import { createServer, type ServerResponse } from "node:http";
import type { AddressInfo } from "node:net";
import type { Page } from "@playwright/test";

const fixtures = new WeakMap<Page, { cursors: string[] }>();

// route.fulfill() closes an SSE response after its body. UI fixtures need a
// real open response so the application stays live until the page disconnects.
export async function mockWorkbenchEventStream(page: Page) {
  const existing = fixtures.get(page);
  if (existing) return existing;
  const clients = new Set<ServerResponse>();
  const cursors: string[] = [];
  const server = createServer((request, response) => {
    response.setHeader("Access-Control-Allow-Origin", "*");
    response.setHeader("Access-Control-Allow-Headers", "Authorization, Content-Type, Last-Event-ID, X-Project-Id");
    response.setHeader("Access-Control-Allow-Methods", "GET, OPTIONS");
    if (request.method === "OPTIONS") {
      response.writeHead(204).end();
      return;
    }
    cursors.push(new URL(request.url!, "http://localhost").searchParams.get("after") ?? "");
    response.writeHead(200, { "Content-Type": "text/event-stream", "Cache-Control": "no-cache" });
    response.write(": fixture connected\n\n");
    clients.add(response);
    response.on("close", () => clients.delete(response));
  });
  await new Promise<void>((resolve, reject) => {
    server.once("error", reject);
    server.listen(0, "127.0.0.1", resolve);
  });
  const { port } = server.address() as AddressInfo;
  page.on("close", () => {
    for (const client of clients) client.destroy();
    server.close();
    server.closeAllConnections();
  });
  await page.route("**/api/v1/workbench/events**", (route) => {
    const query = new URL(route.request().url()).search;
    return route.fulfill({ status: 307, headers: {
      "Access-Control-Allow-Origin": "*",
      "Location": `http://127.0.0.1:${port}/events${query}`
    } });
  });
  const fixture = { cursors };
  fixtures.set(page, fixture);
  return fixture;
}