using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Diagnostics;
using System.IO;
using System.Linq;
using System.Text.RegularExpressions;
using NDesk.Options;
using Sep.Git.Tfs.Core;
using Sep.Git.Tfs.Util;
using StructureMap;

namespace Sep.Git.Tfs.Commands
{
    [Pluggable("fetch")]
    [Description("fetch [options] [tfs-remote-id]...")]
    [RequiresValidGitRepository]
    public class Fetch : GitTfsCommand
    {
        private readonly RemoteOptions remoteOptions;
        private readonly Globals globals;
        private readonly AuthorsFile authors;
        private readonly Labels labels;

        public Fetch(Globals globals, RemoteOptions remoteOptions, AuthorsFile authors, Labels labels)
        {
            this.remoteOptions = remoteOptions;
            this.globals = globals;
            this.authors = authors;
            this.labels = labels;
        }

//        public int? RevisionToFetch { get; set; }

        bool FetchAll { get; set; }
        bool FetchLabels { get; set; }
        bool FetchParents { get; set; }
        string AuthorsFilePath { get; set; }
        string BareBranch { get; set; }
        bool ForceFetchBare { get; set; }

        public virtual OptionSet OptionSet
        {
            get
            {
                return new OptionSet
                {
                    { "all|fetch-all",
                        v => FetchAll = v != null },
                    { "parents",
                        v => FetchParents = v != null },
                    { "authors=", "Path to an Authors file to map TFS users to Git users",
                        v => AuthorsFilePath = v },
                    { "l|with-labels|fetch-labels", "Fetch the labels also when fetching TFS changesets",
                        v => FetchLabels = v != null },
                    { "b|bare-branch=", "The name of the branch on which the fetch will be done for a bare repository",
                        v => BareBranch = v },
                    { "force", "Force fetch of tfs changesets when there is ahead commits (ahead commits will be lost!)",
                        v => ForceFetchBare = v != null },
//                    { "r|revision=",
//                        v => RevisionToFetch = Convert.ToInt32(v) },
                }.Merge(remoteOptions.OptionSet);
            }
        }

        public int Run()
        {
            return Run(globals.RemoteId);
        }

        public int Run(params string[] args)
        {
            authors.Parse(AuthorsFilePath, globals.GitDir);

            foreach (var remote in GetRemotesToFetch(args))
            {
                Trace.WriteLine("Fetching from TFS remote " + remote.Id);
                DoFetch(remote);
                if (labels != null && FetchLabels)
                {
                    Trace.WriteLine("Fetching labels from TFS remote " + remote.Id);
                    labels.Run(remote);
                }
            }
            return 0;
        }

        protected virtual void DoFetch(IGitTfsRemote remote)
        {
            if (remote.Repository.IsBare)
            {
                if(string.IsNullOrEmpty(BareBranch))
                    throw new GitTfsException("error : specify a git branch to fetch on...");
                if (!remote.Repository.HasRef(GitRepository.ShortToLocalName(BareBranch)))
                    throw new GitTfsException("error : the specified git branch doesn't exist...");
                if (!ForceFetchBare && remote.MaxCommitHash != remote.Repository.GetCommit(BareBranch).Sha)
                    throw new GitTfsException("error : fetch is not allowed when there is ahead commits!",
                        new List<string>() {"Remove ahead commits and retry", "use the --force option (ahead commits will be lost!)"});
            }

            // It is possible that we have outdated refs/remotes/tfs/<id>.
            // E.g. someone already fetched changesets from TFS into another git repository and we've pulled it since
            // in that case tfs fetch will retrieve same changes again unnecessarily. To prevent it we will scan tree from HEAD and see if newer changesets from
            // TFS exists (by checking git-tfs-id mark in commit's comments).
            // The process is similar to bootstrapping.
            globals.Repository.MoveTfsRefForwardIfNeeded(remote);

            remote.Fetch();

            if(remote.Repository.IsBare)
                remote.Repository.UpdateRef(GitRepository.ShortToLocalName(BareBranch), remote.MaxCommitHash);
        }

        private IEnumerable<IGitTfsRemote> GetRemotesToFetch(IList<string> args)
        {
            IEnumerable<IGitTfsRemote> remotesToFetch;
            if (FetchParents)
                remotesToFetch = globals.Repository.GetLastParentTfsCommits("HEAD").Select(commit => commit.Remote);
            else if (FetchAll)
                remotesToFetch = globals.Repository.ReadAllTfsRemotes();
            else
                remotesToFetch = args.Select(arg => globals.Repository.ReadTfsRemote(arg));
            return remotesToFetch;
        }
    }
}