using System;
using System.Text;
using System.Text.RegularExpressions;

namespace SourceGit.Commands
{
    public partial class Blame : Command
    {

        [GeneratedRegex(@"^\^?([0-9a-f]+)\s+.*\((.*)\s+(\d+)\s+[\-\+]?\d+\s+\d+\) (.*)")]
        private static partial Regex REG_FORMAT();
        private static readonly DateTime UTC_START = new DateTime(1970, 1, 1, 0, 0, 0, DateTimeKind.Utc).ToLocalTime();

        public Blame(string repo, string file, string revision)
        {
            WorkingDirectory = repo;
            Context = repo;
            Args = $"blame -t {revision} -- \"{file}\"";
            RaiseError = false;

            _result.File = file;
        }

        public Models.BlameData Result()
        {
            var succ = Exec();
            if (!succ)
            {
                return new Models.BlameData();
            }

            if (_needUnifyCommitSHA)
            {
                foreach (var line in _result.LineInfos)
                {
                    if (line.CommitSHA.Length > _minSHALen)
                    {
                        line.CommitSHA = line.CommitSHA.Substring(0, _minSHALen);
                    }
                }
            }

            _result.Content = _content.ToString();
            return _result;
        }

        protected override void OnReadline(string line)
        {
            if (_result.IsBinary)
                return;
            if (string.IsNullOrEmpty(line))
                return;

            if (line.IndexOf('\0', StringComparison.Ordinal) >= 0)
            {
                _result.IsBinary = true;
                _result.LineInfos.Clear();
                return;
            }

            var match = REG_FORMAT().Match(line);
            if (!match.Success)
                return;

            _content.AppendLine(match.Groups[4].Value);

            var commit = match.Groups[1].Value;
            var author = match.Groups[2].Value;
            var timestamp = int.Parse(match.Groups[3].Value);
            var when = UTC_START.AddSeconds(timestamp).ToString("yyyy/MM/dd");

            var info = new Models.BlameLineInfo()
            {
                IsFirstInGroup = commit != _lastSHA,
                CommitSHA = commit,
                Author = author,
                Time = when,
            };

            _result.LineInfos.Add(info);
            _lastSHA = commit;

            if (line[0] == '^')
            {
                _needUnifyCommitSHA = true;
                _minSHALen = Math.Min(_minSHALen, commit.Length);
            }
        }

        private readonly Models.BlameData _result = new Models.BlameData();
        private readonly StringBuilder _content = new StringBuilder();
        private string _lastSHA = string.Empty;
        private bool _needUnifyCommitSHA = false;
        private int _minSHALen = 64;
    }
}
