/*
Script for Google Forms.

"Fixes" other... field in checkbox and radio groups.

Whenever form is submitted and "other" option is selected,
input goes to corresponding checkbox/radio group in form
as a new option, so next respondents don't have to put it
in manually.

To use copy-paste code to your forms project and assign
onSubmit function to project's "on form submit" trigger.
*/

function onSubmit(event) {
  var form = event.source;
  var response= event.response;

  var checkboxes = form.getItems(FormApp.ItemType.CHECKBOX);
  var radios = form.getItems(FormApp.ItemType.MULTIPLE_CHOICE);
  var choosers = checkboxes.concat(radios);

  choosers.filter(function(c) {
    var type = c.getType();
    return (type == FormApp.ItemType.CHECKBOX) ? c.asCheckboxItem().hasOtherOption():
           (type == FormApp.ItemType.MULTIPLE_CHOICE) ? c.asMultipleChoiceItem().hasOtherOption():
           false;
  });


  for (i = 0; i < choosers.length; i++) {
    var chooser = choosers[i];
    chooser = (chooser.getType() == FormApp.ItemType.CHECKBOX) ? chooser.asCheckboxItem():
              (chooser.getType() == FormApp.ItemType.MULTIPLE_CHOICE) ? chooser.asMultipleChoiceItem():
              "Something went wrong. It is definitely Google's fault!";


    var chooserResponse = response.getResponseForItem(choosers[i]);
    if (chooserResponse == null) return;

    chooserResponse = chooserResponse.getResponse();
    var otherField = chooserResponse[chooserResponse.length-1];
    var choices = chooser.getChoices();

    if (!mContains(choices, otherField)) {
      var newChoice = chooser.createChoice(otherField);
      choices.push(newChoice);
      chooser.setChoices(choices);
    }
  }

}

function mContains(choices, item) {
  for (i = 0; i < choices.length; i++) {
    if (choices[i].getValue() == item) {return true;}
  }
  return false;
}