Wino-Mail/Wino.Mail.ViewModels/MailRenderingPageViewModel.cs

using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.IO;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;
using CommunityToolkit.Mvvm.ComponentModel;
using CommunityToolkit.Mvvm.Input;
using CommunityToolkit.Mvvm.Messaging;
using MailKit;

using MimeKit;
using Serilog;
using Wino.Core.Domain;
using Wino.Core.Domain.Entities.Mail;
using Wino.Core.Domain.Entities.Shared;
using Wino.Core.Domain.Enums;
using Wino.Core.Domain.Interfaces;
using Wino.Core.Domain.Models.MailItem;
using Wino.Core.Domain.Models.Menus;
using Wino.Core.Domain.Models.Navigation;
using Wino.Core.Domain.Models.Reader;
using Wino.Mail.ViewModels.Data;
using Wino.Mail.ViewModels.Messages;
using Wino.Messaging.Client.Mails;
using Wino.Messaging.Server;
using Wino.Messaging.UI;
using IMailService = Wino.Core.Domain.Interfaces.IMailService;

namespace Wino.Mail.ViewModels;

public partial class MailRenderingPageViewModel : MailBaseViewModel,
    IRecipient<NewMailItemRenderingRequestedEvent>,
    IRecipient<ThumbnailAdded>,
    ITransferProgress // For listening IMAP message download progress.
{
    private readonly IMailDialogService _dialogService;
    private readonly IUnderlyingThemeService _underlyingThemeService;

    private readonly IMimeFileService _mimeFileService;
    private readonly Core.Domain.Interfaces.IMailService _mailService;
    private readonly IFileService _fileService;
    private readonly IWinoRequestDelegator _requestDelegator;
    private readonly IContactService _contactService;
    private readonly IClipboardService _clipboardService;
    private readonly IUnsubscriptionService _unsubscriptionService;
    private readonly IApplicationConfiguration _applicationConfiguration;
    private readonly IWinoServerConnectionManager _winoServerConnectionManager;
    private bool forceImageLoading = false;

    private MailItemViewModel initializedMailItemViewModel = null;
    private MimeMessageInformation initializedMimeMessageInformation = null;

    // Func to get WebView2 to save current HTML as PDF to given location.
    // Used in 'Save as' and 'Print' functionality.
    public Func<string, Task<bool>> SaveHTMLasPDFFunc { get; set; }

    #region Properties

    public bool ShouldDisplayDownloadProgress => IsIndetermineProgress || (CurrentDownloadPercentage > 0 && CurrentDownloadPercentage <= 100);
    public bool CanUnsubscribe => CurrentRenderModel?.UnsubscribeInfo?.CanUnsubscribe ?? false;
    public bool IsJunkMail => initializedMailItemViewModel?.AssignedFolder != null && initializedMailItemViewModel.AssignedFolder.SpecialFolderType == SpecialFolderType.Junk;

    public bool IsImageRenderingDisabled
    {
        get
        {
            if (IsJunkMail)
            {
                return !forceImageLoading;
            }
            else
            {
                return !CurrentRenderModel?.MailRenderingOptions?.LoadImages ?? false;
            }
        }
    }

    private bool isDarkWebviewRenderer;
    public bool IsDarkWebviewRenderer
    {
        get => isDarkWebviewRenderer;
        set
        {
            if (SetProperty(ref isDarkWebviewRenderer, value))
            {
                InitializeCommandBarItems();
            }
        }
    }

    [ObservableProperty]
    [NotifyPropertyChangedFor(nameof(ShouldDisplayDownloadProgress))]
    public partial bool IsIndetermineProgress { get; set; }

    [ObservableProperty]
    [NotifyPropertyChangedFor(nameof(ShouldDisplayDownloadProgress))]
    public partial double CurrentDownloadPercentage { get; set; }

    [ObservableProperty]
    [NotifyPropertyChangedFor(nameof(CanUnsubscribe))]
    public partial MailRenderModel CurrentRenderModel { get; set; }

