edx-platform/lms/static/coffee/src/customwmd.coffee

# Mostly adapted from math.stackexchange.com: http://cdn.sstatic.net/js/mathjax-editing-new.js

$ ->

  class MathJaxProcessor

    MATHSPLIT = /// (
      \$\$?                          # normal inline or display delimiter
      | \\(?:begin|end)\{[a-z]*\*?\} # \begin{} \end{} style
      | \\[\\{}$]
      | [{}]
      | (?:\n\s*)+                   # only treat as math when there's single new line
      | @@\d+@@                      # delimiter similar to the one used internally
    ) ///i

    CODESPAN = ///
      (^|[^\\])       # match beginning or any previous character other than escape delimiter ('/')
      (`+)            # code span starts
      ([^\n]*?[^`\n]) # code content
      \2              # code span ends
      (?!`)
    ///gm

    constructor: (inlineMark, displayMark) ->
      @inlineMark = inlineMark || "$"
      @displayMark = displayMark || "$$"
      @math = null
      @blocks = null

    processMath: (start, last, preProcess) ->
      block = @blocks.slice(start, last + 1).join("").replace(/&/g, "&")
                                                    .replace(/</g, "&lt;")
                                                    .replace(/>/g, "&gt;")
      if MathJax.Hub.Browser.isMSIE
        block = block.replace /(%[^\n]*)\n/g, "$1<br/>\n"
      @blocks[i] = "" for i in [start+1..last]
      @blocks[start] = "@@#{@math.length}@@"
      block = preProcess(block) if preProcess
      @math.push block

    removeMath: (text) ->

      text = text || ""
      @math = []
      start = end = last = null
      braces = 0

      hasCodeSpans = /`/.test text
      if hasCodeSpans
        text = text.replace(/~/g, "~T").replace CODESPAN, ($0) -> # replace dollar sign in code span temporarily
          $0.replace /\$/g, "~D"
        deTilde = (text) ->
          text.replace /~([TD])/g, ($0, $1) ->
            {T: "~", D: "$"}[$1]
      else
        deTilde = (text) -> text

      @blocks = _split(text.replace(/\r\n?/g, "\n"), MATHSPLIT)

      for current in [1...@blocks.length] by 2
        block = @blocks[current]
        if block.charAt(0) == "@"
          @blocks[current] = "@@#{@math.length}@@"
          @math.push block
        else if start
          if block == end
            if braces
              last = current
            else
              @processMath(start, current, deTilde)
              start = end = last = null
          else if block.match /\n.*\n/
            if last
              current = last
              @processMath(start, current, deTilde)
            start = end = last = null
            braces = 0
          else if block == "{"
            ++braces
          else if block == "}" and braces
            --braces
        else
          if block == @inlineMark or block == @displayMark
            start = current
            end = block
            braces = 0
          else if block.substr(1, 5) == "begin"
            start = current
            end = "\\end" + block.substr(6)
            braces = 0

      if last
        @processMath(start, last, deTilde)
        start = end = last = null

      deTilde(@blocks.join(""))

    @removeMathWrapper: (_this) ->
      (text) -> _this.removeMath(text)

    replaceMath: (text) ->
      text = text.replace /@@(\d+)@@/g, ($0, $1) => @math[$1]
      @math = null
      text

    @replaceMathWrapper: (_this) ->
      (text) -> _this.replaceMath(text)

  if Markdown?

    Markdown.getMathCompatibleConverter = (postProcessor) ->
      postProcessor ||= ((text) -> text)
      converter = Markdown.getSanitizingConverter()
      if MathJax?
        processor = new MathJaxProcessor()
        converter.hooks.chain "preConversion", MathJaxProcessor.removeMathWrapper(processor)
        converter.hooks.chain "postConversion", (text) ->
          postProcessor(MathJaxProcessor.replaceMathWrapper(processor)(text))
      converter

    Markdown.makeWmdEditor = (elem, appended_id, imageUploadUrl, postProcessor) ->
      $elem = $(elem)
      if not $elem.length
        console.log "warning: elem for makeWmdEditor doesn't exist"
        return
      if not $elem.find(".wmd-panel").length
        initialText = $elem.html()
        $elem.empty()
        _append = appended_id || ""
        wmdInputId = "wmd-input#{_append}"
        $wmdPreviewContainer = $("<div>").addClass("wmd-preview-container")
            .append($("<div>").addClass("wmd-preview-label").text(gettext("Preview")))
            .append($("<div>").attr("id", "wmd-preview#{_append}").addClass("wmd-panel wmd-preview"))
        $wmdPanel = $("<div>").addClass("wmd-panel")
                   .append($("<div>").attr("id", "wmd-button-bar#{_append}"))
                   .append($("<label>").addClass("sr").attr("for", wmdInputId).text(gettext("Post body")))
                   .append($("<textarea>").addClass("wmd-input").attr("id", wmdInputId).html(initialText))
                   .append($wmdPreviewContainer)
        $elem.append($wmdPanel)

      converter = Markdown.getMathCompatibleConverter(postProcessor)

      ajaxFileUpload = (imageUploadUrl, input, startUploadHandler) ->
        $("#loading").ajaxStart(-> $(this).show()).ajaxComplete(-> $(this).hide())
        $("#upload").ajaxStart(-> $(this).hide()).ajaxComplete(-> $(this).show())
        $.ajaxFileUpload
          url: imageUploadUrl
          secureuri: false
          fileElementId: 'file-upload'
          dataType: 'json'
          success: (data, status) ->
            fileURL = data['result']['file_url']
            error = data['result']['error']
            if error != ''
              alert error
              if startUploadHandler
                $('#file-upload').unbind('change').change(startUploadHandler)
              console.log error
            else
              $(input).attr('value', fileURL)
          error: (data, status, e) ->
            alert(e)
            if startUploadHandler
              $('#file-upload').unbind('change').change(startUploadHandler)

      imageUploadHandler = (elem, input) ->
        ajaxFileUpload(imageUploadUrl, input, imageUploadHandler)

      editor = new Markdown.Editor(
        converter,
        appended_id, # idPostfix
        null, # help handler
        imageUploadHandler
      )
      delayRenderer = new MathJaxDelayRenderer()
      editor.hooks.chain "onPreviewPush", (text, previewSet) ->
        delayRenderer.render
          text: text
          previewSetter: previewSet
      editor.run()
      editor