import { test, expect } from "vitest";
import { buildApp } from "../src/app.js";
import { loadConfig } from "../src/config.js";
import { SseHub } from "../src/sse/sse-hub.js";

async function readUntil(
  reader: ReadableStreamDefaultReader<Uint8Array>,
  predicate: (text: string) => boolean,
): Promise<string> {
  const decoder = new TextDecoder();
  let text = "";
  const deadline = Date.now() + 1_000;
  while (Date.now() < deadline) {
    const result = await Promise.race([
      reader.read(),
      new Promise<{ timeout: true }>((resolve) =>
        setTimeout(() => resolve({ timeout: true }), Math.max(0, deadline - Date.now())),
      ),
    ]);
    if ("timeout" in result || result.done) break;
    text += decoder.decode(result.value);
    if (predicate(text)) break;
  }
  return text;
}

async function captureReplay(options: { query?: string; lastEventId?: string }): Promise<string> {
  const hub = new SseHub();
  hub.publish("s1", "info", { type: "info", text: "one" });
  hub.publish("s1", "info", { type: "info", text: "two" });
  hub.publish("s1", "info", { type: "info", text: "three" });
  const app = buildApp(loadConfig({ THT_HARNESS_DIR: "/tmp/h" }), {
    hub,
    thtRunner: {} as any,
  });
  await app.listen({ port: 0, host: "127.0.0.1" });
  const port = (app.server.address() as { port: number }).port;
  const controller = new AbortController();

  try {
    const response = await fetch(
      `http://127.0.0.1:${port}/sessions/s1/events${options.query ?? ""}`,
      {
        headers: options.lastEventId ? { "Last-Event-ID": options.lastEventId } : undefined,
        signal: controller.signal,
      },
    );
    const reader = response.body!.getReader();
    const body = await readUntil(reader, (text) => text.includes('"three"'));
    await reader.cancel();
    return body;
  } finally {
    controller.abort();
    await app.close();
  }
}

test("SSE emits ids and honors the native Last-Event-ID replay cursor", async () => {
  const body = await captureReplay({ lastEventId: "1" });

  expect(body).not.toContain('"one"');
  expect(body).toContain("id: 2\nevent: info\n");
  expect(body).toContain('data: {"type":"info","text":"two"}');
  expect(body).toContain("id: 3\nevent: info\n");
  expect(body).toContain('data: {"type":"info","text":"three"}');
});

test("SSE honors the manual lastEventId query cursor", async () => {
  const body = await captureReplay({ query: "?lastEventId=2" });

  expect(body).not.toContain('"one"');
  expect(body).not.toContain('"two"');
  expect(body).toContain("id: 3\nevent: info\n");
  expect(body).toContain('data: {"type":"info","text":"three"}');
});

test("SSE uses the newer valid cursor when header and query are both present", async () => {
  const body = await captureReplay({ query: "?lastEventId=2", lastEventId: "1" });

  expect(body).not.toContain('"two"');
  expect(body).toContain("id: 3\nevent: info\n");
});