(function ($) {
  $('#edit-start-date').after($('#edit-start-date-error'));
  $('#edit-end-date').after($('#edit-end-date-error'));
  $('#edit-retention-date').after($('#edit-retention-date-error'));
  
 $('.date_select').change(function() {
   dateCheck($(this));
 });
  
 function dateCheck(e) {
   var startValid = false,
       endValid = false,
       startValue = $('#edit-start-date').val(),
       endValue = $('#edit-end-date').val();
   $('#edit-start-date-error').css('display', 'none');
   $('#edit-end-date-error').css('display', 'none');
   if (startValue) {
       startValid = isDate(startValue);
     if (!startValid) {
       $('#edit-start-date-error').css('display', 'block');
     }
   }
  if (endValue) {
       endValid = isDate(endValue);
    if (!endValid) {
      $('#edit-end-date-error').css('display', 'block');
    }
   }
   
   if (!startValid || !endValid) {
     $('#edit-retention-date').val('');
     $('#edit-retention-date-error').css('display', 'none');
     return false;
   }
  
   dateCalculation();
 }
  
 function dateCalculation() {
   $('#edit-retention-date-error').css('display', 'none');
   var start = new Date(Date.parse($('#edit-start-date').val()));
   var end = new Date(Date.parse($('#edit-end-date').val()));
   
   if (end < start) {
     $('#edit-retention-date').val('');
     $('#edit-retention-date-error').css('display', 'block');
     return false;
   }
   
   // Add 3 years to start date
   start.setFullYear(start.getFullYear() + 3);
   var startPlusThree = new Date(start);
   
   // Add 1 year to end date
   end.setFullYear(end.getFullYear() + 1);
   var
     endPlusOne = new Date(end),
     retention = new Date(startPlusThree > endPlusOne ? startPlusThree : endPlusOne),
     retentionDisplay = (retention.getMonth() + 1).toString().padStart(2,'0') + '/' + retention.getDate().toString().padStart(2, '0') + '/' + (retention.getFullYear());
   
   $('#edit-retention-date').val(retentionDisplay);
   $('#edit-retention-date-error').css('display', 'none');
   
 }
  
 function isDate(value) {
    var
      monthString = value.substring(0,2),
      dayString = value.substring(3,5),
      yearString = value.substring(6,10),
      month = parseInt(value.substring(0,2), 10),
      day = parseInt(value.substring(3,5), 10),
      year = parseInt(value.substring(6,10), 10),
      result = false,
      // Create date validations
      today = new Date(),
      curYear = today.getFullYear(),
      dayValidate = new RegExp("^$|^([1-9]|0[1-9]|[12][0-9]|3[01]$)"),
      monthValidate = new RegExp("^$|^([1-9]|0[1-9]|1[012]$)"),
      // Year validation: leave room to append  "|" and years beyond 2020
      yearValidate = "^$|^(19[6-9][0-9]|20[012][0-9]",
      monthLength = [31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31];
   
    // Adjust month test for leap years.
    if (year % 400 == 0 || (year % 100 != 0 && year % 4 == 0)) {
      monthLength[1] = 29;
    }

    // Add additional years.
    let i = 2029;
    while (i < curYear) {
      yearValidate = yearValidate + "|" + i;
      i++;
    }
    yearValidate = new RegExp(yearValidate + ")$");

    // Start verifying date.
   result = dayValidate.test(dayString) &&
      monthValidate.test(monthString) &&
      yearValidate.test(yearString) &&
      (day > 0 && day <= monthLength[month - 1]);
   
   return result;
  }
  
}(jQuery));