July 1989 reverse chronologically:
 * var result = compareDesc(
 *   new Date(1987, 1, 11),
 *   new Date(1989, 6, 10)
 * )
 * //=> 1
 *
 * @example
 * // Sort the array of dates in reverse chronological order:
 * var result = [
 *   new Date(1995, 6, 2),
 *   new Date(1987, 1, 11),
 *   new Date(1989, 6, 10)
 * ].sort(compareDesc)
 * //=> [
 * //   Sun Jul 02 1995 00:00:00,
 * //   Mon Jul 10 1989 00:00:00,
 * //   Wed Feb 11 1987 00:00:00
 * // ]
 */
function compareDesc (dirtyDateLeft, dirtyDateRight) {
  var dateLeft = parse(dirtyDateLeft)
  var timeLeft = dateLeft.getTime()
  var dateRight = parse(dirtyDateRight)
  var timeRight = dateRight.getTime()

  if (timeLeft > timeRight) {
    return -1
  } else if (timeLeft < timeRight) {
    return 1
  } else {
    return 0
  }
}

module.exports = compareDesc