/* eslint-disable @typescript-eslint/no-var-requires */
const webStreams = require('node:stream/web');
const util = require('node:util');

if (typeof (globalThis as any).ReadableStream === 'undefined') {
  (globalThis as any).ReadableStream = webStreams.ReadableStream;
}
if (typeof (globalThis as any).TextEncoder === 'undefined') {
  (globalThis as any).TextEncoder = util.TextEncoder;
}
if (typeof (globalThis as any).TextDecoder === 'undefined') {
  (globalThis as any).TextDecoder = util.TextDecoder;
}

import {
  isBootstrapGeneralFrame,
  makeBootstrapEventSource as defaultCreateSource,
} from '../../frontend/src/app/core/services/bootstrap-event.pure';

function makeCaptureableFetch(frames: string[]): { fetchMock: jest.Mock; readCaptured(): { url: string } | null } {
  const encoder = new TextEncoder();
  const state: { captured: { url: string } | null } = { captured: null };
  const fetchMock = jest.fn(async (url: string) => {
    state.captured = { url };
    const body = new ReadableStream<Uint8Array>({
      async start(controller) {
        for (const f of frames) controller.enqueue(encoder.encode(f));
        controller.close();
      },
    });
    return { ok: true, status: 200, body } as unknown as Response;
  });
  return { fetchMock, readCaptured: () => state.captured };
}

describe('isBootstrapGeneralFrame', () => {
  it('accepts a frame with topic === "general"', () => {
    expect(isBootstrapGeneralFrame({ topic: 'general', registrationsEnabled: true })).toBe(true);
  });

  it('rejects frames that do not carry topic === "general"', () => {
    expect(isBootstrapGeneralFrame({ topic: 'scoreboard' })).toBe(false);
    expect(isBootstrapGeneralFrame({ registrationsEnabled: true })).toBe(false);
    expect(isBootstrapGeneralFrame({ status: 'running' })).toBe(false);
    expect(isBootstrapGeneralFrame(null)).toBe(false);
    expect(isBootstrapGeneralFrame(undefined)).toBe(false);
    expect(isBootstrapGeneralFrame('general')).toBe(false);
    expect(isBootstrapGeneralFrame(42)).toBe(false);
  });
});

describe('defaultCreateSource (public SSE opener)', () => {
  let originalFetch: typeof globalThis.fetch | undefined;

  beforeEach(() => {
    originalFetch = (globalThis as any).fetch;
  });

  afterEach(() => {
    (globalThis as any).fetch = originalFetch;
  });

  it('opens /api/v1/event/stream with credentials and Accept text/event-stream', async () => {
    const f = makeCaptureableFetch([]);
    (globalThis as any).fetch = f.fetchMock as any;
    const src = defaultCreateSource('/api/v1/event/stream');
    await new Promise((r) => setTimeout(r, 20));
    const captured = f.readCaptured();
    expect(captured).not.toBeNull();
    expect(captured!.url).toBe('/api/v1/event/stream');
    src.close();
  });

  it('dispatches SSE message frames to message listeners', async () => {
    const frame =
      'data: {"status":"Running","countdownMs":1,"serverNowUtc":"2026-07-22T00:00:00.000Z","startUtc":null,"endUtc":null}\n\n';
    const f = makeCaptureableFetch([frame]);
    (globalThis as any).fetch = f.fetchMock as any;
    const src = defaultCreateSource('/api/v1/event/stream');
    const received: any[] = [];
    src.addEventListener('message', (ev) => {
      const me = ev as MessageEvent;
      received.push(typeof me.data === 'string' ? JSON.parse(me.data) : me.data);
    });
    await new Promise((r) => setTimeout(r, 50));
    expect(received.length).toBeGreaterThanOrEqual(1);
    expect(received[0].status).toBe('Running');
    src.close();
  });

  it('buffers early frames and flushes them when a message listener attaches', async () => {
    const frame =
      'data: {"topic":"general","themeKey":"classic","registrationsEnabled":true}\n\n';
    const f = makeCaptureableFetch([frame]);
    (globalThis as any).fetch = f.fetchMock as any;
    const src = defaultCreateSource('/api/v1/event/stream');
    // Wait for the underlying reader to drain before adding the listener
    // so we exercise the buffering path.
    await new Promise((r) => setTimeout(r, 30));
    const received: any[] = [];
    src.addEventListener('message', (ev) => {
      const me = ev as MessageEvent;
      received.push(typeof me.data === 'string' ? JSON.parse(me.data) : me.data);
    });
    await new Promise((r) => setTimeout(r, 20));
    expect(received.length).toBeGreaterThanOrEqual(1);
    expect(received.some((r) => r && r.topic === 'general')).toBe(true);
    src.close();
  });

  it('forwards error events when the underlying fetch reports failure', async () => {
    const fetchMock = jest.fn(async () => ({ ok: false, status: 500, body: null } as unknown as Response));
    (globalThis as any).fetch = fetchMock as any;
    const src = defaultCreateSource('/api/v1/event/stream');
    const errors: string[] = [];
    src.addEventListener('error', (ev) => errors.push((ev as Event).type));
    await new Promise((r) => setTimeout(r, 30));
    expect(errors).toContain('error');
    src.close();
  });

  it('close() is idempotent and safe to call twice', async () => {
    const f = makeCaptureableFetch([]);
    (globalThis as any).fetch = f.fetchMock as any;
    const src = defaultCreateSource('/api/v1/event/stream');
    src.close();
    expect(() => src.close()).not.toThrow();
  });
});