import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest';
import { pollVisible } from '../../src/lib/ui/poll.js';

let documentStub: EventTarget & { visibilityState: string };
let stop: (() => void) | undefined;
beforeEach(() => {
    vi.useFakeTimers();
    documentStub = Object.assign(new EventTarget(), { visibilityState: 'visible' });
    vi.stubGlobal('document', documentStub);
});
afterEach(() => { stop?.(); stop = undefined; vi.useRealTimers(); vi.unstubAllGlobals(); vi.restoreAllMocks(); });
const visibility = (state: string) => { documentStub.visibilityState = state; documentStub.dispatchEvent(new Event('visibilitychange')); };

describe('visible page polling', () => {
    it('waits for a request to finish before scheduling the next request', async () => {
        let finish!: () => void;
        const task = vi.fn(() => new Promise<void>(resolve => { finish = resolve; }));
        stop = pollVisible(task, 1000);
        await vi.advanceTimersByTimeAsync(5000);
        visibility('visible');
        expect(task).toHaveBeenCalledTimes(1);
        finish(); await vi.advanceTimersByTimeAsync(999);
        expect(task).toHaveBeenCalledTimes(1);
        await vi.advanceTimersByTimeAsync(1);
        expect(task).toHaveBeenCalledTimes(2);
    });
    it('pauses when hidden and refreshes on return, including hiding during a request', async () => {
        let finish!: () => void;
        const task = vi.fn(() => new Promise<void>(resolve => { finish = resolve; }));
        stop = pollVisible(task, 1000);
        visibility('hidden'); finish();
        await vi.advanceTimersByTimeAsync(5000);
        expect(task).toHaveBeenCalledTimes(1);
        visibility('visible');
        expect(task).toHaveBeenCalledTimes(2);
        finish(); stop();
        visibility('visible'); await vi.advanceTimersByTimeAsync(5000);
        expect(task).toHaveBeenCalledTimes(2);
    });
    it('recovers after a failed request and supports a delayed initial refresh', async () => {
        vi.spyOn(console, 'error').mockImplementation(() => {});
        const task = vi.fn().mockRejectedValueOnce(new Error('offline')).mockResolvedValue(undefined);
        stop = pollVisible(task, 1000, false);
        expect(task).not.toHaveBeenCalled();
        await vi.advanceTimersByTimeAsync(2000);
        expect(task).toHaveBeenCalledTimes(2);
    });
});