using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Globalization;
using System.IO;
using System.Linq;
using System.Security.Policy;
using System.Text;
using System.Text.RegularExpressions;
using System.Threading.Tasks;

namespace ytdlp_gui
{
    public class FFmpegProgressEventArgs : EventArgs
    {
        public FFmpegProgressEventArgs(float progress)
        {
            this.progress = progress;
        }

        public readonly float progress;
    }

    public class FFmpegProcess
    {
        public FFmpegProcess(Process process, string output_file)
        {
            this.process = process;
            this.output_file = output_file;
            ci = (CultureInfo)CultureInfo.CurrentCulture.Clone();
            ci.NumberFormat.CurrencyDecimalSeparator = ".";
        }

        ~FFmpegProcess()
        {
            Cancel();
        }

        public async Task Run()
        {
            if (File.Exists(output_file))
                System.IO.File.Delete(output_file);
            process.Start();

            int duration = 0;
            int progress = 0;
            string line = null;
            while ((line = await process.StandardError.ReadLineAsync()) != null)
            {
                Match match;

                match = header_regex.Match(line);
                if (match.Success)
                {
                    GroupCollection groups = match.Groups;
                    duration =
                          int.Parse(groups[1].Value) * 3600
                        + int.Parse(groups[2].Value) * 60
                        + int.Parse(groups[3].Value);
                }

                match = progress_regex.Match(line);
                if (match.Success)
                {
                    GroupCollection groups = match.Groups;
                    progress =
                          int.Parse(groups[1].Value) * 3600
                        + int.Parse(groups[2].Value) * 60
                        + int.Parse(groups[3].Value);

                    Progress?.Invoke(this, new FFmpegProgressEventArgs(Math.Min((float)progress / duration, 1)));
                }
            }

            if (stop)
                return;

            process.WaitForExit();
            Finished?.Invoke(this, new EventArgs());

            return;
        }

        public void Cancel()
        {
            stop = true;
            if (!process.HasExited)
                process.Kill();
            process.WaitForExit();
        }

        private readonly Process process;
        private readonly string output_file;
        private readonly CultureInfo ci;
        private readonly Regex header_regex = new Regex(@"Duration: (\d+):(\d+):(\d+)\.(\d+)");
        private readonly Regex progress_regex = new Regex(@"time=(\d+):(\d+):(\d+)\.(\d+)");
        private bool stop = false;
        public event EventHandler<FFmpegProgressEventArgs> Progress;
        public event EventHandler Finished;
    }

    public class FFmpeg : Program
    {
        public FFmpeg() : base("ffmpeg")
        {
        }

        public FFmpegProcess Convert(string from, string to)
        {
            Process process = new Process();
            process.StartInfo.FileName = program;
            process.StartInfo.Arguments = String.Format(
                "-i \"{0}\" \"{1}\"",
                from.Replace("\"", "\"\"\""),
                to.Replace("\"", "\"\"\"")
            );

            process.StartInfo.UseShellExecute = false;
            process.StartInfo.CreateNoWindow = true;
            // process.StartInfo.RedirectStandardOutput = true;
            process.StartInfo.RedirectStandardError = true;

            return new FFmpegProcess(process, to);
        }
    }
}