Add-ESLint-rules-for-code-quality-enforcement

src/analytics/analytics.service.ts

@@ -1,3 +1,5 @@
+import {  Logger } from '@nestjs/common';
+import { Counter, Histogram } from 'prom-client';
 import { Injectable, Logger, BadRequestException } from '@nestjs/common';
 import { InjectRepository } from '@nestjs/typeorm';
 import { Repository } from 'typeorm';
@@ -10,8 +12,75 @@ import { EventValidationService } from './services/event-validation.service';
 @Injectable()
 export class AnalyticsService implements OnModuleInit {
   private readonly logger = new Logger(AnalyticsService.name);
-  private featureEventsCounter: any | null = null;
 
+  private readonly featureEvents: Counter<'category' | 'action' | 'label'> | null;
+  private readonly assessmentDuration: Histogram<'status'> | null;
+
+  constructor(private readonly metrics: MetricsCollectionService) {
+    const registry = this.metrics.getRegistry();
+
+    this.featureEvents = this.registerMetric(() =>
+      (registry.getSingleMetric('feature_events_total') as Counter<'category' | 'action' | 'label'>) ??
+      new Counter({
+        name: 'feature_events_total',
+        help: 'Feature analytics events',
+        labelNames: ['category', 'action', 'label'] as const,
+        registers: [registry],
+      }),
+    );
+
+    this.assessmentDuration = this.registerMetric(() =>
+      (registry.getSingleMetric('assessment_duration_seconds') as Histogram<'status'>) ??
+      new Histogram({
+        name: 'assessment_duration_seconds',
+        help: 'Time from attempt start to submission or timeout, in seconds',
+        labelNames: ['status'] as const,
+        buckets: [30, 60, 120, 300, 600, 1200, 1800],
+        registers: [registry],
+      }),
+    );
+  }
+
+  // ── Generic event recording ────────────────────────────────────────────────
+
+  recordEvent(category: string, action: string, label = '', value = 1): void {
+    try {
+      this.featureEvents?.inc({ category, action, label }, value);
+    } catch (err) {
+      this.logger.error(
+        `Failed to record analytics event: ${category}.${action}`,
+        err as Error,
+      );
+    }
+  }
+
+  // ── Assessment-domain events ───────────────────────────────────────────────
+
+  recordAssessmentStarted(assessmentId: string): void {
+    this.recordEvent('assessment', 'started', assessmentId);
+  }
+
+  recordAssessmentSubmitted(assessmentId: string, startedAt: Date): void {
+    this.recordEvent('assessment', 'submitted', assessmentId);
+    this.observeDuration(startedAt, 'submitted');
+  }
+
+  recordAssessmentTimedOut(assessmentId: string, startedAt: Date): void {
+    this.recordEvent('assessment', 'timed_out', assessmentId);
+    this.observeDuration(startedAt, 'timed_out');
+  }
+
+  recordAssessmentScore(score: number, maxScore: number): void {
+    const pct = maxScore > 0 ? Math.round((score / maxScore) * 100) : 0;
+    this.recordEvent('assessment', 'score_recorded', '', pct);
+  }
+
+  // ── Private helpers ────────────────────────────────────────────────────────
+
+  private observeDuration(startedAt: Date, status: string): void {
+    try {
+      const seconds = (Date.now() - startedAt.getTime()) / 1000;
+      this.assessmentDuration?.observe({ status }, seconds);
   constructor(
     @InjectRepository(AnalyticsEvent)
     private eventRepository: Repository<AnalyticsEvent>,
@@ -37,12 +106,18 @@ export class AnalyticsService implements OnModuleInit {
           registers: [registry],
         });
     } catch (err) {
-      this.logger.warn('Could not initialize feature events counter', err as Error);
-      this.featureEventsCounter = null;
+      this.logger.error('Failed to observe assessment duration', err as Error);
     }
   }
 
   /**
+   * Wraps metric construction in a try/catch so a misconfigured registry
+   * (e.g. duplicate registration in tests) degrades to a null metric rather
+   * than crashing the service on startup.
+   */
+  private registerMetric<T>(factory: () => T): T | null {
+    try {
+      return factory();
    * Track an event with full validation and batching
    */
   async trackEvent(dto: ITrackEventDto): Promise<void> {
@@ -101,9 +176,11 @@ export class AnalyticsService implements OnModuleInit {
         this.logger.debug(`Analytics event (log only): ${category}.${action} value=${value}`);
       }
     } catch (err) {
-      this.logger.error('Failed to record analytics event', err as Error);
+      this.logger.warn('Could not register metric; proceeding without it', err as Error);
+      return null;
     }
   }
+}
 
   /**
    * Query events with filters