(core) Adding a flag for the UI to check if emails are enabled

Summary:
Front-end code can now test if emails are enabled
and hide some parts of UI based on it.

Test Plan:
Only secondery text was hidden on add users dialog.
Tested manually.

Reviewers: georgegevoian

Reviewed By: georgegevoian

Subscribers: georgegevoian

Differential Revision: https://phab.getgrist.com/D4221

app/client/lib/ACUserManager.ts

@@ -16,6 +16,7 @@ import {
   cssMemberText,
 } from "app/client/ui/UserItem";
 import {createUserImage, cssUserImage} from "app/client/ui/UserImage";
+import {getGristConfig} from 'app/common/urlUtils';
 import {Computed, computed, dom, DomElementArg, Holder, IDisposableOwner, Observable, styled} from "grainjs";
 import {cssMenuItem} from "popweasel";
 
@@ -111,10 +112,9 @@ export function buildACMemberEmail(
         )),
       cssMemberText(
         cssMemberPrimaryPlus(t("Invite new member")),
-        cssMemberSecondaryPlus(
-          // dom.text(use => `We'll email an invite to ${use(emailObs)}`)
-          dom.text(use => t("We'll email an invite to {{email}}", {email: use(emailObs)})) // TODO i18next
-        )
+        getGristConfig().notifierEnabled ? cssMemberSecondaryPlus(
+          dom.text(use => t("We'll email an invite to {{email}}", {email: use(emailObs)}))
+        ) : null,
       ),
       testId("um-add-email")
     )

app/common/gristUrls.ts

@@ -786,6 +786,9 @@ export interface GristLoadConfig {
   canCloseAccount?: boolean;
 
   experimentalPlugins?: boolean;
+
+  // If backend has an email service for sending notifications.
+  notifierEnabled?: boolean;
 }
 
 export const Features = StringUnion(

app/server/lib/FlexServer.ts

@@ -47,7 +47,7 @@ import {initGristSessions, SessionStore} from 'app/server/lib/gristSessions';
 import {HostedStorageManager} from 'app/server/lib/HostedStorageManager';
 import {IBilling} from 'app/server/lib/IBilling';
 import {IDocStorageManager} from 'app/server/lib/IDocStorageManager';
-import {INotifier} from 'app/server/lib/INotifier';
+import {EmptyNotifier, INotifier} from 'app/server/lib/INotifier';
 import {InstallAdmin} from 'app/server/lib/InstallAdmin';
 import log from 'app/server/lib/log';
 import {getLoginSystem} from 'app/server/lib/logins';
@@ -384,7 +384,7 @@ export class FlexServer implements GristServer {
   }
 
   public hasNotifier(): boolean {
-    return Boolean(this._notifier);
+    return Boolean(this._notifier) && this._notifier !== EmptyNotifier;
   }
 
   public getNotifier(): INotifier {

app/server/lib/GristServer.ts

@@ -52,6 +52,7 @@ export interface GristServer {
   getHomeDBManager(): HomeDBManager;
   getStorageManager(): IDocStorageManager;
   getTelemetry(): ITelemetry;
+  hasNotifier(): boolean;
   getNotifier(): INotifier;
   getDocTemplate(): Promise<DocTemplate>;
   getTag(): string;
@@ -142,6 +143,7 @@ export function createDummyGristServer(): GristServer {
     getStorageManager() { throw new Error('no storage manager'); },
     getTelemetry() { return createDummyTelemetry(); },
     getNotifier() { throw new Error('no notifier'); },
+    hasNotifier() { return false; },
     getDocTemplate() { throw new Error('no doc template'); },
     getTag() { return 'tag'; },
     sendAppPage() { return Promise.resolve(); },

app/server/lib/ICreate.ts

@@ -5,7 +5,7 @@ import {HomeDBManager} from 'app/gen-server/lib/HomeDBManager';
 import {ExternalStorage} from 'app/server/lib/ExternalStorage';
 import {createDummyTelemetry, GristServer} from 'app/server/lib/GristServer';
 import {IBilling} from 'app/server/lib/IBilling';
-import {INotifier} from 'app/server/lib/INotifier';
+import {EmptyNotifier, INotifier} from 'app/server/lib/INotifier';
 import {InstallAdmin, SimpleInstallAdmin} from 'app/server/lib/InstallAdmin';
 import {ISandbox, ISandboxCreationOptions} from 'app/server/lib/ISandbox';
 import {IShell} from 'app/server/lib/IShell';
@@ -99,11 +99,7 @@ export function makeSimpleCreator(opts: {
       };
     },
     Notifier(dbManager, gristConfig) {
-      return notifier?.create(dbManager, gristConfig) ?? {
-        get testPending() { return false; },
-        async deleteUser()      { /* do nothing */ },
-        testSetSendMessageCallback() { return undefined; },
-      };
+      return notifier?.create(dbManager, gristConfig) ?? EmptyNotifier;
     },
     ExternalStorage(purpose, extraPrefix) {
       for (const s of storage || []) {

app/server/lib/INotifier.ts

@@ -10,3 +10,12 @@ export interface INotifier {
   // Return undefined if no notification system is available.
   testSetSendMessageCallback(op: (body: SendGridMail, description: string) => Promise<void>): SendGridConfig|undefined;
 }
+
+/**
+ * A notifier that does nothing. Used when no email notifications are configured.
+ */
+export const EmptyNotifier: INotifier = {
+  get testPending() { return false; },
+  async deleteUser()      { /* do nothing */ },
+  testSetSendMessageCallback() { return undefined; },
+} as const;

app/server/lib/sendAppPage.ts

@@ -97,6 +97,7 @@ export function makeGristConfig(options: MakeGristConfigOptions): GristLoadConfi
     templateOrg: getTemplateOrg(),
     canCloseAccount: isAffirmative(process.env.GRIST_ACCOUNT_CLOSE),
     experimentalPlugins: isAffirmative(process.env.GRIST_EXPERIMENTAL_PLUGINS),
+    notifierEnabled: server?.hasNotifier(),
     ...extra,
   };
 }