Libation/Source/FileLiberator/DownloadOptions.cs

using AaxDecrypter;
using DataLayer;
using Dinah.Core;
using LibationFileManager;
using LibationFileManager.Templates;
using System;
using System.IO;

namespace FileLiberator;

public partial class DownloadOptions : IDownloadOptions, IDisposable
{
	public event EventHandler<long>? DownloadSpeedChanged;
	public LibraryBook LibraryBook { get; }
	public LibraryBookDto LibraryBookDto { get; }
	public string DownloadUrl { get; }
	public KeyData[]? DecryptionKeys { get; }
	public required TimeSpan RuntimeLength { get; init; }
	public OutputFormat OutputFormat { get; }
	public required Mpeg4Lib.ChapterInfo ChapterInfo { get; init; }
	public string Title => LibraryBook.Book.Title;
	public string Subtitle => LibraryBook.Book.Subtitle;
	public string? Publisher => LibraryBook.Book.Publisher;
	public string? Language => LibraryBook.Book.Language;
	public string AudibleProductId => LibraryBookDto.AudibleProductId;
	public string? SeriesName => LibraryBookDto.FirstSeries?.Name;
	public string? SeriesNumber => LibraryBookDto.FirstSeries?.Order?.ToString();
	public NAudio.Lame.LameConfig? LameConfig { get; }
	public string UserAgent => AudibleApi.Resources.Download_User_Agent;
	public bool StripUnabridged => Config.AllowLibationFixup && Config.StripUnabridged;
	public bool CreateCueSheet => Config.CreateCueSheet;
	public long DownloadSpeedBps => Config.DownloadSpeedLimit;
	public bool FixupFile => Config.AllowLibationFixup;
	public bool Downsample => Config.AllowLibationFixup && Config.LameDownsampleMono;
	public bool MatchSourceBitrate => Config.AllowLibationFixup && Config.LameMatchSourceBR && Config.LameTargetBitrate;
	public bool MoveMoovToBeginning => Config.MoveMoovToBeginning;
	public AAXClean.FileType? InputType { get; }
	public AudibleApi.Common.DrmType DrmType { get; }
	public AudibleApi.Common.ContentMetadata ContentMetadata { get; }

	public string GetMultipartTitle(MultiConvertFileProperties props)
		=> Templates.ChapterTitle.GetName(LibraryBookDto, props);

	public Configuration Config { get; }
	private readonly IDisposable cancellation;
	public void Dispose()
	{
		cancellation?.Dispose();
		GC.SuppressFinalize(this);
	}

	private DownloadOptions(Configuration config, LibraryBook libraryBook, LicenseInfo licInfo)
	{
		Config = ArgumentValidator.EnsureNotNull(config, nameof(config));
		LibraryBook = ArgumentValidator.EnsureNotNull(libraryBook, nameof(libraryBook));

		ArgumentValidator.EnsureNotNull(licInfo, nameof(licInfo));

		if (licInfo.ContentMetadata is not AudibleApi.Common.ContentMetadata contentMetadata)
			throw new InvalidDataException("Content license doesn't contain content metadata");

		if (contentMetadata.ContentUrl?.OfflineUrl is not string licUrl)
			throw new InvalidDataException("Content license doesn't contain an offline Url");

		DownloadUrl = licUrl;
		DecryptionKeys = licInfo.DecryptionKeys;
		DrmType = licInfo.DrmType;
		ContentMetadata = contentMetadata;
		InputType
		= licInfo.DrmType is AudibleApi.Common.DrmType.Widevine ? AAXClean.FileType.Dash
		: licInfo.DrmType is AudibleApi.Common.DrmType.Adrm && licInfo.DecryptionKeys?.Length == 1 && licInfo.DecryptionKeys[0].KeyPart1.Length == 4 && licInfo.DecryptionKeys[0].KeyPart2 is null ? AAXClean.FileType.Aax
		: licInfo.DrmType is AudibleApi.Common.DrmType.Adrm && licInfo.DecryptionKeys?.Length == 1 && licInfo.DecryptionKeys[0].KeyPart1.Length == 16 && licInfo.DecryptionKeys[0].KeyPart2?.Length == 16 ? AAXClean.FileType.Aaxc
		: null;

		//If DrmType is not Adrm or Widevine, the delivered file is an unencrypted mp3.
		OutputFormat
			= licInfo.DrmType is not AudibleApi.Common.DrmType.Adrm and not AudibleApi.Common.DrmType.Widevine ||
			(config.AllowLibationFixup && config.DecryptToLossy)
			? OutputFormat.Mp3
			: OutputFormat.M4b;

		LameConfig = OutputFormat == OutputFormat.Mp3 ? GetLameOptions(config) : null;

		// no null/empty check for key/iv. unencrypted files do not have them
		LibraryBookDto = LibraryBook.ToDto();

		cancellation =
			config
			.ObservePropertyChanged<long>(
				nameof(Configuration.DownloadSpeedLimit),
				newVal => DownloadSpeedChanged?.Invoke(this, newVal));
	}
}