Enough already. I'm obviously not incentivized/shamed into writing unit tests for things in UNTESTED dir.s. It's just making a mess of the file tree

FileLiberator/DownloadableBase.cs

@@ -0,0 +1,64 @@
+using System;
+using System.Threading.Tasks;
+using DataLayer;
+using Dinah.Core.ErrorHandling;
+using Dinah.Core.Net.Http;
+
+namespace FileLiberator
+{
+	public abstract class DownloadableBase : IDownloadableProcessable
+	{
+		public event EventHandler<LibraryBook> Begin;
+		public event EventHandler<LibraryBook> Completed;
+
+		public event EventHandler<string> DownloadBegin;
+		public event EventHandler<DownloadProgress> DownloadProgressChanged;
+		public event EventHandler<string> DownloadCompleted;
+
+		public event EventHandler<string> StatusUpdate;
+		protected void Invoke_StatusUpdate(string message) => StatusUpdate?.Invoke(this, message);
+
+        public abstract bool Validate(LibraryBook libraryBook);
+
+        public abstract Task<StatusHandler> ProcessItemAsync(LibraryBook libraryBook);
+
+		// do NOT use ConfigureAwait(false) on ProcessAsync()
+		// often calls events which prints to forms in the UI context
+		public async Task<StatusHandler> ProcessAsync(LibraryBook libraryBook)
+        {
+            Begin?.Invoke(this, libraryBook);
+
+            try
+            {
+                return await ProcessItemAsync(libraryBook);
+            }
+            finally
+            {
+                Completed?.Invoke(this, libraryBook);
+            }
+        }
+
+		protected static Task<AudibleApi.Api> GetApiAsync(LibraryBook libraryBook)
+			=> InternalUtilities.AudibleApiActions.GetApiAsync(libraryBook.Account, libraryBook.Book.Locale);
+
+		protected async Task<string> PerformDownloadAsync(string proposedDownloadFilePath, Func<Progress<DownloadProgress>, Task<string>> func)
+		{
+			var progress = new Progress<DownloadProgress>();
+			progress.ProgressChanged += (_, e) => DownloadProgressChanged?.Invoke(this, e);
+
+			DownloadBegin?.Invoke(this, proposedDownloadFilePath);
+
+			try
+			{
+				var result = await func(progress);
+				StatusUpdate?.Invoke(this, result);
+
+				return result;
+			}
+			finally
+			{
+				DownloadCompleted?.Invoke(this, proposedDownloadFilePath);
+			}
+		}
+	}
+}