using System;
using System.Runtime.InteropServices;

namespace MoonWorks.Audio
{
	public class StaticSound : AudioResource
	{
		internal FAudio.FAudioBuffer Handle;
		public ushort Channels { get; }
		public uint SamplesPerSecond { get; }

		public uint LoopStart { get; set; } = 0;
		public uint LoopLength { get; set; } = 0;

		public static StaticSound LoadOgg(AudioDevice device, string filePath)
		{
			var filePointer = FAudio.stb_vorbis_open_filename(filePath, out var error, IntPtr.Zero);

			if (error != 0)
			{
				throw new AudioLoadException("Error loading file!");
			}
			var info = FAudio.stb_vorbis_get_info(filePointer);
			var bufferSize = FAudio.stb_vorbis_stream_length_in_samples(filePointer) * info.channels;
			var buffer = new float[bufferSize];

			FAudio.stb_vorbis_get_samples_float_interleaved(
				filePointer,
				info.channels,
				buffer,
				(int) bufferSize
			);

			FAudio.stb_vorbis_close(filePointer);

			return new StaticSound(
				device,
				(ushort) info.channels,
				info.sample_rate,
				buffer,
				0,
				(uint) buffer.Length
			);
		}

		public StaticSound(
			AudioDevice device,
			ushort channels,
			uint samplesPerSecond,
			float[] buffer,
			uint bufferOffset, /* in floats */
			uint bufferLength  /* in floats */
		) : base(device)
		{
			Channels = channels;
			SamplesPerSecond = samplesPerSecond;

			var bufferLengthInBytes = (int) (bufferLength * sizeof(float));
			Handle = new FAudio.FAudioBuffer();
			Handle.Flags = FAudio.FAUDIO_END_OF_STREAM;
			Handle.pContext = IntPtr.Zero;
			Handle.AudioBytes = (uint) bufferLengthInBytes;
			Handle.pAudioData = Marshal.AllocHGlobal(bufferLengthInBytes);
			Marshal.Copy(buffer, (int) bufferOffset, Handle.pAudioData, (int) bufferLength);
			Handle.PlayBegin = 0;
			Handle.PlayLength = 0;

			LoopStart = 0;
			LoopLength = 0;
		}

		public StaticSoundInstance CreateInstance(bool loop = false)
		{
			return new StaticSoundInstance(Device, this, false, loop);
		}

		protected override void Destroy()
		{
			Marshal.FreeHGlobal(Handle.pAudioData);
		}
	}
}