stocks-exchange-client/lib/v3/refresh.js

STEX (former Stocks.Exchange) provides all the core exchange functionality, and additional merchant tools available via the HTTPS API where all returned messages are in JSON. It's much easier to work with the API by using one of the clients provided by St

var request = require('request');
var fs = require("fs");
var EventEmitter = require('events').EventEmitter;
const jsonfile = require('jsonfile');
const settings_path = 'settings.json';

/**
 * Create a new instance of TokenProvider
 *
 * @param {String} url url to get the access token
 * @param {Object} options
 * @return {TokenProvider}
 *
 * options are:
 *  refresh_token
 *  client_id
 *  client_secret
 *
 *  optionals
 *    access_token
 *    expires_in
 */
function TokenProvider(url, options) {
    EventEmitter.call(this);

    if (!(this instanceof TokenProvider)) {
        //when calling as a function, force new.
        return new TokenProvider(url, options);
    }

    if (!url) {
        throw new Error('missing url parameter');
    }

    ['refresh_token', 'client_id', 'client_secret'].forEach(function (k) {
        if (!(k in options)) {
            throw new Error('missing ' + k + ' parameter');
        }
    });

    this.url = url;
    this.options = options;

    try {
        this.currentToken = jsonfile.readFileSync(settings_path);
    } catch (error) {
        this.currentToken = {
            access_token: this.options.access_token,
            expires_in: this.options.expires_in,
            expires_in_date: this.options.expires_in_date,
            scope: this.options.scope
        };
        jsonfile.writeFileSync(settings_path, this.currentToken);
    }

    if (this.currentToken && 'expires_in' in this.currentToken) {
        if (this.currentToken.expires_in_date == null) {
            this.currentToken.expires_in_date = new Date(new Date().getTime() + (this.currentToken.expires_in * 1000));
        }
    }
}

TokenProvider.prototype = Object.create(EventEmitter.prototype);

/**
 * Return a valid access token.
 *
 * If the current access token is expired,
 * fetch a new one.
 *
 * @param  {Function} done
 */
TokenProvider.prototype.getToken = function (done) {
    if (this.options.s2s) {
        return done(null, this.currentToken.access_token);
    }

    if (this.currentToken && this.currentToken.expires_in_date && new Date(this.currentToken.expires_in_date) > new Date()) {
        return done(null, this.currentToken.access_token);
    }

    request.post({
        url: this.url,
        form: {
            refresh_token: this.options.refresh_token,
            client_id: this.options.client_id,
            client_secret: this.options.client_secret,
            grant_type: 'refresh_token',
            scope: this.options.scope,
        }
    }, function (err, response, body) {
        if (err) return done(err, null);

        if (response.statusCode !== 200) {
            var error;
            if (response.headers['content-type'].indexOf('application/json')) {
                var errorBody = JSON.parse(body);
                error = new Error(errorBody.error);
            } else {
                error = new Error('error refreshing token');
                error.response_body = body;
            }
            if (fs.existsSync(settings_path)) {
                fs.unlinkSync(settings_path)
            }
            return done(error, null);
        } else {
            this.currentToken = JSON.parse(body);

            this.currentToken.expires_in_date =
                new Date((new Date()).getTime() + this.currentToken.expires_in * 1000);

            jsonfile.writeFileSync(settings_path, this.currentToken);
            this.emit('new token', this.currentToken);
            return done(null, this.currentToken.access_token);

        }
    }.bind(this));
};

module.exports = TokenProvider;