searx.ready(function() {

  searx.on('.result', 'click', function() {
    highlightResult(this)(true);
  });

  searx.on('.result a', 'focus', function(e) {
    var el = e.target;
    while (el !== undefined) {
      if (el.classList.contains('result')) {
        if (el.getAttribute("data-vim-selected") === null) {
          highlightResult(el)(true);
        }
        break;
      }
      el = el.parentNode;
    }
  }, true);

  var vimKeys = {
    27: {
      key: 'Escape',
      fun: removeFocus,
      des: 'remove focus from the focused input',
      cat: 'Control'
    },
    73: {
      key: 'i',
      fun: searchInputFocus,
      des: 'focus on the search input',
      cat: 'Control'
    },
    66: {
      key: 'b',
      fun: scrollPage(-window.innerHeight),
      des: 'scroll one page up',
      cat: 'Navigation'
    },
    70: {
      key: 'f',
      fun: scrollPage(window.innerHeight),
      des: 'scroll one page down',
      cat: 'Navigation'
    },
    85: {
      key: 'u',
      fun: scrollPage(-window.innerHeight / 2),
      des: 'scroll half a page up',
      cat: 'Navigation'
    },
    68: {
      key: 'd',
      fun: scrollPage(window.innerHeight / 2),
      des: 'scroll half a page down',
      cat: 'Navigation'
    },
    71: {
      key: 'g',
      fun: scrollPageTo(-document.body.scrollHeight, 'top'),
      des: 'scroll to the top of the page',
      cat: 'Navigation'
    },
    86: {
      key: 'v',
      fun: scrollPageTo(document.body.scrollHeight, 'bottom'),
      des: 'scroll to the bottom of the page',
      cat: 'Navigation'
    },
    75: {
      key: 'k',
      fun: highlightResult('up'),
      des: 'select previous search result',
      cat: 'Results'
    },
    74: {
      key: 'j',
      fun: highlightResult('down'),
      des: 'select next search result',
      cat: 'Results'
    },
    80: {
      key: 'p',
      fun: pageButtonClick(0),
      des: 'go to previous page',
      cat: 'Results'
    },
    78: {
      key: 'n',
      fun: pageButtonClick(1),
      des: 'go to next page',
      cat: 'Results'
    },
    79: {
      key: 'o',
      fun: openResult(false),
      des: 'open search result',
      cat: 'Results'
    },
    84: {
      key: 't',
      fun: openResult(true),
      des: 'open the result in a new tab',
      cat: 'Results'
    },
    82: {
      key: 'r',
      fun: reloadPage,
      des: 'reload page from the server',
      cat: 'Control'
    },
    72: {
      key: 'h',
      fun: toggleHelp,
      des: 'toggle help window',
      cat: 'Other'
    }
  };

  searx.on(document, "keyup", function(e) {
    // check for modifiers so we don't break browser's hotkeys
    if (vimKeys.hasOwnProperty(e.keyCode) && !e.ctrlKey && !e.altKey && !e.shiftKey && !e.metaKey) {
      var tagName = e.target.tagName.toLowerCase();
      if (e.keyCode === 27) {
        if (tagName === 'input' || tagName === 'select' || tagName === 'textarea') {
          vimKeys[e.keyCode].fun();
        }
      } else {
        if (e.target === document.body || tagName === 'a' || tagName === 'button') {
          vimKeys[e.keyCode].fun();
        }
      }
    }
  });

  function highlightResult(which) {
    return function(noScroll) {
      var current = document.querySelector('.result[data-vim-selected]'),
      effectiveWhich = which;
      if (current === null) {
        // no selection : choose the first one
        current = document.querySelector('.result');
        if (current === null) {
          // no first one : there are no results
          return;
        }
        // replace up/down actions by selecting first one
        if (which === "down" || which === "up") {
          effectiveWhich = current;
        }
      }

      var next, results = document.querySelectorAll('.result');

      if (typeof effectiveWhich !== 'string') {
        next = effectiveWhich;
      } else {
        switch (effectiveWhich) {
          case 'visible':
          var top = document.documentElement.scrollTop || document.body.scrollTop;
          var bot = top + document.documentElement.clientHeight;

          for (var i = 0; i < results.length; i++) {
            next = results[i];
            var etop = next.offsetTop;
            var ebot = etop + next.clientHeight;

            if ((ebot <= bot) && (etop > top)) {
              break;
            }
          }
          break;
          case 'down':
          next = current.nextElementSibling;
          if (next === null) {
            next = results[0];
          }
          break;
          case 'up':
          next = current.previousElementSibling;
          if (next === null) {
            next = results[results.length - 1];
          }
          break;
          case 'bottom':
          next = results[results.length - 1];
          break;
          case 'top':
          /* falls through */
          default:
          next = results[0];
        }
      }

