PubNub Twitter Publisher BLOCK JavaScript

pubnub_twitter_block.js

const xhr = require('xhr');
const base64Codec = require('codec/base64');
const crypto = require('crypto');

export default (request) => {
    // see https://apps.twitter.com
    const consumerKey      = "YOUR_CONSUMER_KEY";
    const consumerSecret   = "YOUR_CONSUMER_SECRET";
    const accessToken      = "YOUR_ACCESS_TOKEN";
    const oauthTokenSecret = "YOUR_OAUTH_TOKEN_SECRET";

    const httpReqType = "POST";
    const contentType = "application/x-www-form-urlencoded";
    let url = "https://api.twitter.com/1.1/statuses/update.json";

    if (!request.message.tweet) {
        return request.abort({ "400": "400: Bad Request" });
    }

    let tweetContent = (request.message.tweet || "");
    let content = (tweetContent ? "status=" + encodeURIComponent(tweetContent).replace(/[!'()*]/g, escape) : "");

    let oauth = {
        "oauth_consumer_key": consumerKey,
        "oauth_nonce": base64Codec.btoa(Math.random().toString(36)).replace(/(?!\w)[\x00-\xC0]/g, ""),
        "oauth_signature_method": "HMAC-SHA1",
        "oauth_timestamp": Math.floor(new Date().getTime() / 1000),
        "oauth_token": accessToken,
        "status": tweetContent
    };

    return getOAuthSignature(oauth, httpReqType, url, consumerSecret, oauthTokenSecret).then((result) => {
        oauth.oauth_signature = result;
        delete oauth.status;
        let authHeaderString = objectToRequestString(oauth, 'OAuth ', '="', '"', ', ');

        let http_options = {
            "method": httpReqType,
            "headers": {
                "Content-Type": contentType,
                "Authorization": authHeaderString
            },
            "body": content
        };

        return xhr.fetch(url, http_options).then((response) => response.json()).then((response) => {
            request.message.twtr_response = response;

            return request.ok();
        });
    })
    .catch((error) => {
        return request.abort({ "500": "500: Internal server error" });
    });
};

function getOAuthSignature(oauth, httpReqType, url, consumerSecret, oauthTokenSecret) {
    let parameterString = objectToRequestString(oauth, '', '=', '', '&');
    let signatureBaseString = httpReqType + "&" + encodeURIComponent(url) + "&" + encodeURIComponent(parameterString);
    let signingKey = base64Codec.btoa(encodeURIComponent(consumerSecret) + "&" + encodeURIComponent(oauthTokenSecret));
    return crypto.hmac(signingKey, signatureBaseString, crypto.ALGORITHM.HMAC_SHA1).then((result) => {
        return result;
    });
}

function objectToRequestString(obj, prepend, head, tail, append) {
    let requestString = prepend || "";
    Object.keys(obj).forEach((key, i) => {
        requestString += key + head + encodeURIComponent(obj[key]).replace(/[!'()*]/g, escape) + tail;
        i < Object.keys(obj).length-1 ? requestString += append : null;
    });
    return requestString;
}