Move source code into "Source" folder

Source/AaxDecrypter/AudiobookDownloadBase.cs

@@ -0,0 +1,184 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using Dinah.Core;
+using Dinah.Core.Net.Http;
+using Dinah.Core.StepRunner;
+using FileManager;
+
+namespace AaxDecrypter
+{
+	public enum OutputFormat { M4b, Mp3 }
+
+	public abstract class AudiobookDownloadBase
+	{
+		public event EventHandler<string> RetrievedTitle;
+		public event EventHandler<string> RetrievedAuthors;
+		public event EventHandler<string> RetrievedNarrators;
+		public event EventHandler<byte[]> RetrievedCoverArt;
+		public event EventHandler<DownloadProgress> DecryptProgressUpdate;
+		public event EventHandler<TimeSpan> DecryptTimeRemaining;
+		public event EventHandler<string> FileCreated;
+
+		protected bool IsCanceled { get; set; }
+		
+		protected string OutputFileName { get; private set; }
+		protected DownloadOptions DownloadOptions { get; }
+		protected NetworkFileStream InputFileStream => (nfsPersister ??= OpenNetworkFileStream()).NetworkFileStream;
+
+		// Don't give the property a 'set'. This should have to be an obvious choice; not accidental
+		protected void SetOutputFileName(string newOutputFileName) => OutputFileName = newOutputFileName;
+
+		protected abstract StepSequence Steps { get; }
+		private NetworkFileStreamPersister nfsPersister;
+
+		private string jsonDownloadState { get; }
+		public string TempFilePath { get; }
+
+		protected AudiobookDownloadBase(string outFileName, string cacheDirectory, DownloadOptions dlLic)
+		{
+			OutputFileName = ArgumentValidator.EnsureNotNullOrWhiteSpace(outFileName, nameof(outFileName));
+
+			var outDir = Path.GetDirectoryName(OutputFileName);
+			if (!Directory.Exists(outDir))
+				throw new DirectoryNotFoundException($"Directory does not exist: {nameof(outDir)}");
+
+			if (!Directory.Exists(cacheDirectory))
+				throw new DirectoryNotFoundException($"Directory does not exist: {nameof(cacheDirectory)}");
+
+			jsonDownloadState = Path.Combine(cacheDirectory, Path.GetFileName(Path.ChangeExtension(OutputFileName, ".json")));
+			TempFilePath = Path.ChangeExtension(jsonDownloadState, ".aaxc");
+
+			DownloadOptions = ArgumentValidator.EnsureNotNull(dlLic, nameof(dlLic));
+
+			// delete file after validation is complete
+			FileUtility.SaferDelete(OutputFileName);
+		}
+
+		public abstract void Cancel();
+
+		public virtual void SetCoverArt(byte[] coverArt)
+		{
+			if (coverArt is not null)
+				OnRetrievedCoverArt(coverArt);
+		}
+
+		public bool Run()
+		{
+			var (IsSuccess, Elapsed) = Steps.Run();
+
+			if (!IsSuccess)
+				Serilog.Log.Logger.Error("Conversion failed");
+
+			return IsSuccess;
+		}
+
+		protected void OnRetrievedTitle(string title)
+			=> RetrievedTitle?.Invoke(this, title);
+		protected void OnRetrievedAuthors(string authors)
+			=> RetrievedAuthors?.Invoke(this, authors);
+		protected void OnRetrievedNarrators(string narrators)
+			=> RetrievedNarrators?.Invoke(this, narrators);
+
+		protected void OnRetrievedCoverArt(byte[] coverArt)
+			=> RetrievedCoverArt?.Invoke(this, coverArt);
+
+		protected void OnDecryptProgressUpdate(DownloadProgress downloadProgress) 
+			=> DecryptProgressUpdate?.Invoke(this, downloadProgress);
+		protected void OnDecryptTimeRemaining(TimeSpan timeRemaining)
+			=> DecryptTimeRemaining?.Invoke(this, timeRemaining);
+		protected void OnFileCreated(string path)
+			=> FileCreated?.Invoke(this, path);
+
+		protected void CloseInputFileStream()
+		{
+			nfsPersister?.NetworkFileStream?.Close();
+			nfsPersister?.Dispose();
+		}
+
+		protected bool Step_CreateCue()
+		{
+			if (!DownloadOptions.CreateCueSheet) return true;
+
+			// not a critical step. its failure should not prevent future steps from running
+			try
+			{
+				var path = Path.ChangeExtension(OutputFileName, ".cue");
+				path = FileUtility.GetValidFilename(path);
+				File.WriteAllText(path, Cue.CreateContents(Path.GetFileName(OutputFileName), DownloadOptions.ChapterInfo));
+				OnFileCreated(path);
+			}
+			catch (Exception ex)
+			{
+				Serilog.Log.Logger.Error(ex, $"{nameof(Step_CreateCue)}. FAILED");
+			}
+			return !IsCanceled;
+		}
+
+		protected bool Step_Cleanup()
+		{
+			bool success = !IsCanceled;
+			if (success)
+			{
+				FileUtility.SaferDelete(jsonDownloadState);
+
+				if (DownloadOptions.AudibleKey is not null && 
+					DownloadOptions.AudibleIV is not null && 
+					DownloadOptions.RetainEncryptedFile)
+				{
+					string aaxPath = Path.ChangeExtension(TempFilePath, ".aax");
+					FileUtility.SaferMove(TempFilePath, aaxPath);
+
+					//Write aax decryption key
+					string keyPath = Path.ChangeExtension(aaxPath, ".key");
+					FileUtility.SaferDelete(keyPath);
+					File.WriteAllText(keyPath, $"Key={DownloadOptions.AudibleKey}\r\nIV={DownloadOptions.AudibleIV}");
+
+					OnFileCreated(aaxPath);
+					OnFileCreated(keyPath);
+				}
+				else
+					FileUtility.SaferDelete(TempFilePath);
+			}
+			else
+			{
+				FileUtility.SaferDelete(OutputFileName);
+			}
+
+
+			return success;
+		}
+
+		private NetworkFileStreamPersister OpenNetworkFileStream()
+		{
+			if (!File.Exists(jsonDownloadState))
+				return NewNetworkFilePersister();
+
+			try
+			{
+				var nfsp = new NetworkFileStreamPersister(jsonDownloadState);
+				// If More than ~1 hour has elapsed since getting the download url, it will expire.
+				// The new url will be to the same file.
+				nfsp.NetworkFileStream.SetUriForSameFile(new Uri(DownloadOptions.DownloadUrl));
+				return nfsp;
+			}
+			catch
+			{
+				FileUtility.SaferDelete(jsonDownloadState);
+				FileUtility.SaferDelete(TempFilePath);
+				return NewNetworkFilePersister();
+			}
+		}
+
+		private NetworkFileStreamPersister NewNetworkFilePersister()
+		{
+			var headers = new System.Net.WebHeaderCollection
+			{
+				{ "User-Agent", DownloadOptions.UserAgent }
+			};
+
+			var networkFileStream = new NetworkFileStream(TempFilePath, new Uri(DownloadOptions.DownloadUrl), 0, headers);
+			return new NetworkFileStreamPersister(networkFileStream, jsonDownloadState);
+		}
+	}
+}