using System;
using System.IO;

namespace Ryuclaw.Audio.Shared
{
    public class WaveReader
    {
        private WaveHeader _header;
        public byte[] AudioData { get; private set; }

        public WaveReader()
        {
            _header = new WaveHeader();
            AudioData = new byte[0];
        }

        public void Load(string filePath)
        {
            using (var stream = new FileStream(filePath, FileMode.Open))
            using (var reader = new BinaryReader(stream))
            {
                // RIFF header
                string chunkID = new string(reader.ReadChars(4));
                if (chunkID != "RIFF") throw new Exception("Not a valid WAV file.");

                var ChunkSize = reader.ReadInt32(); // Chunk size
                string format = new string(reader.ReadChars(4));
                if (format != "WAVE") throw new Exception("Not a valid WAV file.");

                // fmt sub-chunk
                string subchunk1ID = new string(reader.ReadChars(4));
                if (subchunk1ID != "fmt ") throw new Exception("Expected fmt chunk.");

                int subChunk1Size = reader.ReadInt32();
                short audioFormat = reader.ReadInt16();
                var NumChannels = reader.ReadInt16();
                var SampleRate = reader.ReadInt32();
                var ByteRate = reader.ReadInt32(); // Byte rate
                var BlockAlign = reader.ReadInt16(); // Block align
                var BitsPerSample = reader.ReadInt16();
                _header = new WaveHeader(SampleRate, ChunkSize, ByteRate, BitsPerSample, NumChannels, BlockAlign);
                if (audioFormat != 1 || subChunk1Size != 16)
                {
                    throw new Exception("Only PCM format WAV files are supported.");
                }

                // data sub-chunk
                string subchunk2ID = new string(reader.ReadChars(4));
                if (subchunk2ID != "data") throw new Exception("Expected data chunk.");

                int subChunk2Size = reader.ReadInt32();
                AudioData = reader.ReadBytes(subChunk2Size);
            }
        }
    }
}