analytics/examples/nestjs-backend/user.controller.ts

/**
 * UserController - Example with analytics tracking
 *
 * Demonstrates various tracking patterns in a NestJS controller.
 */

import {
  Controller,
  Post,
  Get,
  Body,
  Param,
  Request,
  Inject,
  UseInterceptors,
} from '@nestjs/common';

import { BackendAnalyticsClient } from '@analytics/client';
import { ANALYTICS_CLIENT } from './analytics.module';
import { AnalyticsInterceptor } from './analytics.interceptor';
import { TrackAnalytics } from './track-analytics.decorator';

// ─────────────────────────────────────────────────────────────────────────────
// DTOs
// ─────────────────────────────────────────────────────────────────────────────

interface SignupDto {
  email: string;
  name: string;
  plan?: string;
}

interface User {
  id: string;
  email: string;
  name: string;
  plan: string;
}

// ─────────────────────────────────────────────────────────────────────────────
// Controller
// ─────────────────────────────────────────────────────────────────────────────

@Controller('users')
@UseInterceptors(AnalyticsInterceptor) // Track all requests
export class UserController {
  constructor(
    @Inject(ANALYTICS_CLIENT)
    private readonly analytics: BackendAnalyticsClient,
  ) {}

  /**
   * Signup endpoint with automatic tracking via decorator.
   */
  @Post('signup')
  @TrackAnalytics({
    event: 'user_signup',
    category: 'auth',
    extractMetadata: ({ result }) => ({
      userId: result.id,
      plan: result.plan,
      emailDomain: result.email.split('@')[1],
    }),
  })
  async signup(@Body() dto: SignupDto): Promise<User> {
    // Your signup logic here
    const user: User = {
      id: `usr_${Date.now()}`,
      email: dto.email,
      name: dto.name,
      plan: dto.plan || 'free',
    };

    return user;
  }

  /**
   * Profile view with manual tracking.
   *
   * Use manual tracking when you need more control.
   */
  @Get(':id')
  async getProfile(@Param('id') id: string, @Request() req: any): Promise<User | null> {
    // Your fetch logic here
    const user: User = {
      id,
      email: 'user@example.com',
      name: 'Example User',
      plan: 'pro',
    };

    // Manual tracking with full context
    this.analytics.trackEngagement({
      sessionId: req.headers['x-session-id'] || 'unknown',
      userId: req.user?.id, // Viewer's ID
      type: 'profile_view',
      action: 'view',
      metadata: {
        viewedProfileId: id,
        viewedUserPlan: user.plan,
        viewerIsAuthenticated: Boolean(req.user),
      },
    });

    return user;
  }

  /**
   * Upgrade plan with funnel tracking.
   */
  @Post(':id/upgrade')
  async upgradePlan(
    @Param('id') id: string,
    @Body() body: { plan: string },
    @Request() req: any,
  ): Promise<{ success: boolean }> {
    const sessionId = req.headers['x-session-id'] || 'unknown';

    // Track upgrade funnel step
    this.analytics.trackEngagement({
      sessionId,
      userId: id,
      type: 'funnel_step',
      action: 'plan_upgrade',
      metadata: {
        funnelId: 'upgrade',
        step: 'upgrade_completed',
        fromPlan: 'free', // You'd fetch this from DB
        toPlan: body.plan,
      },
    });

    return { success: true };
  }

  /**
   * Account deletion with GDPR tracking.
   */
  @Post(':id/delete')
  async deleteAccount(@Param('id') id: string, @Request() req: any): Promise<{ deleted: boolean }> {
    const sessionId = req.headers['x-session-id'] || 'unknown';

    // Track before deletion (important for compliance)
    this.analytics.trackEngagement({
      sessionId,
      userId: id,
      type: 'account_action',
      action: 'deletion_requested',
      metadata: {
        requestedBy: req.user?.id === id ? 'self' : 'admin',
        gdprRequest: true,
      },
    });

    // Your deletion logic here

    return { deleted: true };
  }
}