using System;
using System.Collections.Generic;
using System.IO;
using System.IO.Compression;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Tango.Core;
using Tango.Core.DI;
using Tango.Core.IO;
using Tango.FileSystem;
using Tango.FileSystem.Network;
using Tango.Integration.ExternalBridge;
using Tango.PPC.Common.ExternalBridge;
using Tango.Transport;
using Tango.Transport.Transporters;
using Tango.WebRTC;

namespace Tango.PPC.Common.FileSystem
{
    [TangoCreateWhenRegistered]
    public class DefaultFileSystemService : ExtendedObject, IFileSystemService, IExternalBridgeRequestHandler
    {
        private enum FileSystemOperationMode
        {
            Upload,
            Download
        }

        private class FileSystemOperation
        {
            public FileSystemOperationMode Mode { get; set; }
            public String Id { get; set; }
            public String Path { get; set; }
            public bool IsPathTempZip { get; set; }

            public FileSystemOperation(FileSystemOperationMode mode, String path)
            {
                Mode = mode;
                Id = Guid.NewGuid().ToString();
                Path = path;
            }
        }

        private FileSystemManager _manager;
        private Dictionary<String, FileSystemOperation> _operations;
        private Dictionary<ExternalBridgeReceiver, BasicTransporter> _webRtcClients;

        public bool Enabled { get; set; } = true;
        public bool EnableWebRTC { get; set; } = true;

        public DefaultFileSystemService(IPPCExternalBridgeService externalBridge)
        {
            _webRtcClients = new Dictionary<ExternalBridgeReceiver, BasicTransporter>();
            _manager = new FileSystemManager();
            _operations = new Dictionary<string, FileSystemOperation>();
            externalBridge.RegisterRequestHandler(this);
        }

        [ExternalBridgeRequestHandlerMethod(typeof(InitWebRtcRequest))]
        public async void OnInitWebRtcRequest(InitWebRtcRequest request, String token, ExternalBridgeReceiver receiver)
        {
            try
            {
                if (!EnableWebRTC)
                {
                    await receiver.SendErrorResponse(new InvalidOperationException("The file system service WebRTC channel is disabled on this machine."), token);
                    return;
                }

                if (_webRtcClients.ContainsKey(receiver))
                {
                    _webRtcClients[receiver].Dispose();
                }

                var webRtcAdapter = new WebRtcTransportAdapter(receiver, WebRtcTransportAdapterMode.Passive, request.DataChannelName);
                webRtcAdapter.Ready += (x, e) =>
                {
                    LogManager.Log("File System via WebRTC is ready.");
                };

                BasicTransporter webRtcTransporter = new BasicTransporter(webRtcAdapter);
                webRtcTransporter = new BasicTransporter(webRtcAdapter);
                webRtcTransporter.ComponentName = "File System Passive WebRTC Transporter";
                webRtcTransporter.UseKeepAlive = false;
                webRtcTransporter.RegisterRequestHandler<ChunkDownloadRequest>(WebRtcChunkDownloadRequestReceived);
                await webRtcTransporter.Connect();
                await receiver.SendGenericResponse(new InitWebRtcResponse(), token);
                _webRtcClients[receiver] = webRtcTransporter;
            }
            catch (Exception ex)
            {
                await receiver.SendErrorResponse(ex, token);
            }
        }

        private void WebRtcChunkDownloadRequestReceived(ITransporter transporter, ChunkDownloadRequest request, string token)
        {
            OnChunkDownloadRequest(request, token, transporter);
        }

        [ExternalBridgeRequestHandlerMethod(typeof(GetFileSystemItemRequest))]
        public async void OnGetFileSystemItemRequest(GetFileSystemItemRequest request, String token, ExternalBridgeReceiver receiver)
        {
            try
            {
                FileSystemItemDTO dto = _manager.GetFolder(request);
                await receiver.SendGenericResponse(new GetFileSystemItemResponse() { FileSystemItem = dto }, token);
            }
            catch (Exception ex)
            {
                await receiver.SendErrorResponse(ex, token);
            }
        }

        [ExternalBridgeRequestHandlerMethod(typeof(FileUploadRequest))]
        public async void OnFileUploadRequest(FileUploadRequest request, String token, ExternalBridgeReceiver receiver)
        {
            try
            {
                using (var stream = new FileStream(request.Path, FileMode.Create)) { }

                FileSystemOperation operation = new FileSystemOperation(FileSystemOperationMode.Upload, request.Path);
                _operations.Add(operation.Id, operation);

                await receiver.SendGenericResponse(new FileUploadResponse() { OperationId = operation.Id }, token);
            }
            catch (Exception ex)
            {
                await receiver.SendErrorResponse(ex, token);
            }
        }

        [ExternalBridgeRequestHandlerMethod(typeof(FileDownloadRequest))]
        public async void OnFileDownloadRequest(FileDownloadRequest request, String token, ExternalBridgeReceiver receiver)
        {
            try
            {
                if (!File.Exists(request.Path))
                {
                    await receiver.SendErrorResponse(new FileNotFoundException("Could not find the specified file."), token);
                    return;
                }

                FileSystemOperation operation = new FileSystemOperation(FileSystemOperationMode.Download, request.Path);

                _operations.Add(operation.Id, operation);

                await receiver.SendGenericResponse(new FileDownloadResponse()
                {
                    OperationId = operation.Id,
                    Length = new FileInfo(request.Path).Length
                }, token);
            }
            catch (Exception ex)
            {
                await receiver.SendErrorResponse(ex, token);
            }
        }

