using System;
using System.Collections.Concurrent;
using System.Diagnostics;
using System.IO;
using System.Linq;
using System.Text.RegularExpressions;
using System.Threading;
using System.Threading.Tasks;
using MediaBrowser.Controller.Entities;
using MediaBrowser.Controller.Entities.Movies;
using MediaBrowser.Controller.Entities.TV;
using MediaBrowser.Controller.Library;
using MediaBrowser.Controller.Plugins;
using Microsoft.Extensions.Logging;

using Microsoft.Extensions.Hosting;

namespace JellyfinPlugin
{
    public class LibraryMonitor : IHostedService, IDisposable
    {
        private readonly ILibraryManager _libraryManager;
        private readonly ILogger<LibraryMonitor> _logger;
        private readonly SemaphoreSlim _ffmpegSemaphore = new SemaphoreSlim(2, 2);

        public LibraryMonitor(ILibraryManager libraryManager, ILogger<LibraryMonitor> logger)
        {
            _libraryManager = libraryManager;
            _logger = logger;
        }

        public Task StartAsync(CancellationToken cancellationToken)
        {
            _libraryManager.ItemAdded += OnItemAddedOrUpdated;
            _libraryManager.ItemUpdated += OnItemAddedOrUpdated;
            return Task.CompletedTask;
        }

        public Task StopAsync(CancellationToken cancellationToken)
        {
            return Task.CompletedTask;
        }


        private void OnItemAddedOrUpdated(object? sender, ItemChangeEventArgs e)
        {
            if (e.Item is Video video && (video is Movie || video is Episode))
            {
                if (!Plugin.Instance!.Configuration.IsEnabled) return;

                // Fire and forget, don't block library scan
                _ = Task.Run(() => ProcessVideoAsync(video));
            }
        }

        private async Task ProcessVideoAsync(Video video)
        {
            try
            {
                if (video.ProviderIds != null && video.ProviderIds.ContainsKey("BlackBarCrop"))
                {
                    return;
                }

                var path = video.Path;
                if (string.IsNullOrEmpty(path) || !File.Exists(path)) return;

                await _ffmpegSemaphore.WaitAsync();
                try
                {
                    string cropData = await DetectCropAsync(path);
                    if (!string.IsNullOrEmpty(cropData))
                    {
                        if (video.ProviderIds == null)
                        {
                            video.ProviderIds = new System.Collections.Generic.Dictionary<string, string>();
                        }
                        video.ProviderIds["BlackBarCrop"] = cropData;
                        // Jellyfin 12.0 signature requires passing item, item, type, cancellationToken
                        await _libraryManager.UpdateItemAsync(video, video, ItemUpdateType.MetadataEdit, CancellationToken.None);
                        _logger.LogInformation("Zapisano proporcje crop {CropData} dla pliku {Path}", cropData, path);
                    }
                }
                finally
                {
                    _ffmpegSemaphore.Release();
                }
            }
            catch (Exception ex)
            {
                _logger.LogError(ex, "Błąd podczas procesowania wideo: {Path}", video.Path);
            }
        }

        private async Task<string> DetectCropAsync(string filePath)
        {
            var config = Plugin.Instance!.Configuration;
            double limit = config.CropDetectLimit;
            string limitStr = limit.ToString(System.Globalization.CultureInfo.InvariantCulture);

            var startInfo = new ProcessStartInfo
            {
                FileName = "ffmpeg", 
                Arguments = $"-skip_frame nokey -i \"{filePath}\" -vf \"cropdetect=limit={limitStr}:round=16:reset=0\" -f null -",
                RedirectStandardError = true,
                RedirectStandardOutput = true,
                UseShellExecute = false,
                CreateNoWindow = true
            };

            using var process = new Process { StartInfo = startInfo };
            process.Start();

            string output = await process.StandardError.ReadToEndAsync();
            await process.WaitForExitAsync();

            var regex = new Regex(@"crop=([0-9]+):([0-9]+):([0-9]+):([0-9]+)");
            var matches = regex.Matches(output);
            
            var crops = new ConcurrentDictionary<string, int>();
            int totalFrames = 0;

            foreach (Match match in matches)
            {
                string cropStr = match.Value.Replace("crop=", "");
                crops.AddOrUpdate(cropStr, 1, (_, count) => count + 1);
                totalFrames++;
            }

            if (totalFrames == 0) return string.Empty;

            var validCrops = crops.Where(kvp => (double)kvp.Value / totalFrames > 0.05).ToList();
            if (!validCrops.Any())
            {
                validCrops = crops.OrderByDescending(kvp => kvp.Value).Take(1).ToList();
            }

            int minX = int.MaxValue, minY = int.MaxValue, maxXW = 0, maxYH = 0;

            foreach (var kvp in validCrops)
            {
                var parts = kvp.Key.Split(':');
                if (parts.Length == 4 && 
                    int.TryParse(parts[0], out int w) && int.TryParse(parts[1], out int h) &&
                    int.TryParse(parts[2], out int x) && int.TryParse(parts[3], out int y))
                {
                    minX = Math.Min(minX, x);
                    minY = Math.Min(minY, y);
                    maxXW = Math.Max(maxXW, x + w);
                    maxYH = Math.Max(maxYH, y + h);
                }
            }

            int finalW = maxXW - minX;
            int finalH = maxYH - minY;

            if (finalW <= 0 || finalH <= 0) return string.Empty;

            // Sprawdzanie czy faktycznie coś wycięto w pionie lub poziomie.
            // Zazwyczaj filmy 1080p mają h=1080. 
            // Możemy zwrócić pusty string, jeśli ucięcie jest minimalne (np. mniej niż 10 px z każdej strony).
            // To zapobiega wymuszaniu transkodowania z byle powodu.

            return $"{finalW}:{finalH}:{minX}:{minY}";
        }

        public void Dispose()
        {
            _libraryManager.ItemAdded -= OnItemAddedOrUpdated;
            _libraryManager.ItemUpdated -= OnItemAddedOrUpdated;
            _ffmpegSemaphore.Dispose();
        }
    }
}