using System.Windows.Threading;

namespace VideoDownloader.Tests.Infrastructure;

/// <summary>
/// WPF/WebView2 E2E 테스트용 STA 디스패처. 전용 STA 스레드에서 Dispatcher.Run() 으로
/// 메시지 펌프를 돌리며, 테스트 코드는 InvokeAsync 로 UI 스레드에 작업을 올린다.
/// WebView2 이벤트(비동기)는 UI 스레드 디스패처에서 발생하므로 async 흐름도 이 펌프 위에서 완결된다.
/// </summary>
public sealed class StaDispatcher : IDisposable
{
    private readonly Thread _thread;
    private readonly TaskCompletionSource _ready = new(TaskCreationOptions.RunContinuationsAsynchronously);
    private Dispatcher? _dispatcher;

    private StaDispatcher(Thread thread)
    {
        _thread = thread;
    }

    public Dispatcher Dispatcher =>
        _dispatcher ?? throw new InvalidOperationException("STA dispatcher not started");

    public static StaDispatcher Start()
    {
        var sta = default(StaDispatcher)!;
        var thread = new Thread(() =>
        {
            sta._dispatcher = Dispatcher.CurrentDispatcher;
            sta._ready.TrySetResult();
            Dispatcher.Run();
        });
        thread.SetApartmentState(ApartmentState.STA);
        thread.IsBackground = true;
        sta = new StaDispatcher(thread);
        thread.Start();
        sta._ready.Task.Wait(5000);
        return sta;
    }

    public Task<T> InvokeAsync<T>(Func<Task<T>> func)
        => Dispatcher.InvokeAsync(func).Task.Unwrap();

    public Task InvokeAsync(Func<Task> func)
        => Dispatcher.InvokeAsync(func).Task.Unwrap();

    public T Invoke<T>(Func<T> func) => Dispatcher.Invoke(func);

    public void Invoke(Action action) => Dispatcher.Invoke(action);

    public void Dispose()
    {
        try { Dispatcher.InvokeShutdown(); } catch { }
        try { _thread.Join(5000); } catch { }
    }
}

/// <summary>WebView2 비동기 초기화/이벤트 대기 공통 유틸.</summary>
public static class Wait
{
    public static async Task<T> Until<T>(Func<Task<T>> poll, Func<T, bool> done, int timeoutMs = 15000, int intervalMs = 100)
    {
        var sw = System.Diagnostics.Stopwatch.StartNew();
        while (sw.ElapsedMilliseconds < timeoutMs)
        {
            var v = await poll();
            if (done(v)) return v;
            await Task.Delay(intervalMs);
        }
        throw new TimeoutException($"조건 미충족 ({timeoutMs}ms 초과)");
    }
}