    [ObservableProperty]
    public partial string Subject { get; set; }

    [ObservableProperty]
    public partial string FromAddress { get; set; }

    [ObservableProperty]
    public partial string FromName { get; set; }

    [ObservableProperty]
    public partial string ContactPicture { get; set; }

    [ObservableProperty]
    public partial DateTime CreationDate { get; set; }
    public ObservableCollection<AccountContactViewModel> ToItems { get; set; } = [];
    public ObservableCollection<AccountContactViewModel> CcItems { get; set; } = [];
    public ObservableCollection<AccountContactViewModel> BccItems { get; set; } = [];
    public ObservableCollection<MailAttachmentViewModel> Attachments { get; set; } = [];
    public ObservableCollection<MailOperationMenuItem> MenuItems { get; set; } = [];

    #endregion

    public INativeAppService NativeAppService { get; }
    public IStatePersistanceService StatePersistenceService { get; }
    public IPreferencesService PreferencesService { get; }
    public IPrintService PrintService { get; }

    public MailRenderingPageViewModel(IMailDialogService dialogService,
                                      INativeAppService nativeAppService,
                                      IUnderlyingThemeService underlyingThemeService,
                                      IMimeFileService mimeFileService,
                                      IMailService mailService,
                                      IFileService fileService,
                                      IWinoRequestDelegator requestDelegator,
                                      IStatePersistanceService statePersistenceService,
                                      IContactService contactService,
                                      IClipboardService clipboardService,
                                      IUnsubscriptionService unsubscriptionService,
                                      IPreferencesService preferencesService,
                                      IPrintService printService,
                                      IApplicationConfiguration applicationConfiguration,
                                      IWinoServerConnectionManager winoServerConnectionManager)
    {
        _dialogService = dialogService;
        NativeAppService = nativeAppService;
        StatePersistenceService = statePersistenceService;
        _contactService = contactService;
        PreferencesService = preferencesService;
        PrintService = printService;
        _applicationConfiguration = applicationConfiguration;
        _winoServerConnectionManager = winoServerConnectionManager;
        _clipboardService = clipboardService;
        _unsubscriptionService = unsubscriptionService;
        _underlyingThemeService = underlyingThemeService;
        _mimeFileService = mimeFileService;
        _mailService = mailService;
        _fileService = fileService;
        _requestDelegator = requestDelegator;
    }

    [RelayCommand]
    private async Task CopyClipboard(string copyText)
    {
        try
        {
            await _clipboardService.CopyClipboardAsync(copyText);

            _dialogService.InfoBarMessage(Translator.ClipboardTextCopied_Title, string.Format(Translator.ClipboardTextCopied_Message, copyText), InfoBarMessageType.Information);
        }
        catch (Exception)
        {
            _dialogService.InfoBarMessage(Translator.GeneralTitle_Error, string.Format(Translator.ClipboardTextCopyFailed_Message, copyText), InfoBarMessageType.Error);
        }
    }

    [RelayCommand]
    private async Task ForceImageLoading()
    {
        if (initializedMailItemViewModel == null && initializedMimeMessageInformation == null) return;

        await RenderAsync(initializedMimeMessageInformation, ignoreJunkFilter: true);
    }

    [RelayCommand]
    private async Task UnsubscribeAsync()
    {
        if (!(CurrentRenderModel?.UnsubscribeInfo?.CanUnsubscribe ?? false)) return;

        bool confirmed;

        // Try to unsubscribe by http first.
        if (CurrentRenderModel.UnsubscribeInfo.HttpLink is not null)
        {
            if (!Uri.IsWellFormedUriString(CurrentRenderModel.UnsubscribeInfo.HttpLink, UriKind.RelativeOrAbsolute))
            {
                _dialogService.InfoBarMessage(Translator.Info_UnsubscribeLinkInvalidTitle, Translator.Info_UnsubscribeLinkInvalidMessage, InfoBarMessageType.Error);
                return;
            }

