The produce of a HelsinkiJS mini-workshop. Pulls in the profile images of members of the HelsinkiJS group and renders them as a webpage.

fbclient.js

// Import the required modules
var fs = require("fs");
var parseUrl = require("url").parse;
var http = require("http");
var express = require("express");
var handlebars = require("handlebars");
var Q = require("q");
var FB = require('fb');

// Read the template file from disk
var index = fs.readFileSync("index.html", "utf-8");

// Pre-compile the Handlerbars template
var template = handlebars.compile(index);

// Create an Expres.JS app
var app = express();

// Application settings
var helsinkiJSGroupId = "208755712538736";
var FBApp = {
    ID: "<fb app id>",
    secret: "<fb app secret>"
};


/**
 * Helper for doing HTTP requests in Node.js
 * @param  {string} method The HTTP request method
 * @param  {string} url    The URL to fetch
 * @return {promise}       Returns a (Q.js) promise/deferred
 */
function requestWithPromise(method, url) {
    var def = Q.defer();
    var parsed = parseUrl(url);
    var opts = {
        method: method,
        hostname: parsed.hostname,
        port: parsed.port,
        path: parsed.path,
        headers: {}
        };
    var data = "";
    var req =
        http.request(opts).
            on("response", function (res) {
                res.
                on("data", function (chunk) {
                    data += String(chunk);
                }).
                on("end", function () {
                    def.resolve([res.statusCode, res]);
                });
            }).
            on("error", function () {
                def.reject();
            }).
            end();

    return def.promise;
}

/**
 * Request an access token from FB
 * @return {promise} Returns a (Q.js) promise/deferred
 */
function getAccessToken() {
    var defer = Q.defer();

    FB.api('oauth/access_token', {
        client_id: FBApp.ID,
        client_secret: FBApp.secret,
        grant_type: 'client_credentials'
    }, function (res) {
        if(!res || res.error) {
            defer.reject(res);
            return;
        }

        var accessToken = res.access_token;

        FB.setAccessToken(accessToken);

        defer.resolve();
    });

    return defer.promise;
}

/**
 * Fetch the group member data from FB
 * @return {promise} Returns a (Q.js) promise/deferred
 */
function getGroupMembers() {
    var defer = Q.defer();

    FB.api(helsinkiJSGroupId + "/members", function (fbres) {
        if(!fbres || fbres.error) {
            console.log(!fbres ? 'error occurred' : fbres.error);

            defer.reject(fbres.error);
        }

        defer.resolve(fbres);
    });

    return defer.promise;
}

/**
 * Returns the user id's of an array of user objects
 * @param  {array} res Array of user object
 * @return {array}     Array of user id's
 */
function extractUserIds(res) {
    return res.data.map(function (user) { return user.id; });
}


/**
 * Fetch a URL to a single users profile image
 * @param  {string} userId The user's id
 * @return {string}        The URL to the profile image
 */
function fetchUserProfileImage(userId) {
    var defer = Q.defer();

    // Not using the FB.api, because it chokes on the redirect to the image as 
    // it attempts to parse it as JSON. Also, we're really only interested in 
    // the location header in the response.
    requestWithPromise("GET", "http://graph.facebook.com/" + userId + "/picture").
    spread(function (status, res) {
        defer.resolve(res.headers.location);
    }, function () {
        defer.reject("graph request failed");
    });

    return defer.promise;
}

/**
 * Fetch URL's to a user's profile image
 * @param  {String} ids Array of user id's
 * @return {array}      Array of URL's
 */
function fetchProfileImages(ids) {
    var defer = Q.defer();
    var promises = ids.map(function (id) {
        return fetchUserProfileImage(id);
    });

    Q.all(promises).
    then(function (images) {
        defer.resolve(images);
    }, function (err) {
        console.log("single profile fetch error", err);
    }).
    done();

    return defer.promise;
}

/**
 * Returns a dumb input echoing function, with a prefix message
 * @param  {string} msg Message to prepend
 * @return {function}
 */
function makeErrH(msg) {
    return function () {
        console.log(msg, arguments);
    };
}

// Bind a handler for the / URL (on localhost)
app.get("/", function (req, res) {
    getAccessToken().
    then(getGroupMembers, makeErrH("access token failed")).
    then(extractUserIds, makeErrH("group data failed")).
    then(fetchProfileImages, makeErrH("profile images failed")).
    then(function (images) {
        // Send the response
        res.send(
            // Render the template
            template({ images: images })
            );
    }, function () {
        res.send("Sorry, there was an error :(");
    }).
    done();
});

// Bind the express.js app on port 8080 on localhost
app.listen(8080);

index.html

<!doctype html>
<html>
<head>
    <title>HelsinkiJS Group Members</title>
</head>
<body>
    <h1>Members of the HelsinkiJS Facebook Group</h1>
    {{#images}}
        <img src="{{.}}">
    {{/images}}
</body>
</html>

package.json

{
    "name": "HSJS Workshop",
    "version": "0.0.0",
    "description": "HelsinkiJS Pair Programming",
    "dependencies": {
        "q": "*",
        "handlebars": "*",
        "express": "*",
        "facebook-node-sdk": "Thuzi/facebook-node-sdk"
    }
}