      if (next) {
        current.removeAttribute('data-vim-selected');
        next.setAttribute('data-vim-selected', 'true');
        var link = next.querySelector('h3 a') || next.querySelector('a');
        if (link !== null) {
          link.focus();
        }
        if (!noScroll) {
          scrollPageToSelected();
        }
      }
    };
  }

  function reloadPage() {
    document.location.reload(true);
  }

  function removeFocus() {
    if (document.activeElement) {
      document.activeElement.blur();
    }
  }

  function pageButtonClick(num) {
    return function() {
      var buttons = $('div#pagination button[type="submit"]');
      if (buttons.length !== 2) {
        console.log('page navigation with this theme is not supported');
        return;
      }
      if (num >= 0 && num < buttons.length) {
        buttons[num].click();
      } else {
        console.log('pageButtonClick(): invalid argument');
      }
    };
  }

  function scrollPageToSelected() {
    var sel = document.querySelector('.result[data-vim-selected]');
    if (sel === null) {
      return;
    }
    var wtop = document.documentElement.scrollTop || document.body.scrollTop,
    wheight = document.documentElement.clientHeight,
    etop = sel.offsetTop,
    ebot = etop + sel.clientHeight,
    offset = 120;
    // first element ?
    if ((sel.previousElementSibling === null) && (ebot < wheight)) {
      // set to the top of page if the first element
      // is fully included in the viewport
      window.scroll(window.scrollX, 0);
      return;
    }
    if (wtop > (etop - offset)) {
      window.scroll(window.scrollX, etop - offset);
    } else {
      var wbot = wtop + wheight;
      if (wbot < (ebot + offset)) {
        window.scroll(window.scrollX, ebot - wheight + offset);
      }
    }
  }

  function scrollPage(amount) {
    return function() {
      window.scrollBy(0, amount);
      highlightResult('visible')();
    };
  }

  function scrollPageTo(position, nav) {
    return function() {
      window.scrollTo(0, position);
      highlightResult(nav)();
    };
  }

  function searchInputFocus() {
    window.scrollTo(0, 0);
    document.querySelector('#q').focus();
  }

  function openResult(newTab) {
    return function() {
      var link = document.querySelector('.result[data-vim-selected] h3 a');
      if (link !== null) {
        var url = link.getAttribute('href');
        if (newTab) {
          window.open(url);
        } else {
          window.location.href = url;
        }
      }
    };
  }

  function toggleHelp() {
    var helpPanel = document.querySelector('#vim-hotkeys-help');
    if (helpPanel.length) {
      helpPanel.classList.toggle('hidden');
      return;
    }

    var categories = {};

    for (var k in vimKeys) {
      var key = vimKeys[k];
      categories[key.cat] = categories[key.cat] || [];
      categories[key.cat].push(key);
    }

    var sorted = Object.keys(categories).sort(function(a, b) {
      return categories[b].length - categories[a].length;
    });

    if (sorted.length === 0) {
      return;
    }

    var html = '<div id="vim-hotkeys-help" class="well vim-hotkeys-help">';
    html += '<div class="container-fluid">';

    html += '<div class="row">';
    html += '<div class="col-sm-12">';
    html += '<h3>How to navigate searx with Vim-like hotkeys</h3>';
    html += '</div>'; // col-sm-12
    html += '</div>'; // row

    for (var i = 0; i < sorted.length; i++) {
      var cat = categories[sorted[i]];

      var lastCategory = i === (sorted.length - 1);
      var first = i % 2 === 0;

      if (first) {
        html += '<div class="row dflex">';
      }
      html += '<div class="col-sm-' + (first && lastCategory ? 12 : 6) + ' dflex">';

      html += '<div class="panel panel-default iflex">';
      html += '<div class="panel-heading">' + cat[0].cat + '</div>';
      html += '<div class="panel-body">';
      html += '<ul class="list-unstyled">';

      for (var cj in cat) {
        html += '<li><kbd>' + cat[cj].key + '</kbd> ' + cat[cj].des + '</li>';
      }

      html += '</ul>';
      html += '</div>'; // panel-body
      html += '</div>'; // panel
      html += '</div>'; // col-sm-*

      if (!first || lastCategory) {
        html += '</div>'; // row
      }
    }

    html += '</div>'; // container-fluid
    html += '</div>'; // vim-hotkeys-help

    $('body').append(html);
  }
});