(function () {
  'use strict';

  /* globals jQuery, MathJax */
  /*
   * ext-mathjax.js
   *
   * Licensed under the Apache License
   *
   * Copyright(c) 2013 Jo Segaert
   *
   */

  svgEditor.addExtension('mathjax', function () {
    var $ = jQuery;
    var svgCanvas = svgEditor.canvas;

    // Configuration of the MathJax extention.

    // This will be added to the head tag before MathJax is loaded.
    /* mathjaxConfiguration = '<script type="text/x-mathjax-config">\
    MathJax.Hub.Config({\
      extensions: ["tex2jax.js"],\
      jax: ["input/TeX","output/SVG"],\
      showProcessingMessages: true,\
      showMathMenu: false,\
      showMathMenuMSIE: false,\
      errorSettings: {\
        message: ["[Math Processing Error]"],\
        style: {color: "#CC0000", "font-style":"italic"}\
      },\
      elements: [],\
        tex2jax: {\
        ignoreClass: "tex2jax_ignore2", processClass: "tex2jax_process2",\
      },\
      TeX: {\
        extensions: ["AMSmath.js","AMSsymbols.js","noErrors.js","noUndefined.js"]\
      },\
      "SVG": {\
      }\
    });\
    </script>', */
    // mathjaxSrc = 'http://cdn.mathjax.org/mathjax/latest/MathJax.js',
    // Had been on https://c328740.ssl.cf1.rackcdn.com/mathjax/latest/MathJax.js?config=TeX-AMS-MML_SVG.js
    // Obtained Text-AMS-MML_SVG.js from https://cdnjs.cloudflare.com/ajax/libs/mathjax/2.3/config/TeX-AMS-MML_SVG.js
    var mathjaxSrcSecure = 'mathjax/MathJax.js?config=TeX-AMS-MML_SVG.js',
        _svgEditor = svgEditor,
        uiStrings = _svgEditor.uiStrings;

    var math = void 0,
        locationX = void 0,
        locationY = void 0,
        mathjaxLoaded = false;

    // TODO: Implement language support. Move these uiStrings to the locale files and the code to the langReady callback.
    $.extend(uiStrings, {
      mathjax: {
        embed_svg: 'Save as mathematics',
        embed_mathml: 'Save as figure',
        svg_save_warning: 'The math will be transformed into a figure is manipulatable like everything else. You will not be able to manipulate the TeX-code anymore. ',
        mathml_save_warning: 'Advised. The math will be saved as a figure.',
        title: 'Mathematics code editor'
      }
    });

    function saveMath() {
      var code = $('#mathjax_code_textarea').val();
      // displaystyle to force MathJax NOT to use the inline style. Because it is
      // less fancy!
      MathJax.Hub.queue.Push(['Text', math, '\\displaystyle{' + code + '}']);

      /*
       * The MathJax library doesn't want to bloat your webpage so it creates
       * every symbol (glymph) you need only once. These are saved in a <svg> on
       * the top of your html document, just under the body tag. Each glymph has
       * its unique id and is saved as a <path> in the <defs> tag of the <svg>
       *
       * Then when the symbols are needed in the rest of your html document they
       * are refferd to by a <use> tag.
       * Because of bug 1076 we can't just grab the defs tag on the top and add it
       * to your formula's <svg> and copy the lot. So we have to replace each
       * <use> tag by it's <path>.
       */
      MathJax.Hub.queue.Push(function () {
        var mathjaxMath = $('.MathJax_SVG');
        var svg = $(mathjaxMath.html());
        svg.find('use').each(function () {
          // TODO: find a less pragmatic and more elegant solution to this.
          var id = $(this).attr('href') ? $(this).attr('href').slice(1) // Works in Chrome.
          : $(this).attr('xlink:href').slice(1); // Works in Firefox.
          var glymph = $('#' + id).clone().removeAttr('id');
          var x = $(this).attr('x');
          var y = $(this).attr('y');
          var transform = $(this).attr('transform');
          if (transform && (x || y)) {
            glymph.attr('transform', transform + ' translate(' + x + ',' + y + ')');
          } else if (transform) {
            glymph.attr('transform', transform);
          } else if (x || y) {
            glymph.attr('transform', 'translate(' + x + ',' + y + ')');
          }
          $(this).replaceWith(glymph);
        });
        // Remove the style tag because it interferes with SVG-Edit.
        svg.removeAttr('style');
        svg.attr('xmlns', 'http://www.w3.org/2000/svg');
        svgCanvas.importSvgString($('<div>').append(svg.clone()).html(), true);
        svgCanvas.ungroupSelectedElement();
        // TODO: To undo the adding of the Formula you now have to undo twice.
        // This should only be once!
        svgCanvas.moveSelectedElements(locationX, locationY, true);
      });
    }

