using CG.Web.MegaApiClient;
using Compression.BSA;
using SevenZipExtractor;
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Net.Http;
using System.Reflection;
using System.Text;
using System.Text.RegularExpressions;
using System.Threading.Tasks;
using Wabbajack.Common;

namespace Wabbajack
{
    public class Installer
    {
        public Installer(ModList mod_list, string output_folder, Action<string> log_fn)
        {
            Outputfolder = output_folder;
            ModList = mod_list;
            Log_Fn = log_fn;
        }

        public string Outputfolder { get; }
        public string DownloadFolder
        {
            get
            {
                return Path.Combine(Outputfolder, "downloads");
            }
        }
        public ModList ModList { get; }
        public Action<string> Log_Fn { get; }
        public Dictionary<string, string> HashedArchives { get; private set; }

        public string NexusAPIKey { get; private set; }

        public void Info(string msg, params object[] args)
        {
            if (args.Length > 0)
                msg = String.Format(msg, args);
            Log_Fn(msg);
        }

        public void Status(string msg, params object[] args)
        {
            if (args.Length > 0)
                msg = String.Format(msg, args);
            WorkQueue.Report(msg, 0);
        }

        public void Status(int progress, string msg, params object[] args)
        {
            if (args.Length > 0)
                msg = String.Format(msg, args);
            WorkQueue.Report(msg, progress);
        }
        private void Error(string msg, params object[] args)
        {
            if (args.Length > 0)
                msg = String.Format(msg, args);
            Log_Fn(msg);
            throw new Exception(msg);
        }

        public void Install()
        {
            Directory.CreateDirectory(Outputfolder);
            Directory.CreateDirectory(DownloadFolder);

            HashArchives();
            DownloadArchives();
            HashArchives();

            var missing = ModList.Archives.Where(a => !HashedArchives.ContainsKey(a.Hash)).ToList();
            if (missing.Count > 0)
            {
                foreach (var a in missing)
                    Info("Unable to download {0}", a.Name);
                Error("Cannot continue, was unable to download one or more archives");
            }
            BuildFolderStructure();
            InstallArchives();
            InstallIncludedFiles();
            BuildBSAs();

            Info("Installation complete! You may exit the program.");
        }

        private void BuildBSAs()
        {
            var bsas = ModList.Directives.OfType<CreateBSA>().ToList();
            Info($"Building {bsas.Count} bsa files");

            bsas.Do(bsa =>
            {
                Status($"Building {bsa.To}");
                var source_dir = Path.Combine(Outputfolder, Consts.BSACreationDir, bsa.TempID);
                var source_files = Directory.EnumerateFiles(source_dir, "*", SearchOption.AllDirectories)
                                            .Select(e => e.Substring(source_dir.Length + 1))
                                            .ToList();

                using (var a = new BSABuilder())
                {

                    //a.Create(Path.Combine(Outputfolder, bsa.To), (bsa_archive_type_t)bsa.Type, entries);
                    a.HeaderType = (VersionType)bsa.Type;
                    a.FileFlags = (FileFlags)bsa.FileFlags;
                    a.ArchiveFlags = (ArchiveFlags)bsa.ArchiveFlags;

                    source_files.PMap(f =>
                    {
                        Status($"Adding {f} to BSA");
                        using (var fs = File.OpenRead(Path.Combine(source_dir, f)))
                            a.AddFile(f, fs);
                    });

                    Info($"Writing {bsa.To}");
                    a.Build(Path.Combine(Outputfolder, bsa.To));

                }
            });

        }

        private void InstallIncludedFiles()
        {
            Info("Writing inline files");
            ModList.Directives
                   .OfType<InlineFile>()
                   .PMap(directive =>
                   {
                       Status("Writing included file {0}", directive.To);
                       var out_path = Path.Combine(Outputfolder, directive.To);
                       if (File.Exists(out_path)) File.Delete(out_path);

                       File.WriteAllBytes(out_path, directive.SourceData.FromBase64());
                   });
        }

        private void BuildFolderStructure()
        {
            Info("Building Folder Structure");
            ModList.Directives
                   .Select(d => Path.Combine(Outputfolder, Path.GetDirectoryName(d.To)))
                   .ToHashSet()
                   .Do(f => {
                       if (Directory.Exists(f)) return;
                       Directory.CreateDirectory(f);
                   });
        }

        private void InstallArchives()
        {
            Info("Installing Archives");
            var grouped = ModList.Directives
                                 .OfType<FromArchive>()
                                 .GroupBy(e => e.ArchiveHash)
                                 .ToDictionary(k => k.Key);
            var archives = ModList.Archives
                                  .Select(a => new { Archive = a, AbsolutePath = HashedArchives[a.Hash] })
                                  .ToList();

            archives.PMap(a => InstallArchive(a.Archive, a.AbsolutePath, grouped[a.Archive.Hash]));

