/**
 * 路由表式 fetch 替身(站点用户信息解析器 / API spider 测试用)。
 * 路由键:`METHOD path?query`(query 可省略,省略时匹配任意 query;METHOD 省略为任意方法);
 * 值为响应描述或函数。未命中返回 404。记录全部请求(含头与 body)供断言。
 */

export interface MockRouteResponse {
  status?: number;
  body?: string | object;
  contentType?: string;
  headers?: Record<string, string>;
}

export type MockRouteHandler = MockRouteResponse | ((req: MockFetchRequest) => MockRouteResponse);

export interface MockFetchRequest {
  method: string;
  url: URL;
  headers: Record<string, string>;
  body: string | null;
}

export interface MockFetch {
  fetch: typeof globalThis.fetch;
  requests: MockFetchRequest[];
  /** 追加/覆盖路由 */
  route(key: string, handler: MockRouteHandler): void;
}

function match(key: string, req: MockFetchRequest): boolean {
  let method: string | null = null;
  let target = key;
  const sp = key.indexOf(" ");
  if (sp > 0 && /^[A-Z]+$/.test(key.slice(0, sp))) {
    method = key.slice(0, sp);
    target = key.slice(sp + 1);
  }
  if (method && method !== req.method) return false;
  // 可带主机:"https://api.x.com/path"
  let host: string | null = null;
  if (/^https?:\/\//.test(target)) {
    const u = new URL(target);
    host = u.host;
    target = u.pathname + u.search;
  }
  if (host && host !== req.url.host) return false;
  const [path, query] = target.split("?");
  if (path !== req.url.pathname) return false;
  if (query === undefined) return true;
  const want = new URLSearchParams(query);
  for (const [k, v] of want) if (req.url.searchParams.get(k) !== v) return false;
  return true;
}

export function createMockFetch(routes: Record<string, MockRouteHandler> = {}): MockFetch {
  const table = new Map<string, MockRouteHandler>(Object.entries(routes));
  const requests: MockFetchRequest[] = [];
  const fetchImpl = async (input: string | URL | Request, init?: RequestInit): Promise<Response> => {
    const url = new URL(typeof input === "string" ? input : input instanceof URL ? input.href : input.url);
    const headers: Record<string, string> = {};
    new Headers(init?.headers).forEach((v, k) => {
      headers[k] = v;
    });
    const req: MockFetchRequest = {
      method: (init?.method ?? "GET").toUpperCase(),
      url,
      headers,
      body: typeof init?.body === "string" ? init.body : null,
    };
    requests.push(req);
    // 后加入的路由优先,便于测试覆盖默认路由;同时更具体(带 query)的键优先
    const keys = [...table.keys()].reverse().sort((a, b) => Number(b.includes("?")) - Number(a.includes("?")));
    for (const key of keys) {
      if (!match(key, req)) continue;
      const h = table.get(key)!;
      const r = typeof h === "function" ? h(req) : h;
      const isJson = r.body !== undefined && typeof r.body !== "string";
      const body = r.body === undefined ? "" : isJson ? JSON.stringify(r.body) : (r.body as string);
      return new Response(body, {
        status: r.status ?? 200,
        headers: {
          "content-type": r.contentType ?? (isJson ? "application/json" : "text/html; charset=utf-8"),
          ...(r.headers ?? {}),
        },
      });
    }
    return new Response("not found", { status: 404 });
  };
  return {
    fetch: fetchImpl as typeof globalThis.fetch,
    requests,
    route(key, handler) {
      table.delete(key);
      table.set(key, handler);
    },
  };
}