using System;
using System.IO;

namespace MoonWorks.Audio
{
	public class StreamingSoundOgg : StreamingSound
	{
		// FIXME: what should this value be?
		public const int BUFFER_SIZE = 1024 * 128;

		internal IntPtr FileHandle { get; }
		internal FAudio.stb_vorbis_info Info { get; }

		private readonly float[] buffer;

		public override SoundState State { get; protected set; }

		public static StreamingSoundOgg Load(
			AudioDevice device,
			string filePath,
			bool is3D = false,
			bool loop = false
		)
		{
			var fileHandle = FAudio.stb_vorbis_open_filename(filePath, out var error, IntPtr.Zero);
			if (error != 0)
			{
				Logger.LogError("Error opening OGG file!");
				throw new AudioLoadException("Error opening OGG file!");
			}

			var info = FAudio.stb_vorbis_get_info(fileHandle);

			return new StreamingSoundOgg(
				device,
				fileHandle,
				info,
				is3D,
				loop
			);
		}

		internal StreamingSoundOgg(
			AudioDevice device,
			IntPtr fileHandle,
			FAudio.stb_vorbis_info info,
			bool is3D,
			bool loop
		) : base(
			device,
			3, /* float type */
			32, /* size of float */
			(ushort) (4 * info.channels),
			(ushort) info.channels,
			info.sample_rate,
			is3D,
			loop
		)
		{
			FileHandle = fileHandle;
			Info = info;
			buffer = new float[BUFFER_SIZE];

			device.AddDynamicSoundInstance(this);
		}

		protected override void AddBuffer(
			out float[] buffer,
			out uint bufferOffset,
			out uint bufferLength,
			out bool reachedEnd
		)
		{
			buffer = this.buffer;

			/* NOTE: this function returns samples per channel, not total samples */
			var samples = FAudio.stb_vorbis_get_samples_float_interleaved(
				FileHandle,
				Info.channels,
				buffer,
				buffer.Length
			);

			var sampleCount = samples * Info.channels;
			bufferOffset = 0;
			bufferLength = (uint) sampleCount;
			reachedEnd = sampleCount < buffer.Length;
		}

		protected override void SeekStart()
		{
			FAudio.stb_vorbis_seek_start(FileHandle);
		}

		protected override void Destroy()
		{
			FAudio.stb_vorbis_close(FileHandle);
		}
	}
}