feat: add basic analytics (#29)

packages/bolt/app/lib/analytics.ts

@@ -0,0 +1,103 @@
+import { Analytics, type IdentifyParams, type PageParams, type TrackParams } from '@segment/analytics-node';
+import { CLIENT_ORIGIN } from '~/lib/constants';
+import { request as doRequest } from '~/lib/fetch';
+import { logger } from '~/utils/logger';
+
+export interface Identity {
+  userId?: string | null;
+  guestId?: string | null;
+  segmentWriteKey?: string | null;
+}
+
+const MESSAGE_PREFIX = 'Bolt';
+
+export enum AnalyticsTrackEvent {
+  MessageSent = `${MESSAGE_PREFIX} Message Sent`,
+  ChatCreated = `${MESSAGE_PREFIX} Chat Created`,
+}
+
+export enum AnalyticsAction {
+  Identify = 'identify',
+  Page = 'page',
+  Track = 'track',
+}
+
+// we can omit the user ID since it's retrieved from the user's session
+type OmitUserId<T> = Omit<T, 'userId'>;
+
+export type AnalyticsEvent =
+  | { action: AnalyticsAction.Identify; payload: OmitUserId<IdentifyParams> }
+  | { action: AnalyticsAction.Page; payload: OmitUserId<PageParams> }
+  | { action: AnalyticsAction.Track; payload: OmitUserId<TrackParams> };
+
+export async function identifyUser(access: string): Promise<Identity | undefined> {
+  const response = await doRequest(`${CLIENT_ORIGIN}/api/identify`, {
+    method: 'GET',
+    headers: { authorization: `Bearer ${access}` },
+  });
+
+  const body = await response.json();
+
+  if (!response.ok) {
+    return undefined;
+  }
+
+  // convert numerical identity values to strings
+  const stringified = Object.entries(body).map(([key, value]) => [
+    key,
+    typeof value === 'number' ? value.toString() : value,
+  ]);
+
+  return Object.fromEntries(stringified) as Identity;
+}
+
+// send an analytics event from the client
+export async function sendAnalyticsEvent(event: AnalyticsEvent) {
+  // don't send analytics events when in dev mode
+  if (import.meta.env.DEV) {
+    return;
+  }
+
+  const request = await fetch('/api/analytics', {
+    method: 'POST',
+    headers: {
+      'Content-Type': 'application/json',
+    },
+    body: JSON.stringify(event),
+  });
+
+  if (!request.ok) {
+    logger.error(`Error handling Segment Analytics action: ${event.action}`);
+  }
+}
+
+// send an analytics event from the server
+export async function sendEventInternal(identity: Identity, { action, payload }: AnalyticsEvent) {
+  const { userId, segmentWriteKey: writeKey } = identity;
+
+  if (!userId || !writeKey) {
+    logger.warn('Missing user ID or write key when logging analytics');
+    return { success: false as const, error: 'missing-data' };
+  }
+
+  const analytics = new Analytics({ flushAt: 1, writeKey }).on('error', logger.error);
+
+  try {
+    await new Promise((resolve, reject) => {
+      if (action === AnalyticsAction.Identify) {
+        analytics.identify({ ...payload, userId }, resolve);
+      } else if (action === AnalyticsAction.Page) {
+        analytics.page({ ...payload, userId }, resolve);
+      } else if (action === AnalyticsAction.Track) {
+        analytics.track({ ...payload, userId }, resolve);
+      } else {
+        reject();
+      }
+    });
+  } catch {
+    logger.error(`Error handling Segment Analytics action: ${action}`);
+    return { success: false as const, error: 'invalid-action' };
+  }
+
+  return { success: true as const };
+}