disqus-azure-p2-2.js

// Disqus API public key
var apiPublic = 'YOUR_PUBLIC_KEY';
    
// Disqus API secret key
var apiSecret = 'YOUR_SECRET_KEY';
    
// Should match exactly what you've entered in your Disqus API application
var oAuthRedirectUri = 'https://MOBILE_SERVICE_NAME.azure-mobile.net/api/disqus_callback/';

// Master key from your mobile service configuration
var azureMasterKey = 'AZURE_MASTER_KEY';

exports.get = function(request, response) {
        
	// Retrieve the code from the query
	var code = request.query.code;
	
	if (code !== undefined) {
	    
	    // Code is set, so we know we're handling an OAuth callback request
	    // Make POST request for the temporary access token
	    var httpRequest = require('request');
	    
	    httpRequest({
	      uri: 'https://disqus.com/api/oauth/2.0/access_token/',
	      method: 'POST',
	      form: {
	          grant_type: 'authorization_code',
	          client_id: apiPublic,
	          client_secret: apiSecret,
	          code: code,
	          redirect_uri: oAuthRedirectUri
	      }
	    }, function(httpError, httpResponse, httpBody) {
	       
	       // Handle response from Disqus here
	       if (httpError || httpResponse.statusCode !== 200) {
	           
	           // Error
	           console.error('Error retrieving access token: ' + httpBody);
	           response.send(
	           	httpResponse.statusCode, 
	           	'Unable to connect to Disqus.'
	           );
	       }
	       else {
	           
	           // Everything is good, respond with the access token
	           
	           /* Body of request looks like this:
	           {
	              "access_token": "c2d06abacfbb40179e47f62f06546ea9",
	              "refresh_token": "9182211bf2f746a4b5c5b1e3766443d6",
	              "expires_in": 2592000,
	              "username": "batman"
	              "user_id": "947103743"
	            }
	            */
	           var authorization = JSON.parse(httpBody);
               
               // Get a reference to our user table
               // TODO make sure you replace USER_TABLE_NAME with your actual table
               var userTable = request.service.tables.getTable('USER_TABLE_NAME');
               
               userTable.where({ userId: authorization.user_id.toString() }).read({
                    success: function (results) {
                       if (results.length === 0) {
                           
                           // This user hasn't authenticated yet, so insert a new entry
                           userTable.insert(getUserEntry(authorization));
                       }
                       else {
                           
                           // User exists, so update the entry
                           var entry = getUserEntry(authorization);
                           entry.id = results[0].id;
                           userTable.update(entry);
                       }
                    },
                    error: function (error) {
                        console.error('Error reading database', error);
                        response.send(500, error);
                    }
               });
               
               var oneHundredYears = new Date().setUTCDate(new Date().getUTCDate() + 30000);
               var token = generateToken(oneHundredYears, authorization.user_id, azureMasterKey);
	           
	           response.send(
	           	statusCodes.OK, 
	           	'Success! This is your Azure token: ' +
	            		token
	           );
	       }
	    });
	}
	else {
	    
	    // No code in query, so send the user to the authorize URL
	    var redirectUri = 'https://disqus.com/api/oauth/2.0/authorize/' + 
	        '?client_id=' + apiPublic + 
	        '&scope=read,write' +
	        '&response_type=code';
	        
	    response.redirect(redirectUri);
	}
};

function getUserEntry(authorization) {
    return { 
        accessToken: authorization.access_token,
        refreshToken: authorization.refresh_token,
        userId: authorization.user_id,
        username: authorization.username,
        expires: Math.round((new Date().getTime() / 1000) + authorization.expires_in)
    };
}

// Generates a token recognized by Azure mobile services as an authenticated user
function generateToken(expiryDate, userId, masterKey) {
 
    var crypto = require('crypto');
    
    function base64(input) {
    	return new Buffer(input, 'utf8').toString('base64');
    }
    
    function urlFriendly(b64) {
    	return b64.replace(/\+/g, '-').replace(/\//g, '_').replace(new RegExp('=', 'g'), '');
    }
    
    function signature(input) {
    	var key = crypto.createHash('sha256').update(masterKey + 'JWTSig').digest('binary');
    	var str = crypto.createHmac('sha256', key).update(input).digest('base64');
    	return urlFriendly(str);
    }
    
    var s1 = '{"alg":"HS256","typ":"JWT","kid":0}';
    var j2 = {
    	'exp':  expiryDate.valueOf() / 1000,
    	'iss': 'urn:microsoft:windows-azure:zumo',
    	'ver': 1,
    	'aud': 'Disqus',
    	'uid': userId 
    };
    var s2 = JSON.stringify(j2);
    var b1 = urlFriendly(base64(s1));
    var b2 = urlFriendly(base64(s2));
    var b3 = signature(b1 + "." + b2);
    
    return [b1,b2,b3].join('.');
}