// Pass Tracking Parameters to a Form on Another Page Using GTM
// http://zackphilipps.com/store-gclid-cookie-send-to-hubspot/

function getCookie(name) {
  var value = '; ' + document.cookie;
  var parts = value.split('; ' + name + '=');
  if (parts.length == 2)
    return parts.pop().split(';').shift();
}

function setCookie(name, value, days) {
  var date = new Date();
  date.setTime(date.getTime() + (days * 24 * 60 * 60 * 1000));
  var expires = '; expires=' + date.toGMTString();
  document.cookie = name + '=' + value + expires + ';path=/';
}

function getParam(p) {
  var match = RegExp('[?&]' + p + '=([^&]*)').exec(window.location.search);
  return match && decodeURIComponent(match[1].replace(/\+/g, ' '));
}

function assignTrackingParameterToCookie(fieldParam, formType) {
  var field = getParam(fieldParam),
    inputs;
  if(field) {
    setCookie(fieldParam, field, 365);
  }
  if(formType == 'gform') {
    inputs = document.querySelectorAll('.' + fieldParam + ' input[type="text"]');
    assignCookieValueToFormInput(fieldParam, inputs);
  } else if(formType == 'hubspot') {
    inputs = document.querySelectorAll('.hs-input[name="gclid__c"]');
    assignCookieValueToFormInput(fieldParam, inputs);
  }
}

function assignCookieValueToFormInput(fieldParam, inputs) {
  var field = getCookie(fieldParam),
    length = inputs.length;
  if(field && length) {
    for(var i = 0; i < length; i++) {
      inputs[i].value = field;
    }
  }
}

assignTrackingParameterToCookie('gclid', 'hubspot');