using Amphora;
using System;

namespace Susurrus.XAudio2.UnitTests
{
    /// <summary>
    /// Makes sounds with nothing in them, so a test can start a voice without anyone hearing it.
    /// </summary>
    public static class SilentSounds
    {
        public static DecodedSound Of(
            int frameCount, int channelCount = 1, int sampleRate = 48000, SampleFormat format = SampleFormat.Pcm16)
        {
            int byteCount = frameCount * channelCount * DecodedSound.GetBytesPerSample(format);
            return new DecodedSound(new ByteView(new byte[byteCount]), sampleRate, channelCount, format);
        }

        /// <summary>
        /// Returns a WAV file of 16-bit silence.
        /// </summary>
        public static byte[] Wav(int frameCount, int channelCount, int sampleRate = 48000)
        {
            int dataBytes = frameCount * channelCount * 2;
            byte[] returnMe = new byte[44 + dataBytes];
            Put(returnMe, 0, "RIFF");
            Put(returnMe, 4, 36 + dataBytes);
            Put(returnMe, 8, "WAVE");
            Put(returnMe, 12, "fmt ");
            Put(returnMe, 16, 16);
            Put(returnMe, 20, (short)1);
            Put(returnMe, 22, (short)channelCount);
            Put(returnMe, 24, sampleRate);
            Put(returnMe, 28, sampleRate * channelCount * 2);
            Put(returnMe, 32, (short)(channelCount * 2));
            Put(returnMe, 34, (short)16);
            Put(returnMe, 36, "data");
            Put(returnMe, 40, dataBytes);
            return returnMe;
        }

        private static void Put(byte[] bytes, int index, string text)
        {
            System.Text.Encoding.ASCII.GetBytes(text, 0, text.Length, bytes, index);
        }

        private static void Put(byte[] bytes, int index, int value)
        {
            BitConverter.GetBytes(value).CopyTo(bytes, index);
        }

        private static void Put(byte[] bytes, int index, short value)
        {
            BitConverter.GetBytes(value).CopyTo(bytes, index);
        }

        /// <summary>
        /// Makes a sound that lasts about ten milliseconds at 48000 frames per second.
        /// </summary>
        public static DecodedSound Short(int channelCount = 1)
        {
            return Of(frameCount: 480, channelCount);
        }

        /// <summary>
        /// Makes a sound long enough to still be playing when a test has finished with it.
        /// </summary>
        public static DecodedSound Long(int channelCount = 1)
        {
            return Of(frameCount: 48000 * 30, channelCount);
        }
    }
}