using System;
using System.Collections.Generic;
using System.Text;
using System.Text.RegularExpressions;

namespace Nikse.SubtitleEdit.Core.SubtitleFormats
{
    public class Pe2 : SubtitleFormat
    {
        private static readonly Regex RegexTimeCode = new Regex(@"^\d\d:\d\d:\d\d:\d\d ", RegexOptions.Compiled);
        private static readonly Regex RegexTimeCodeEnd = new Regex(@"^\d\d:\d\d:\d\d:\d\d$", RegexOptions.Compiled);

        private enum ExpectingLine
        {
            TimeStart,
            Text,
            TimeEndOrText,
        }

        public override string Extension => ".txt";

        public override string Name => "PE2";

        public override bool IsTimeBased => true;

        public override bool IsMine(List<string> lines, string fileName)
        {
            var sb = new StringBuilder();
            foreach (string line in lines)
                sb.AppendLine(line);
            string s = sb.ToString();
            if (!s.Contains("#PE2"))
                return false; 

            var subtitle = new Subtitle();
            LoadSubtitle(subtitle, lines, fileName);
            return subtitle.Paragraphs.Count > _errorCount;
        }

        public override string ToText(Subtitle subtitle, string title)
        {
            //#PE2 Format file
            //10:00:05:16 You will get a loan of//Rs 1.5 million in 15 minutes.
            //10:00:08:19
            //10:00:09:01 What have you brought//as the guarantee?
            //10:00:12:01
            //10:00:12:11 What?//I didn't get you.
            //10:00:14:11
            //10:00:14:15 We will sanction your loan.
            //10:00:16:00

            const string writeFormat = "{0} {2}{3}{1}";
            var sb = new StringBuilder();
            sb.AppendLine("#PE2 Format file");
            foreach (Paragraph p in subtitle.Paragraphs)
            {
                string text = p.Text.Replace(Environment.NewLine, "//");
                sb.AppendLine(string.Format(writeFormat, EncodeTimeCode(p.StartTime), EncodeTimeCode(p.EndTime), text, Environment.NewLine));
            }
            return sb.ToString().Trim();
        }

        public override void LoadSubtitle(Subtitle subtitle, List<string> lines, string fileName)
        {
            Paragraph paragraph = null;
            var expecting = ExpectingLine.TimeStart;
            _errorCount = 0;

            subtitle.Paragraphs.Clear();
            foreach (string line in lines)
            {
                if (RegexTimeCode.IsMatch(line))
                {
                    string[] parts = line.Substring(0, 11).Split(SplitCharColon, StringSplitOptions.RemoveEmptyEntries);
                    if (parts.Length == 4)
                    {
                        try
                        {
                            var tc = DecodeTimeCodeFramesFourParts(parts);
                            if (paragraph != null)
                            {
                                if (paragraph.EndTime.TotalMilliseconds < 0.001)
                                    paragraph.EndTime.TotalMilliseconds = tc.TotalMilliseconds - Configuration.Settings.General.MinimumMillisecondsBetweenLines;
                                subtitle.Paragraphs.Add(paragraph);
                            }
                            paragraph = new Paragraph { StartTime = tc };
                            expecting = ExpectingLine.Text;
                            if (line.Length > 12)
                                paragraph.Text = line.Substring(12).Trim().Replace("//", Environment.NewLine);
                        }
                        catch
                        {
                            _errorCount++;
                        }
                    }
                }
                else if (RegexTimeCodeEnd.IsMatch(line))
                {
                    string[] parts = line.Substring(0, 11).Split(SplitCharColon, StringSplitOptions.RemoveEmptyEntries);
                    if (parts.Length == 4 && paragraph != null)
                    {
                        var tc = DecodeTimeCodeFramesFourParts(parts);
                        paragraph.EndTime = tc;
                        subtitle.Paragraphs.Add(paragraph);
                        if (paragraph.StartTime.TotalMilliseconds < 0.001)
                            _errorCount++;
                        paragraph = null;
                        expecting = ExpectingLine.TimeStart;
                    }
                }
                else
                {
                    if (expecting == ExpectingLine.Text && paragraph != null)
                    {
                        if (line.Length > 0)
                        {
                            string text = line.Replace("//", Environment.NewLine);
                            paragraph.Text += Environment.NewLine + text;
                            expecting = ExpectingLine.TimeEndOrText;

                            if (paragraph.Text.Length > 2000)
                            {
                                _errorCount += 100;
                                return;
                            }
                        }
                    }
                    else if (!string.IsNullOrWhiteSpace(line) && line != "#PE2 Format file")
                    {
                        _errorCount++;
                    }
                }
            }
            if (!string.IsNullOrEmpty(paragraph?.Text) && paragraph.EndTime.TotalMilliseconds < 0.001)
            {
                paragraph.EndTime.TotalMilliseconds = 3000;
            }
            subtitle.Renumber();
        }

        private static string EncodeTimeCode(TimeCode time)
        {
            return time.ToHHMMSSFF();
        }

    }
}