(core) Send emails when 2FA settings are updated

Summary: When user 2FA status is changed, we now send out emails via SendGrid.

Test Plan: Server tests.

Reviewers: alexmojaki

Reviewed By: alexmojaki

Subscribers: alexmojaki

Differential Revision: https://phab.getgrist.com/D3280

app/gen-server/lib/HomeDBManager.ts

@@ -35,6 +35,7 @@ import {makeId} from 'app/server/lib/idUtils';
 import * as log from 'app/server/lib/log';
 import {Permit} from 'app/server/lib/Permit';
 import {WebHookSecret} from "app/server/lib/Triggers";
+import {StringUnion} from 'app/common/StringUnion';
 import {EventEmitter} from 'events';
 import flatten = require('lodash/flatten');
 import pick = require('lodash/pick');
@@ -48,6 +49,17 @@ import * as uuidv4 from "uuid/v4";
 // fixed.  See https://github.com/typeorm/typeorm/issues/1884#issuecomment-380767213
 applyPatch();
 
+export const NotifierEvents = StringUnion(
+  'addUser',
+  'userChange',
+  'firstLogin',
+  'addBillingManager',
+  'teamCreator',
+  'trialPeriodEndingSoon',
+);
+
+export type NotifierEvent = typeof NotifierEvents.type;
+
 // Nominal email address of a user who can view anything (for thumbnails).
 export const PREVIEWER_EMAIL = 'thumbnail@getgrist.com';
 
@@ -190,6 +202,10 @@ export class HomeDBManager extends EventEmitter {
 
   private _docAuthCache = new MapWithTTL<string, Promise<DocAuthResult>>(DOC_AUTH_CACHE_TTL);
 
+  public emit(event: NotifierEvent, ...args: any[]): boolean {
+    return super.emit(event, ...args);
+  }
+
   /**
    * Five aclRules, each with one group (with the names 'owners', 'editors', 'viewers',
    * 'guests', and 'members') are created by default on every new entity (Organization,

app/server/lib/FlexServer.ts

@@ -99,7 +99,6 @@ export class FlexServer implements GristServer {
   public host: string;
   public tag: string;
   public info = new Array<[string, any]>();
-  public notifier: INotifier;
   public usage: Usage;
   public housekeeper: Housekeeper;
   public server: http.Server;
@@ -123,6 +122,7 @@ export class FlexServer implements GristServer {
   private _storageManager: IDocStorageManager;
   private _docWorkerMap: IDocWorkerMap;
   private _widgetRepository: IWidgetRepository;
+  private _notifier: INotifier;
   private _internalPermitStore: IPermitStore;  // store for permits that stay within our servers
   private _externalPermitStore: IPermitStore;  // store for permits that pass through outside servers
   private _disabled: boolean = false;
@@ -286,6 +286,11 @@ export class FlexServer implements GristServer {
     return this._widgetRepository;
   }
 
+  public getNotifier(): INotifier {
+    if (!this._notifier) { throw new Error('no notifier available'); }
+    return this._notifier;
+  }
+
   public addLogging() {
     if (this._check('logging')) { return; }
     if (process.env.GRIST_LOG_SKIP_HTTP) { return; }
@@ -1254,7 +1259,7 @@ export class FlexServer implements GristServer {
     // and all that is needed is a refactor to pass that info along.  But there is also the
     // case of notification(s) from stripe.  May need to associate a preferred base domain
     // with org/user and persist that?
-    this.notifier = this.create.Notifier(this._dbManager, this);
+    this._notifier = this.create.Notifier(this._dbManager, this);
   }
 
   public getGristConfig(): GristLoadConfig {

app/server/lib/GristServer.ts

@@ -9,6 +9,7 @@ import * as Comm from 'app/server/lib/Comm';
 import { Hosts } from 'app/server/lib/extractOrg';
 import { ICreate } from 'app/server/lib/ICreate';
 import { IDocStorageManager } from 'app/server/lib/IDocStorageManager';
+import { INotifier } from 'app/server/lib/INotifier';
 import { IPermitStore } from 'app/server/lib/Permit';
 import { Sessions } from 'app/server/lib/Sessions';
 import * as express from 'express';
@@ -34,6 +35,7 @@ export interface GristServer {
   getHosts(): Hosts;
   getHomeDBManager(): HomeDBManager;
   getStorageManager(): IDocStorageManager;
+  getNotifier(): INotifier;
 }
 
 export interface GristLoginSystem {