using System;
using System.IO;
using System.Threading;
using System.Threading.Tasks;
using System.Windows.Media.Imaging;
using LibVLCSharp.Shared;

public static class VideoFrameExtractor
{
    public static BitmapImage GetFrame200(string videoPath)
    {
        Core.Initialize();
        using var libVLC = new LibVLC("--no-xlib");
        using var media = new Media(libVLC, videoPath, FromType.FromPath);
        using var mp = new MediaPlayer(media);

        mp.Play();

        while (!mp.IsPlaying)
            Thread.Sleep(10);

        // Seek to ~200th frame at 30 fps
        mp.Time = (long)((200.0 / 30.0) * 1000);
        Thread.Sleep(500);

        if (!mp.IsPlaying)
            mp.Play();

        Thread.Sleep(1000);

        string path = Path.GetTempFileName() + ".png";

        if (!mp.TakeSnapshot(0, path, 0, 0))
            throw new Exception("Snapshot failed.");

        // Wait for snapshot file to be fully written and valid
        int attempts = 10;
        while (attempts-- > 0)
        {
            if (File.Exists(path) && new FileInfo(path).Length > 0)
                break;
            Thread.Sleep(100);
        }

        if (!File.Exists(path))
            throw new FileNotFoundException("Snapshot file not found", path);

        var fileInfo = new FileInfo(path);
        if (fileInfo.Length == 0)
            throw new Exception("Snapshot file is empty or corrupted.");

        BitmapImage image = null;

        try
        {
            using (var fs = new FileStream(path, FileMode.Open, FileAccess.Read, FileShare.Read))
            {
                if (fs == null)
                    throw new Exception("FileStream is null.");

                image = new BitmapImage();

                image.BeginInit();
                image.CacheOption = BitmapCacheOption.OnLoad;
                // Removed CreateOptions.IgnoreImageCache here to avoid ArgumentNullException
                image.StreamSource = fs ?? throw new Exception("StreamSource cannot be null.");
                fs.Position = 0;
                image.EndInit();
                image.Freeze();
            }
        }
        catch (Exception ex)
        {
            Console.WriteLine($"Error loading snapshot image from {path}: {ex}");
            throw new Exception("Failed to load snapshot image.", ex);
        }

        // Async delayed delete of temp snapshot file (after 1 minute)
        DeleteFileLaterAsync(path);

        return image!;
    }

    private static async void DeleteFileLaterAsync(string path, int delayMs = 60000)
    {
        try
        {
            await Task.Delay(delayMs);
            File.Delete(path);
        }
        catch (Exception ex)
        {
            Console.WriteLine($"[WARNING] Failed to delete temp snapshot file {path}: {ex.Message}");
        }
    }
}