        [ExternalBridgeRequestHandlerMethod(typeof(FolderDownloadRequest))]
        public async void OnFolderDownloadRequest(FolderDownloadRequest request, String token, ExternalBridgeReceiver receiver)
        {
            try
            {
                if (!Directory.Exists(request.Path))
                {
                    await receiver.SendErrorResponse(new FileNotFoundException("Could not find the specified directory."), token);
                    return;
                }

                var tempFile = TemporaryManager.CreateImaginaryFile();

                ZipFile.CreateFromDirectory(request.Path, tempFile);

                FileSystemOperation operation = new FileSystemOperation(FileSystemOperationMode.Download, tempFile);
                operation.IsPathTempZip = true;

                _operations.Add(operation.Id, operation);

                await receiver.SendGenericResponse(new FolderDownloadResponse()
                {
                    OperationId = operation.Id,
                    Length = new FileInfo(tempFile).Length
                }, token);
            }
            catch (Exception ex)
            {
                await receiver.SendErrorResponse(ex, token);
            }
        }

        [ExternalBridgeRequestHandlerMethod(typeof(ChunkUploadRequest))]
        public async void OnChunkUploadRequest(ChunkUploadRequest request, String token, ExternalBridgeReceiver receiver)
        {
            try
            {
                FileSystemOperation operation;
                _operations.TryGetValue(request.OperationId, out operation);

                if (operation == null)
                {
                    await receiver.SendErrorResponse(new ArgumentException("Invalid operation id."), token);
                    return;
                }

                using (var stream = new FileStream(operation.Path, FileMode.Append))
                {
                    stream.Write(request.Data, 0, request.Data.Length);
                }

                await receiver.SendGenericResponse(new ChunkUploadResponse(), token, new TransportResponseConfig() { Priority = QueuePriority.Low });
            }
            catch (Exception ex)
            {
                await receiver.SendErrorResponse(ex, token);
            }
        }

        [ExternalBridgeRequestHandlerMethod(typeof(ChunkDownloadRequest))]
        public async void OnChunkDownloadRequest(ChunkDownloadRequest request, String token, ITransporter receiver)
        {
            FileSystemOperation operation;
            _operations.TryGetValue(request.OperationId, out operation);

            if (operation == null)
            {
                await receiver.SendErrorResponse(new ArgumentException("Invalid operation id."), token);
                return;
            }

            FileStream stream = null;

            try
            {
                stream = new FileStream(operation.Path, FileMode.Open);
                stream.Position = request.Position;
                byte[] data = new byte[Math.Min(request.MaxChunkSize, stream.Length - stream.Position)];
                await stream.ReadAsync(data, 0, data.Length);
                stream.Dispose();
                stream = null;
                await receiver.SendGenericResponse(new ChunkDownloadResponse()
                {
                    Data = data
                }, token, new TransportResponseConfig() { Priority = QueuePriority.Low });
            }
            catch (Exception ex)
            {
                stream?.Dispose();
                await receiver.SendErrorResponse(ex, token);
            }
        }

        [ExternalBridgeRequestHandlerMethod(typeof(AbortOperationRequest))]
        public async void OnAbortOperationRequest(AbortOperationRequest request, String token, ExternalBridgeReceiver receiver)
        {
            FileSystemOperation operation;
            _operations.TryGetValue(request.OperationId, out operation);

            if (operation == null)
            {
                await receiver.SendErrorResponse(new ArgumentException("Invalid operation id."), token);
                return;
            }

            try
            {
                if (operation.Mode == FileSystemOperationMode.Upload)
                {
                    if (File.Exists(operation.Path))
                    {
                        File.Delete(operation.Path);
                    }
                    else if (Directory.Exists(operation.Path))
                    {
                        Directory.Delete(operation.Path, true);
                    }
                }
                else if (operation.IsPathTempZip)
                {
                    if (File.Exists(operation.Path))
                    {
                        File.Delete(operation.Path);
                    }
                }

                await receiver.SendGenericResponse(new AbortOperationResponse(), token);
            }
            catch (Exception ex)
            {
                await receiver.SendErrorResponse(ex, token);
            }
        }

        [ExternalBridgeRequestHandlerMethod(typeof(MoveRequest))]
        public async void OnMoveRequest(MoveRequest request, String token, ExternalBridgeReceiver receiver)
        {
            try
            {
                _manager.Move(request);
                await receiver.SendGenericResponse(new MoveResponse(), token);
            }
            catch (Exception ex)
            {
                await receiver.SendErrorResponse(ex, token);
            }
        }

        [ExternalBridgeRequestHandlerMethod(typeof(CopyRequest))]
        public async void OnCopyRequest(CopyRequest request, String token, ExternalBridgeReceiver receiver)
        {
            try
            {
                _manager.Copy(request);
                await receiver.SendGenericResponse(new CopyResponse(), token);
            }
            catch (Exception ex)
            {
                await receiver.SendErrorResponse(ex, token);
            }
        }

        [ExternalBridgeRequestHandlerMethod(typeof(DeleteRequest))]
        public async void OnDeleteRequest(DeleteRequest request, String token, ExternalBridgeReceiver receiver)
        {
            try
            {
                _manager.Delete(request.Path);
                await receiver.SendGenericResponse(new DeleteResponse(), token);
            }
            catch (Exception ex)
            {
                await receiver.SendErrorResponse(ex, token);
            }
        }

        public void OnReceiverDisconnected(ExternalBridgeReceiver receiver)
        {
            if (_webRtcClients.ContainsKey(receiver))
            {
                try
                {
                    var webRtcTransporter = _webRtcClients[receiver];
                    _webRtcClients.Remove(receiver);
                    webRtcTransporter.Dispose();
                }
                catch (Exception ex)
                {
                    LogManager.Log(ex, "Error disposing the WebRTC transporter.");
                }
            }
        }
    }
}