            // Support for List-Unsubscribe-Post header. It can be done without launching browser.
            // https://datatracker.ietf.org/doc/html/rfc8058
            if (CurrentRenderModel.UnsubscribeInfo.IsOneClick)
            {
                confirmed = await _dialogService.ShowConfirmationDialogAsync(string.Format(Translator.DialogMessage_UnsubscribeConfirmationOneClickMessage, FromName), Translator.DialogMessage_UnsubscribeConfirmationTitle, Translator.Unsubscribe);
                if (!confirmed) return;

                bool isOneClickUnsubscribed = await _unsubscriptionService.OneClickUnsubscribeAsync(CurrentRenderModel.UnsubscribeInfo);

                if (isOneClickUnsubscribed)
                {
                    _dialogService.InfoBarMessage(Translator.Unsubscribe, string.Format(Translator.Info_UnsubscribeSuccessMessage, FromName), InfoBarMessageType.Success);
                }
                else
                {
                    _dialogService.InfoBarMessage(Translator.GeneralTitle_Error, Translator.Info_UnsubscribeErrorMessage, InfoBarMessageType.Error);
                }
            }
            else
            {
                confirmed = await _dialogService.ShowConfirmationDialogAsync(string.Format(Translator.DialogMessage_UnsubscribeConfirmationGoToWebsiteMessage, FromName), Translator.DialogMessage_UnsubscribeConfirmationTitle, Translator.DialogMessage_UnsubscribeConfirmationGoToWebsiteConfirmButton);
                if (!confirmed) return;

                await NativeAppService.LaunchUriAsync(new Uri(CurrentRenderModel.UnsubscribeInfo.HttpLink));
            }
        }
        else if (CurrentRenderModel.UnsubscribeInfo.MailToLink is not null)
        {
            confirmed = await _dialogService.ShowConfirmationDialogAsync(string.Format(Translator.DialogMessage_UnsubscribeConfirmationMailtoMessage, FromName, new string(CurrentRenderModel.UnsubscribeInfo.MailToLink.Skip(7).ToArray())), Translator.DialogMessage_UnsubscribeConfirmationTitle, Translator.Unsubscribe);

            if (!confirmed) return;

            // TODO: Implement automatic mail send after user confirms the action.
            // Currently it will launch compose page and user should manually press send button.
            await NativeAppService.LaunchUriAsync(new Uri(CurrentRenderModel.UnsubscribeInfo.MailToLink));
        }
    }

    [RelayCommand]
    private async Task OperationClicked(MailOperationMenuItem menuItem)
    {
        if (menuItem == null) return;

        await HandleMailOperationAsync(menuItem.Operation);
    }

    private async Task HandleMailOperationAsync(MailOperation operation)
    {
        // Toggle theme
        if (operation == MailOperation.DarkEditor || operation == MailOperation.LightEditor)
            IsDarkWebviewRenderer = !IsDarkWebviewRenderer;
        else if (operation == MailOperation.SaveAs)
        {
            await SaveAsAsync();
        }
        else if (operation == MailOperation.Print)
        {
            await PrintAsync();
        }
        else if (operation == MailOperation.ViewMessageSource)
        {
            await _dialogService.ShowMessageSourceDialogAsync(initializedMimeMessageInformation.MimeMessage.ToString());
        }
        else if (operation == MailOperation.Reply || operation == MailOperation.ReplyAll || operation == MailOperation.Forward)
        {
            if (initializedMailItemViewModel == null) return;

