using System;
using System.Collections.Concurrent;
using System.Diagnostics;
using System.Linq;
using System.Text.RegularExpressions;
using System.Threading.Tasks;

namespace JellyfinPlugin
{
    public static class CropHelper
    {
        public static async Task<string> DetectCropAsync(string filePath, double limit)
        {
            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;

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