import { afterEach, describe, expect, it, vi } from "vitest";

import {
  createEventStream,
  eventStreamHeaders,
  SSE_HEARTBEAT_MS,
  SSE_MAX_LIFETIME_MS,
} from "./sse";

const decoder = new TextDecoder();

afterEach(() => {
  vi.useRealTimers();
});

describe("SSE stream", () => {
  it("uses the required heartbeat, reconnect lifetime, and proxy headers", () => {
    expect(SSE_HEARTBEAT_MS).toBe(90_000);
    expect(SSE_MAX_LIFETIME_MS).toBe(30 * 60 * 1_000);
    const headers = eventStreamHeaders();
    expect(headers.get("content-type")).toContain("text/event-stream");
    expect(headers.get("cache-control")).toBe("no-cache, no-transform");
    expect(headers.get("x-accel-buffering")).toBe("no");
  });

  it("heartbeats, sends only the supplied envelope, and closes on schedule", async () => {
    vi.useFakeTimers();
    const onClose = vi.fn();
    const channel = createEventStream({
      heartbeatMs: 50,
      maximumLifetimeMs: 99,
      onClose,
    });
    const reader = channel.stream.getReader();

    expect(decoder.decode((await reader.read()).value)).toBe(": connected\n\n");
    channel.send({ type: "page.updated", id: "opaque", version: 7 });
    expect(decoder.decode((await reader.read()).value)).toBe(
      'event: invalidation\ndata: {"type":"page.updated","id":"opaque","version":7}\n\n',
    );
    channel.sendNamed("deployment", "release-2");
    expect(decoder.decode((await reader.read()).value)).toBe(
      "event: deployment\ndata: release-2\n\n",
    );
    vi.advanceTimersByTime(50);
    expect(decoder.decode((await reader.read()).value)).toMatch(/^: heartbeat /u);
    vi.advanceTimersByTime(49);
    expect((await reader.read()).done).toBe(true);
    expect(onClose).toHaveBeenCalledTimes(1);
  });

  it("rejects event names that could inject another SSE field", () => {
    const channel = createEventStream();
    expect(() => channel.sendNamed("deployment\ndata", "release-2")).toThrow(
      "SSE event names",
    );
    channel.close();
  });
});