            // Create new draft.
            var draftOptions = new DraftCreationOptions()
            {
                Reason = operation switch
                {
                    MailOperation.Reply => DraftCreationReason.Reply,
                    MailOperation.ReplyAll => DraftCreationReason.ReplyAll,
                    MailOperation.Forward => DraftCreationReason.Forward,
                    _ => DraftCreationReason.Empty
                },
                ReferencedMessage = new ReferencedMessage()
                {
                    MimeMessage = initializedMimeMessageInformation.MimeMessage,
                    MailCopy = initializedMailItemViewModel.MailCopy
                }
            };

            var (draftMailCopy, draftBase64MimeMessage) = await _mailService.CreateDraftAsync(initializedMailItemViewModel.AssignedAccount.Id, draftOptions).ConfigureAwait(false);

            var draftPreparationRequest = new DraftPreparationRequest(initializedMailItemViewModel.AssignedAccount, draftMailCopy, draftBase64MimeMessage, draftOptions.Reason, initializedMailItemViewModel.MailCopy);

            await _requestDelegator.ExecuteAsync(draftPreparationRequest);

        }
        else if (initializedMailItemViewModel != null)
        {
            // All other operations require a mail item.
            var prepRequest = new MailOperationPreperationRequest(operation, initializedMailItemViewModel.MailCopy);
            await _requestDelegator.ExecuteAsync(prepRequest);
        }
    }

    private CancellationTokenSource renderCancellationTokenSource = new CancellationTokenSource();

    public override async void OnNavigatedTo(NavigationMode mode, object parameters)
    {
        base.OnNavigatedTo(mode, parameters);

        renderCancellationTokenSource.Cancel();

        initializedMailItemViewModel = null;
        initializedMimeMessageInformation = null;

        // Dispose existing content first.
        Messenger.Send(new CancelRenderingContentRequested());

        // This page can be accessed for 2 purposes.
        // 1. Rendering a mail item when the user selects.
        // 2. Rendering an existing EML file with MimeMessage.

        // MimeMessage rendering must be readonly and no command bar items must be shown except common
        // items like dark/light editor, zoom, print etc.

        // Configure common rendering properties first.
        IsDarkWebviewRenderer = _underlyingThemeService.IsUnderlyingThemeDark();

        renderCancellationTokenSource = new CancellationTokenSource();

        // Mime content might not be available for now and might require a download.
        try
        {
            if (parameters is MailItemViewModel selectedMailItemViewModel)
                await RenderAsync(selectedMailItemViewModel, renderCancellationTokenSource.Token);
            else if (parameters is MimeMessageInformation mimeMessageInformation)
                await RenderAsync(mimeMessageInformation);

            InitializeCommandBarItems();
        }
        catch (OperationCanceledException)
        {
            Log.Information("Canceled mail rendering.");
        }
        catch (Exception ex)
        {
            _dialogService.InfoBarMessage(Translator.Info_MailRenderingFailedTitle, string.Format(Translator.Info_MailRenderingFailedMessage, ex.Message), InfoBarMessageType.Error);

            Log.Error(ex, "Failed to render mail.");
        }
    }

    private async Task HandleSingleItemDownloadAsync(MailItemViewModel mailItemViewModel)
    {
        try
        {
            // To show the progress on the UI.
            CurrentDownloadPercentage = 1;

            var package = new DownloadMissingMessageRequested(mailItemViewModel.AssignedAccount.Id, mailItemViewModel.MailCopy);
            await _winoServerConnectionManager.GetResponseAsync<bool, DownloadMissingMessageRequested>(package);
        }
        catch (OperationCanceledException)
        {
            Log.Information("MIME download is canceled.");
        }
        catch (Exception ex)
        {
            _dialogService.InfoBarMessage(Translator.GeneralTitle_Error, ex.Message, InfoBarMessageType.Error);
        }
        finally
        {
            ResetProgress();
        }
    }

    private async Task RenderAsync(MailItemViewModel mailItemViewModel, CancellationToken cancellationToken = default)
    {
        ResetProgress();
        var isMimeExists = await _mimeFileService.IsMimeExistAsync(mailItemViewModel.AssignedAccount.Id, mailItemViewModel.MailCopy.FileId);

        if (!isMimeExists)
        {
            await HandleSingleItemDownloadAsync(mailItemViewModel);
        }

