First pass on adding domainevents to segment service

no issue

- In order to listen to `DomainEvents` for `MilestoneCreatedEvents` we need to add a `DomainEvents` listener and handler to the Segment analytics service.
- For better readability and to be more consistent with how code is currently written in Ghost, I refactored the service index file and split the two types of event listener into separate classes which is much cleaner and easier to test.

ghost/core/core/server/services/segment/DomainEventsAnalytics.js

@@ -0,0 +1,40 @@
+const _ = require('lodash');
+const logging = require('@tryghost/logging');
+const DomainEvents = require('@tryghost/domain-events');
+const {MilestoneCreatedEvent} = require('@tryghost/milestones');
+
+module.exports = class DomainEventsAnalytics {
+    #analytics;
+    #trackDefaults;
+    #prefix;
+    #sentry;
+
+    constructor(deps) {
+        this.#analytics = deps.analytics;
+        this.#trackDefaults = deps.trackDefaults;
+        this.#prefix = deps.prefix;
+        this.#sentry = deps.sentry;
+    }
+
+    async #handleMilestoneCreatedEvent(type, event) {
+        if (type === MilestoneCreatedEvent
+            && event.data.milestone
+            && event.data.milestone.value === 100
+        ) {
+            const eventName = event.data.milestone.type === 'arr' ? '$100 MRR reached' : '100 members reached';
+
+            try {
+                this.#analytics.track(_.extend(this.#trackDefaults, {}, {event: this.#prefix + eventName}));
+            } catch (err) {
+                logging.error(err);
+                this.#sentry.captureException(err);
+            }
+        }
+    }
+
+    subscribeToDomainEvents() {
+        DomainEvents.subscribe(MilestoneCreatedEvent, async (event) => {
+            await this.#handleMilestoneCreatedEvent(MilestoneCreatedEvent, event);
+        });
+    }
+};

ghost/core/core/server/services/segment/ModelEventsAnalytics.js

@@ -0,0 +1,63 @@
+const _ = require('lodash');
+const logging = require('@tryghost/logging');
+// Listens to model events to layer on analytics - also uses the "fake" theme.uploaded event from the theme API
+const events = require('../../lib/common/events');
+
+const TO_TRACK = [
+    {
+        event: 'post.published',
+        name: 'Post Published'
+    },
+    {
+        event: 'page.published',
+        name: 'Page Published'
+    },
+    {
+        event: 'theme.uploaded',
+        name: 'Theme Uploaded',
+        // {keyOnSuppliedEventData: keyOnTrackedEventData}
+        // - used to extract specific properties from event data and give them meaningful names
+        data: {name: 'name'}
+    },
+    {
+        event: 'integration.added',
+        name: 'Custom Integration Added'
+    },
+    {
+        event: 'settings.edited',
+        name: 'Stripe enabled',
+        data: {key: 'key', value: 'value'}
+    }
+];
+
+module.exports = class ModelEventsAnalytics {
+    #analytics;
+    #trackDefaults;
+    #prefix;
+    #sentry;
+    #toTrack;
+
+    constructor(deps) {
+        this.#analytics = deps.analytics;
+        this.#trackDefaults = deps.trackDefaults;
+        this.#prefix = deps.prefix;
+        this.#sentry = deps.sentry;
+        this.#toTrack = TO_TRACK;
+    }
+
+    subscribeToModelEvents() {
+        this.#toTrack.forEach(({event, name, data = {}}) => {
+            events.on(event, function (eventData = {}) {
+                // extract desired properties from eventData and rename keys if necessary
+                const mappedData = _.mapValues(data || {}, v => eventData[v]);
+
+                try {
+                    this.#analytics.track(_.extend(this.#trackDefaults, mappedData, {event: this.#prefix + name}));
+                } catch (err) {
+                    logging.error(err);
+                    this.#sentry.captureException(err);
+                }
+            });
+        });
+    }
+};

ghost/core/core/server/services/segment/index.js

@@ -1,51 +1,32 @@
-const _ = require('lodash');
 const Analytics = require('analytics-node');
-const logging = require('@tryghost/logging');
-
 const config = require('../../../shared/config');
 const sentry = require('../../../shared/sentry');
 
-// Listens to model events to layer on analytics - also uses the "fake" theme.uploaded event from the theme API
-const events = require('../../lib/common/events');
+const ModelEventsAnalytics = require('./ModelEventsAnalytics');
+const DomainEventsAnalytics = require('./DomainEventsAnalytics');
 
 module.exports.init = function () {
     const analytics = new Analytics(config.get('segment:key'));
     const trackDefaults = config.get('segment:trackDefaults') || {};
     const prefix = config.get('segment:prefix') || '';
 
-    const toTrack = [
-        {
-            event: 'post.published',
-            name: 'Post Published'
-        },
-        {
-            event: 'page.published',
-            name: 'Page Published'
-        },
-        {
-            event: 'theme.uploaded',
-            name: 'Theme Uploaded',
-            // {keyOnSuppliedEventData: keyOnTrackedEventData}
-            // - used to extract specific properties from event data and give them meaningful names
-            data: {name: 'name'}
-        },
-        {
-            event: 'integration.added',
-            name: 'Custom Integration Added'
-        }
-    ];
-
-    _.each(toTrack, function (track) {
-        events.on(track.event, function (eventData = {}) {
-            // extract desired properties from eventData and rename keys if necessary
-            const data = _.mapValues(track.data || {}, v => eventData[v]);
-
-            try {
-                analytics.track(_.extend(trackDefaults, data, {event: prefix + track.name}));
-            } catch (err) {
-                logging.error(err);
-                sentry.captureException(err);
-            }
-        });
+    const subscribeToDomainEvents = new DomainEventsAnalytics({
+        analytics,
+        trackDefaults,
+        prefix,
+        sentry
     });
+
+    const modelEventsAnalytics = new ModelEventsAnalytics({
+        analytics,
+        trackDefaults,
+        prefix,
+        sentry
+    });
+
+    // Listen to model events
+    modelEventsAnalytics.subscribeToModelEvents();
+
+    // Listen to domain events
+    subscribeToDomainEvents.subscribeToDomainEvents();
 };

ghost/core/test/unit/server/services/segment/index.test.js

@@ -0,0 +1,11 @@
+const assert = require('assert');
+
+describe('Segment Analytics Service', function () {
+    let segmentService;
+
+    it('Provides expected public API', async function () {
+        segmentService = require('../../../../../core/server/services/segment');
+
+        assert.ok(segmentService.initAndRun);
+    });
+});