(core) Direct users to last visited site when possible

Summary:
When clicking the logo in the top-left corner, or finishing a tutorial, we
now direct users to the site they last visited, if possible. If unknown, a
new redirect endpoint, /welcome/home, is used instead, which directs users
to a sensible location based on the number of sites they have.

Test Plan: Browser tests.

Reviewers: paulfitz

Reviewed By: paulfitz

Differential Revision: https://phab.getgrist.com/D3878

app/client/lib/localStorageObs.ts

@@ -26,14 +26,24 @@ export function sessionStorageBoolObs(key: string, defValue = false): Observable
   return getStorageBoolObs(getSessionStorage(), key, defValue);
 }
 
+function getStorageObs(store: Storage, key: string, defaultValue?: string) {
+  const obs = Observable.create<string|null>(null, store.getItem(key) ?? defaultValue ?? null);
+  obs.addListener((val) => (val === null) ? store.removeItem(key) : store.setItem(key, val));
+  return obs;
+}
+
 /**
  * Helper to create a string observable whose state is stored in localStorage.
  */
 export function localStorageObs(key: string, defaultValue?: string): Observable<string|null> {
-  const store = getStorage();
-  const obs = Observable.create<string|null>(null, store.getItem(key) ?? defaultValue ?? null);
-  obs.addListener((val) => (val === null) ? store.removeItem(key) : store.setItem(key, val));
-  return obs;
+  return getStorageObs(getStorage(), key, defaultValue);
+}
+
+/**
+ * Similar to `localStorageObs`, but always uses sessionStorage (or an in-memory equivalent).
+ */
+export function sessionStorageObs(key: string, defaultValue?: string): Observable<string|null> {
+  return getStorageObs(getSessionStorage(), key, defaultValue);
 }
 
 /**

app/client/models/AppModel.ts

@@ -1,6 +1,7 @@
 import {BehavioralPromptsManager} from 'app/client/components/BehavioralPromptsManager';
 import {get as getBrowserGlobals} from 'app/client/lib/browserGlobals';
 import {makeT} from 'app/client/lib/localization';
+import {sessionStorageObs} from 'app/client/lib/localStorageObs';
 import {error} from 'app/client/lib/log';
 import {reportError, setErrorNotifier} from 'app/client/models/errors';
 import {urlState} from 'app/client/models/gristUrlState';
@@ -83,6 +84,7 @@ export interface AppModel {
   isTeamSite: boolean;                  // Is it a team site?
   isLegacySite: boolean;                // Is it a legacy site?
   orgError?: OrgError;                  // If currentOrg is null, the error that caused it.
+  lastVisitedOrgDomain: Observable<string|null>;
 
   currentProduct: Product|null;         // The current org's product.
   currentFeatures: Features;            // Features of the current org's product.
@@ -227,6 +229,8 @@ export class AppModelImpl extends Disposable implements AppModel {
 
   public readonly currentOrgUsage: Observable<OrgUsageSummary|null> = Observable.create(this, null);
 
+  public readonly lastVisitedOrgDomain = this.autoDispose(sessionStorageObs('grist-last-visited-org-domain'));
+
   public readonly currentProduct = this.currentOrg?.billingAccount?.product ?? null;
   public readonly currentFeatures = this.currentProduct?.features ?? {};
 
@@ -284,6 +288,14 @@ export class AppModelImpl extends Disposable implements AppModel {
       this.dismissedPopups.set(seen ? DismissedPopup.values : []);
       this.behavioralPromptsManager.reset();
     };
+
+    this.autoDispose(subscribe(urlState().state, async (_use, {doc, org}) => {
+      // Keep track of the last valid org domain the user visited, ignoring those
+      // with a document id in the URL.
+      if (!this.currentOrg || doc) { return; }
+
+      this.lastVisitedOrgDomain.set(org ?? null);
+    }));
   }
 
   public get planName() {

app/client/models/gristUrlState.ts

@@ -85,6 +85,10 @@ export function getLoginOrSignupUrl(nextUrl: string = _getCurrentUrl()): string
   return _getLoginLogoutUrl('signin', nextUrl);
 }
 
