New attachment templates that support saving and opening attachment when composing message.

Wino.Core.Domain/Interfaces/IDialogServiceBase.cs

@@ -3,6 +3,7 @@ using System.Collections.Generic;
 using System.Threading.Tasks;
 using Wino.Core.Domain.Enums;
 using Wino.Core.Domain.Models.Accounts;
+using Wino.Core.Domain.Models.Common;
 
 namespace Wino.Core.Domain.Interfaces
 {
@@ -25,5 +26,7 @@ namespace Wino.Core.Domain.Interfaces
         Task<bool> ShowCustomThemeBuilderDialogAsync();
         Task<AccountCreationDialogResult> ShowAccountProviderSelectionDialogAsync(List<IProviderDetail> availableProviders);
         IAccountCreationDialog GetAccountCreationDialog(MailProviderType type);
+        Task<List<SharedFile>> PickFilesAsync(params object[] typeFilters);
+        Task<string> PickFilePathAsync(string saveFileName);
     }
 }

Wino.Core.Domain/Models/Common/SharedFile.cs

@@ -0,0 +1,14 @@
+using System.IO;
+
+namespace Wino.Core.Domain.Models.Common
+{
+    /// <summary>
+    /// Abstraction for StorageFile
+    /// </summary>
+    /// <param name="FullFilePath">Full path of the file.</param>
+    /// <param name="Data">Content</param>
+    public record SharedFile(string FullFilePath, byte[] Data)
+    {
+        public string FileName => Path.GetFileName(FullFilePath);
+    }
+}

Wino.Core.Domain/Translations/en_US/resources.json

@@ -261,6 +261,8 @@
     "Info_BackgroundExecutionDeniedTitle": "Denied Background Execution",
     "Info_BackgroundExecutionUnknownErrorMessage": "Unknown exception occurred when registering background synchronizer.",
     "Info_BackgroundExecutionUnknownErrorTitle": "Background Execution Failure",
+    "Info_FailedToOpenFileTitle": "Failed to launch file.",
+    "Info_FailedToOpenFileMessage": "File might be removed from the disk.",
     "Info_ComposerMissingMIMEMessage": "Couldn't locate the MIME file. Synchronizing may help.",
     "Info_ComposerMissingMIMETitle": "Failed",
     "Info_ContactExistsMessage": "This contact is already in the recipient list.",