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 bestCrop = crops.OrderByDescending(kvp => kvp.Value).FirstOrDefault().Key;
            
            return bestCrop ?? string.Empty;
        }
    }
}