Refactor code for improved robustness and modern JavaScript standards

webchart-example.js

@@ -1,105 +1,133 @@
-var http = require('http');
-var qs = require('querystring');
-var OAuth2 = require('oauth').OAuth2;
-var readline = require('readline');
+const http = require('http');
+const { URL } = require('url');
+const { OAuth2 } = require('oauth');
+const readline = require('readline');
 
 // Read client secret from environment variable
-var clientID = 'MIE-localhost';
-var clientSecret = process.env.CLIENT_SECRET;
+const clientID = 'MIE-localhost';
+let clientSecret = process.env.CLIENT_SECRET;
 
 if (!clientSecret) {
-    const rl = readline.createInterface({
-        input: process.stdin,
-        output: process.stdout
-    });
+  const rl = readline.createInterface({
+    input: process.stdin,
+    output: process.stdout,
+  });
 
-    rl.question('Enter the client secret: ', (input) => {
-        clientSecret = input;
-        rl.close();
-        startServer();
-    });
-} else {
+  rl.question('Enter the client secret: ', (input) => {
+    clientSecret = input;
+    rl.close();
     startServer();
+  });
+} else {
+  startServer();
 }
 
+/**
+ * Starts the HTTP server and sets up the OAuth2 authentication flow.
+ */
 function startServer() {
-    var oauth2 = new OAuth2(
-        clientID,
-        clientSecret,
-        'https://fhirr4sandbox.webch.art',
-        '/webchart.cgi/oauth/authenticate/',
-        '/webchart.cgi/oauth/token/',
-        null
-    );
-
-    // Wrapper function to add logging
-    function addLoggingToOAuth2(oauth2Instance) {
-        const methodsToLog = ['getAuthorizeUrl', 'getOAuthAccessToken', '_request'];
-
-        methodsToLog.forEach(method => {
-            const originalMethod = oauth2Instance[method];
-            oauth2Instance[method] = function(...args) {
-                console.log(`Calling ${method} with arguments:`, args);
-                return originalMethod.apply(oauth2Instance, args);
-            };
-        });
-    }
-
-    // Add logging to OAuth2 instance
-    addLoggingToOAuth2(oauth2);
-
-    http.createServer(function (req, res) {
-        var p = req.url.split('/');
-        var pLen = p.length;
-
-        var authURL = oauth2.getAuthorizeUrl({
-            response_type: 'code', // Explicitly specify the response type
-            redirect_uri: 'http://localhost:8080/code',
-            scope: 'launch/patient openid fhirUser offline_access patient/*.read',
-            state: 'some random string to protect against cross-site request forgery attacks',
-            aud: 'https://fhirr4sandbox.webch.art/webchart.cgi' // Add the correct audience
-        });
-
-        console.log('authURL: ', authURL);
-
-        var body = '<a href="' + authURL + '"> Get Code </a>';
-        if (pLen === 2 && p[1] === '') {
-            res.writeHead(200, {
-                'Content-Length': body.length,
-                'Content-Type': 'text/html' });
-            res.end(body);
-        } else if (pLen === 2 && p[1].indexOf('code') === 0) {
-            var qsObj = qs.parse(p[1].split('?')[1]); 
-
-            console.log('qsObj: ', qsObj);
-
-            oauth2.getOAuthAccessToken(
-                qsObj.code,
-                {
-                    'redirect_uri': 'http://localhost:8080/code',
-                    'grant_type': 'authorization_code' // Set the grant_type
-                },
-                function (e, access_token, refresh_token, results){
-                    if (e) {
-                        console.log(e);
-                        res.end(e);
-                    } else if (results.error) {
-                        console.log(results);
-                        res.end(JSON.stringify(results));
-                    }
-                    else {
-                        console.log('Obtained access_token: ', access_token);
-                        res.end(access_token);
-                    }
-            });
-
-        } else {
-            // Unhandled url
-            res.writeHead(404, {'Content-Type': 'text/plain'});
-            res.end('Not Found');
+  const oauth2 = new OAuth2(
+    clientID,
+    clientSecret,
+    'https://fhirr4sandbox.webch.art',
+    '/webchart.cgi/oauth/authenticate/',
+    '/webchart.cgi/oauth/token/',
+    null
+  );
+
+  /**
+   * Adds logging functionality to specified methods of the OAuth2 instance.
+   * @param {OAuth2} oauth2Instance - The OAuth2 instance to enhance.
+   */
+  function addLoggingToOAuth2(oauth2Instance) {
+    const methodsToLog = ['getAuthorizeUrl', 'getOAuthAccessToken', '_request'];
+
+    methodsToLog.forEach((method) => {
+      const originalMethod = oauth2Instance[method];
+      oauth2Instance[method] = function (...args) {
+        console.log(`Calling ${method} with arguments:`, args);
+        return originalMethod.apply(oauth2Instance, args);
+      };
+    });
+  }
+
+  // Add logging to OAuth2 instance
+  addLoggingToOAuth2(oauth2);
+
+  const authURL = oauth2.getAuthorizeUrl({
+    response_type: 'code',
+    redirect_uri: 'http://localhost:8080/code',
+    scope: 'launch/patient openid fhirUser offline_access patient/*.read',
+    state: 'some random string to protect against cross-site request forgery attacks',
+    aud: 'https://fhirr4sandbox.webch.art/webchart.cgi',
+  });
+
+  console.log('authURL: ', authURL);
+
+  http
+    .createServer((req, res) => {
+      try {
+        const urlObj = new URL(req.url, `http://${req.headers.host}`);
+        const pathname = urlObj.pathname;
+        const params = urlObj.searchParams;
+
+        if (pathname === '/') {
+          const body = `<a href="${authURL}">Get Code</a>`;
+          res.writeHead(200, { 'Content-Type': 'text/html' });
+          res.end(body);
+          return;
+        }
+
+        if (pathname === '/code') {
+          const code = params.get('code');
+
+          if (!code) {
+            res.writeHead(400, { 'Content-Type': 'text/plain' });
+            res.end('Bad Request: Missing code parameter');
+            return;
+          }
+
+          console.log('Received code:', code);
+
+          oauth2.getOAuthAccessToken(
+            code,
+            {
+              redirect_uri: 'http://localhost:8080/code',
+              grant_type: 'authorization_code',
+            },
+            (e, access_token, refresh_token, results) => {
+              if (e) {
+                console.error('Error obtaining access token:', e);
+                res.writeHead(500, { 'Content-Type': 'text/plain' });
+                res.end('Internal Server Error');
+                return;
+              }
+
+              if (results.error) {
+                console.error('OAuth error:', results);
+                res.writeHead(400, { 'Content-Type': 'application/json' });
+                res.end(JSON.stringify(results));
+                return;
+              }
+
+              console.log('Obtained access_token:', access_token);
+              res.writeHead(200, { 'Content-Type': 'text/plain' });
+              res.end(access_token);
+            }
+          );
+          return;
         }
 
-    }).listen(8080, () => {
-        console.log('Server is listening on port 8080');
+        // Unhandled URL
+        res.writeHead(404, { 'Content-Type': 'text/plain' });
+        res.end('Not Found');
+      } catch (error) {
+        console.error('Server error:', error);
+        res.writeHead(500, { 'Content-Type': 'text/plain' });
+        res.end('Internal Server Error');
+      }
+    })
+    .listen(8080, () => {
+      console.log('Server is listening on port 8080');
     });
-}
+}