import assertString from './util/assertString';
/* eslint-disable max-len */
// from http://goo.gl/0ejHHW

var iso8601 = /^([\+-]?\d{4}(?!\d{2}\b))((-?)((0[1-9]|1[0-2])(\3([12]\d|0[1-9]|3[01]))?|W([0-4]\d|5[0-3])(-?[1-7])?|(00[1-9]|0[1-9]\d|[12]\d{2}|3([0-5]\d|6[1-6])))([T\s]((([01]\d|2[0-3])((:?)[0-5]\d)?|24:?00)([\.,]\d+(?!:))?)?(\17[0-5]\d([\.,]\d+)?)?([zZ]|([\+-])([01]\d|2[0-3]):?([0-5]\d)?)?)?)?$/;
/* eslint-enable max-len */

var isValidDate = function isValidDate(str) {
  // str must have passed the ISO8601 check
  // this check is meant to catch invalid dates
  // like 2009-02-31
  // first check for ordinal dates
  var ordinalMatch = str.match(/^(\d{4})-?(\d{3})([ T]{1}\.*|$)/);

  if (ordinalMatch) {
    var oYear = Number(ordinalMatch[1]);
    var oDay = Number(ordinalMatch[2]); // if is leap year

    if (oYear % 4 === 0 && oYear % 100 !== 0 || oYear % 400 === 0) return oDay <= 366;
    return oDay <= 365;
  }

  var match = str.match(/(\d{4})-?(\d{0,2})-?(\d*)/).map(Number);
  var year = match[1];
  var month = match[2];
  var day = match[3];
  var monthString = month ? "0".concat(month).slice(-2) : month;
  var dayString = day ? "0".concat(day).slice(-2) : day; // create a date object and compare

  var d = new Date("".concat(year, "-").concat(monthString || '01', "-").concat(dayString || '01'));

  if (month && day) {
    return d.getUTCFullYear() === year && d.getUTCMonth() + 1 === month && d.getUTCDate() === day;
  }

  return true;
};

export default function isISO8601(str, options) {
  assertString(str);
  var check = iso8601.test(str);
  if (!options) return check;
  if (check && options.strict) return isValidDate(str);
  return check;
}