using DTLib.Dtsod;
using DTLib.Filesystem;
using System.Net.Sockets;
using System.Text;
using static DTLib.PublicLog;

namespace DTLib.Network
{
    //
    // передача файлов по сети
    //
    public class FSP
    {
        Socket MainSocket { get; init; }
        public static bool debug = false;
        public FSP(Socket _mainSocket) => MainSocket=_mainSocket;

        public uint BytesDownloaded = 0;
        public uint BytesUploaded = 0;
        public uint Filesize = 0;

        public SafeMutex Mutex = new();

        // скачивает файл с помощью FSP протокола
        public void DownloadFile(string filePath_server, string filePath_client)
        {
            Mutex.Execute(() =>
            {
                Debug("b", $"requesting file download: {filePath_server}\n");
                MainSocket.SendPackage("requesting file download".ToBytes());
                MainSocket.SendPackage(filePath_server.ToBytes());
            });
            DownloadFile(filePath_client);
        }

        public void DownloadFile(string filePath_client)
        {
            using System.IO.Stream fileStream = File.OpenWrite(filePath_client);
            Download_SharedCode(fileStream, true);
            fileStream.Close();
            Debug(new string[] { "g", $"   downloaded {BytesDownloaded} of {Filesize} bytes\n" });
        }

        public byte[] DownloadFileToMemory(string filePath_server)
        {
            Mutex.Execute(() =>
            {
                Debug("b", $"requesting file download: {filePath_server}\n");
                MainSocket.SendPackage("requesting file download".ToBytes());
                MainSocket.SendPackage(filePath_server.ToBytes());
            });
            return DownloadFileToMemory();
        }

        public byte[] DownloadFileToMemory()
        {
            using var fileStream = new System.IO.MemoryStream();
            Download_SharedCode(fileStream, false);
            byte[] output = fileStream.GetBuffer();
            fileStream.Close();
            Debug(new string[] { "g", $"   downloaded {BytesDownloaded} of {Filesize} bytes\n" });
            return output;
        }

        void Download_SharedCode(System.IO.Stream fileStream, bool requiresFlushing)
        {
            Mutex.Execute(() =>
            {
                BytesDownloaded=0;
                Filesize=SimpleConverter.ToString(MainSocket.GetPackage()).ToUInt();
                MainSocket.SendPackage("ready".ToBytes());
                int packagesCount = 0;
                byte[] buffer = new byte[5120];
                int fullPackagesCount = SimpleConverter.Truncate(Filesize/buffer.Length);
                // получение полных пакетов файла
                for(byte n = 0; packagesCount<fullPackagesCount; packagesCount++)
                {
                    buffer=MainSocket.GetPackage();
                    BytesDownloaded+=(uint)buffer.Length;
                    fileStream.Write(buffer, 0, buffer.Length);
                    if(requiresFlushing)
                    {
                        if(n==100)
                        {
                            fileStream.Flush();
                            n=0;
                        }
                        else
                            n++;
                    }
                }
                // получение остатка
                if((Filesize-fileStream.Position)>0)
                {
                    MainSocket.SendPackage("remain request".ToBytes());
                    buffer=MainSocket.GetPackage();
                    BytesDownloaded+=(uint)buffer.Length;
                    fileStream.Write(buffer, 0, buffer.Length);
                }
            });
            if(requiresFlushing)
                fileStream.Flush();
        }

        // отдаёт файл с помощью FSP протокола
        public void UploadFile(string filePath)
        {
            BytesUploaded=0;
            Debug("b", $"uploading file {filePath}\n");
            using System.IO.FileStream fileStream = File.OpenRead(filePath);
            Filesize=File.GetSize(filePath).ToUInt();
            Mutex.Execute(() =>
            {
                MainSocket.SendPackage(Filesize.ToString().ToBytes());
                MainSocket.GetAnswer("ready");
                byte[] buffer = new byte[5120];
                int packagesCount = 0;
                int fullPackagesCount = SimpleConverter.Truncate(Filesize/buffer.Length);
                // отправка полных пакетов файла
                for(; packagesCount<fullPackagesCount; packagesCount++)
                {
                    fileStream.Read(buffer, 0, buffer.Length);
                    MainSocket.SendPackage(buffer);
                    BytesUploaded+=(uint)buffer.Length;
                }
                // отправка остатка
                if((Filesize-fileStream.Position)>0)
                {
                    MainSocket.GetAnswer("remain request");
                    buffer=new byte[(Filesize-fileStream.Position).ToInt()];
                    fileStream.Read(buffer, 0, buffer.Length);
                    MainSocket.SendPackage(buffer);
                    BytesUploaded+=(uint)buffer.Length;
                }
            });
            fileStream.Close();
            Debug(new string[] { "g", $"   uploaded {BytesUploaded} of {Filesize} bytes\n" });
        }

        public void DownloadByManifest(string dirOnServer, string dirOnClient, bool overwrite = false, bool delete_excess = false)
        {
            if(!dirOnClient.EndsWith("\\"))
                dirOnClient+="\\";
            if(!dirOnServer.EndsWith("\\"))
                dirOnServer+="\\";
            Debug("b", "downloading manifest <", "c", dirOnServer+"manifest.dtsod", "b", ">\n");
            var manifest = new DtsodV22(SimpleConverter.ToString(DownloadFileToMemory(dirOnServer+"manifest.dtsod")));
            Debug("g", $"found {manifest.Values.Count} files in manifest\n");
            var hasher = new Hasher();
            foreach(string fileOnServer in manifest.Keys)
            {
                string fileOnClient = dirOnClient+fileOnServer;
                Debug("b", "file <", "c", fileOnClient, "b", ">...  ");
                if(!File.Exists(fileOnClient))
                {
                    DebugNoTime("y", "doesn't exist\n");
                    DownloadFile(dirOnServer+fileOnServer, fileOnClient);
                }
                else if(overwrite&&hasher.HashFile(fileOnClient).HashToString()!=manifest[fileOnServer])
                {
                    DebugNoTime("y", "outdated\n");
                    DownloadFile(dirOnServer+fileOnServer, fileOnClient);
                }
                else
                    DebugNoTime("g", "without changes\n");
            }
            // удаление лишних файлов
            if(delete_excess)
            {
                foreach(string file in Directory.GetAllFiles(dirOnClient))
                {
                    if(!manifest.ContainsKey(file.Remove(0, dirOnClient.Length)))
                    {
                        Debug("y", $"deleting excess file: {file}\n");
                        File.Delete(file);
                    }
                }
            }
        }

        public static void CreateManifest(string dir)
        {
            if(!dir.EndsWith("\\"))
                dir+="\\";
            Log($"b", $"creating manifest of {dir}\n");
            StringBuilder manifestBuilder = new();
            Hasher hasher = new();
            if(Directory.GetFiles(dir).Contains(dir+"manifest.dtsod"))
                File.Delete(dir+"manifest.dtsod");
            foreach(string _file in Directory.GetAllFiles(dir))
            {
                string file = _file.Remove(0, dir.Length);
                manifestBuilder.Append(file);
                manifestBuilder.Append(": \"");
                byte[] hash = hasher.HashFile(dir+file);
                manifestBuilder.Append(hash.HashToString());
                manifestBuilder.Append("\";\n");
            }
            Debug($"g", $"   manifest of {dir} created\n");
            File.WriteAllText(dir+"manifest.dtsod", manifestBuilder.ToString());
        }

        static void Debug(params string[] msg)
        {
            if(debug)
                Log(msg);
        }
        static void DebugNoTime(params string[] msg)
        {
            if(debug)
                LogNoTime(msg);
        }
    }
}