feat(core/http): add server-cache module

Author: Char2sGu

packages/core/http/ng-package.json

@@ -0,0 +1,6 @@
+{
+  "$schema": "../../../node_modules/ng-packagr/ng-package.schema.json",
+  "lib": {
+    "entryFile": "src/public-api.ts"
+  }
+}

packages/core/http/src/public-api.ts

@@ -0,0 +1 @@
+export * from './server-cache';

packages/core/http/src/server-cache.ts

@@ -0,0 +1,34 @@
+import { HttpContextToken, HttpInterceptorFn } from '@angular/common/http';
+import { inject, InjectionToken, REQUEST_CONTEXT } from '@angular/core';
+import { Observable, shareReplay } from 'rxjs';
+
+export class HttpServerCache extends Map<string, Observable<any>> {}
+
+export const HTTP_SERVER_CACHE = new InjectionToken<HttpServerCache | null>(
+  'HTTP_SERVER_CACHE',
+  {
+    factory: () => {
+      const context = inject(REQUEST_CONTEXT);
+      if (!context) return null;
+      if (typeof context !== 'object') return null;
+      const cache = Reflect.get(context, HttpServerCache.name);
+      if (!cache) return null;
+      return cache;
+    },
+  },
+);
+
+export const HTTP_SERVER_CACHE_KEY = new HttpContextToken<string | null>(
+  () => null,
+);
+
+export const httpServerCacheInterceptor: HttpInterceptorFn = (req, next) => {
+  const cache = inject(HTTP_SERVER_CACHE);
+  if (!cache) return next(req);
+  const key = req.context.get(HTTP_SERVER_CACHE_KEY);
+  if (!key) return next(req);
+  if (cache.has(key)) return cache.get(key)!;
+  const result$ = next(req).pipe(shareReplay(1));
+  cache.set(key, result$);
+  return result$;
+};