namespace FluidSim.Audio
{
    internal class RingBuffer
    {
        private readonly float[] buffer;
        private volatile int readPos;
        private volatile int writePos;

        public RingBuffer(int capacity)
        {
            if ((capacity & (capacity - 1)) != 0)
                throw new ArgumentException("Capacity must be a power of two.");
            buffer = new float[capacity];
        }

        public int Count => (writePos - readPos) & (buffer.Length - 1);
        public int Space => (readPos - writePos - 1) & (buffer.Length - 1);

        public int Write(float[] data, int count)
        {
            int space = Space;
            int toWrite = Math.Min(count, space);
            int mask = buffer.Length - 1;
            for (int i = 0; i < toWrite; i++)
                buffer[(writePos + i) & mask] = data[i];
            writePos = (writePos + toWrite) & mask;
            return toWrite;
        }

        public int Read(float[] destination, int count)
        {
            int available = Count;
            int toRead = Math.Min(count, available);
            int mask = buffer.Length - 1;
            for (int i = 0; i < toRead; i++)
                destination[i] = buffer[(readPos + i) & mask];
            readPos = (readPos + toRead) & mask;
            return toRead;
        }
    }
}