using OpenCvSharp;
using System;
using System.Collections.Concurrent;
using System.IO;
using System.Threading;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Media.Imaging;

namespace ILSOS_KS.Views.PopUP
{
    public sealed class ImageProcessor
    {
        private static readonly Lazy<ImageProcessor> _instance =
            new Lazy<ImageProcessor>(() => new ImageProcessor());

        public static ImageProcessor Instance => _instance.Value;

        private readonly ConcurrentQueue<(Mat mat, string filePath, int quality)> _saveQueue
            = new ConcurrentQueue<(Mat, string, int)>();

        private readonly int _maxConcurrency = 4;
        private readonly SemaphoreSlim _semaphore;

        private int _totalToSave;
        private int _savedCount;
        private bool _progressVisible;
        private DateTime _lastProgressUpdate = DateTime.MinValue;
        private bool _isWorkerRunning;

        public BitmapSource ImagePreview { get; private set; }
        public bool IsLoading { get; private set; }

        public event Action<double> ProgressChanged; // 0.0 ~ 1.0
        public event Action<bool> ProgressBarVisibilityChanged;

        private ImageProcessor()
        {
            _semaphore = new SemaphoreSlim(_maxConcurrency);
            AsyncLog.I("[ImageProcessor] 초기화 완료");
        }

        public void SaveImageFile(Mat matTop, string filePath = null, int jpegQuality = 95, int maxWidth = 1920, int maxHeight = 1080)
        {
            if (matTop == null || matTop.Empty()) return;

            IsLoading = true;

            string pathToSave = filePath ?? Path.Combine(
                "C:\\Temp",
                $"capture_{DateTime.Now:yyyyMMdd_HHmmssfff}.jpg"
            );

            string directory = Path.GetDirectoryName(pathToSave);
            if (!Directory.Exists(directory))
                Directory.CreateDirectory(directory);

            Mat matToSave = matTop;
            if (matTop.Width > maxWidth || matTop.Height > maxHeight)
            {
                double scale = Math.Min((double)maxWidth / matTop.Width, (double)maxHeight / matTop.Height);
                int newWidth = (int)(matTop.Width * scale);
                int newHeight = (int)(matTop.Height * scale);
                matToSave = new Mat();
                Cv2.Resize(matTop, matToSave, new OpenCvSharp.Size(newWidth, newHeight));
            }

            _saveQueue.Enqueue((matToSave, pathToSave, jpegQuality));
            Interlocked.Increment(ref _totalToSave);

            ShowProgressBar();
            SafeReportProgress();

            if (!_isWorkerRunning)
            {
                _isWorkerRunning = true;
                Task.Run(() => SaveWorkerAsync());
            }
        }

        private async Task SaveWorkerAsync()
        {
            try
            {
                while (!_saveQueue.IsEmpty)
                {
                    if (_saveQueue.TryDequeue(out var item))
                    {
                        try
                        {
                            await _semaphore.WaitAsync();

                            try
                            {
                                Cv2.ImWrite(item.filePath, item.mat,
                                    new ImageEncodingParam(ImwriteFlags.JpegQuality, item.quality));
                                AsyncLog.I($"[저장 완료] {item.filePath} (품질: {item.quality})");
                            }
                            catch (Exception ex)
                            {
                                AsyncLog.I($"[이미지 저장 실패] {item.filePath}", ex);
                            }
                            finally
                            {
                                item.mat?.Dispose();
                                Interlocked.Increment(ref _savedCount);
                                SafeReportProgress();
                                _semaphore.Release();
                            }
                        }
                        catch (Exception ex)
                        {
                            AsyncLog.I("[세마포어 처리 실패]", ex);
                        }
                    }
                    else
                    {
                        await Task.Delay(20);
                    }
                }
            }
            catch (Exception ex)
            {
                AsyncLog.I("[SaveWorkerAsync 전체 실패]", ex);
            }
            finally
            {
                _isWorkerRunning = false;
                _totalToSave = 0;
                _savedCount = 0;
                SafeHideProgressBar();
            }
        }

        private void SafeReportProgress()
        {
            try
            {
                Application.Current.Dispatcher.BeginInvoke(new Action(() =>
                {
                    int total = _totalToSave;
                    int saved = _savedCount;
                    double progress = total > 0 ? Math.Min((double)saved / total, 1.0) : 0.0;

                    if ((DateTime.Now - _lastProgressUpdate).TotalMilliseconds < 50) return;
                    _lastProgressUpdate = DateTime.Now;

                    ProgressChanged?.Invoke(progress);
                }));
            }
            catch (Exception ex)
            {
                AsyncLog.I("[ProgressChanged 호출 실패]", ex);
            }
        }

        private void ShowProgressBar()
        {
            if (_progressVisible) return;

            _progressVisible = true;
            try
            {
                Application.Current.Dispatcher.BeginInvoke(new Action(() =>
                {
                    ProgressBarVisibilityChanged?.Invoke(true);
                }));
            }
            catch (Exception ex)
            {
                AsyncLog.I("[ProgressBar 표시 실패]", ex);
            }
        }

        private void SafeHideProgressBar()
        {
            if (!_progressVisible) return;

            _progressVisible = false;
            try
            {
                Application.Current.Dispatcher.BeginInvoke(new Action(() =>
                {
                    ProgressBarVisibilityChanged?.Invoke(false);
                    IsLoading = false;
                }));
            }
            catch (Exception ex)
            {
                AsyncLog.I("[ProgressBar 숨기기 실패]", ex);
            }
        }
    }

    public static class MatExtensions
    {
        public static BitmapSource ToBitmapSource(this Mat mat)
        {
            try
            {
                if (mat == null || mat.Empty()) return null;
                return OpenCvSharp.WpfExtensions.BitmapSourceConverter.ToBitmapSource(mat);
            }
            catch
            {
                return null;
            }
        }
    }

    public static class BitmapSourceExtensions
    {
        public static byte[] ToJpegBytes(this BitmapSource bitmapSource, int quality = 95)
        {
            if (bitmapSource == null) return null;

            JpegBitmapEncoder encoder = new JpegBitmapEncoder
            {
                QualityLevel = quality
            };
            encoder.Frames.Add(BitmapFrame.Create(bitmapSource));

            using (MemoryStream ms = new MemoryStream())
            {
                encoder.Save(ms);
                return ms.ToArray();
            }
        }

        public static MemoryStream ToJpegStream(this BitmapSource bitmapSource, int quality = 95)
        {
            if (bitmapSource == null) return null;

            JpegBitmapEncoder encoder = new JpegBitmapEncoder
            {
                QualityLevel = quality
            };
            encoder.Frames.Add(BitmapFrame.Create(bitmapSource));

            MemoryStream ms = new MemoryStream();
            encoder.Save(ms);
            ms.Position = 0;
            return ms;
        }
    }
}