export function installWindow() {
  const host = globalThis as { window?: unknown };
  if (host.window === undefined) host.window = globalThis;
}

export async function withFakeTimers(run: (tick: (ms: number) => void) => Promise<void>): Promise<void> {
  const originalSet = globalThis.setTimeout;
  const originalClear = globalThis.clearTimeout;
  const host = globalThis as { window?: unknown };
  const originalWindow = host.window;
  host.window = globalThis;
  let now = 0;
  let sequence = 1;
  const queue = new Map<number, { at: number; fn: () => void }>();
  globalThis.setTimeout = ((fn: TimerHandler, ms?: number) => {
    const id = sequence;
    sequence += 1;
    queue.set(id, {
      at: now + (typeof ms === "number" ? ms : 0),
      fn: () => { if (typeof fn === "function") fn(); },
    });
    return id as unknown as ReturnType<typeof setTimeout>;
  }) as unknown as typeof setTimeout;
  globalThis.clearTimeout = ((id?: ReturnType<typeof setTimeout>) => {
    if (typeof id === "number") queue.delete(id);
  }) as unknown as typeof clearTimeout;
  const tick = (ms: number) => {
    now += ms;
    const due = [...queue.entries()]
      .filter((entry) => entry[1].at <= now)
      .sort((left, right) => left[1].at - right[1].at);
    for (const [id, item] of due) {
      if (!queue.has(id)) continue;
      queue.delete(id);
      item.fn();
    }
  };
  try {
    await run(tick);
  } finally {
    globalThis.setTimeout = originalSet;
    globalThis.clearTimeout = originalClear;
    if (originalWindow === undefined) delete host.window;
    else host.window = originalWindow;
  }
}