+export function getWelcomeHomeUrl() {
+  return _buildUrl('welcome/home').href;
+}
+
 // Returns the relative URL (i.e. path) of the current page, except when it's the
 // "/signed-out" page, in which case it returns the home page ("/").
 // This is a good URL to use for a post-login redirect.
@@ -97,14 +101,19 @@ function _getCurrentUrl(): string {
 
 // Returns the URL for the given login page, with 'next' param optionally set.
 function _getLoginLogoutUrl(page: 'login'|'logout'|'signin'|'signup', nextUrl?: string | null): string {
-  const startUrl = new URL(window.location.href);
-  startUrl.pathname = addOrgToPath('', window.location.href, true) + '/' + page;
-  startUrl.search = '';
-  startUrl.hash = '';
+  const startUrl = _buildUrl(page);
   if (nextUrl) { startUrl.searchParams.set('next', nextUrl); }
   return startUrl.href;
 }
 
+function _buildUrl(page?: string): URL {
+  const startUrl = new URL(window.location.href);
+  startUrl.pathname = addOrgToPath('', window.location.href, true) + '/' + (page ?? '');
+  startUrl.search = '';
+  startUrl.hash = '';
+  return startUrl;
+}
+
 /**
  * Implements the interface expected by UrlState. It is only exported for the sake of tests; the
  * only public interface is the urlState() accessor.

app/client/ui/AppHeader.ts

@@ -1,4 +1,4 @@
-import {urlState} from 'app/client/models/gristUrlState';
+import {getWelcomeHomeUrl, urlState} from 'app/client/models/gristUrlState';
 import {buildAppMenuBillingItem} from 'app/client/ui/BillingButtons';
 import {getTheme} from 'app/client/ui/CustomThemes';
 import {cssLeftPane} from 'app/client/ui/PagePanels';
@@ -48,7 +48,7 @@ export class AppHeader extends Disposable {
       cssAppLogo(
         {title: `Version ${version.version}` +
           ((version.gitcommit as string) !== 'unknown' ? ` (${version.gitcommit})` : '')},
-        urlState().setLinkUrl({}),
+        this._setHomePageUrl(),
         testId('dm-logo')
       ),
       cssOrg(
@@ -79,6 +79,15 @@ export class AppHeader extends Disposable {
       ),
     );
   }
+
+  private _setHomePageUrl() {
+    const lastVisitedOrg = this._appModel.lastVisitedOrgDomain.get();
+    if (lastVisitedOrg) {
+      return urlState().setLinkUrl({org: lastVisitedOrg});
+    } else {
+      return {href: getWelcomeHomeUrl()};
+    }
+  }
 }
 
 export function productPill(org: Organization|null, options: {large?: boolean} = {}): DomContents {

app/client/ui/DocTutorial.ts

@@ -1,5 +1,5 @@
 import {GristDoc} from 'app/client/components/GristDoc';
-import {urlState} from 'app/client/models/gristUrlState';
+import {getWelcomeHomeUrl, urlState} from 'app/client/models/gristUrlState';
 import {renderer} from 'app/client/ui/DocTutorialRenderer';
 import {cssPopupBody, FloatingPopup} from 'app/client/ui/FloatingPopup';
 import {sanitizeHTML} from 'app/client/ui/sanitizeHTML';
@@ -242,7 +242,12 @@ export class DocTutorial extends FloatingPopup {
   private async _finishTutorial() {
     this._saveCurrentSlidePositionDebounced.cancel();
     await this._saveCurrentSlidePosition();
-    await urlState().pushUrl({});
+    const lastVisitedOrg = this._appModel.lastVisitedOrgDomain.get();
+    if (lastVisitedOrg) {
+      await urlState().pushUrl({org: lastVisitedOrg});
+    } else {
+      window.location.assign(getWelcomeHomeUrl());
+    }
   }
 
   private async _restartTutorial() {