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

import {
  HeaderStash,
  normalizeHeaders,
  type OnBeforeSendHeadersDetails,
  type WebRequestLike,
} from '../../src/background/capture/headers.js';

function details(over: Partial<OnBeforeSendHeadersDetails> = {}): OnBeforeSendHeadersDetails {
  return {
    requestId: '1',
    url: 'https://cdn.example.com/big.zip',
    method: 'GET',
    tabId: 7,
    requestHeaders: [
      { name: 'User-Agent', value: 'Firefox' },
      { name: 'Referer', value: 'https://example.com/page' },
      { name: 'Cookie', value: 'sid=abc' },
    ],
    ...over,
  };
}

describe('normalizeHeaders', () => {
  it('lower-cases names and drops valueless entries', () => {
    expect(
      normalizeHeaders([
        { name: 'Accept-Encoding', value: 'gzip' },
        { name: 'X-Empty' },
      ]),
    ).toEqual({ 'accept-encoding': 'gzip' });
  });

  it('joins repeated header names with ", "', () => {
    expect(
      normalizeHeaders([
        { name: 'X-Fwd', value: 'a' },
        { name: 'x-fwd', value: 'b' },
      ]),
    ).toEqual({ 'x-fwd': 'a, b' });
  });

  it('returns {} for missing headers', () => {
    expect(normalizeHeaders(undefined)).toEqual({});
  });
});

describe('HeaderStash', () => {
  let now = 1_000_000;
  const clock = () => now;

  afterEach(() => {
    now = 1_000_000;
  });

  it('stashes and reads back normalized headers', () => {
    const s = new HeaderStash({ now: clock, sweepIntervalMs: 0 });
    s.put(details());
    const got = s.peek('1');
    expect(got).toMatchObject({
      requestId: '1',
      method: 'GET',
      tabId: 7,
      headers: { 'user-agent': 'Firefox', referer: 'https://example.com/page', cookie: 'sid=abc' },
    });
  });

  it('take() reads once then the entry is gone', () => {
    const s = new HeaderStash({ now: clock, sweepIntervalMs: 0 });
    s.put(details());
    expect(s.take('1')).toBeDefined();
    expect(s.take('1')).toBeUndefined();
    expect(s.size).toBe(0);
  });

  it('evicts the oldest entry past the size cap', () => {
    const s = new HeaderStash({ now: clock, maxEntries: 2, sweepIntervalMs: 0 });
    s.put(details({ requestId: 'a' }));
    s.put(details({ requestId: 'b' }));
    s.put(details({ requestId: 'c' }));
    expect(s.size).toBe(2);
    expect(s.peek('a')).toBeUndefined();
    expect(s.peek('b')).toBeDefined();
    expect(s.peek('c')).toBeDefined();
  });

  it('re-putting a requestId refreshes its recency and TTL (redirect case)', () => {
    const s = new HeaderStash({ now: clock, maxEntries: 2, ttlMs: 1000, sweepIntervalMs: 0 });
    s.put(details({ requestId: 'a' }));
    now += 10;
    s.put(details({ requestId: 'b' }));
    now += 10;
    s.put(details({ requestId: 'a', url: 'https://cdn.example.com/redirected.zip' })); // a moves to newest
    s.put(details({ requestId: 'c' })); // evicts the now-oldest, which is b
    expect(s.peek('b')).toBeUndefined();
    expect(s.peek('a')?.url).toBe('https://cdn.example.com/redirected.zip');
    now += 995; // < 1000 since the re-put of a
    expect(s.peek('a')).toBeDefined();
  });

  it('treats an entry past its TTL as absent and deletes it on read', () => {
    const s = new HeaderStash({ now: clock, ttlMs: 5 * 60_000, sweepIntervalMs: 0 });
    s.put(details());
    now += 5 * 60_000 + 1;
    expect(s.peek('1')).toBeUndefined();
    expect(s.size).toBe(0);
  });

  it('sweep() drops expired entries and keeps fresh ones', () => {
    const s = new HeaderStash({ now: clock, ttlMs: 1000, sweepIntervalMs: 0 });
    s.put(details({ requestId: 'old1' }));
    s.put(details({ requestId: 'old2' }));
    now += 1001;
    s.put(details({ requestId: 'fresh' }));
    expect(s.sweep()).toBe(2);
    expect(s.size).toBe(1);
    expect(s.peek('fresh')).toBeDefined();
  });

  it('drop() forgets one request', () => {
    const s = new HeaderStash({ now: clock, sweepIntervalMs: 0 });
    s.put(details({ requestId: 'x' }));
    s.drop('x');
    expect(s.peek('x')).toBeUndefined();
  });
});

// --- attach() wiring ---------------------------------------------------------------

class FakeEvent<L extends (...a: never[]) => void> {
  listeners: L[] = [];
  addListener = (l: L): void => void this.listeners.push(l);
  removeListener = (l: L): void => {
    this.listeners = this.listeners.filter((x) => x !== l);
  };
  emit(...args: Parameters<L>): void {
    for (const l of this.listeners) (l as (...a: Parameters<L>) => void)(...args);
  }
}

function fakeWebRequest() {
  return {
    onBeforeSendHeaders: new FakeEvent<(d: OnBeforeSendHeadersDetails) => void>(),
    onCompleted: new FakeEvent<(d: { requestId: string }) => void>(),
    onErrorOccurred: new FakeEvent<(d: { requestId: string }) => void>(),
  };
}

describe('HeaderStash.attach', () => {
  it('stashes on onBeforeSendHeaders and forgets on onCompleted / onErrorOccurred', () => {
    const wr = fakeWebRequest();
    const s = new HeaderStash({ sweepIntervalMs: 0 });
    s.attach(wr as unknown as WebRequestLike);

    wr.onBeforeSendHeaders.emit(details({ requestId: 'done' }));
    wr.onBeforeSendHeaders.emit(details({ requestId: 'failed' }));
    expect(s.size).toBe(2);

    wr.onCompleted.emit({ requestId: 'done' });
    wr.onErrorOccurred.emit({ requestId: 'failed' });
    expect(s.size).toBe(0);

    s.detach();
    wr.onBeforeSendHeaders.emit(details({ requestId: 'after-detach' }));
    expect(s.size).toBe(0);
    expect(wr.onBeforeSendHeaders.listeners).toHaveLength(0);
  });

  it('runs a background sweep on its interval', () => {
    vi.useFakeTimers();
    let t = 0;
    const s = new HeaderStash({ now: () => t, ttlMs: 1000, sweepIntervalMs: 500 });
    const wr = fakeWebRequest();
    s.attach(wr as unknown as WebRequestLike);
    wr.onBeforeSendHeaders.emit(details({ requestId: 'a' }));

    t = 2000;
    vi.advanceTimersByTime(500);
    expect(s.size).toBe(0);

    s.detach();
    vi.useRealTimers();
  });

  it('refuses a double attach', () => {
    const s = new HeaderStash({ sweepIntervalMs: 0 });
    const wr = fakeWebRequest();
    s.attach(wr as unknown as WebRequestLike);
    expect(() => s.attach(wr as unknown as WebRequestLike)).toThrow(/already attached/);
    s.detach();
  });
});