Add support for CAS auth strategy

.env.example

@@ -37,6 +37,10 @@ REACT_APP_OAUTH2_PROVIDER3_ENDPOINT=http://localhost:8000/login?provider=test&co
 # REACT_APP_OAUTH2_PROVIDER2_NAME=Cognito
 # REACT_APP_OAUTH2_PROVIDER2_ENDPOINT=
 
+REACT_APP_CAS_PROVIDER1=
+REACT_APP_CAS_PROVIDER1_NAME=
+REACT_APP_CAS_PROVIDER1_ENDPOINT=
+
 REACT_APP_MODULE_BACKEND_URL=https://source-academy.github.io/modules
 REACT_APP_SHAREDB_BACKEND_URL=
 REACT_APP_SICPJS_BACKEND_URL="http://127.0.0.1:8080/"

src/commons/sagas/__tests__/BackendSaga.ts

@@ -78,7 +78,7 @@ import {
 import { mockGradingSummary } from '../../mocks/GradingMocks';
 import { mockNotifications } from '../../mocks/UserMocks';
 import { Notification } from '../../notificationBadge/NotificationBadgeTypes';
-import { computeRedirectUri } from '../../utils/AuthHelper';
+import { AuthProviderType, computeRedirectUri } from '../../utils/AuthHelper';
 import Constants from '../../utils/Constants';
 import {
   showSuccessMessage,
@@ -286,7 +286,8 @@ describe('Test FETCH_AUTH action', () => {
   Constants.authProviders.set(providerId, {
     name: providerId,
     endpoint: `https://test/?client_id=${clientId}`,
-    isDefault: true
+    isDefault: true,
+    type: AuthProviderType.OAUTH2
   });
   const redirectUrl = computeRedirectUri(providerId);
 

src/commons/utils/AuthHelper.ts

@@ -1,13 +1,25 @@
 import Constants from './Constants';
 
+export enum AuthProviderType {
+  OAUTH2 = 'OAUTH2',
+  CAS = 'CAS'
+}
+
 export function computeEndpointUrl(providerId: string): string | undefined {
   const ep = Constants.authProviders.get(providerId);
   if (!ep) {
     return undefined;
   }
   try {
     const epUrl = new URL(ep.endpoint);
-    epUrl.searchParams.set('redirect_uri', computeRedirectUri(providerId)!);
+    switch (ep.type) {
+      case AuthProviderType.OAUTH2:
+        epUrl.searchParams.set('redirect_uri', computeRedirectUri(providerId)!);
+        break;
+      case AuthProviderType.CAS:
+        epUrl.searchParams.set('service', computeRedirectUri(providerId)!);
+        break;
+    }
     return epUrl.toString();
   } catch (e) {
     // in dev, sometimes the endpoint is a dummy; allow that

src/commons/utils/Constants.ts

@@ -1,5 +1,7 @@
 import { Chapter, Variant } from 'js-slang/dist/types';
 
+import { AuthProviderType } from './AuthHelper';
+
 function isTrue(value?: string, defaultTo?: boolean): boolean {
   return typeof value === 'undefined' && typeof defaultTo !== 'undefined'
     ? defaultTo
@@ -46,8 +48,10 @@ const caFulfillmentLevel = isTest
   ? 24
   : parseInt(process.env.REACT_APP_CA_FULFILLMENT_LEVEL || '0');
 
-const authProviders: Map<string, { name: string; endpoint: string; isDefault: boolean }> =
-  new Map();
+const authProviders: Map<
+  string,
+  { name: string; endpoint: string; isDefault: boolean; type: AuthProviderType }
+> = new Map();
 
 for (let i = 1; ; ++i) {
   const id = process.env[`REACT_APP_OAUTH2_PROVIDER${i}`];
@@ -58,7 +62,19 @@ for (let i = 1; ; ++i) {
   const name = process.env[`REACT_APP_OAUTH2_PROVIDER${i}_NAME`] || 'Unnamed provider';
   const endpoint = process.env[`REACT_APP_OAUTH2_PROVIDER${i}_ENDPOINT`] || '';
 
-  authProviders.set(id, { name, endpoint, isDefault: i === 1 });
+  authProviders.set(id, { name, endpoint, isDefault: i === 1, type: AuthProviderType.OAUTH2 });
+}
+
+for (let i = 1; ; ++i) {
+  const id = process.env[`REACT_APP_CAS_PROVIDER${i}`];
+  if (!id) {
+    break;
+  }
+
+  const name = process.env[`REACT_APP_CAS_PROVIDER${i}_NAME`] || 'Unnamed provider';
+  const endpoint = process.env[`REACT_APP_CAS_PROVIDER${i}_ENDPOINT`] || '';
+
+  authProviders.set(id, { name, endpoint, isDefault: false, type: AuthProviderType.CAS });
 }
 
 export enum Links {

src/pages/login/Login.tsx

@@ -30,7 +30,10 @@ const Login: React.FunctionComponent<{}> = () => {
   const location = useLocation();
   const { isLoggedIn, courseId } = useSession();
   const navigate = useNavigate();
-  const { code, provider: providerId } = parseQuery(location.search);
+  const { code, ticket, provider: providerId } = parseQuery(location.search);
+
+  // `code` parameter from OAuth2 redirect, `ticket` from CAS redirect
+  const authCode = code || ticket;
 
   const handleLogin = React.useCallback(
     (providerId: string) => dispatch(login(providerId)),
@@ -49,12 +52,12 @@ const Login: React.FunctionComponent<{}> = () => {
     }
 
     // Else fetch JWT tokens and user info from backend when auth provider code is present
-    if (code && !isLoggedIn) {
-      dispatch(fetchAuth(code, providerId));
+    if (authCode && !isLoggedIn) {
+      dispatch(fetchAuth(authCode, providerId));
     }
-  }, [code, providerId, dispatch, courseId, navigate, isLoggedIn]);
+  }, [authCode, providerId, dispatch, courseId, navigate, isLoggedIn]);
 
-  if (code) {
+  if (authCode) {
     return (
       <div className={classNames('Login', Classes.DARK)}>
         <Card className={classNames('login-card', Classes.ELEVATION_4)}>