        }

        private void InstallArchive(Archive archive, string absolutePath, IGrouping<string, FromArchive> grouping)
        {
            Status("Extracting {0}", archive.Name);
            var files = grouping.GroupBy(e => e.From)
                                .ToDictionary(e => e.Key);

            using (var a = new ArchiveFile(absolutePath))
            {
                a.Extract(entry =>
                {
                    if (files.TryGetValue(entry.FileName, out var directives))
                    {
                        var directive = directives.First();
                        var absolute = Path.Combine(Outputfolder, directive.To);
                        if (absolute.FileExists()) File.Delete(absolute);
                        return File.OpenWrite(absolute);
                    }
                    return null;
                });
            }

            Status("Copying duplicated files for {0}", archive.Name);

            foreach (var dups in files.Where(e => e.Value.Count() > 1).Select(v => v.Value))
            {
                var ffrom = dups.First();
                var from_path = Path.Combine(Outputfolder, ffrom.To);
                foreach (var to in dups.Skip(1))
                {
                    var to_path = Path.Combine(Outputfolder, to.To);
                    if (to_path.FileExists()) File.Delete(to_path);
                    File.Copy(from_path, to_path);
                }
            };

            // Now patch all the files from this archive
            foreach (var to_patch in grouping.OfType<PatchedFromArchive>())
            {
                using (var patch_stream = new MemoryStream())
                {
                    Status("Patching {0}", Path.GetFileName(to_patch.To));
                    // Read in the patch data

                    var patch_data = to_patch.Patch.FromBase64();

                    var to_file = Path.Combine(Outputfolder, to_patch.To);
                    MemoryStream old_data = new MemoryStream(File.ReadAllBytes(to_file));

                    // Remove the file we're about to patch
                    File.Delete(to_file);

                    // Patch it
                    using (var out_stream = File.OpenWrite(to_file))
                    {
                        BSDiff.Apply(old_data, () => new MemoryStream(patch_data), out_stream);
                    }
                }

            }
        }

        private void DownloadArchives()
        {
            var missing = ModList.Archives.Where(a => !HashedArchives.ContainsKey(a.Hash)).ToList();
            Info("Missing {0} archives", missing.Count);

            Info("Getting Nexus API Key, if a browser appears, please accept");
            NexusAPIKey = NexusAPI.GetNexusAPIKey();

            var user_status = NexusAPI.GetUserStatus(NexusAPIKey);

            if (!user_status.is_premium) {
                Info($"Automated installs with Wabbajack requires a premium nexus account. {user_status.name} is not a premium account");
                return;
            }

            DownloadMissingArchives(missing);
            return;
        }

        private void DownloadMissingArchives(List<Archive> missing)
        {
            missing.PMap(archive =>
            {
                Info($"Downloading {archive.Name}");
                var output_path = Path.Combine(DownloadFolder, archive.Name);

                if (output_path.FileExists())
                    File.Delete(output_path);

                switch (archive) {
                    case NexusMod a:
                        Info($"Downloading Nexus Archive - {archive.Name} - {a.GameName} - {a.ModID} - {a.FileID}");
                        string url;
                        try
                        {
                            url = NexusAPI.GetNexusDownloadLink(a as NexusMod, NexusAPIKey);
                        }
                        catch (Exception ex)
                        {
                            Info($"{a.Name} - Error Getting Nexus Download URL - {ex.Message}");
                            return;
                        }
                        DownloadURLDirect(archive, url);
                        break;
                    case MEGAArchive a:
                        DownloadMegaArchive(a);
                        break;
                    case GoogleDriveMod a:
                        DownloadGoogleDriveArchive(a);
                        break;
                    case MODDBArchive a:
                        DownloadModDBArchive(archive, (archive as MODDBArchive).URL);
                        break;
                    case MediaFireArchive a:
                        DownloadMediaFireArchive(archive, a.URL);
                        break;
                    case DirectURLArchive a:
                        DownloadURLDirect(archive, a.URL, headers:a.Headers);
                        break;
                    default:
                        break;

