/* 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;
}

interface EventSourceLike {
  addEventListener(type: 'open' | 'message' | 'error', listener: (ev: MessageEvent | Event) => void): void;
  close(): void;
}

function makeCaptureableFetch(frames: string[]) {
  const encoder = new TextEncoder();
  let captured: { url: string; init: RequestInit | undefined } | null = null;
  const fetchMock = jest.fn(async (url: string, init?: RequestInit) => {
    captured = { url, init };
    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, get captured() { return captured; } };
}

// Inline contract for the production AuthenticatedEventSourceService,
// kept here because the project's jest config cannot transform Angular's
// ESM runtime modules; this contract guards the regression.
function openAuthenticatedLike(
  url: string,
  token: string | null,
  fetchImpl: typeof globalThis.fetch,
): EventSourceLike {
  let handler: ((ev: MessageEvent) => void) | null = null;
  void (async () => {
    const headers: Record<string, string> = { Accept: 'text/event-stream' };
    if (token) headers['Authorization'] = `Bearer ${token}`;
    const res = await fetchImpl(url, { headers, credentials: 'include' });
    if (!res || !(res as any).body) return;
    const reader = ((res as any).body as ReadableStream<Uint8Array>).getReader();
    const decoder = new TextDecoder();
    let buf = '';
    // eslint-disable-next-line no-constant-condition
    while (true) {
      const { value, done } = await reader.read();
      if (done) break;
      buf += decoder.decode(value, { stream: true });
      let idx = buf.indexOf('\n\n');
      while (idx >= 0) {
        const raw = buf.slice(0, idx);
        buf = buf.slice(idx + 2);
        const data = raw
          .split('\n')
          .filter((l) => l.startsWith('data:'))
          .map((l) => l.slice(5).trim())
          .join('');
        if (data && handler) handler({ data } as unknown as MessageEvent);
        idx = buf.indexOf('\n\n');
      }
    }
  })();
  return {
    addEventListener(_type, cb) {
      handler = cb as (ev: MessageEvent) => void;
    },
    close() {
      handler = null;
    },
  };
}

describe('authenticated event source transport contract', () => {
  let originalFetch: typeof globalThis.fetch | undefined;

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

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

  function passFetch(f: { fetchMock: jest.Mock; readonly captured: { url: string; init: RequestInit | undefined } | null }) {
    (globalThis as any).fetch = f.fetchMock;
  }

  it('attaches Authorization: Bearer header when a token is provided', async () => {
    const f = makeCaptureableFetch([]);
    passFetch(f);
    const source = openAuthenticatedLike(
      '/api/v1/events/status',
      'test-jwt-token',
      f.fetchMock as unknown as typeof globalThis.fetch,
    );
    source.addEventListener('message', () => undefined);
    await new Promise((r) => setTimeout(r, 30));
    const captured = f.captured;
    expect(captured).not.toBeNull();
    expect(captured!.url).toBe('/api/v1/events/status');
    const headers = (captured!.init?.headers ?? {}) as Record<string, string>;
    expect(headers['Authorization']).toBe('Bearer test-jwt-token');
    expect(headers['Accept']).toBe('text/event-stream');
    source.close();
  });

  it('applies a running SSE frame via the EventSourceLike contract', async () => {
    const frame =
      'data: {"state":"running","serverNowUtc":"2026-07-22T00:00:00.000Z","eventStartUtc":"2026-07-21T00:00:00.000Z","eventEndUtc":"2026-07-28T00:00:00.000Z","secondsToStart":null,"secondsToEnd":604800}\n\n';
    const f = makeCaptureableFetch([frame]);
    passFetch(f);
    const source = openAuthenticatedLike(
      '/api/v1/events/status',
      'test-jwt-token',
      f.fetchMock as unknown as typeof globalThis.fetch,
    );
    const received: any[] = [];
    source.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, 30));
    expect(received.length).toBe(1);
    expect(received[0].state).toBe('running');
    source.close();
  });

  it('omits Authorization header when no token is provided', async () => {
    const f = makeCaptureableFetch([]);
    passFetch(f);
    const source = openAuthenticatedLike(
      '/api/v1/events/status',
      null,
      f.fetchMock as unknown as typeof globalThis.fetch,
    );
    source.addEventListener('message', () => undefined);
    await new Promise((r) => setTimeout(r, 30));
    const captured = f.captured;
    expect(captured).not.toBeNull();
    const headers = (captured!.init?.headers ?? {}) as Record<string, string>;
    expect(headers['Authorization']).toBeUndefined();
    source.close();
  });
});