utils.js

var request = require('request');

var MEDIUM_IMG_CDN = "https://cdn-images-1.medium.com/max/";

var utils = {
  loadMediumPost: function(mediumURL, cb) {
    if(mediumURL.match(/^http/i)) {
      mediumURL = mediumURL.replace(/#.+$/, '');
      request(mediumURL, {qs: {format: 'json'}}, function(err, res, body) {
        if(err) return cb(err);
        var json_string = body.substr(body.indexOf('{'));
        var json = JSON.parse(json_string);
        return cb(null, json);
      });
    }
    else {
      json = require(process.cwd() + "/" + mediumURL);
      return cb(null, json);
    }
  },
  processSection: function(s) {
    var section = "";
    if(s.backgroundImage) {
      var imgwidth = parseInt(s.backgroundImage.originalWidth,10);
      var imgsrc = MEDIUM_IMG_CDN+Math.max(imgwidth*2,2000)+"/"+s.backgroundImage.id;
      section = "\n![]("+imgsrc+")";
    }
    return section;
  },
  getYouTubeEmbed: function(iframesrc, cb) {
    request(iframesrc, function(err, res) {
      var tokens = res.body.match(/youtube.com%2Fembed%2F([^%]+)%3F/);
      if (tokens && tokens.length > 1) {
        var videoId = tokens[1];
        return cb(null, `<iframe width="560" height="315" src="https://www.youtube.com/embed/${videoId}" frameborder="0" allowfullscreen></iframe>`);
      }
      cb(null, `<iframe src="${iframesrc}" frameborder=0></iframe>`);
    });
  },
  getGitHubEmbed: function(iframesrc, cb) {
    request(iframesrc, function(err, res) {
      if (err) return cb(err);
      var tokens = res.body.match(/script src="https:\/\/gist.github.com\/([^"]*)"/);
      if (!tokens) return cb(new Error("GitHub embed not found"));
      var scriptsrc = `https://gist.github.com/${tokens[1]}`;
      request(scriptsrc, function(err, res) {
        if (err) return cb(err);
        var html = res.body.split('\n').map((line, idx) => {
          if (idx === 0) return ''; // skip stylesheet
          line = line.replace(/document.write\('(.*)'\)/, '$1');
          line = line
              .replace(/\\n\s*/g, '\n')
              .replace(/\n+/g, '\n')
              .replace(/\\(.)/g, '$1')
              .replace(/`/g, '&#96;');
          return line;
        }).join('\n');
        return cb(null, html);
      });
    });
  },

  processParagraph: function(p, cb) {

    var markups_array = utils.createMarkupsArray(p.markups);

    if(markups_array.length > 0) {
      var previousIndex=0, text=p.text, tokens=[];
      for(var j=0;j<markups_array.length;j++) {
        if(markups_array[j]) {
          token = text.substring(previousIndex, j);
          previousIndex = j;
          tokens.push(token);
          tokens.push(markups_array[j]);
        }
      }
      tokens.push(text.substring(j-1));
      p.text = tokens.join('');
    }

    if (p.type !== 8 && p.type !== 10) {
      p.text = p.text
          .replace(/>/g, '&gt;')
          .replace(/</g, '&lt;');
    }
    var markup = "";
    switch(p.type) {
      case 1:
        markup = "\n";
        break;
      case 2:
        p.text = "\n# "+p.text.replace(/\n/g,'\n# ');
        break;
      case 3:
        p.text = "\n## "+p.text.replace(/\n/g,'\n## ');
        break;
      case 4: // image & caption
        var imgwidth = parseInt(p.metadata.originalWidth,10);
        var imgsrc = MEDIUM_IMG_CDN+Math.max(imgwidth*2,2000)+"/"+p.metadata.id;
        var text = "\n!["+p.text+"]("+imgsrc+")";
        if (p.text) {
          text += "*"+p.text+"*";
        }
        p.text = text;
        break;
      case 6:
        markup = "> ";
        break;
      case 7: // quote
        p.text = "> # "+p.text.replace(/\n/g,'\n> # ');
        break;
      case 8:
        p.text = "\n```\n" + p.text + "\n```\n";
        break;
      case 9:
        markup = "\n* ";
        break;
      case 10:
        markup = "\n1. ";
        break;
      case 11:
        return utils.getYouTubeEmbed('https://medium.com/media/'+p.iframe.mediaResourceId, function(err, embed) {
          cb(null, `\n${embed}`);
        });
      case 13:
        markup = "\n### ";
        break;
      case 15: // caption for section image
        p.text = "*"+p.text+"*";
        break;
    }

    p.text = markup + p.text;

    if(p.alignment == 2&& p.type != 6 && p.type != 7) p.text = "<center>" + p.text + "</center>";

    return cb(null, p.text);
  },
  addMarkup: function(markups_array, open, close, start, end) {
    if(markups_array[start])
      markups_array[start] += open;
    else
      markups_array[start] = open;

    if(markups_array[end])
      markups_array[end] += close;
    else
      markups_array[end] = close;

    return markups_array;
  },
  createMarkupsArray: function(markups) {
    if(!markups || markups.length == 0) return [];
    var markups_array = [];
    for(var j=0;j<markups.length;j++) {
      var m = markups[j];
      switch(m.type) {
        case 1: // bold
          utils.addMarkup(markups_array, "**","**",m.start,m.end);
          break;
        case 2: // italic
          utils.addMarkup(markups_array, "*","*",m.start,m.end);
          break;
        case 3: // anchor tag
          utils.addMarkup(markups_array, "[", "]("+m.href+")", m.start, m.end);
          break;
        case 10: // code
          utils.addMarkup(markups_array, '`', '`', m.start, m.end);
          break;
        default:
          console.error("Unknown markup type "+m.type, m);
          break;
      }
    }
    return markups_array;
  }
}

module.exports = utils;