Add core Endpoint/ApiClient base classes

src/core/http/ApiClient.ts

@@ -0,0 +1,47 @@
+import { Endpoint } from './Endpoint';
+
+export class ApiError extends Error {
+  constructor(
+    message: string,
+    readonly status: number,
+    readonly body: string
+  ) {
+    super(message);
+    this.name = 'ApiError';
+  }
+}
+
+export abstract class ApiClient {
+  protected constructor(protected readonly baseUrl: string) {}
+
+  protected buildHeaders(): Record<string, string> {
+    return { Accept: 'application/json' };
+  }
+
+  protected async request<TResponse, TParams = void>(
+    endpoint: Endpoint<TResponse, TParams>,
+    params: TParams
+  ): Promise<TResponse> {
+    const query = endpoint.query(params);
+    const qs = query ? `?${new URLSearchParams(query).toString()}` : '';
+    const url = `${this.baseUrl}${endpoint.path(params)}${qs}`;
+    const body = endpoint.body(params);
+    const headers = this.buildHeaders();
+
+    const init: RequestInit = { method: endpoint.method, headers };
+    if (body !== undefined) {
+      init.body = JSON.stringify(body);
+      headers['Content-Type'] = 'application/json';
+    }
+
+    const res = await fetch(url, init);
+    const text = await res.text();
+    const ok = res.ok || endpoint.acceptableStatuses.includes(res.status);
+    if (!ok) {
+      throw new ApiError(`${endpoint.method} ${url} returned ${res.status}`, res.status, text);
+    }
+
+    const json = text.length > 0 ? JSON.parse(text) : undefined;
+    return endpoint.parseResponse(json);
+  }
+}

src/core/http/Endpoint.ts

@@ -0,0 +1,18 @@
+export type HttpMethod = 'GET' | 'POST' | 'PUT' | 'DELETE' | 'PATCH';
+
+export abstract class Endpoint<TResponse, TParams = void> {
+  abstract readonly method: HttpMethod;
+  readonly acceptableStatuses: number[] = [];
+
+  abstract path(params: TParams): string;
+
+  query(_params: TParams): Record<string, string> | undefined {
+    return undefined;
+  }
+
+  body(_params: TParams): unknown {
+    return undefined;
+  }
+
+  abstract parseResponse(json: unknown): TResponse;
+}