namespace NSpeex
{
    using System;
    using System.Runtime.InteropServices;

    public class SpeexDecoder
    {
        private readonly Bits bits = new Bits();
        private float[] decodedData;
        private readonly IDecoder decoder;
        private readonly int frameSize;
        private readonly int sampleRate;

        public SpeexDecoder(BandMode mode, bool enhanced = true)
        {
            switch (mode)
            {
                case BandMode.Wide:
                    this.decoder = new SbDecoder(false);
                    this.sampleRate = 0x3e80;
                    break;
                default:
                    this.decoder = new NbDecoder();
                    this.sampleRate = 0x1f40;
                    break;
            }
            this.decoder.PerceptualEnhancement = enhanced;
            this.frameSize = this.decoder.FrameSize;
            this.decodedData = new float[this.sampleRate * 2];
        }

        private static short ConvertToShort(float value)
        {
            if (value > 32767f)
            {
                value = 32767f;
            }
            else if (value < -32768f)
            {
                value = -32768f;
            }
            return (short)Math.Round((double)value);
        }

        public int Decode(byte[] inData, int inOffset, int inCount, short[] outData, int outOffset, bool lostFrame)
        {
            if (this.decodedData.Length < (outData.Length * 2))
            {
                this.decodedData = new float[outData.Length * 2];
            }
            if (lostFrame || (inData == null))
            {
                this.decoder.Decode(null, this.decodedData);
                int index = 0;
                while (index < this.frameSize)
                {
                    outData[outOffset] = ConvertToShort(this.decodedData[index]);
                    index++;
                    outOffset++;
                }
                return this.frameSize;
            }
            this.bits.ReadFrom(inData, inOffset, inCount);
            int num2 = 0;
            while (this.decoder.Decode(this.bits, this.decodedData) == 0)
            {
                int num3 = 0;
                while (num3 < this.frameSize)
                {
                    outData[outOffset] = ConvertToShort(this.decodedData[num3]);
                    num3++;
                    outOffset++;
                }
                num2 += this.frameSize;
            }
            return num2;
        }

    }
}