Add audible locale setting.

Rename DomainServices => ScrapingDomainServices

ScrapingDomainServices/UNTESTED/IProcessableExt.cs

@@ -0,0 +1,53 @@
+using System;
+using System.Threading.Tasks;
+using DataLayer;
+using Dinah.Core.ErrorHandling;
+
+namespace DomainServices
+{
+    public static class IProcessableExt
+    {
+        //
+        // DO NOT USE ConfigureAwait(false) WITH ProcessAsync() unless ensuring ProcessAsync() implementation is cross-thread compatible
+        // - ValidateAsync() doesn't need UI context. however, each class already uses ConfigureAwait(false)
+        // - ProcessAsync() often does a lot with forms in the UI context
+        //
+
+
+        /// <summary>Process the first valid product. Create default context</summary>
+        /// <returns>Returns either the status handler from the process, or null if all books have been processed</returns>
+        public static async Task<StatusHandler> ProcessFirstValidAsync(this IProcessable processable)
+        {
+            var libraryBook = await processable.GetNextValidAsync();
+            if (libraryBook == null)
+                return null;
+
+            var status = await processable.ProcessAsync(libraryBook);
+            if (status == null)
+                throw new Exception("Processable should never return a null status");
+
+            return status;
+        }
+
+        // i'd love to turn this into Task<IEnumerable<LibraryBook>>
+        // since enumeration is a blocking operation, this won't be possible until
+        // 2019's C# 8 async streams, aka async enumerables, aka async iterators: https://blogs.msdn.microsoft.com/dotnet/2018/11/12/building-c-8-0/
+        public static async Task<LibraryBook> GetNextValidAsync(this IProcessable processable)
+        {
+            var libraryBooks = LibraryQueries.GetLibrary_Flat_NoTracking();
+
+            foreach (var libraryBook in libraryBooks)
+                if (await processable.ValidateAsync(libraryBook))
+                    return libraryBook;
+
+            return null;
+        }
+
+        public static async Task<StatusHandler> ProcessValidateLibraryBookAsync(this IProcessable processable, LibraryBook libraryBook)
+        {
+            if (!await processable.ValidateAsync(libraryBook))
+                return new StatusHandler { "Validation failed" };
+            return await processable.ProcessAsync(libraryBook);
+        }
+    }
+}