using System;
using System.Collections.Generic;
using System.Linq;

namespace SourceGit.Commands {

    /// <summary>
    ///     取得提交列表
    /// </summary>
    public class Commits : Command {
        private static readonly string GPGSIG_START = "gpgsig -----BEGIN PGP SIGNATURE-----";
        private static readonly string GPGSIG_END = " -----END PGP SIGNATURE-----";

        private List<Models.Commit> commits = new List<Models.Commit>();
        private Models.Commit current = null;
        private bool isSkipingGpgsig = false;
        private bool isHeadFounded = false;
        private bool findFirstMerged = true;

        public Commits(string path, string limits, bool needFindHead = true) {
            Cwd = path;
            Args = "log --date-order --decorate=full --pretty=raw " + limits;
            findFirstMerged = needFindHead;
        }

        public List<Models.Commit> Result() {
            Exec();

            if (current != null) {
                current.Message = current.Message.Trim();
                commits.Add(current);
            }

            if (findFirstMerged && !isHeadFounded && commits.Count > 0) {
                MarkFirstMerged();
            }

            return commits;
        }

        public override void OnReadline(string line) {
            if (isSkipingGpgsig) {
                if (line.StartsWith(GPGSIG_END, StringComparison.Ordinal)) isSkipingGpgsig = false;
                return;
            } else if (line.StartsWith(GPGSIG_START, StringComparison.Ordinal)) {
                isSkipingGpgsig = true;
                return;
            }

            if (line.StartsWith("commit ", StringComparison.Ordinal)) {
                if (current != null) {
                    current.Message = current.Message.Trim();
                    commits.Add(current);
                }

                current = new Models.Commit();
                line = line.Substring(7);

                var decoratorStart = line.IndexOf('(');
                if (decoratorStart < 0) {
                    current.SHA = line.Trim();
                } else {
                    current.SHA = line.Substring(0, decoratorStart).Trim();
                    current.IsMerged = ParseDecorators(current.Decorators, line.Substring(decoratorStart + 1));
                    if (!isHeadFounded) isHeadFounded = current.IsMerged;
                }

                return;
            }

            if (current == null) return;

            if (line.StartsWith("tree ", StringComparison.Ordinal)) {
                return;
            } else if (line.StartsWith("parent ", StringComparison.Ordinal)) {
                current.Parents.Add(line.Substring("parent ".Length));
            } else if (line.StartsWith("author ", StringComparison.Ordinal)) {
                current.Author.Parse(line);
            } else if (line.StartsWith("committer ", StringComparison.Ordinal)) {
                current.Committer.Parse(line);
            } else if (string.IsNullOrEmpty(current.Subject)) {
                current.Subject = line.Trim();
            } else {
                current.Message += (line.Trim() + "\n");
            }
        }

        private bool ParseDecorators(List<Models.Decorator> decorators, string data) {
            bool isHeadOfCurrent = false;

            var subs = data.Split(new char[] { ',', ')', '(' }, StringSplitOptions.RemoveEmptyEntries);
            foreach (var sub in subs) {
                var d = sub.Trim();
                if (d.StartsWith("tag: refs/tags/", StringComparison.Ordinal)) {
                    decorators.Add(new Models.Decorator() {
                        Type = Models.DecoratorType.Tag,
                        Name = d.Substring(15).Trim(),
                    });
                } else if (d.EndsWith("/HEAD", StringComparison.Ordinal)) {
                    continue;
                } else if (d.StartsWith("HEAD -> refs/heads/", StringComparison.Ordinal)) {
                    isHeadOfCurrent = true;
                    decorators.Add(new Models.Decorator() {
                        Type = Models.DecoratorType.CurrentBranchHead,
                        Name = d.Substring(19).Trim(),
                    });
                } else if (d.StartsWith("refs/heads/", StringComparison.Ordinal)) {
                    decorators.Add(new Models.Decorator() {
                        Type = Models.DecoratorType.LocalBranchHead,
                        Name = d.Substring(11).Trim(),
                    });
                } else if (d.StartsWith("refs/remotes/", StringComparison.Ordinal)) {
                    decorators.Add(new Models.Decorator() {
                        Type = Models.DecoratorType.RemoteBranchHead,
                        Name = d.Substring(13).Trim(),
                    });
                }
            }

            return isHeadOfCurrent;
        }

        private void MarkFirstMerged() {
            Args = $"log --since=\"{commits.Last().Committer.Time}\" --min-parents=2 --format=\"%H\"";

            var rs = ReadToEnd();
            var shas = rs.Output.Split(new char[] { '\n' }, StringSplitOptions.RemoveEmptyEntries);
            if (shas.Length == 0) return;

            var merges = commits.Where(x => x.Parents.Count > 1).ToList();
            foreach (var sha in shas) {
                var c = merges.Find(x => x.SHA == sha);
                if (c != null) {
                    c.IsMerged = true;
                    return;
                }
            }
        }
    }
}