        // Find the MIME for this item and render it.
        var mimeMessageInformation = await _mimeFileService.GetMimeMessageInformationAsync(mailItemViewModel.MailCopy.FileId,
                                                                                           mailItemViewModel.AssignedAccount.Id,
                                                                                           cancellationToken).ConfigureAwait(false);

        if (mimeMessageInformation == null)
        {
            _dialogService.InfoBarMessage(Translator.Info_MessageCorruptedTitle, Translator.Info_MessageCorruptedMessage, InfoBarMessageType.Error);
            return;
        }

        initializedMailItemViewModel = mailItemViewModel;
        await RenderAsync(mimeMessageInformation);
    }

    private async Task RenderAsync(MimeMessageInformation mimeMessageInformation, bool ignoreJunkFilter = false)
    {
        forceImageLoading = ignoreJunkFilter;

        var message = mimeMessageInformation.MimeMessage;
        var messagePath = mimeMessageInformation.Path;

        initializedMimeMessageInformation = mimeMessageInformation;

        // TODO: Handle S/MIME decryption.
        // initializedMimeMessageInformation.MimeMessage.Body is MultipartSigned

        var renderingOptions = PreferencesService.GetRenderingOptions();

        // Prepare account contacts info in advance, to avoid UI shifts after clearing collections.
        var toAccountContacts = await GetAccountContacts(message.To);
        var ccAccountContacts = await GetAccountContacts(message.Cc);
        var bccAccountContacts = await GetAccountContacts(message.Bcc);

        await ExecuteUIThread(() =>
        {
            Attachments.Clear();
            ToItems.Clear();
            CcItems.Clear();
            BccItems.Clear();

            foreach (var item in toAccountContacts)
                ToItems.Add(item);
            foreach (var item in ccAccountContacts)
                CcItems.Add(item);
            foreach (var item in bccAccountContacts)
                BccItems.Add(item);

            Subject = string.IsNullOrWhiteSpace(message.Subject) ? Translator.MailItemNoSubject : message.Subject;

            // TODO: FromName and FromAddress is probably not correct here for mail lists.
            FromAddress = message.From.Mailboxes.FirstOrDefault()?.Address ?? Translator.UnknownAddress;
            FromName = message.From.Mailboxes.FirstOrDefault()?.Name ?? Translator.UnknownSender;
            CreationDate = message.Date.DateTime;
            ContactPicture = initializedMailItemViewModel?.SenderContact?.Base64ContactPicture;

            // Automatically disable images for Junk folder to prevent pixel tracking.
            // This can only work for selected mail item rendering, not for EML file rendering.
            if (initializedMailItemViewModel != null &&
                initializedMailItemViewModel.AssignedFolder.SpecialFolderType == SpecialFolderType.Junk)
            {
                renderingOptions.LoadImages = false;
            }

            // Load images if forced.
            if (ignoreJunkFilter)
            {
                renderingOptions.LoadImages = true;
            }

            CurrentRenderModel = _mimeFileService.GetMailRenderModel(message, messagePath, renderingOptions);

            Messenger.Send(new HtmlRenderingRequested(CurrentRenderModel.RenderHtml));

            foreach (var attachment in CurrentRenderModel.Attachments)
            {
                Attachments.Add(new MailAttachmentViewModel(attachment));
            }

            OnPropertyChanged(nameof(IsImageRenderingDisabled));

            StatePersistenceService.IsReadingMail = true;
        });
    }

    private async Task<List<AccountContactViewModel>> GetAccountContacts(InternetAddressList internetAddresses)
    {
        List<AccountContactViewModel> accounts = [];
        foreach (var item in internetAddresses)
        {
            if (item is MailboxAddress mailboxAddress)
            {
                var foundContact = await _contactService.GetAddressInformationByAddressAsync(mailboxAddress.Address).ConfigureAwait(false)
                    ?? new AccountContact() { Name = mailboxAddress.Name, Address = mailboxAddress.Address };

                var contactViewModel = new AccountContactViewModel(foundContact);

