Update users currentChallengeId when on a new challenge (#101)

Closes #94

packages/learn/src/redux/app/index.js

@@ -39,6 +39,8 @@ export const isSignedInSelector = state => state[ns].isSignedIn;
 export const userSelector = state => state[ns].user || {};
 export const completedChallengesSelector = state =>
   state[ns].user.completedChallenges || [];
+export const currentChallengeIdSelector = state =>
+  userSelector(state).currentChallengeId || '';
 
 export const reducer = handleActions(
   {

packages/learn/src/templates/Challenges/redux/current-challenge-epic.js

@@ -0,0 +1,29 @@
+import { ofType } from 'redux-observable';
+
+import { types } from './';
+import { filter, switchMap, catchError, mapTo } from 'rxjs/operators';
+import {
+  isSignedInSelector,
+  currentChallengeIdSelector
+} from '../../../redux/app';
+import { postJSON$ } from '../utils/ajax-stream';
+import { _csrf } from '../../../redux/cookieVaules';
+import { of } from 'rxjs/observable/of';
+
+function currentChallengeEpic(action$, { getState }) {
+  return action$.pipe(
+    ofType(types.challengeMounted),
+    filter(() => isSignedInSelector(getState())),
+    filter(({ payload }) => payload !== currentChallengeIdSelector(getState())),
+    switchMap(({ payload }) =>
+      postJSON$('/external/update-my-current-challenge', {
+        currentChallengeId: payload,
+        _csrf
+      })
+    ),
+    mapTo({ type: 'currentChallengeUpdateComplete' }),
+    catchError(() => of({ type: 'current-challenge-update-error' }))
+  );
+}
+
+export default currentChallengeEpic;

packages/learn/src/templates/Challenges/redux/index.js

@@ -8,6 +8,7 @@ import executeChallengeEpic from './execute-challenge-epic';
 import codeLockEpic from './code-lock-epic';
 import createQuestionEpic from './create-question-epic';
 import codeStorageEpic from './code-storage-epic';
+import currentChallengeEpic from './current-challenge-epic';
 
 const ns = 'challenge';
 export const backendNS = 'backendChallenge';
@@ -37,7 +38,8 @@ export const epics = [
   completionEpic,
   createQuestionEpic,
   executeChallengeEpic,
-  codeStorageEpic
+  codeStorageEpic,
+  currentChallengeEpic
 ];
 
 export const types = createTypes(