twitter-oauth-for-express.js

var oauth   = require('oauth')
  , request = require('request')
  ;

module.exports = function(app, params, cb) {
  if(!params.consumer_key)            { throw new Error('Please provide a consumer key.');    }
  if(!params.consumer_secret)         { throw new Error('Please provide a consumer secret.'); }
  if(!params.callback_url)            { throw new Error('Please provide callback url.');      }
  if(!cb)                             { throw new Error('Please provide a callback');         }

  var base_route      = params.base_route || '/auth/twitter'
    , cb_route        = base_route + '/callback'
    , twitter_url     = params.twitter_url || 'https://twitter.com'
    , consumer_key    = params.consumer_key
    , consumer_secret = params.consumer_secret
    , callback_url    = params.callback_url
    ;

  function consumer() {
    return new oauth.OAuth(
        twitter_url + "/oauth/request_token"
      , twitter_url + "/oauth/access_token"
      , consumer_key
      , consumer_secret
      , "1.0A"
      , callback_url + cb_route
      , "HMAC-SHA1");
  }

  app.get(base_route, function(request, response) {
    consumer().getOAuthRequestToken(
      function(error, oauth_token, oauth_token_secret, results) {
      if (error) { return cb(error,request,response); }
      else {
        request.session.oauth_request_token        = oauth_token;
        request.session.oauth_request_token_secret = oauth_token_secret;
        response.redirect( twitter_url + "/oauth/authorize?oauth_token=" + 
          request.session.oauth_request_token );
      }
    });
  });

  app.get(cb_route, function(request, response) {
    if(request.query.denied) { 
      return cb( new Error('You choose not to login. Try again when you are ready!')
        , request, response, 'twitter');
    }
    consumer().getOAuthAccessToken( request.session.oauth_request_token
        , request.session.oauth_request_token_secret
        , request.query.oauth_verifier
        , function(error, oauth_access_token, oauth_access_token_secret, results) {
            if (error) { return cb(error,request,response,'twitter'); }
            request.session.oauth_access_token        = oauth_access_token;
            request.session.oauth_access_token_secret = oauth_access_token_secret;
            consumer().get( twitter_url + "/account/verify_credentials.json"
              , request.session.oauth_access_token
              , request.session.oauth_access_token_secret
              , function (error, twitter_user) {
                if (error) { return cb(error,request,response,'twitter'); }
                try {
                  cb(null,request,response,'twitter',JSON.parse(twitter_user));
                } catch(exc) {
                  cb(exc,request,response,'twitter');
                }
            });
    });
  });
};