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

svgEditor.addExtension('mathjax', function () {
  const $ = jQuery;

  // Configuration of the MathJax extention.

  // This will be added to the head tag before MathJax is loaded.
  const /* 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
    mathjaxSrcSecure = 'mathjax/MathJax.js?config=TeX-AMS-MML_SVG.js',
    {uiStrings} = svgEditor;
  let
    math,
    locationX,
    locationY,
    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 () {
    const 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 () {
        const mathjaxMath = $('.MathJax_SVG');
        const svg = $(mathjaxMath.html());
        svg.find('use').each(function () {
          // TODO: find a less pragmatic and more elegant solution to this.
          const id = $(this).attr('href')
            ? $(this).attr('href').slice(1) // Works in Chrome.
            : $(this).attr('xlink:href').slice(1); // Works in Firefox.
          const glymph = $('#' + id).clone().removeAttr('id');
          const x = $(this).attr('x');
          const y = $(this).attr('y');
          const 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.extPath + 'mathjax-icons.xml',
    buttons: [{
      id: 'tool_mathjax',
      type: 'mode',
      title: 'Add Mathematics',
      events: {
        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 `s.type = 'module';` once modules widely supported
            //   and if this ends up providing an ES6 module export
            $.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 () {
      if (svgCanvas.getMode() === 'mathjax') {
        return {started: true};
      }
    },
    mouseUp (opts) {
      if (svgCanvas.getMode() === 'mathjax') {
        // Get the coordinates from your mouse.
        const 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 () {
      $('<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');
    }
  };
});