marked.setOptions({
    renderer: new marked.Renderer(),
    gfm: true,
    tables: true,
    breaks: false,
    pedantic: false,
    sanitize: false, // IMPORTANT, because we do MathJax before markdown,
                     //            however we do escaping in 'CreatePreview'.
    smartLists: true,
    smartypants: false
  });
  
var Preview = {
  delay: 50,        // delay after keystroke before updating

  preview: null,     // filled in by Init below
  buffer: null,      // filled in by Init below

  timeout: null,     // store setTimout id
  mjRunning: false,  // true when MathJax is processing
  oldText: null,     // used to check if an update is needed

  //
  //  Get the preview and buffer DIV's
  //
  Init: function () {
    this.timeout = null; 
    this.mjRunning = false; 
    this.oldText = null; 
    
    this.preview = document.getElementById("marked-mathjax-preview");
    this.buffer = document.getElementById("marked-mathjax-preview-buffer");
    this.preview.classList.add('Current'); //bad bugs happen if this isn't here. 
  },

  //
  //  Switch the buffer and preview, and display the right one.
  //  (We use visibility:hidden rather than display:none since
  //  the results of running MathJax are more accurate that way.)
  //
  SwapBuffers: function () {
    var buffer = this.preview, preview = this.buffer;
    this.buffer = buffer; this.preview = preview;
    buffer.style.display = "none";
    buffer.style.position = "absolute";
    buffer.style.height = "auto"; //dunno
    buffer.style.top = "0px"; 
    buffer.style.left = "0px"; 

    preview.style.display = "inline-block"; 
    preview.style.position = ""; //dunno
    preview.style.width = "90%"; 
    preview.style.height = "auto"; 
    preview.style.overflow = "auto"; 

    buffer.classList.remove('Current'); 
    preview.classList.add('Current');
    

    // preview.style.display = "";
  },

  //
  //  This gets called when a key is pressed in the textarea.
  //  We check if there is already a pending update and clear it if so.
  //  Then set up an update to occur after a small delay (so if more keys
  //    are pressed, the update won't occur until after there has been 
  //    a pause in the typing).
  //  The callback function is set up below, after the Preview object is set up.
  //
  Update: function () {
    if (this.timeout) {clearTimeout(this.timeout)}
    this.timeout = setTimeout(this.callback,this.delay);
  },

  //
  //  Creates the preview and runs MathJax on it.
  //  If MathJax is already trying to render the code, return
  //  If the text hasn't changed, return
  //  Otherwise, indicate that MathJax is running, and start the
  //    typesetting.  After it is done, call PreviewDone.
  //  
  CreatePreview: function () {
    Preview.timeout = null;
    if (this.mjRunning) return;
    var text = document.getElementById("marked-mathjax-input").value;
    if (text === this.oldtext) return;
    text = this.Escape(text);                       //Escape tags before doing stuff
    this.buffer.innerHTML = this.oldtext = text;
    this.mjRunning = true;
    MathJax.Hub.Queue(
      ["Typeset",MathJax.Hub,this.buffer],
      ["PreviewDone",this],
      ["resetEquationNumbers", MathJax.InputJax.TeX]
    );
  },

  //
  //  Indicate that MathJax is no longer running,
  //  do markdown over MathJax's result, 
  //  and swap the buffers to show the results.
  //
  PreviewDone: function () {
    this.mjRunning = false;
    text = this.buffer.innerHTML;
    // replace occurrences of > at the beginning of a new line
    // with > again, so Markdown blockquotes are handled correctly
    text = text.replace(/^>/mg, '>');
    this.buffer.innerHTML = marked (text);
    this.SwapBuffers();
  },

  Escape: function (html, encode) {
    return html
      .replace(!encode ? /&(?!#?\w+;)/g : /&/g, '&')
      .replace(/</g, '&lt;')
      .replace(/>/g, '&gt;')
      .replace(/"/g, '&quot;')
     .replace(/'/g, '&#39;');
  }


};

//
//  Cache a callback to the CreatePreview action
//
Preview.callback = MathJax.Callback(["CreatePreview",Preview]);
Preview.callback.autoReset = true;  // make sure it can run more than once