📈(frontend) get user analytics

We will identify users by their email address.
This will help us understand how users interact
with the platform and improve the user experience.

src/frontend/apps/impress/src/features/auth/hooks/__tests__/useAuth.test.tsx

@@ -0,0 +1,81 @@
+import { renderHook, waitFor } from '@testing-library/react';
+import fetchMock from 'fetch-mock';
+import { Fragment } from 'react';
+
+import { AbstractAnalytic } from '@/libs';
+import { AppWrapper } from '@/tests/utils';
+
+import { useAuth } from '../useAuth';
+
+const trackEventMock = jest.fn();
+const flag = true;
+class TestAnalytic extends AbstractAnalytic {
+  public constructor() {
+    super();
+  }
+
+  public Provider() {
+    return <Fragment />;
+  }
+
+  public trackEvent(props: any) {
+    trackEventMock(props);
+  }
+
+  public isFeatureFlagActivated(flagName: string): boolean {
+    if (flagName === 'CopyAsHTML') {
+      return flag;
+    }
+
+    return true;
+  }
+}
+
+jest.mock('next/router', () => ({
+  ...jest.requireActual('next/router'),
+  useRouter: () => ({
+    pathname: '/dashboard',
+    replace: jest.fn(),
+  }),
+}));
+
+const dummyUser = { id: '123', email: 'test@example.com' };
+
+describe('useAuth hook - trackEvent effect', () => {
+  beforeEach(() => {
+    jest.clearAllMocks();
+    fetchMock.restore();
+  });
+
+  test('calls trackEvent when user exists, isSuccess is true, and event was not tracked yet', async () => {
+    new TestAnalytic();
+
+    fetchMock.get('http://test.jest/api/v1.0/users/me/', {
+      body: JSON.stringify(dummyUser),
+    });
+
+    renderHook(() => useAuth(), {
+      wrapper: AppWrapper,
+    });
+
+    await waitFor(() => {
+      expect(trackEventMock).toHaveBeenCalledWith({
+        eventName: 'user',
+        id: dummyUser.id,
+        email: dummyUser.email,
+      });
+    });
+  });
+
+  test('does not call trackEvent if already tracked', () => {
+    fetchMock.get('http://test.jest/api/v1.0/users/me/', {
+      body: JSON.stringify(dummyUser),
+    });
+
+    renderHook(() => useAuth(), {
+      wrapper: AppWrapper,
+    });
+
+    expect(trackEventMock).not.toHaveBeenCalled();
+  });
+});

src/frontend/apps/impress/src/features/auth/hooks/useAuth.tsx

@@ -1,6 +1,8 @@
 import { useRouter } from 'next/router';
 import { useEffect, useState } from 'react';
 
+import { useAnalytics } from '@/libs';
+
 import { useAuthQuery } from '../api';
 
 const regexpUrlsAuth = [/\/docs\/$/g, /\/docs$/g, /^\/$/g];
@@ -8,7 +10,8 @@ const regexpUrlsAuth = [/\/docs\/$/g, /\/docs$/g, /^\/$/g];
 export const useAuth = () => {
   const { data: user, ...authStates } = useAuthQuery();
   const { pathname } = useRouter();
-
+  const { trackEvent } = useAnalytics();
+  const [hasTracked, setHasTracked] = useState(authStates.isFetched);
   const [pathAllowed, setPathAllowed] = useState<boolean>(
     !regexpUrlsAuth.some((regexp) => !!pathname.match(regexp)),
   );
@@ -17,6 +20,17 @@ export const useAuth = () => {
     setPathAllowed(!regexpUrlsAuth.some((regexp) => !!pathname.match(regexp)));
   }, [pathname]);
 
+  useEffect(() => {
+    if (!hasTracked && user && authStates.isSuccess) {
+      trackEvent({
+        eventName: 'user',
+        id: user?.id || '',
+        email: user?.email || '',
+      });
+      setHasTracked(true);
+    }
+  }, [hasTracked, authStates.isSuccess, user, trackEvent]);
+
   return {
     user,
     authenticated: !!user && authStates.isSuccess,

src/frontend/apps/impress/src/services/PosthogAnalytic.tsx

@@ -3,7 +3,7 @@ import posthog from 'posthog-js';
 import { PostHogProvider as PHProvider } from 'posthog-js/react';
 import { JSX, PropsWithChildren, ReactNode, useEffect } from 'react';
 
-import { AbstractAnalytic } from '@/libs/';
+import { AbstractAnalytic, AnalyticEvent } from '@/libs/';
 
 export class PostHogAnalytic extends AbstractAnalytic {
   private conf?: PostHogConf = undefined;
@@ -18,7 +18,11 @@ export class PostHogAnalytic extends AbstractAnalytic {
     return <PostHogProvider conf={this.conf}>{children}</PostHogProvider>;
   }
 
-  public trackEvent(): void {}
+  public trackEvent(evt: AnalyticEvent): void {
+    if (evt.eventName === 'user') {
+      posthog.identify(evt.id, { email: evt.email });
+    }
+  }
 
   public isFeatureFlagActivated(flagName: string): boolean {
     if (