added first cache

libs/cache/src/providers/memory-cache.ts

@@ -0,0 +1,48 @@
+import { CacheProvider } from '../types';
+
+/**
+ * Simple in-memory cache provider.
+ */
+export class MemoryCache implements CacheProvider {
+  private store = new Map<string, any>();
+  private defaultTTL: number;
+  private keyPrefix: string;
+
+  constructor(options: { ttl?: number; keyPrefix?: string } = {}) {
+    this.defaultTTL = options.ttl ?? 3600;
+    this.keyPrefix = options.keyPrefix ?? 'cache:';
+  }
+
+  private getKey(key: string): string {
+    return `${this.keyPrefix}${key}`;
+  }
+
+  async get<T>(key: string): Promise<T | null> {
+    const fullKey = this.getKey(key);
+    const entry = this.store.get(fullKey);
+    if (!entry) return null;
+    if (entry.expiry < Date.now()) {
+      this.store.delete(fullKey);
+      return null;
+    }
+    return entry.value;
+  }
+
+  async set<T>(key: string, value: T, ttl?: number): Promise<void> {
+    const fullKey = this.getKey(key);
+    const expiry = Date.now() + 1000 * (ttl ?? this.defaultTTL);
+    this.store.set(fullKey, { value, expiry });
+  }
+
+  async del(key: string): Promise<void> {
+    this.store.delete(this.getKey(key));
+  }
+
+  async exists(key: string): Promise<boolean> {
+    return (await this.get(key)) !== null;
+  }
+
+  async clear(): Promise<void> {
+    this.store.clear();
+  }
+}