using MaterialDesignThemes.Wpf;
using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Diagnostics;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Input;
using Tango.BL.Enumerations;
using Tango.Core.Commands;
using Tango.FileSystem;
using Tango.FSE.Common;
using Tango.FSE.Common.Connection;
using Tango.FSE.Common.FileSystem;
using Tango.FSE.Common.Notifications;

namespace Tango.FSE.Firmware.ViewModels
{
    public class FileSystemViewVM : FSEViewModel
    {
        #region Properties

        private FileSystemItem _currentItem;
        /// <summary>
        /// Gets or sets the current file system item.
        /// </summary>
        public FileSystemItem CurrentItem
        {
            get { return _currentItem; }
            set { _currentItem = value; RaisePropertyChangedAuto(); OnCurrentItemChanged(); }
        }

        private String _currentPath;
        /// <summary>
        /// Gets or sets the current remote path.
        /// </summary>
        public String CurrentPath
        {
            get { return _currentPath; }
            set { _currentPath = value; RaisePropertyChangedAuto(); }
        }

        /// <summary>
        /// Gets or sets the selected file system items.
        /// </summary>
        public ObservableCollection<FileSystemItem> SelectedItems { get; set; }

        /// <summary>
        /// Gets or sets the list of file system handlers downloads/uploads.
        /// </summary>
        public ObservableCollection<FileSystemHandler> FileSystemHandlers { get; set; }

        #endregion

        #region Commands

        /// <summary>
        /// Navigates to the current path.
        /// </summary>
        public RelayCommand NavigateCommand { get; set; }

        /// <summary>
        /// Opens the current selected item (context menu).
        /// </summary>
        public RelayCommand<FileSystemItem> OpenItemCommand { get; set; }

        /// <summary>
        /// Navigates back.
        /// </summary>
        public RelayCommand BackCommand { get; set; }

        /// <summary>
        /// Navigates to the specified folder.
        /// </summary>
        public RelayCommand<String> NavigateToFolderCommand { get; set; }

        /// <summary>
        /// Deletes the specified file system item (context menu or DEL key).
        /// </summary>
        public RelayCommand<IList<FileSystemItem>> DeleteCommand { get; set; }

        /// <summary>
        /// Handles the drag & drop of items from the operation system shell onto the file system view.
        /// </summary>
        public RelayCommand<List<FileSystemItem>> DropCommand { get; set; }

        /// <summary>
        /// Handles the drag & drop of items from the file system view onto the operation system shell.
        /// </summary>
        public RelayCommand<List<DragItem>> DragCommand { get; set; }

        /// <summary>
        /// Removes the specified file system handler.
        /// </summary>
        public RelayCommand<FileSystemHandler> DeleteFileSystemHandlerCommand { get; set; }

        /// <summary>
        /// Opens the parent directory of a file system handler item.
        /// A download will execute the local explorer.exe.
        /// An upload will navigate to the remote parent folder.
        /// </summary>
        public RelayCommand<FileSystemHandler> OpenFileSystemHandlerDestinationCommand { get; set; }

        /// <summary>
        /// Downloads the specified remote items.
        /// </summary>
        public RelayCommand<List<FileSystemItem>> DownloadCommand { get; set; }

        /// <summary>
        /// Invokes a dialog for choosing items to upload and starts the upload.
        /// </summary>
        public RelayCommand UploadCommand { get; set; }

        /// <summary>
        /// Creates a new folder at the current remote path.
        /// </summary>
        public RelayCommand NewFolderCommand { get; set; }

        #endregion

        #region Constructors

        /// <summary>
        /// Initializes a new instance of the <see cref="FileSystemViewVM"/> class.
        /// </summary>
        public FileSystemViewVM()
        {
            SelectedItems = new ObservableCollection<FileSystemItem>();
            FileSystemHandlers = new ObservableCollection<FileSystemHandler>();
            NavigateCommand = new RelayCommand(NavigateToCurrentPath);
            OpenItemCommand = new RelayCommand<FileSystemItem>(OpenFileSystemItem);
            BackCommand = new RelayCommand(NavigateBack, () => !(CurrentItem is FolderItem) || !(CurrentItem as FolderItem).IsRoot);
            NavigateToFolderCommand = new RelayCommand<string>(async (x) => await Navigate(x));
            DeleteCommand = new RelayCommand<IList<FileSystemItem>>(DeleteSelectedItems);
            DragCommand = new RelayCommand<List<DragItem>>(OnItemsDraggedOut);
            DropCommand = new RelayCommand<List<FileSystemItem>>(OnItemsDroppedIn);
            DeleteFileSystemHandlerCommand = new RelayCommand<FileSystemHandler>(DeleteFileSystemHandler);
            OpenFileSystemHandlerDestinationCommand = new RelayCommand<FileSystemHandler>(OpenFileSystemHandlerDestination);
            DownloadCommand = new RelayCommand<List<FileSystemItem>>(DownloadSelectedItems);
            NewFolderCommand = new RelayCommand(CreateNewFolder);
            UploadCommand = new RelayCommand(UploadFilesAndFolder);
        }

