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

namespace SourceGit.Commands {
    public class QueryBranches : Command {
        private static readonly string PREFIX_LOCAL = "refs/heads/";
        private static readonly string PREFIX_REMOTE = "refs/remotes/";
        private static readonly Regex REG_AHEAD_BEHIND = new Regex(@"^(\d+)\s(\d+)$");

        public QueryBranches(string repo) {
            WorkingDirectory = repo;
            Context = repo;
            Args = "branch -l --all -v --format=\"%(refname)$%(objectname)$%(HEAD)$%(upstream)$(upstream:trackshort)\"";
        }

        public List<Models.Branch> Result() {
            Exec();
            return _branches;
        }

        protected override void OnReadline(string line) {
            var parts = line.Split('$');
            if (parts.Length != 5) return;

            var branch = new Models.Branch();
            var refName = parts[0];
            if (refName.EndsWith("/HEAD")) return;

            if (refName.StartsWith(PREFIX_LOCAL, StringComparison.Ordinal)) {
                branch.Name = refName.Substring(PREFIX_LOCAL.Length);
                branch.IsLocal = true;
            } else if (refName.StartsWith(PREFIX_REMOTE, StringComparison.Ordinal)) {
                var name = refName.Substring(PREFIX_REMOTE.Length);
                var shortNameIdx = name.IndexOf('/');
                if (shortNameIdx < 0) return;

                branch.Remote = name.Substring(0, shortNameIdx);
                branch.Name = name.Substring(branch.Remote.Length + 1);
                branch.IsLocal = false;
            } else {
                branch.Name = refName;
                branch.IsLocal = true;
            }

            branch.FullName = refName;
            branch.Head = parts[1];
            branch.IsCurrent = parts[2] == "*";
            branch.Upstream = parts[3];

            if (!string.IsNullOrEmpty(parts[4]) && !parts[4].Equals("=")) {
                branch.UpstreamTrackStatus = ParseTrackStatus(branch.FullName, branch.Upstream);
            }

            _branches.Add(branch);
        }

        private string ParseTrackStatus(string local, string upstream) {
            var cmd = new Command();
            cmd.WorkingDirectory = WorkingDirectory;
            cmd.Context = Context;
            cmd.Args = $"rev-list --left-right --count {local}...{upstream}";

            var rs = cmd.ReadToEnd();
            if (!rs.IsSuccess) return string.Empty;

            var match = REG_AHEAD_BEHIND.Match(rs.StdOut);
            if (!match.Success) return string.Empty;

            var ahead = int.Parse(match.Groups[1].Value);
            var behind = int.Parse(match.Groups[2].Value);
            var track = "";
            if (ahead > 0) track += $"{ahead}↑";
            if (behind > 0) track += $" {behind}↓";
            return track.Trim();
        }

        private List<Models.Branch> _branches = new List<Models.Branch>();
    }
}