using System;
using System.Threading.Tasks;
using AAXClean;
using Dinah.Core.Net.Http;

namespace AaxDecrypter
{
	public abstract class AaxcDownloadConvertBase : AudiobookDownloadBase
	{
		public event EventHandler<AppleTags> RetrievedMetadata;

		protected AaxFile AaxFile;

		protected AaxcDownloadConvertBase(string outFileName, string cacheDirectory, IDownloadOptions dlOptions)
			: base(outFileName, cacheDirectory, dlOptions) { }

		/// <summary>Setting cover art by this method will insert the art into the audiobook metadata</summary>
		public override void SetCoverArt(byte[] coverArt)
		{
			base.SetCoverArt(coverArt);
			if (coverArt is not null && AaxFile?.AppleTags is not null)
				AaxFile.AppleTags.Cover = coverArt;
		}

		protected bool Step_GetMetadata()
		{
			AaxFile = new AaxFile(InputFileStream);

			if (DownloadOptions.StripUnabridged)
			{
				AaxFile.AppleTags.Title = AaxFile.AppleTags.TitleSansUnabridged;
				AaxFile.AppleTags.Album = AaxFile.AppleTags.Album?.Replace(" (Unabridged)", "");
			}

			//Finishing configuring lame encoder.
			if (DownloadOptions.OutputFormat == OutputFormat.Mp3)
			{
				double bitrateMultiple = 1;

				if (AaxFile.AudioChannels == 2)
				{
					if (DownloadOptions.Downsample)
						bitrateMultiple = 0.5;
					else
						DownloadOptions.LameConfig.Mode = NAudio.Lame.MPEGMode.Stereo;
				}

				if (DownloadOptions.MatchSourceBitrate)
				{
					int kbps = (int)(AaxFile.AverageBitrate * bitrateMultiple / 1024);

					if (DownloadOptions.LameConfig.VBR is null)
						DownloadOptions.LameConfig.BitRate = kbps;
					else if (DownloadOptions.LameConfig.VBR == NAudio.Lame.VBRMode.ABR)
						DownloadOptions.LameConfig.ABRRateKbps = kbps;
				}
			}

			OnRetrievedTitle(AaxFile.AppleTags.TitleSansUnabridged);
			OnRetrievedAuthors(AaxFile.AppleTags.FirstAuthor ?? "[unknown]");
			OnRetrievedNarrators(AaxFile.AppleTags.Narrator ?? "[unknown]");
			OnRetrievedCoverArt(AaxFile.AppleTags.Cover);

			RetrievedMetadata?.Invoke(this, AaxFile.AppleTags);

			return !IsCanceled;
		}

		protected DownloadProgress Step_DownloadAudiobook_Start()
		{
			var zeroProgress = new DownloadProgress
			{
				BytesReceived = 0,
				ProgressPercentage = 0,
				TotalBytesToReceive = InputFileStream.Length
			};

			OnDecryptProgressUpdate(zeroProgress);

			AaxFile.SetDecryptionKey(DownloadOptions.AudibleKey, DownloadOptions.AudibleIV);
			return zeroProgress;
		}

		protected void Step_DownloadAudiobook_End(DownloadProgress zeroProgress)
		{
			AaxFile.Close();

			CloseInputFileStream();

			OnDecryptProgressUpdate(zeroProgress);
		}

		protected void AaxFile_ConversionProgressUpdate(object sender, ConversionProgressEventArgs e)
		{
			var duration = AaxFile.Duration;
			var remainingSecsToProcess = (duration - e.ProcessPosition).TotalSeconds;
			var estTimeRemaining = remainingSecsToProcess / e.ProcessSpeed;

			if (double.IsNormal(estTimeRemaining))
				OnDecryptTimeRemaining(TimeSpan.FromSeconds(estTimeRemaining));

			var progressPercent = (e.ProcessPosition / e.TotalDuration);

			OnDecryptProgressUpdate(
				new DownloadProgress
				{
					ProgressPercentage = 100 * progressPercent,
					BytesReceived = (long)(InputFileStream.Length * progressPercent),
					TotalBytesToReceive = InputFileStream.Length
				});
		}

		public override async Task CancelAsync()
		{
			IsCanceled = true;
			if (AaxFile != null)
				await AaxFile.CancelAsync();
			AaxFile?.Dispose();
			CloseInputFileStream();
		}
	}
}