node-deeplink/lib/deeplink.js

Easily create an endpoint in your web server that redirects deep links to mobile apps

const fs = require('fs');
const inliner = require('html-inline');
const stream = require('stream');
const path = require('path');

module.exports = function(options) {
  options = options || {};
  if (!options.fallback) {
    throw new Error('Error (deeplink): options.fallback cannot be null');
  }
  options.android_package_name = options.android_package_name || '';
  options.ios_store_link = options.ios_store_link || '';
  options.title = options.title || '';

  const deeplink = function(req, res, next) {
    const opts = {};
    Object.keys(options).forEach(function(k) {
      opts[k] = options[k];
    });

    if (req.query.url) {
      opts.url = req.query.url;
    }

    // bail out if we didn't get url
    if (!opts.url) {
      return next();
    }

    if (req.query.fallback) {
      opts.fallback = req.query.fallback;
    }

    // read template file
    const file = fs.createReadStream(
      path.join(__dirname, '/public/index.html')
    );

    // replace all template tokens with values from options
    const detoken = new stream.Transform({ objectMode: true });
    detoken._transform = function(chunk, encoding, done) {
      let data = chunk.toString();
      Object.keys(opts).forEach(function(key) {
        data = data.replace('{{' + key + '}}', opts[key]);
      });

      this.push(data);
      done();
    };

    // inline template js with html
    const inline = inliner({ basedir: path.join(__dirname, '/public') });

    // make sure the page is being sent as html
    res.set('Content-Type', 'text/html;charset=utf-8');

    // read file --> detokenize --> inline js --> send out
    file
      .pipe(detoken)
      .pipe(inline)
      .pipe(res);
  };

  return deeplink;
};