Google Drive API credential generation/token refreshing in MEAN.js

googleDriveOAuth2Middleware.js

// This is valid for MEAN.js 0.4.0
// Requires a couple of changes to work:
//      Add Drive scope to users Express route
//      Modify the Passport.js google strategy to put a token expiration date into the database
//      User middleware function below to auth API calls

exports.requiresOAuth2Token = function (req, res, next) {
    var OAuth2 = google.auth.OAuth2;
    var client = new OAuth2(config.google.clientID, config.google.clientSecret, config.google.callbackURL);
    client.setCredentials({
        access_token: req.user.providerData.accessToken,
        refresh_token: req.user.providerData.refreshToken
    });
    if (req.user.providerData.tokenExpires < Math.floor((Date.now() / 1000)) - 120) {
        console.log('Token needs to be refreshed');
        client.refreshAccessToken(function(err, tokens) {
            if (err) {
                return res.status(400).send({
                    message: errorHandler.getErrorMessage(err)
                });
            } else {
                var query = {_id: req.user._id};
                var update = {providerData:
                    _.extend(req.user.providerData, {
                        accessToken: tokens.access_token,
                        tokenExpires: Math.floor(tokens.expiry_date / 1000)
                    }
                )};
                var opts = {};
                User.update(query, update, opts, function(err, num) {
                    if(err) {
                        console.log(err);
                    } else {
                        console.log(num + ' record(s) updated');
                        req.user.client = client;
                        next();
                    }
                });
            }
        });
    } else {
        console.log('Current token still valid');
        req.user.client = client;
        next();
    }
};