using System;

using System.Collections.Generic;

using System.IO;

using System.Linq;

using System.Text;

using System.Text.RegularExpressions;

​

namespace FfmpegChapterTool

{

    class Program

    {

        // Config

        static readonly TimeSpan _videoLength = new TimeSpan(0, 6, 0);

        static readonly string _example = @"

00:00:00 - Intro

00:02:30 - The Middle

00:04:45 - Outro

";

​

        static readonly Regex _regex = new Regex(@"((\d{2}):(\d{2}):(\d{2}))\s+-\s+(.*)", RegexOptions.Compiled);

​

        record ParsedLine(string Title, TimeSpan Timestamp, string RawTimeStampValue);

​

        static bool TryParseLine(string input, out ParsedLine result)

        {

            var match = _regex.Match(input);

​

            result = null;

​

            if (!match.Success || match.Groups.Count < 5)

            {

                return false;

            }

​

            var title = match.Groups[5].Value;

            var rawTimeStampValue = match.Groups[1].Value;

​

            if (!TimeSpan.TryParse(rawTimeStampValue, out TimeSpan parsedTimestamp))

            {

                return false;

            }

​

            result = new ParsedLine(title, parsedTimestamp, rawTimeStampValue);

​

            return true;

        }

​

        static IEnumerable<ParsedLine> ReadFile(string path)

        {

            var fileStream = File.OpenRead(path);

​

            return ReadStream(fileStream);

        }

​

        static IEnumerable<ParsedLine> ReadString(string raw, Encoding encoding)

        {

            var memoryStream = new MemoryStream(encoding.GetBytes(raw ?? string.Empty));

​

            return ReadStream(memoryStream);

        }

​

        static IEnumerable<ParsedLine> ReadStream(Stream stream)

        {

            using var streamReader = new StreamReader(stream);

            string line = string.Empty;

​

            while ((line = streamReader.ReadLine()) != null)

            {

                if (TryParseLine(line, out ParsedLine result))

                {

                    yield return result;

                }

            }

        }

​

        static string GetChapter(int chapterNum, ParsedLine parsedLine, ParsedLine ParsedLineNext) => $@"# Chapter {chapterNum} - {parsedLine.Title}

[CHAPTER]

TIMEBASE=1/1000

# Chapter {chapterNum} starts at {parsedLine.RawTimeStampValue}

START={parsedLine.Timestamp.TotalSeconds * 1000}

# Chapter {chapterNum} ends at {ParsedLineNext.RawTimeStampValue}

END={ParsedLineNext.Timestamp.TotalSeconds * 1000 - 1}

title={parsedLine.Title}

";

​

        static void Main(string[] args)

        {

            // var results = ReadFile("test.md").ToList();

            var results = ReadString(_example, Encoding.UTF8).ToList();            

​

            for (int i = 0; i < results.Count - 1; i++)

            {

                var line = GetChapter(i + 1, results[i], results[i + 1]);

​

                Console.WriteLine(line);

            }

​

            var finalLine = GetChapter(results.Count, results.Last(), new ParsedLine("End", _videoLength, _videoLength.ToString()));

​

            Console.WriteLine(finalLine);

        }

    }

}