                // Make sure that user account first in the list.
                if (string.Equals(contactViewModel.Address, initializedMailItemViewModel?.AssignedAccount?.Address, StringComparison.OrdinalIgnoreCase))
                {
                    contactViewModel.IsMe = true;
                    accounts.Insert(0, contactViewModel);
                }
                else
                {
                    accounts.Add(contactViewModel);
                }
            }
            else if (item is GroupAddress groupAddress)
            {
                accounts.AddRange(await GetAccountContacts(groupAddress.Members));
            }
        }

        if (accounts.Count > 0)
            accounts[^1].IsSemicolon = false;

        return accounts;
    }

    public override void OnNavigatedFrom(NavigationMode mode, object parameters)
    {
        base.OnNavigatedFrom(mode, parameters);

        renderCancellationTokenSource.Cancel();
        CurrentDownloadPercentage = 0d;

        initializedMailItemViewModel = null;
        initializedMimeMessageInformation = null;

        forceImageLoading = false;

        StatePersistenceService.IsReadingMail = false;
    }

    private void ResetProgress()
    {
        CurrentDownloadPercentage = 0;
        IsIndetermineProgress = false;
    }

    private void InitializeCommandBarItems()
    {
        MenuItems.Clear();

        // Add light/dark editor theme switch.
        if (IsDarkWebviewRenderer)
            MenuItems.Add(MailOperationMenuItem.Create(MailOperation.LightEditor));
        else
            MenuItems.Add(MailOperationMenuItem.Create(MailOperation.DarkEditor));

        // Save As PDF
        MenuItems.Add(MailOperationMenuItem.Create(MailOperation.SaveAs, true, true));

        // Print
        MenuItems.Add(MailOperationMenuItem.Create(MailOperation.Print, true, true));

        if (initializedMailItemViewModel == null)
            return;

        MenuItems.Add(MailOperationMenuItem.Create(MailOperation.Seperator));

        // You can't do these to draft items.
        if (!initializedMailItemViewModel.IsDraft)
        {
            // Reply
            MenuItems.Add(MailOperationMenuItem.Create(MailOperation.Reply));

            // Reply All
            MenuItems.Add(MailOperationMenuItem.Create(MailOperation.ReplyAll));

            // Forward
            MenuItems.Add(MailOperationMenuItem.Create(MailOperation.Forward));
        }

        if (initializedMimeMessageInformation?.MimeMessage != null)
        {
            MenuItems.Add(MailOperationMenuItem.Create(MailOperation.ViewMessageSource, true, true));
        }

        // Archive - Unarchive
        if (initializedMailItemViewModel.AssignedFolder.SpecialFolderType == SpecialFolderType.Archive)
            MenuItems.Add(MailOperationMenuItem.Create(MailOperation.UnArchive));
        else
            MenuItems.Add(MailOperationMenuItem.Create(MailOperation.Archive));

        // Delete
        MenuItems.Add(MailOperationMenuItem.Create(MailOperation.SoftDelete));

        // Flag - Clear Flag
        if (initializedMailItemViewModel.IsFlagged)
            MenuItems.Add(MailOperationMenuItem.Create(MailOperation.ClearFlag));
        else
            MenuItems.Add(MailOperationMenuItem.Create(MailOperation.SetFlag));

        // Secondary items.

        // Read - Unread
        if (initializedMailItemViewModel.IsRead)
            MenuItems.Add(MailOperationMenuItem.Create(MailOperation.MarkAsUnread, true, false));
        else
            MenuItems.Add(MailOperationMenuItem.Create(MailOperation.MarkAsRead, true, false));
    }

    protected override async void OnMailUpdated(MailCopy updatedMail)
    {
        base.OnMailUpdated(updatedMail);

        if (initializedMailItemViewModel == null) return;

        // Check if the updated mail is the same mail item we are rendering.
        // This is done with UniqueId to include FolderId into calculations.
        if (initializedMailItemViewModel.UniqueId != updatedMail.UniqueId) return;

