read-content.js

var supermarked = require('supermarked'),
   fs = require('fs'),
   cheerio = require('cheerio'),
   Handlebars = require('handlebars'),
   barrier = require('./barrier.js'),
   figureTemplate = Handlebars.compile(
      '<figure id="demo-{{name}}" data-demo="{{name}}" {{#if autoplay}}data-autoplay{{/if}}></figure>'
   ),
   MARKDOWN_OPTS = { ignoreMath: true, smartypants: true, gfm: true, tables: true },
   MD_PREFIX = '{{#if pdfLink}}This page is also [available as a PDF]({{pdfLink}}).{{/if}}\n',
   MD_POSTFIX = fs.readFileSync('content/postfix.md');

Handlebars.registerHelper("demo", function (name, mode) {
   var autoplay = (mode == "autoplay");

   console.log(new Handlebars.SafeString(figureTemplate({ name: name, autoplay: autoplay })));
   return new Handlebars.SafeString(figureTemplate({ name: name, autoplay: autoplay }));
});

function postProcessMarkup($) {
   $('pre').each(function (i, ele) {
      var code = $(ele);

      if (/deprecated/i.exec(code.text())) {

         var details = $('<details>');
         code.replaceWith(details);
         details
            .append('<summary>Deprecated API</summary>')
            .append(code);
      }
   });

   return $;
}

function outline($) {

   var mainHeadingEle = $('h1').first(),

      mainHeading = {
         text: mainHeadingEle.text(),
         id: mainHeadingEle.attr('id')
      },

      sectionHeadings = [];

   $('h2').each(function (i, element) {
      var jEle = $(element),
         text = jEle.text();

      sectionHeadings.push({
         text: text,
         id: jEle.attr('id')
      });
   });

   mainHeadingEle.remove();

   return {
      content: $.html(),
      heading: mainHeading,
      sections: sectionHeadings,
      multipleSections: sectionHeadings.length > 1
   }
}

function readContent(requestedPage, opts, callback) {

   console.log('request for page:', requestedPage.blue);

   function pdfFile(pageName) {
      return 'pdf/' + pageName + '.pdf';
   }

   function pdfUrl(pageName) {
      return '/' + pageName + '.pdf';
   }

   function markdownFile(pageName) {
      return 'content/' + pageName + '.md';
   }

   fs.exists(markdownFile(requestedPage), function (requestedMarkdownExists) {

      var actualPage = requestedMarkdownExists ? requestedPage : '404',
         markdownToRead = markdownFile(actualPage),
         markdownContent,
         bar = barrier(function () {

            var surroundedMarkdown = MD_PREFIX + markdownContent + MD_POSTFIX,
               filledInMarkdown = Handlebars.compile(surroundedMarkdown)(opts),
               html = supermarked(filledInMarkdown, MARKDOWN_OPTS),
               $ = postProcessMarkup(cheerio.load(html)),
               response = outline($);

            response.status = requestedMarkdownExists ? 200 : 404;

            if (!requestedMarkdownExists) {
               console.log('no such markdown file:'.red, markdownFile(requestedPage));
            }

            callback(response);
         });

      opts.page = actualPage;
      opts.isDownloadPage = (actualPage == 'download');

      fs.exists(pdfFile(requestedPage), bar.add(function (exists) {
         if (exists) {
            opts.pdfLink = pdfUrl(requestedPage);
         }
      }));

      // fileToRead should point to legit page by now (possibly 404)
      fs.readFile(markdownToRead, bar.add(function (err, markdownBuffer) {

         markdownContent = markdownBuffer.toString();
      }));
   });
}

module.exports = readContent;