AI Implementation feature(820): Project Scaffold and Platform Foundations (#1)

backend/src/common/services/event-status.service.ts

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+import { Injectable } from '@nestjs/common';
+import { SettingsService } from '../../modules/settings/settings.module';
+
+export type EventStatusName = 'Stopped' | 'Running';
+
+export interface EventStatus {
+  status: EventStatusName;
+  startUtc: string;
+  endUtc: string;
+  serverNowUtc: string;
+  countdownMs: number;
+}
+
+@Injectable()
+export class EventStatusService {
+  constructor(private readonly settings: SettingsService) {}
+
+  async getStatus(now: Date = new Date()): Promise<EventStatus> {
+    const startStr = await this.settings.get('eventStartUtc');
+    const endStr = await this.settings.get('eventEndUtc');
+    const start = new Date(startStr);
+    const end = new Date(endStr);
+    const nowMs = now.getTime();
+    const startMs = start.getTime();
+    const endMs = end.getTime();
+
+    let status: EventStatusName = 'Stopped';
+    let countdownMs = 0;
+    if (nowMs < startMs) {
+      status = 'Stopped';
+      countdownMs = startMs - nowMs;
+    } else if (nowMs <= endMs) {
+      status = 'Running';
+      countdownMs = endMs - nowMs;
+    } else {
+      status = 'Stopped';
+      countdownMs = 0;
+    }
+
+    return {
+      status,
+      startUtc: start.toISOString(),
+      endUtc: end.toISOString(),
+      serverNowUtc: now.toISOString(),
+      countdownMs,
+    };
+  }
+}

backend/src/common/services/login-backoff.service.ts

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+import { Injectable } from '@nestjs/common';
+
+const MAX_FAILS = 5;
+const BACKOFF_MS = [1_000, 5_000, 30_000, 120_000, 600_000, 1_800_000];
+
+@Injectable()
+export class LoginBackoffService {
+  private counters = new Map<string, { count: number; blockedUntil: number }>();
+
+  private key(ip: string, username: string): string {
+    return `${ip}::${username}`;
+  }
+
+  isBlocked(ip: string, username: string, now: number = Date.now()): number {
+    const k = this.key(ip, username);
+    const entry = this.counters.get(k);
+    if (!entry) return 0;
+    if (entry.blockedUntil > now) return entry.blockedUntil - now;
+    return 0;
+  }
+
+  recordFailure(ip: string, username: string, now: number = Date.now()): void {
+    const k = this.key(ip, username);
+    const entry = this.counters.get(k) ?? { count: 0, blockedUntil: 0 };
+    entry.count++;
+    if (entry.count > MAX_FAILS) {
+      const idx = Math.min(entry.count - MAX_FAILS - 1, BACKOFF_MS.length - 1);
+      entry.blockedUntil = now + BACKOFF_MS[idx];
+    } else if (entry.count === MAX_FAILS) {
+      entry.blockedUntil = now + BACKOFF_MS[0];
+    }
+    this.counters.set(k, entry);
+  }
+
+  reset(ip: string, username: string): void {
+    this.counters.delete(this.key(ip, username));
+  }
+}

backend/src/common/services/registration-rate-limit.service.ts

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+import { Injectable } from '@nestjs/common';
+
+const WINDOW_MS = 60_000;
+const MAX_PER_WINDOW = 10;
+
+@Injectable()
+export class RegistrationRateLimitService {
+  private hits: Map<string, number[]> = new Map();
+
+  isAllowed(ip: string, now: number = Date.now()): boolean {
+    const arr = (this.hits.get(ip) ?? []).filter((t) => now - t < WINDOW_MS);
+    this.hits.set(ip, arr);
+    return arr.length < MAX_PER_WINDOW;
+  }
+
+  record(ip: string, now: number = Date.now()): void {
+    const arr = (this.hits.get(ip) ?? []).filter((t) => now - t < WINDOW_MS);
+    arr.push(now);
+    this.hits.set(ip, arr);
+  }
+}

backend/src/common/services/sse-hub.service.ts

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+import { Injectable } from '@nestjs/common';
+import { Subject, Observable } from 'rxjs';
+
+@Injectable()
+export class SseHubService {
+  private readonly eventSubject = new Subject<any>();
+  private readonly scoreboardSubject = new Subject<any>();
+
+  emitEvent(payload: any): void {
+    this.eventSubject.next(payload);
+  }
+
+  emitScoreboard(payload: any): void {
+    this.scoreboardSubject.next(payload);
+  }
+
+  event$(): Observable<any> {
+    return this.eventSubject.asObservable();
+  }
+
+  scoreboard$(): Observable<any> {
+    return this.scoreboardSubject.asObservable();
+  }
+}