            }
            });
        }

        private void DownloadMediaFireArchive(Archive a, string url)
        {
            var client = new HttpClient();
            var result = client.GetStringSync(url);
            var regex = new Regex("(?<= href =\\\").*\\.mediafire\\.com.*(?=\\\")");
            var confirm = regex.Match(result);
            DownloadURLDirect(a, confirm.ToString(), client);
        }

        private void DownloadMegaArchive(MEGAArchive m)
        {
            var client = new MegaApiClient();
            Status("Logging into MEGA (as anonymous)");
            client.LoginAnonymous();
            var file_link = new Uri(m.URL);
            var node = client.GetNodeFromLink(file_link);
            Status("Downloading MEGA file: {0}", m.Name);

            var output_path = Path.Combine(DownloadFolder, m.Name);
            client.DownloadFile(file_link, output_path);
        }

        private void DownloadGoogleDriveArchive(GoogleDriveMod a)
        {
            var initial_url = $"https://drive.google.com/uc?id={a.Id}&export=download";
            var client = new HttpClient();
            var result = client.GetStringSync(initial_url);
            var regex = new Regex("(?<=/uc\\?export=download&amp;confirm=).*(?=;id=)");
            var confirm = regex.Match(result);
            DownloadURLDirect(a, $"https://drive.google.com/uc?export=download&confirm={confirm}&id={a.Id}", client);
        }

        private void DownloadModDBArchive(Archive archive, string url)
        {
            var client = new HttpClient();
            var result = client.GetStringSync(url);
            var regex = new Regex("https:\\/\\/www\\.moddb\\.com\\/downloads\\/mirror\\/.*(?=\\\")");
            var match = regex.Match(result);
            DownloadURLDirect(archive, match.Value);
        }

        private void DownloadURLDirect(Archive archive, string url, HttpClient client = null, List<string> headers = null)
        {
            try
            {
                if (client == null)
                {
                    client = new HttpClient();
                    client.DefaultRequestHeaders.Add("User-Agent", Consts.UserAgent);
                }

                if (headers != null) {
                    foreach (var header in headers)
                    {
                        var idx = header.IndexOf(':');
                        var k = header.Substring(0, idx);
                        var v = header.Substring(idx + 1);
                        client.DefaultRequestHeaders.Add(k, v);
                    }
                }

                long total_read = 0;
                int buffer_size = 1024 * 32;

                var response = client.GetSync(url);
                var stream = response.Content.ReadAsStreamAsync();
                try
                {
                    stream.Wait();
                }
                catch (Exception ex)
                {

                };
                if (stream.IsFaulted)
                {
                    Info($"While downloading {url} - {Utils.ExceptionToString(stream.Exception)}");
                    return;
                }

                string header_var = "1";
                if (response.Content.Headers.Contains("Content-Length"))
                    header_var = response.Content.Headers.GetValues("Content-Length").FirstOrDefault();

                long content_size = header_var != null ? long.Parse(header_var) : 1;

                var output_path = Path.Combine(DownloadFolder, archive.Name);
;

                using (var webs = stream.Result)
                using (var fs = File.OpenWrite(output_path))
                {
                    var buffer = new byte[buffer_size];
                    while (true)
                    {
                        var read = webs.Read(buffer, 0, buffer_size);
                        if (read == 0) break;
                        Status((int)(total_read * 100 / content_size), "Downloading {0}", archive.Name);

                        fs.Write(buffer, 0, read);
                        total_read += read;

                    }
                }
                Status("Hashing {0}", archive.Name);
                HashArchive(output_path);
            }
            catch (Exception ex)
            {
                Info($"{archive.Name} - Error downloading from: {url}");
            }
        }

        private object GetNexusAPIKey()
        {
            throw new NotImplementedException();
        }

        private void HashArchives()
        {
            HashedArchives = Directory.EnumerateFiles(DownloadFolder)
                                      .Where(e => Consts.SupportedArchives.Contains(Path.GetExtension(e)))
                                      .PMap(e => (HashArchive(e), e))
                                      .ToDictionary(e => e.Item1, e => e.Item2);

        }

        private string HashArchive(string e)
        {
            var cache = e + ".sha";
            if (cache.FileExists() && new FileInfo(cache).LastWriteTime >= new FileInfo(e).LastWriteTime)
                return File.ReadAllText(cache);

            Status("Hashing {0}", Path.GetFileName(e));
            File.WriteAllText(cache, Utils.FileSHA256(e));
            return HashArchive(e);

        }

        public static string CheckForModPack()
        {
            using (var s = File.OpenRead(Assembly.GetExecutingAssembly().Location))
            {
                var magic_bytes = Encoding.ASCII.GetBytes(Consts.ModPackMagic);
                s.Position = s.Length - magic_bytes.Length;
                using (var br = new BinaryReader(s))
                {
                    var bytes = br.ReadBytes(magic_bytes.Length);
                    var magic = Encoding.ASCII.GetString(bytes);
                    if (magic != Consts.ModPackMagic)
                    {

                        return null;
                    }

                    s.Position = s.Length - magic_bytes.Length - 8;
                    var start_pos = br.ReadInt64();
                    s.Position = start_pos;
                    long length = br.ReadInt64();

                    return br.ReadBytes((int)length).BZip2String();

                }
            }
        }

    }
}