(function () {
  'use strict';

  window.HtmlHelpers = (function() {

    // `parseResponse` takes a raw HttpClient response and an options object.
    // Returns an object with `element` being an contextual fragment of the
    // HTML in the response and `ifPrefix` being the prefix that was used to
    // "unique-ify" the ids of the received HTML.
    // Original Response IDs can optionally be kept by adding `keepIds: true`
    // to the `options` object.
    function parseResponse(response, options) {
      options = options || {};

      return response.text().then(function (responseText) {
        var docFrag = document.createRange().createContextualFragment(responseText);
        var idPrefix;
        if (!options.keepIds) {
          idPrefix = _getIdPrefix();
          _prefixIds(docFrag, idPrefix);
        }
        return Promise.resolve({ idPrefix: idPrefix, element: docFrag });
      },
      function (error) {
        return Promise.reject(error);
      }).catch(function (error) { console.error(error); });
    }

    function _prefixIds(element, idPrefix) {
      var idAttrs = ['id', 'for', 'data-conditional-input', 'data-modal-trigger'];

      idAttrs.forEach(function(attr) {
        Array.from(element.querySelectorAll('[' + attr + ']')).forEach(function(input) {
          var value = idPrefix + input.getAttribute(attr);
          input.setAttribute(attr, value);
        });
      });
    }

    function _getIdPrefix() {
      // leading 'r'(andom) to overcome the fact that IDs
      // starting with a numeric value are not valid in CSS
      return 'r' + Math.floor(Math.random() * 100000) + '__';
    }

    return {
      parseResponse: parseResponse,
    }
  })();
})();