using System;
using System.Runtime.InteropServices;

namespace Susurrus.XAudio2.UnitTests
{
    /// <summary>
    /// Silent 16-bit mono samples, pinned so a voice can read them.
    /// </summary>
    public class PinnedSilence : IDisposable
    {
        private readonly byte[] samples;
        private GCHandle pin;

        public int FrameCount { get; }

        public PinnedSilence(int frameCount)
        {
            this.FrameCount = frameCount;
            this.samples = new byte[frameCount * 2];
            this.pin = GCHandle.Alloc(samples, GCHandleType.Pinned);
        }

        public XAudio2Buffer Buffer()
        {
            XAudio2Buffer returnMe = new XAudio2Buffer();
            returnMe.AudioBytes = (uint)samples.Length;
            returnMe.AudioData = pin.AddrOfPinnedObject();
            return returnMe;
        }

        public void Dispose()
        {
            pin.Free();
        }
    }
}