feat: added services, model and environment

src/app/core/services/cache.service.ts

@@ -0,0 +1,53 @@
+import { Injectable } from '@angular/core';
+
+// Cache expiration time. (In a real shop this should not be the beast approach due to stock changes)
+const CACHE_TTL_MS = 60 * 60 * 1000;
+
+// Prefix for cache keys to avoid collisions with other localStorage entries.
+const CACHE_PREFIX = 'itx-cache:';
+
+interface CacheEntry<T> {
+  timestamp: number;
+  data: T;
+}
+
+// Generic cache service
+@Injectable({ providedIn: 'root' })
+export class CacheService {
+  // returns cached item if it exists and is not expired, otherwise fetches it using the provided fetcher function.
+  async getOrFetch<T>(key: string, fetcher: () => Promise<T>): Promise<T> {
+    const cached = this.read<T>(key);
+    if (cached && Date.now() - cached.timestamp < CACHE_TTL_MS) {
+      return cached.data;
+    }
+
+    const data = await fetcher();
+    this.write(key, data);
+    return data;
+  }
+
+  // Clears all cache entries managed by this service.
+  clear(): void {
+    Object.keys(localStorage)
+      .filter((key) => key.startsWith(CACHE_PREFIX))
+      .forEach((key) => localStorage.removeItem(key));
+  }
+
+  private read<T>(key: string): CacheEntry<T> | null {
+    const raw = localStorage.getItem(CACHE_PREFIX + key);
+    if (!raw) {
+      return null;
+    }
+    try {
+      return JSON.parse(raw) as CacheEntry<T>;
+    } catch {
+      // corrupted data
+      return null;
+    }
+  }
+
+  private write<T>(key: string, data: T): void {
+    const entry: CacheEntry<T> = { timestamp: Date.now(), data };
+    localStorage.setItem(CACHE_PREFIX + key, JSON.stringify(entry));
+  }
+}