        #endregion

        #region Override Methods

        /// <summary>
        /// Called when the application has been started.
        /// </summary>
        public override void OnApplicationStarted()
        {
            base.OnApplicationStarted();
            MachineProvider.MachineConnected += MachineProvider_MachineConnected;
        }

        #endregion

        #region Event Handlers

        private async void MachineProvider_MachineConnected(object sender, MachineConnectedEventArgs e)
        {
            if (e.DifferentFromPrevious && e.MachineOperator.IsConnected && AuthenticationProvider.CurrentUser.HasPermission(Permissions.FSE_FirmwareFileSystemRead))
            {
                try
                {
                    await Navigate(null, true);
                }
                catch (Exception ex)
                {
                    LogManager.Log(ex, "Error initializing firmware file system.");
                    NotificationProvider.PushSnackbarItem(MessageType.Warning, "Firmware Module Error", true, "Could not initialize the remote firmware file system provider.", TimeSpan.FromSeconds(10));
                }
            }
        }

        #endregion

        #region Private Methods

        private async void NavigateBack()
        {
            if (CurrentItem.Path.Length == 1)
            {
                await Navigate(null);
            }
            else
            {
                String parent = Path.GetDirectoryName(CurrentItem.Path);
                await Navigate(parent);
            }
        }

        private void NavigateToCurrentPath()
        {
            InvokeUI(async () =>
            {
                await Navigate(CurrentPath);
            });
        }

        private async void OpenFileSystemItem(FileSystemItem item)
        {
            if (item == null) return;

            if (item.Type == FileSystemItemType.Folder || item.Type == FileSystemItemType.Drive)
            {
                await Navigate(item.Path);
            }
            else if (item.Type == FileSystemItemType.File)
            {
                //TODO: Download/Open file?...
            }
        }

        private async void DeleteSelectedItems(IList<FileSystemItem> items)
        {
            if (items != null && items.Count > 0)
            {
                if (await NotificationProvider.ShowWarningQuestion($"Are you sure you want to delete {(items.Count == 1 ? $"'{items.First().Name}'" : $"the {items.Count} selected files/folders")}?", "DELETE"))
                {
                    using (var task = NotificationProvider.PushTaskItem("Removing..."))
                    {
                        int remainingItems = items.Count;

                        foreach (var item in items)
                        {
                            task.UpdateProgress($"Removing '{item.Name}'...");

                            try
                            {
                                remainingItems--;
                                await FirmwareStorageProvider.Delete(item);
                            }
                            catch (Exception ex)
                            {
                                LogManager.Log(ex, $"Could not remove '{item.Name}'.");

                                if (remainingItems > 0)
                                {
                                    if (!await NotificationProvider.ShowWarningQuestion($"Could not remove '{item.Name}'.\n{ex.FlattenMessage()}\nDo you wish to continue removing the remaining items?"))
                                    {
                                        break;
                                    }
                                }
                                else
                                {
                                    await NotificationProvider.ShowError($"Could not remove '{item.Name}'.\n{ex.FlattenMessage()}");
                                }
                            }
                        }
                    }

                    NavigateToCurrentPath();
                }
            }
        }

        private async void OnItemsDraggedOut(List<DragItem> items)
        {
            if (items.Exists(x => x.FileSystemItem.Type != FileSystemItemType.File))
            {
                await NotificationProvider.ShowError("Firmware file system does not support folder downloads.");
                return;
            }

            foreach (var item in items)
            {
                String destination = Path.Combine(item.Destination, item.FileSystemItem.Name);

                if (File.Exists(destination))
                {
                    if (!await NotificationProvider.ShowWarningQuestion($"'{item.FileSystemItem.Name}' already exists on '{item.Destination}'. Do you want to overwrite?"))
                    {
                        continue;
                    }
                }

                try
                {
                    var handler = await FirmwareStorageProvider.Download(item.FileSystemItem as FileItem, destination);
                    FileSystemHandlers.Insert(0, handler);
                }
                catch (Exception ex)
                {
                    await NotificationProvider.ShowError(ex.FlattenMessage());
                }
            }
        }

        private void OnItemsDroppedIn(List<FileSystemItem> items)
        {
            UploadFiles(items.Select(x => x.Path).ToList());
        }

        private async void DeleteFileSystemHandler(FileSystemHandler handler)
        {
            if (handler.Status != FileSystemHandlerStatus.Completed && handler.Status != FileSystemHandlerStatus.Failed)
            {
                if (await NotificationProvider.ShowWarningQuestion($"This item is currently {handler.Status}. Do you wish to abort and delete this item?"))
                {
                    try
                    {
                        handler.Abort();
                    }
                    catch { }

                    FileSystemHandlers.Remove(handler);
                }
            }
            else
            {
                FileSystemHandlers.Remove(handler);
            }
        }

        private async void OpenFileSystemHandlerDestination(FileSystemHandler handler)
        {
            if (handler.Type == FileSystemHandlerType.FileDownload || handler.Type == FileSystemHandlerType.FolderDownload)
            {
                await StorageProvider.ShowInExplorer(handler.Destination);
            }
            else
            {
                await Navigate(Path.GetDirectoryName(handler.Destination));
            }
        }

        private async Task Navigate(String path, bool throwError = false)
        {
            try
            {
                IsFree = false;

