import { describe, expect, test } from 'bun:test';
import { OutboundQueue } from '../src/index.js';

/**
 * Regression coverage for the long-poll waiter `since` cursor.
 *
 * The bug being guarded against: when `enqueue` woke a pending
 * `drain` waiter, it used a `since=0` snapshot and replayed every
 * event that had ever been queued — including the ones the waiter
 * had already processed in a previous poll. Downstream the queue
 * fed `Shade.acceptTransferEnvelope`, so the duplicate replay
 * dispatched the same envelope into `manager.decrypt` twice. The
 * second decrypt consumed an already-used skipped key, fell into
 * the stale-counter branch of `ratchetDecrypt`, and corrupted the
 * Double Ratchet receive chain — surfacing as
 * `DecryptionError: wrong key or tampered data` on every
 * subsequent message.
 */
describe('OutboundQueue — waiter since cursor', () => {
  test('mid-poll enqueue must not replay events the waiter already saw', async () => {
    const queue = new OutboundQueue({ idleEvictionMs: 0 });
    const peer = 'alice';
    const e1 = queue.enqueue(peer, { kind: 'envelope', bytes: new Uint8Array([1]) });
    const e2 = queue.enqueue(peer, { kind: 'envelope', bytes: new Uint8Array([2]) });

    // First poll drains both events (no blocking — they're already there).
    const first = await queue.drain(peer, 0, 0);
    expect(first.map((e) => e.id)).toEqual([e1.id, e2.id]);

    // Now the waiter polls past the last seen id. It blocks because
    // there are no events newer than `since`. Concurrently a fresh
    // event gets enqueued — that's the path the bug fired on.
    const blockMs = 5_000;
    const polling = queue.drain(peer, e2.id, blockMs);
    // Yield so `drain` actually parks on the waiter list before we
    // race the enqueue against it.
    await Promise.resolve();
    const e3 = queue.enqueue(peer, { kind: 'envelope', bytes: new Uint8Array([3]) });
    const woken = await polling;

    // Pre-fix: would resolve with [e1, e2, e3] (a `since=0` snapshot
    // drained verbatim). Post-fix: only the events newer than the
    // waiter's recorded `since` come through.
    expect(woken.map((e) => e.id)).toEqual([e3.id]);
  });

  test('parked waiter at the head still gets the new event when others have polled past it', async () => {
    const queue = new OutboundQueue({ idleEvictionMs: 0 });
    const peer = 'alice';
    const e1 = queue.enqueue(peer, { kind: 'envelope', bytes: new Uint8Array([1]) });

    // A waiter that parks past the head — there are no events newer
    // than e1.id, so it has to block.
    const polling = queue.drain(peer, e1.id, 5_000);
    await Promise.resolve();
    const e2 = queue.enqueue(peer, { kind: 'envelope', bytes: new Uint8Array([2]) });
    const woken = await polling;
    expect(woken.map((e) => e.id)).toEqual([e2.id]);
  });
});