From 53154739737609bfdcfe23d3cd9b37c116458600 Mon Sep 17 00:00:00 2001
From: Sergey Krylov <ksv741@mail.ru>
Date: Sat, 13 Jun 2026 18:56:58 +0300
Subject: [PATCH] feat: add cache module with getOrFetch pattern and
 configurable TTL

---
 .../backend/src/modules/cache/cache.module.ts | 16 +++++++
 .../src/modules/cache/cache.service.ts        | 44 +++++++++++++++++++
 2 files changed, 60 insertions(+)
 create mode 100644 apps/backend/src/modules/cache/cache.module.ts
 create mode 100644 apps/backend/src/modules/cache/cache.service.ts

diff --git a/apps/backend/src/modules/cache/cache.module.ts b/apps/backend/src/modules/cache/cache.module.ts
new file mode 100644
index 0000000..4682d12
--- /dev/null
+++ b/apps/backend/src/modules/cache/cache.module.ts
@@ -0,0 +1,16 @@
+import { Module } from '@nestjs/common';
+import { CacheModule as NestCacheModule } from '@nestjs/cache-manager';
+import { CacheService } from './cache.service';
+
+@Module({
+  imports: [
+    NestCacheModule.register({
+      ttl: 900,
+      max: 1000,
+      isGlobal: true,
+    }),
+  ],
+  providers: [CacheService],
+  exports: [CacheService],
+})
+export class CacheModule {}
diff --git a/apps/backend/src/modules/cache/cache.service.ts b/apps/backend/src/modules/cache/cache.service.ts
new file mode 100644
index 0000000..11efcd2
--- /dev/null
+++ b/apps/backend/src/modules/cache/cache.service.ts
@@ -0,0 +1,44 @@
+import { Injectable, Inject } from '@nestjs/common';
+import { CACHE_MANAGER } from '@nestjs/cache-manager';
+import { Cache } from 'cache-manager';
+import { ConfigService } from '@nestjs/config';
+
+@Injectable()
+export class CacheService {
+  constructor(
+    @Inject(CACHE_MANAGER) private cacheManager: Cache,
+    private configService: ConfigService,
+  ) {}
+
+  async get<T>(key: string): Promise<T | undefined> {
+    return this.cacheManager.get<T>(key);
+  }
+
+  async set(key: string, value: unknown, ttl?: number): Promise<void> {
+    await this.cacheManager.set(key, value, ttl);
+  }
+
+  private buildKey(...parts: string[]): string {
+    return parts.join(':');
+  }
+
+  async getOrFetch<T>(
+    keyPrefix: string,
+    keyParts: string[],
+    fetchFn: () => Promise<T>,
+    ttlConfigKey: string,
+  ): Promise<{ data: T; fromCache: boolean; cachedAt: string | null }> {
+    const key = this.buildKey(keyPrefix, ...keyParts);
+    const ttl = this.configService.get<number>(`app.cache.${ttlConfigKey}`, 900);
+
+    const cached = await this.get<T>(key);
+    if (cached !== undefined) {
+      return { data: cached, fromCache: true, cachedAt: null };
+    }
+
+    const data = await fetchFn();
+    await this.set(key, data, ttl);
+
+    return { data, fromCache: false, cachedAt: new Date().toISOString() };
+  }
+}