                Mouse.OverrideCursor = Cursors.AppStarting;

                if (path != null)
                {
                    CurrentItem = await FirmwareStorageProvider.GetFolder(path) as FileSystemItem;
                }
                else
                {
                    CurrentItem = await FirmwareStorageProvider.GetRoot() as FileSystemItem;
                }
            }
            catch (Exception ex)
            {
                IsFree = true;
                Mouse.OverrideCursor = null;
                if (!throwError)
                {
                    await NotificationProvider.ShowError($"Error navigating to the specified path.\n{ex.FlattenMessage()}");
                }
                else
                {
                    throw ex;
                }
            }
            finally
            {
                IsFree = true;
                Mouse.OverrideCursor = null;
            }
        }

        private async void DownloadSelectedItems(List<FileSystemItem> items)
        {
            if (items.Exists(x => x.Type != FileSystemItemType.File))
            {
                await NotificationProvider.ShowError("Firmware file system does not support folder downloads.");
                return;
            }

            if (items.Count == 1)
            {
                var fileItem = items.First() as FileItem;

                var result = await StorageProvider.SaveFile("Select download destination file", $"{fileItem.Description}|*{fileItem.Extension}", fileItem.Name, fileItem.Extension);
                if (result)
                {
                    try
                    {
                        var handler = await FirmwareStorageProvider.Download(fileItem, result.SelectedItem);
                        FileSystemHandlers.Insert(0, handler);
                    }
                    catch (Exception ex)
                    {
                        await NotificationProvider.ShowError(ex.FlattenMessage());
                    }
                }
            }
            else
            {
                var result = await StorageProvider.SelectFolder("Select download destination folder");
                if (result)
                {
                    foreach (var item in items.OfType<FileItem>())
                    {
                        String destination = Path.Combine(result.SelectedItem, item.Name);

                        if (File.Exists(destination))
                        {
                            if (!await NotificationProvider.ShowWarningQuestion($"'{item.Name}' already exists on '{result.SelectedItem}'. Do you want to overwrite?"))
                            {
                                continue;
                            }
                        }

                        try
                        {
                            var handler = await FirmwareStorageProvider.Download(item, destination);
                            FileSystemHandlers.Insert(0, handler);
                        }
                        catch (Exception ex)
                        {
                            await NotificationProvider.ShowError(ex.FlattenMessage());
                        }
                    }
                }
            }
        }

        private async void UploadFilesAndFolder()
        {
            var result = await StorageProvider.OpenFiles("Select files to upload");
            if (result)
            {
                UploadFiles(result.SelectedItems);
            }
        }

        private async void UploadFiles(List<String> files)
        {
            try
            {
                String currentPathBefore = CurrentPath;

                foreach (var file in files)
                {
                    if (!File.Exists(file))
                    {
                        await NotificationProvider.ShowError($"File '{file}' cannot be uploaded.");
                        return;
                    }
                }

                foreach (var file in files)
                {
                    String itemName = Path.GetFileName(file);

                    if ((CurrentItem as IFileSystemContainer).Items.ToList().Exists(x => x.Name.ToLower() == itemName.ToLower()))
                    {
                        if (!await NotificationProvider.ShowWarningQuestion($"'{itemName}' already exists on '{CurrentItem.Name}'. Do you want to overwrite?"))
                        {
                            continue;
                        }
                    }

                    var handler = await FirmwareStorageProvider.Upload(file, Path.Combine(CurrentItem.Path, Path.GetFileName(file)));

                    handler.StatusChanged += (x, status) =>
                    {
                        if (status == FileSystemHandlerStatus.Completed && currentPathBefore == CurrentPath)
                        {
                            NavigateToCurrentPath();
                        }
                    };

                    FileSystemHandlers.Insert(0, handler);
                }
            }
            catch (Exception ex)
            {
                await NotificationProvider.ShowError($"Error uploading to file system.\n{ex.FlattenMessage()}");
            }
        }

        private async void CreateNewFolder()
        {
            if (CurrentItem == null) return;

            var result = await NotificationProvider.ShowInputBox(
                "New Folder",
                $"Please enter a folder name and press 'ENTER'.",
                PackIconKind.FolderAdd, "untitled",
                "folder name",
                100,
                "CREATE");

            if (result.Confirmed)
            {
                try
                {
                    using (NotificationProvider.PushTaskItem("Creating new folder..."))
                    {
                        var folderItem = await FirmwareStorageProvider.CreateFolder(CurrentItem, result.Input);
                        NavigateToCurrentPath(); //Instead of inserting folder item just refresh the current path...
                    }
                }
                catch (Exception ex)
                {
                    LogManager.Log(ex, $"Error creating new folder '{Path.Combine(CurrentItem.Path, result.Input)}.");
                    await NotificationProvider.ShowError($"Error creating folder '{result.Input}'.\n{ex.FlattenMessage()}");
                }
            }
        }

        private void OnCurrentItemChanged()
        {
            CurrentPath = CurrentItem.Path;
            InvalidateRelayCommands();
        }

        #endregion
    }
}