        // Mail operation might change the mail item like mark read/unread or change flag.
        // So we need to update the mail item view model when this happens.
        // Also command bar items must be re-initialized since the items loaded based on the mail item.

        await ExecuteUIThread(() => { InitializeCommandBarItems(); });
    }

    [RelayCommand]
    private async Task OpenAttachmentAsync(MailAttachmentViewModel attachmentViewModel)
    {
        try
        {
            var fileFolderPath = Path.Combine(initializedMimeMessageInformation.Path, attachmentViewModel.FileName);
            var directoryInfo = new DirectoryInfo(initializedMimeMessageInformation.Path);

            var fileExists = File.Exists(fileFolderPath);

            if (!fileExists)
                await SaveAttachmentInternalAsync(attachmentViewModel, initializedMimeMessageInformation.Path);

            await LaunchFileInternalAsync(fileFolderPath);
        }
        catch (Exception ex)
        {
            Log.Error(ex, "Failed to open attachment.");

            _dialogService.InfoBarMessage(Translator.Info_AttachmentOpenFailedTitle, Translator.Info_AttachmentOpenFailedMessage, InfoBarMessageType.Error);
        }
    }

    [RelayCommand]
    private async Task SaveAttachmentAsync(MailAttachmentViewModel attachmentViewModel)
    {
        if (attachmentViewModel == null)
            return;

        try
        {
            attachmentViewModel.IsBusy = true;

            var pickedPath = await _dialogService.PickWindowsFolderAsync();

            if (string.IsNullOrEmpty(pickedPath)) return;

            await SaveAttachmentInternalAsync(attachmentViewModel, pickedPath);

            _dialogService.InfoBarMessage(Translator.Info_AttachmentSaveSuccessTitle, Translator.Info_AttachmentSaveSuccessMessage, InfoBarMessageType.Success);
        }
        catch (Exception ex)
        {
            Log.Error(ex, "Failed to save attachment.");

            _dialogService.InfoBarMessage(Translator.Info_AttachmentSaveFailedTitle, Translator.Info_AttachmentSaveFailedMessage, InfoBarMessageType.Error);
        }
        finally
        {
            attachmentViewModel.IsBusy = false;
        }
    }

    [RelayCommand]
    private async Task SaveAllAttachmentsAsync()
    {
        var pickedPath = await _dialogService.PickWindowsFolderAsync();

        if (string.IsNullOrEmpty(pickedPath)) return;

        try
        {

            foreach (var attachmentViewModel in Attachments)
            {
                await SaveAttachmentInternalAsync(attachmentViewModel, pickedPath);
            }

            _dialogService.InfoBarMessage(Translator.Info_AttachmentSaveSuccessTitle, Translator.Info_AttachmentSaveSuccessMessage, InfoBarMessageType.Success);
        }
        catch (Exception ex)
        {
            Log.Error(ex, "Failed to save attachment.");

            _dialogService.InfoBarMessage(Translator.Info_AttachmentSaveFailedTitle, Translator.Info_AttachmentSaveFailedMessage, InfoBarMessageType.Error);
        }
    }

    private async Task PrintAsync()
    {
        // Printing:
        // 1. Let WebView2 save the current HTML as PDF to temporary location.
        // 2. Saving as PDF will divide pages correctly for Win2D CanvasBitmap.
        // 3. Use Win2D CanvasBitmap as IPrintDocumentSource and WinRT APIs to print the PDF.

