(function collonadeClosure() {
  'use strict';

  document.addEventListener('DOMContentLoaded', function DOMContentLoaded() {

    var ASC = 'asc';
    var DESC = 'desc';

    var table = document.querySelector('table');
    var ths = Array.from(table.querySelectorAll('th'));

    // attach click handler to each table-header
    ths.map(function(th) {
      th.addEventListener('click', clickHandler);
    });

    // handles click on table header
    function clickHandler(event) {
      event.preventDefault();
      // should instead be smthg like: JSON.parse(this.dataset.sortparams);
      // hardcoded for now
      var sortParams = {sorting: 'name', prefix: 'terms'};
      if (sortParams.order) {
        sortParams.order = sortParams.order === ASC ? DESC : ASC;
      } else {
        sortParams.order = ASC;
      }
      var params = makeParams(sortParams.prefix, sortParams);
      var url = new URL(window.location);
      for (var p in params) {
        url.searchParams.set(p, params[p]);
      }
      fetchTableFrom(url);
      markSorted(this, sortParams.order);
    }

    function markSorted(th, order) {
      ths.forEach(function(th) {
        th.classList.remove('sorted-asc', 'sorted-desc');
      });
      th.classList.add('sorted-' + order);
    }

    // fetches new sorted table from url with params and replaces contents of current table
    function fetchTableFrom(url) {
      fetch(url, {
        credentials: 'same-origin'
      }).then(function(response) {
        if (!response.ok) {
           throw ('Looks like there was a problem fetching ' + url.toString() + '. Status Code: ' + response.status);
         }
         // Examine the text in the response
         response.text().then(function(data) {
           // replace contents of table body
           table.querySelector('tbody').innerHTML = data;
         });
      }).catch(function(err) {
        console.error(err);
      });
    }

    // returns default sort-params for with specific prefix
    function makeParams(prefix, custom) {
      var defaultParams = Object.assign({
        pagesize: 20,
        page: 0,
        order: ASC
      }, custom);
      var res = {};
      for (var p in defaultParams) {
        res[prefix + '-' + p] = defaultParams[p];
      }
      res['table-only'] = 'true';
      return res;
    }

  });
})();