feat(endpoints): add common behaviors

Author: Char2sGu

packages/endpoints/src/behaviors.ts

@@ -0,0 +1,80 @@
+import { Observable, shareReplay } from 'rxjs';
+
+import { EndpointInvokeConfig, EndpointInvoker } from './invoker';
+
+/**
+ * Decorator of an {@link EndpointInvoker} instance that
+ * prepends a prefix to the path of each invocation.
+ *
+ * @usageNotes
+ *  ```ts
+ *  provide({
+ *    token: EndpointInvoker,
+ *    useFactory: (
+ *      invoker: EndpointInvoker = inject(HttpClientEndpointInvoker),
+ *    ) => {
+ *      // behaviors are applied in reverse order (last -> first)
+ *      invoker = new PrefixEndpointPath(invoker, "https://my.api/");
+ *      invoker = new CacheEndpointResponse(invoker, c => c.method === 'GET');
+ *      invoker = // other behaviors here...
+ *      return invoker;
+ *    },
+ *  }),
+ *  ```
+ *
+ */
+export class PrefixEndpointPath implements EndpointInvoker {
+  constructor(
+    private kernel: EndpointInvoker,
+    private prefix: string,
+  ) {}
+
+  invoke<T>(config: EndpointInvokeConfig): Observable<T> {
+    config.path = this.prefix + config.path;
+    return this.kernel.invoke(config);
+  }
+}
+
+/**
+ * Decorator of an {@link EndpointInvoker} instance that
+ * caches the responses of endpoint invocations when a given criteria is met.
+ *
+ * @usageNotes
+ *  ```ts
+ *  provide({
+ *    token: EndpointInvoker,
+ *    useFactory: (
+ *      invoker: EndpointInvoker = inject(HttpClientEndpointInvoker),
+ *    ) => {
+ *      // behaviors are applied in reverse order (last -> first)
+ *      invoker = new PrefixEndpointPath(invoker, "https://my.api/");
+ *      invoker = new CacheEndpointResponse(invoker, c => c.method === 'GET');
+ *      invoker = // other behaviors here...
+ *      return invoker;
+ *    },
+ *  }),
+ *  ```
+ */
+export class CacheEndpointResponse implements EndpointInvoker {
+  private cache = new Map<string, Observable<unknown>>();
+
+  /**
+   * @param criteria a function that determines whether
+   * an endpoint invocation should be cached.
+   */
+  constructor(
+    private kernel: EndpointInvoker,
+    private criteria: (config: EndpointInvokeConfig) => boolean,
+  ) {}
+
+  invoke<T>(config: EndpointInvokeConfig): Observable<T> {
+    if (this.criteria(config)) {
+      const cached = this.cache.get(config.path);
+      if (cached) return cached as Observable<T>;
+      const observable = this.kernel.invoke<T>(config).pipe(shareReplay(1));
+      this.cache.set(config.path, observable);
+      return observable;
+    }
+    return this.kernel.invoke(config);
+  }
+}

packages/endpoints/src/public-api.ts

@@ -1,3 +1,4 @@
+export * from './behaviors';
 export * from './convenience';
 export * from './core';
 export * from './generators';