        try
        {
            var printFilePath = Path.Combine(_applicationConfiguration.ApplicationTempFolderPath, "print.pdf");

            if (File.Exists(printFilePath)) File.Delete(printFilePath);

            await SaveHTMLasPDFFunc(printFilePath);

            var result = await PrintService.PrintPdfFileAsync(printFilePath, Subject);

            if (result == PrintingResult.Submitted)
            {
                _dialogService.InfoBarMessage(Translator.DialogMessage_PrintingSuccessTitle, Translator.DialogMessage_PrintingSuccessMessage, InfoBarMessageType.Success);
            }
            else if (result != PrintingResult.Canceled)
            {
                var message = string.Format(Translator.DialogMessage_PrintingFailedMessage, result);
                _dialogService.InfoBarMessage(Translator.DialogMessage_PrintingFailedTitle, message, InfoBarMessageType.Warning);
            }
        }
        catch (Exception ex)
        {
            Log.Error(ex, "Failed to print mail.");
            _dialogService.InfoBarMessage(string.Empty, ex.Message, InfoBarMessageType.Error);
        }
    }

    private async Task SaveAsAsync()
    {
        try
        {
            var pickedFolder = await _dialogService.PickWindowsFolderAsync();

            if (string.IsNullOrEmpty(pickedFolder)) return;

            var pdfFilePath = Path.Combine(pickedFolder, $"{initializedMailItemViewModel.FromAddress}.pdf");

            bool isSaved = await SaveHTMLasPDFFunc(pdfFilePath);

            if (isSaved)
            {
                _dialogService.InfoBarMessage(Translator.Info_PDFSaveSuccessTitle,
                                              string.Format(Translator.Info_PDFSaveSuccessMessage, pdfFilePath),
                                              InfoBarMessageType.Success);
            }
        }
        catch (Exception ex)
        {
            Log.Error(ex, "Failed to save as PDF.");
            _dialogService.InfoBarMessage(Translator.Info_PDFSaveFailedTitle, ex.Message, InfoBarMessageType.Error);
        }
    }

    // Returns created file path.
    private async Task<string> SaveAttachmentInternalAsync(MailAttachmentViewModel attachmentViewModel, string saveFolderPath)
    {
        var fullFilePath = Path.Combine(saveFolderPath, attachmentViewModel.FileName);
        var stream = await _fileService.GetFileStreamAsync(saveFolderPath, attachmentViewModel.FileName);

        using (stream)
        {
            await attachmentViewModel.MimeContent.DecodeToAsync(stream);
        }

        return fullFilePath;
    }

    private async Task LaunchFileInternalAsync(string filePath)
    {
        try
        {
            await NativeAppService.LaunchFileAsync(filePath);
        }
        catch (Exception ex)
        {
            _dialogService.InfoBarMessage(Translator.Info_FileLaunchFailedTitle, ex.Message, InfoBarMessageType.Error);
        }
    }

    void ITransferProgress.Report(long bytesTransferred, long totalSize)
        => _ = ExecuteUIThread(() => { CurrentDownloadPercentage = bytesTransferred * 100 / Math.Max(1, totalSize); });

    // For upload.
    void ITransferProgress.Report(long bytesTransferred) { }

    public async void Receive(NewMailItemRenderingRequestedEvent message)
    {
        try
        {
            await RenderAsync(message.MailItemViewModel, renderCancellationTokenSource.Token);
        }
        catch (OperationCanceledException)
        {
            Log.Information("Canceled mail rendering.");
        }
        catch (Exception ex)
        {
            _dialogService.InfoBarMessage(Translator.Info_MailRenderingFailedTitle, string.Format(Translator.Info_MailRenderingFailedMessage, ex.Message), InfoBarMessageType.Error);

            Log.Error(ex, "Failed to render mail.");
        }
    }

    public void Receive(ThumbnailAdded message)
    {
        UpdateThumbnails(ToItems, message.Email);
        UpdateThumbnails(CcItems, message.Email);
        UpdateThumbnails(BccItems, message.Email);
    }

    private void UpdateThumbnails(ObservableCollection<AccountContactViewModel> items, string email)
    {
        if (Dispatcher == null || items.Count == 0) return;

        Dispatcher.ExecuteOnUIThread(() =>
        {
            foreach (var item in items)
            {
                if (item.Address.Equals(email, StringComparison.OrdinalIgnoreCase))
                {
                    item.ThumbnailUpdatedEvent = !item.ThumbnailUpdatedEvent;
                }
            }
        });
    }
}