    return {
      name: 'MathJax',
      svgicons: svgEditor.curConfig.extIconsPath + 'mathjax-icons.xml',
      buttons: [{
        id: 'tool_mathjax',
        type: 'mode',
        title: 'Add Mathematics',
        events: {
          click: function click() {
            // Only load Mathjax when needed, we don't want to strain Svg-Edit any more.
            // From this point on it is very probable that it will be needed, so load it.
            if (mathjaxLoaded === false) {
              $('<div id="mathjax">' + '<!-- Here is where MathJax creates the math -->' + '<div id="mathjax_creator" class="tex2jax_process" style="display:none">' + '$${}$$' + '</div>' + '<div id="mathjax_overlay"></div>' + '<div id="mathjax_container">' + '<div id="tool_mathjax_back" class="toolbar_button">' + '<button id="tool_mathjax_save">OK</button>' + '<button id="tool_mathjax_cancel">Cancel</button>' + '</div>' + '<fieldset>' + '<legend id="mathjax_legend">Mathematics Editor</legend>' + '<label>' + '<span id="mathjax_explication">Please type your mathematics in ' + '<a href="https://en.wikipedia.org/wiki/Help:Displaying_a_formula" target="_blank">TeX</a> code.</span></label>' + '<textarea id="mathjax_code_textarea" spellcheck="false"></textarea>' + '</fieldset>' + '</div>' + '</div>').insertAfter('#svg_prefs').hide();

              // Make the MathEditor draggable.
              $('#mathjax_container').draggable({ cancel: 'button,fieldset', containment: 'window' });

              // Add functionality and picture to cancel button.
              $('#tool_mathjax_cancel').prepend($.getSvgIcon('cancel', true)).on('click touched', function () {
                $('#mathjax').hide();
              });

              // Add functionality and picture to the save button.
              $('#tool_mathjax_save').prepend($.getSvgIcon('ok', true)).on('click touched', function () {
                saveMath();
                $('#mathjax').hide();
              });

              // MathJax preprocessing has to ignore most of the page.
              $('body').addClass('tex2jax_ignore');

              // Now get (and run) the MathJax Library.
              // Todo: insert script with modules once widely supported
              //   and if MathJax (and its `TeX-AMS-MML_SVG.js` dependency) ends up
              //   providing an ES6 module export: https://github.com/mathjax/MathJax/issues/1998
              /*
              const s = document.createElement('script');
              const modularVersion = !('svgEditor' in window) ||
                !window.svgEditor ||
                window.svgEditor.modules !== false;
              if (modularVersion) {
                s.type = 'module'; // Make this the default when widely supported
              }
              s.src = curConfig.extPath + mathjaxSrcSecure;
              // See `executeAfterLoads` in `svgutils.js`
              */
              $.getScript(mathjaxSrcSecure).done(function (script, textStatus) {
                // When MathJax is loaded get the div where the math will be rendered.
                MathJax.Hub.queue.Push(function () {
                  math = MathJax.Hub.getAllJax('#mathjax_creator')[0];
                  console.log(math);
                  mathjaxLoaded = true;
                  console.log('MathJax Loaded');
                });
              })
              // If it fails.
              .fail(function () {
                console.log('Failed loadeing MathJax.');
                $.alert('Failed loading MathJax. You will not be able to change the mathematics.');
              });
            }
            // Set the mode.
            svgCanvas.setMode('mathjax');
          }
        }
      }],

      mouseDown: function mouseDown() {
        if (svgCanvas.getMode() === 'mathjax') {
          return { started: true };
        }
      },
      mouseUp: function mouseUp(opts) {
        if (svgCanvas.getMode() === 'mathjax') {
          // Get the coordinates from your mouse.
          var zoom = svgCanvas.getZoom();
          // Get the actual coordinate by dividing by the zoom value
          locationX = opts.mouse_x / zoom;
          locationY = opts.mouse_y / zoom;

          $('#mathjax').show();
          return { started: false }; // Otherwise the last selected object dissapears.
        }
      },
      callback: function callback() {
        $('<style>').text('#mathjax fieldset{' + 'padding: 5px;' + 'margin: 5px;' + 'border: 1px solid #DDD;' + '}' + '#mathjax label{' + 'display: block;' + 'margin: .5em;' + '}' + '#mathjax legend {' + 'max-width:195px;' + '}' + '#mathjax_overlay {' + 'position: absolute;' + 'top: 0;' + 'left: 0;' + 'right: 0;' + 'bottom: 0;' + 'background-color: black;' + 'opacity: 0.6;' + 'z-index: 20000;' + '}' + '#mathjax_container {' + 'position: absolute;' + 'top: 50px;' + 'padding: 10px;' + 'background-color: #B0B0B0;' + 'border: 1px outset #777;' + 'opacity: 1.0;' + 'font-family: Verdana, Helvetica, sans-serif;' + 'font-size: .8em;' + 'z-index: 20001;' + '}' + '#tool_mathjax_back {' + 'margin-left: 1em;' + 'overflow: auto;' + '}' + '#mathjax_legend{' + 'font-weight: bold;' + 'font-size:1.1em;' + '}' + '#mathjax_code_textarea {\\n' + 'margin: 5px .7em;' + 'overflow: hidden;' + 'width: 416px;' + 'display: block;' + 'height: 100px;' + '}').appendTo('head');

        // Add the MathJax configuration.
        // $(mathjaxConfiguration).appendTo('head');
      }
    };
  });

}());