Added logic to update the recommendations_enabled setting on add/delete (#17975)

closes https://github.com/TryGhost/Product/issues/3799

- the recommendations_enabled setting is updated when a recommendation
is created or deleted. It's enabled as soon as there is at least one
recommendation in the database
- the recommendations_enabled setting exists to avoid fetching the
recommendation count from the database directly in themes. The setting
is cached and doesn't need a read every time from the database

ghost/core/core/server/services/recommendations/RecommendationEnablerService.js

@@ -0,0 +1,28 @@
+module.exports = class RecommendationEnablerService {
+    /** @type {import('../settings/SettingsBREADService')} */
+    #settingsService;
+
+    /**
+     * @param {object} deps
+     * @param {import('../settings/SettingsBREADService')} deps.settingsService
+     */
+    constructor(deps) {
+        this.#settingsService = deps.settingsService;
+    }
+
+    /**
+     * @returns {string}
+     */
+    getSetting() {
+        this.#settingsService.read('recommendations_enabled');
+    }
+
+    /**
+     *
+     * @param {string} value
+     * @returns Promise<void>
+     */
+    async setSetting(value) {
+        this.#settingsService.edit([{key: 'recommendations_enabled', value}], {context: {internal: true}});
+    }
+};

ghost/core/core/server/services/recommendations/RecommendationServiceWrapper.js

@@ -23,7 +23,14 @@ class RecommendationServiceWrapper {
         const urlUtils = require('../../../shared/url-utils');
         const models = require('../../models');
         const sentry = require('../../../shared/sentry');
-        const {BookshelfRecommendationRepository, RecommendationService, RecommendationController, WellknownService} = require('@tryghost/recommendations');
+        const settings = require('../settings');
+        const RecommendationEnablerService = require('./RecommendationEnablerService');
+        const {
+            BookshelfRecommendationRepository,
+            RecommendationService,
+            RecommendationController,
+            WellknownService
+        } = require('@tryghost/recommendations');
 
         const mentions = require('../mentions');
 
@@ -37,11 +44,15 @@ class RecommendationServiceWrapper {
             urlUtils
         });
 
+        const settingsService = settings.getSettingsBREADServiceInstance();
+        const recommendationEnablerService = new RecommendationEnablerService({settingsService});
+
         this.repository = new BookshelfRecommendationRepository(models.Recommendation, {
             sentry
         });
         this.service = new RecommendationService({
             repository: this.repository,
+            recommendationEnablerService,
             wellknownService,
             mentionSendingService: mentions.sendingService
         });

ghost/core/core/server/services/settings/SettingsBREADService.js

@@ -147,7 +147,7 @@ class SettingsBREADService {
      * @param {Object[]} settings
      * @param {Object} options
      * @param {Object} [options.context]
-     * @param {Object} [stripeConnectData]
+     * @param {Object|null} [stripeConnectData]
      * @returns
      */
     async edit(settings, options, stripeConnectData) {

ghost/recommendations/src/RecommendationService.ts

@@ -8,6 +8,11 @@ type MentionSendingService = {
     sendAll(options: {url: URL, links: URL[]}): Promise<void>
 }
 
+type RecommendationEnablerService = {
+    getSetting(): string,
+    setSetting(value: string): Promise<void>
+}
+
 const messages = {
     notFound: "Recommendation with id {id} not found"
 }
@@ -16,22 +21,40 @@ export class RecommendationService {
     repository: RecommendationRepository;
     wellknownService: WellknownService;
     mentionSendingService: MentionSendingService;
+    recommendationEnablerService: RecommendationEnablerService;
 
-    constructor(deps: {repository: RecommendationRepository, wellknownService: WellknownService, mentionSendingService: MentionSendingService}) {
+    constructor(deps: {
+        repository: RecommendationRepository,
+        wellknownService: WellknownService,
+        mentionSendingService: MentionSendingService,
+        recommendationEnablerService: RecommendationEnablerService,
+    }) {
         this.repository = deps.repository;
         this.wellknownService = deps.wellknownService;
         this.mentionSendingService = deps.mentionSendingService;
+        this.recommendationEnablerService = deps.recommendationEnablerService;
     }
 
     async init() {
-        await this.updateWellknown();
+        const recommendations = await this.listRecommendations();
+        await this.updateWellknown(recommendations);
     }
 
-    async updateWellknown() {
-        const recommendations = await this.listRecommendations();
+    async updateWellknown(recommendations: Recommendation[]) {
         await this.wellknownService.set(recommendations);
     }
 
+    async updateRecommendationsEnabledSetting(recommendations: Recommendation[]) {
+        const expectedSetting = (recommendations.length > 0).toString();
+        const currentSetting = this.recommendationEnablerService.getSetting();
+
+        if (currentSetting && currentSetting === expectedSetting) {
+            return;
+        }
+
+        await this.recommendationEnablerService.setSetting(expectedSetting);
+    }
+
     private sendMentionToRecommendation(recommendation: Recommendation) {
          this.mentionSendingService.sendAll({
             url: this.wellknownService.getURL(),
@@ -44,7 +67,10 @@ export class RecommendationService {
     async addRecommendation(addRecommendation: AddRecommendation) {
         const recommendation = Recommendation.create(addRecommendation);
         await this.repository.save(recommendation);
-        await this.updateWellknown();
+
+        const recommendations = await this.listRecommendations();
+        await this.updateWellknown(recommendations);
+        await this.updateRecommendationsEnabledSetting(recommendations);
 
         // Only send an update for the mentioned URL
         this.sendMentionToRecommendation(recommendation);
@@ -63,7 +89,9 @@ export class RecommendationService {
         existing.edit(recommendationEdit);
         await this.repository.save(existing);
 
-        await this.updateWellknown();
+        const recommendations = await this.listRecommendations();
+        await this.updateWellknown(recommendations);
+
         this.sendMentionToRecommendation(existing);
         return existing;
     }
@@ -78,7 +106,10 @@ export class RecommendationService {
 
         existing.delete();
         await this.repository.save(existing);
-        await this.updateWellknown();
+
+        const recommendations = await this.listRecommendations();
+        await this.updateWellknown(recommendations);
+        await this.updateRecommendationsEnabledSetting(recommendations);
 
         // Send a mention (because it was deleted, according to the webmentions spec)
         this.sendMentionToRecommendation(existing);