gdata.js

var querystring = require('querystring');
var https = require('https');
var EventEmitter = require('events').EventEmitter;

var URL = require('url');

var oauthBase = 'https://accounts.google.com/o/oauth2';

module.exports = function(client_id, client_secret, redirect_uri) {
    var clientID = client_id;
    var clientSecret = client_secret;
    var redirectURI = redirect_uri;
    var token;
    
    var client = new EventEmitter();
    client.getAccessToken = function(scope, req, res, callback) {
        if(req.query.error) {
            callback(req.query.error);
        } else if(!req.query.code) {
            var height = 750;
            var width = 980;
            resp = "<script type='text/javascript'>var left= (screen.width / 2) - (" + width + " / 2); var top = (screen.height / 2) - (" + height + " / 2); window.open('" + oauthBase + '/auth?' + querystring.stringify({client_id: clientID, redirect_uri: redirectURI, scope: scope, response_type: 'code'}) + "', 'auth', 'menubar=no,toolbar=no,status=no,width=" + width + ",height=" + height + ",toolbar=no,left=' + left + 'top=' + top);</script>";
            res.end(resp + '<a target=_new href=\'' + oauthBase + '/auth?' + querystring.stringify({client_id: clientID , 
                                                                                    redirect_uri: redirectURI, 
                                                                                    scope: scope, 
                                                                                    response_type: 'code'}) + '\'>Authenticate</a>');
        } else {
             doPost({grant_type:'authorization_code',
                      code:req.query.code,
                      client_id:clientID,
                      client_secret:clientSecret,
                      redirect_uri:redirectURI}, function(err, tkn) {
                          if(!err && tkn && !tkn.error)
                              token = tkn;
                          callback(err, tkn);
                      });
        }
    }
    
    client.setToken = function(tkn) {
        token = tkn;
    }
    client.getFeed = function(url, params, callback) {
        if(!callback && typeof params === 'function') {
            callback = params;
            params = {};
        }
        params.oauth_token = token.access_token;
        params.alt = 'json';
        var reqUrl = url + '?' + querystring.stringify(params);
        doRequest(url, params, function(err, body) {
            callback(err, body);
        });
    };
    
    
    function doRequest(url, params, callback) {
        var path = URL.parse(url).pathname + '?' + querystring.stringify(params);
        var options = {
            host: 'www.google.com',
            port: 443,
            path: path,
            method: 'GET'
        };

        var httpsReq = https.request(options, function(httpsRes) {
            if(httpsRes.statusCode === 401) {
                refreshToken(function(err, result) {
                    if(!err && result && !result.error && result.access_token) {
                        token.access_token = result.access_token;
                        token.refresh_token = result.refresh_token;
                        client.emit('tokenRefresh');
                        client.getFeed(url, params, callback);
                    }
                });
            } else {
                var data = '';
                httpsRes.on('data', function(moreData) {
                    data += moreData;
                });
                httpsRes.on('end', function() {
                    try {
                        callback(null, JSON.parse(data.toString()));
                    } catch(err) {
                        callback(err, null);
                    }
                })
            }
        });
        httpsReq.on('error', function(e) {
            callback(e, null);
        });
        httpsReq.end();
    }
    
    function refreshToken(callback) {
        doPost({client_id:clientID,
                client_secret:clientSecret,
                refresh_token:token.refresh_token,
                grant_type:'refresh_token'
               }, function(err, result) {
                   if(err || !result || !result.access_token) {
                       console.error('err', err);
                       console.error('result', result);
                   }
                   callback(err, result);
               });
    }
    return client;
}


function doPost(body, callback) {
    var options = {
        host: 'accounts.google.com',
        port: 443,
        path: '/o/oauth2/token',
        method: 'POST',
        headers: {'Content-Type':'application/x-www-form-urlencoded'}
    };
    var httpsReq = https.request(options, function(httpsRes) {
        if(httpsRes.statusCode === 200) {
            httpsRes.on('data', function(data) {
                callback(null, JSON.parse(data.toString()));
            });
        } else {
            httpsRes.on('data', function(data) {
                console.error("refreshing token -- statusCode !== 200, yoikes! data:", data.toString());
                callback(data.toString());
            });
        }
    });
    httpsReq.write(querystring.stringify(body));
    httpsReq.on('error', function(e) {
        callback(e, null);
    });
    httpsReq.end();
}