feat: preserve file query param through auth0 process (#412)

src/constants/app.ts

@@ -1,6 +1,7 @@
 import { isMobile } from 'react-device-detect';
 
 export const IS_READONLY_MODE = isMobile;
+export const FILE_PARAM_KEY = 'file-param-before-login';
 export const DEFAULT_FILE_NAME = 'Untitled';
 export const EXAMPLE_FILES = [
   {

src/quadratic/QuadraticAuth.tsx

@@ -5,6 +5,8 @@ import { captureException, setUser } from '@sentry/react';
 import { QuadraticApp } from './QuadraticApp';
 import apiClientSingleton from '../api-client/apiClientSingleton';
 import { useEffect } from 'react';
+import { debug } from '../debugFlags';
+import { FILE_PARAM_KEY } from '../constants/app';
 
 export const QuadraticAuth = () => {
   const {
@@ -47,6 +49,16 @@ export const QuadraticAuth = () => {
     }
 
     if (!Auth0IsAuthenticated) {
+      // If we're not authenticated but there is a `file` query param,
+      // store it for later so it doesn't get lost. In `useLocalFiles` we'll
+      // grab it and apply it
+      const file = new URLSearchParams(window.location.search).get('file');
+      if (file) {
+        sessionStorage.setItem(FILE_PARAM_KEY, file);
+        if (debug)
+          console.log('[QuadraticAuth] user is not logged in, saving `file` query param for after login: ', file);
+      }
+
       loginWithRedirect({ screen_hint: 'signup' });
       return <QuadraticLoading></QuadraticLoading>;
     }

src/storage/useLocalFiles.ts

@@ -11,7 +11,7 @@ import { downloadFile } from './downloadFile';
 import { SheetController } from '../grid/controller/sheetController';
 import { useSetRecoilState } from 'recoil';
 import { editorInteractionStateAtom } from '../atoms/editorInteractionStateAtom';
-import { DEFAULT_FILE_NAME, EXAMPLE_FILES } from '../constants/app';
+import { DEFAULT_FILE_NAME, EXAMPLE_FILES, FILE_PARAM_KEY } from '../constants/app';
 import apiClientSingleton from '../api-client/apiClientSingleton';
 import mixpanel from 'mixpanel-browser';
 
@@ -357,8 +357,16 @@ export const useLocalFiles = (sheetController: SheetController): LocalFiles => {
     }
 
     // Get URL params we need at initialize time
-    const file = getURLParameter('file');
     const local = getURLParameter('local');
+    let file = getURLParameter('file');
+    // We get the `file` query param from the URL, but if a user had it present
+    // _before_ they logged in, we lose it through the Auth0 process, so we
+    // store it in sessionStorage and use it (then delete it) if its present
+    const fileParamBeforeLogin = sessionStorage.getItem(FILE_PARAM_KEY);
+    if (fileParamBeforeLogin) {
+      file = fileParamBeforeLogin;
+      sessionStorage.removeItem(FILE_PARAM_KEY);
+    }
 
     // Migrate files from old version of the app (one-time, if necessary thing)
     // Note: eventually this code can be removed