From 74b0e52f9a2ac243af50ab419da9c296b74a1540 Mon Sep 17 00:00:00 2001
From: James Salter <iteration@gmail.com>
Date: Wed, 21 Jul 2021 08:23:42 +0100
Subject: [PATCH] Enforce anon/pseudo-anon via types

---
 src/PosthogAnalytics.ts       | 48 +++++++++++++++++++++++++----------
 test/PosthogAnalytics-test.ts | 25 +++++++++++++-----
 2 files changed, 54 insertions(+), 19 deletions(-)

diff --git a/src/PosthogAnalytics.ts b/src/PosthogAnalytics.ts
index 5b2a601adc..133c9275d4 100644
--- a/src/PosthogAnalytics.ts
+++ b/src/PosthogAnalytics.ts
@@ -1,11 +1,28 @@
 import posthog from 'posthog-js';
 import SdkConfig from './SdkConfig';
 
-export interface IEvent {
-    key: string;
+interface IEvent {
+    // The event name that will be used by PostHog.
+    // TODO: standard format (camel case? snake? UpperCase?)
+    eventName: string;
+
+    // The properties of the event that will be stored in PostHog.
     properties: {}
 }
 
+// If an event extends IPseudonymousEvent, the event contains pseudonymous data
+// that won't be sent unless the user has explicitly consented to pseudonymous tracking.
+// For example, hashed user IDs or room IDs.
+export interface IPseudonymousEvent extends IEvent {}
+
+// If an event extends IAnonymousEvent, the event strictly contains *only* anonymous data which
+// may be sent without explicit user consent.
+export interface IAnonymousEvent extends IEvent {}
+
+export interface IRoomEvent extends IPseudonymousEvent {
+    hashedRoomId: string
+}
+
 export interface IOnboardingLoginBegin extends IEvent {
     key: "onboarding_login_begin",
 }
@@ -55,27 +72,32 @@ export class PosthogAnalytics {
         this.onlyTrackAnonymousEvents = enabled;
     }
 
-    public track<E extends IEvent>(
-        key: E["key"],
+    public trackPseudonymousEvent<E extends IPseudonymousEvent>(
+        eventName: E["eventName"],
         properties: E["properties"],
-        anonymous = false,
     ) {
         if (!this.initialised) return;
-        if (this.onlyTrackAnonymousEvents && !anonymous) return;
-
-        this.posthog.capture(key, properties);
+        if (this.onlyTrackAnonymousEvents) return;
+        this.posthog.capture(eventName, properties);
     }
 
-    public async trackRoomEvent<E extends IEvent>(
-        key: E["key"],
-        roomId: string,
+    public trackAnonymousEvent<E extends IAnonymousEvent>(
+        eventName: E["eventName"],
         properties: E["properties"],
-        ...args
+    ) {
+        if (!this.initialised) return;
+        this.posthog.capture(eventName, properties);
+    }
+
+    public async trackRoomEvent<E extends IRoomEvent>(
+        eventName: E["eventName"],
+        roomId: string,
+        properties: Omit<E["properties"], "roomId">,
     ) {
         const updatedProperties = {
             ...properties,
             hashedRoomId: roomId ? await hashHex(roomId) : null,
         };
-        this.track(key, updatedProperties, ...args);
+        this.trackPseudonymousEvent(eventName, updatedProperties);
     }
 }
diff --git a/test/PosthogAnalytics-test.ts b/test/PosthogAnalytics-test.ts
index 56e6af8666..dfadac921d 100644
--- a/test/PosthogAnalytics-test.ts
+++ b/test/PosthogAnalytics-test.ts
@@ -1,4 +1,4 @@
-import { IEvent, PosthogAnalytics } from '../src/PosthogAnalytics';
+import { IAnonymousEvent, IRoomEvent, PosthogAnalytics } from '../src/PosthogAnalytics';
 import SdkConfig from '../src/SdkConfig';
 const crypto = require('crypto');
 
@@ -12,13 +12,20 @@ class FakePosthog {
     }
 }
 
-export interface ITestEvent extends IEvent {
+export interface ITestEvent extends IAnonymousEvent {
     key: "jest_test_event",
     properties: {
         foo: string
     }
 }
 
+export interface ITestRoomEvent extends IRoomEvent {
+    key: "jest_test_room_event",
+    properties: {
+        foo: string
+    }
+}
+
 describe("PosthogAnalytics", () => {
     let analytics: PosthogAnalytics;
     let fakePosthog: FakePosthog;
@@ -61,7 +68,7 @@ describe("PosthogAnalytics", () => {
 
     it("Should pass track() to posthog", () => {
         analytics.init(false);
-        analytics.track<ITestEvent>("jest_test_event", {
+        analytics.trackAnonymousEvent<ITestEvent>("jest_test_event", {
             foo: "bar",
         });
         expect(fakePosthog.capture.mock.calls[0][0]).toBe("jest_test_event");
@@ -71,7 +78,7 @@ describe("PosthogAnalytics", () => {
     it("Should pass trackRoomEvent to posthog", () => {
         analytics.init(false);
         const roomId = "42";
-        return analytics.trackRoomEvent<ITestEvent>("jest_test_event", roomId, {
+        return analytics.trackRoomEvent<IRoomEvent>("jest_test_event", roomId, {
             foo: "bar",
         }).then(() => {
             expect(fakePosthog.capture.mock.calls[0][0]).toBe("jest_test_event");
@@ -82,11 +89,17 @@ describe("PosthogAnalytics", () => {
         });
     });
 
-    it("Should silently not send messages if not inititalised", () => {
-        analytics.track<ITestEvent>("jest_test_event", {
+    it("Should silently not track if not inititalised", () => {
+        analytics.trackAnonymousEvent<ITestEvent>("jest_test_event", {
             foo: "bar",
         });
 
         expect(fakePosthog.capture.mock.calls.length).toBe(0);
     });
+
+    it("Should not track non-anonymous messages if onlyTrackAnonymousEvents is true", () => {
+        analytics.trackAnonymousEvent<ITestEvent>("jest_test_event", {
+            foo: "bar",
+        });
+    });
 });