using System;
using System.IO;

namespace StegoPrint {
    public class WaveStream : Stream, IDisposable {
        private Stream m_Stream;
        private long m_DataPos;
        private int m_Length;

        private WaveFormat m_Format;

        public WaveFormat Format {
            get { return m_Format; }
        }

        private string ReadChunk (BinaryReader reader) {
            byte[] ch = new byte[4];
            reader.Read (ch, 0, ch.Length);
            return System.Text.Encoding.ASCII.GetString (ch);
        }

        private void ReadHeader () {
            BinaryReader Reader = new BinaryReader (m_Stream);
            if (ReadChunk (Reader) != "RIFF")
                throw new Exception ("Invalid file format");

            Reader.ReadInt32 (); // File length minus first 8 bytes of RIFF description, we don't use it

            if (ReadChunk (Reader) != "WAVE")
                throw new Exception ("Invalid file format");

            if (ReadChunk (Reader) != "fmt ")
                throw new Exception ("Invalid file format");

            int len = Reader.ReadInt32 ();
            if (len < 16) // bad format chunk length
                throw new Exception ("Invalid file format");

            m_Format = new WaveFormat (22050, 16, 2); // initialize to any format
            m_Format.wFormatTag = Reader.ReadInt16 ();
            m_Format.nChannels = Reader.ReadInt16 ();
            m_Format.nSamplesPerSec = Reader.ReadInt32 ();
            m_Format.nAvgBytesPerSec = Reader.ReadInt32 ();
            m_Format.nBlockAlign = Reader.ReadInt16 ();
            m_Format.wBitsPerSample = Reader.ReadInt16 ();

            // advance in the stream to skip the wave format block 
            len -= 16; // minimum format size
            while (len > 0) {
                Reader.ReadByte ();
                len--;
            }

            // assume the data chunk is aligned
            while (m_Stream.Position < m_Stream.Length && ReadChunk (Reader) != "data")
            ;

            if (m_Stream.Position >= m_Stream.Length)
                throw new Exception ("Invalid file format");

            m_Length = Reader.ReadInt32 ();
            m_DataPos = m_Stream.Position;

            Position = 0;
        }

        /// <summary>ReadChunk(reader) - Changed to CopyChunk(reader, writer)</summary>
        /// <param name="reader">source stream</param>
        /// <returns>four characters</returns>
        private string CopyChunk (BinaryReader reader, BinaryWriter writer) {
            byte[] ch = new byte[4];
            reader.Read (ch, 0, ch.Length);

            //copy the chunk
            writer.Write (ch);

            return System.Text.Encoding.ASCII.GetString (ch);
        }

        /// <summary>ReadHeader() - Changed to CopyHeader(destination)</summary>
        private void CopyHeader (Stream destinationStream) {
            BinaryReader reader = new BinaryReader (m_Stream);
            BinaryWriter writer = new BinaryWriter (destinationStream);

            if (CopyChunk (reader, writer) != "RIFF")
                throw new Exception ("Invalid file format");

            writer.Write (reader.ReadInt32 ()); // File length minus first 8 bytes of RIFF description

            if (CopyChunk (reader, writer) != "WAVE")
                throw new Exception ("Invalid file format");

            if (CopyChunk (reader, writer) != "fmt ")
                throw new Exception ("Invalid file format");

            int len = reader.ReadInt32 ();
            if (len < 16) { // bad format chunk length
                throw new Exception ("Invalid file format");
            } else {
                writer.Write (len);
            }

            m_Format = new WaveFormat (22050, 16, 2); // initialize to any format
            m_Format.wFormatTag = reader.ReadInt16 ();
            m_Format.nChannels = reader.ReadInt16 ();
            m_Format.nSamplesPerSec = reader.ReadInt32 ();
            m_Format.nAvgBytesPerSec = reader.ReadInt32 ();
            m_Format.nBlockAlign = reader.ReadInt16 ();
            m_Format.wBitsPerSample = reader.ReadInt16 ();

            //copy format information
            writer.Write (m_Format.wFormatTag);
            writer.Write (m_Format.nChannels);
            writer.Write (m_Format.nSamplesPerSec);
            writer.Write (m_Format.nAvgBytesPerSec);
            writer.Write (m_Format.nBlockAlign);
            writer.Write (m_Format.wBitsPerSample);

            // advance in the stream to skip the wave format block 
            len -= 16; // minimum format size
            writer.Write (reader.ReadBytes (len));
            len = 0;
            /*while (len > 0)
            {
            	reader.ReadByte();
            	len--;
            }*/

            // assume the data chunk is aligned
            while (m_Stream.Position < m_Stream.Length && CopyChunk (reader, writer) != "data")
            ;

            if (m_Stream.Position >= m_Stream.Length)
                throw new Exception ("Invalid file format");

            m_Length = reader.ReadInt32 ();
            writer.Write (m_Length);

            m_DataPos = m_Stream.Position;
            Position = 0;
        }

        /// <summary>Write a new header</summary>
        public static Stream CreateStream (Stream waveData, WaveFormat format) {
            MemoryStream stream = new MemoryStream ();
            BinaryWriter writer = new BinaryWriter (stream);

            writer.Write (System.Text.Encoding.ASCII.GetBytes ("RIFF".ToCharArray ()));

            writer.Write ((Int32) (waveData.Length + 36)); //File length minus first 8 bytes of RIFF description

            writer.Write (System.Text.Encoding.ASCII.GetBytes ("WAVEfmt ".ToCharArray ()));

            writer.Write ((Int32) 16); //length of following chunk: 16

            writer.Write ((Int16) format.wFormatTag);
            writer.Write ((Int16) format.nChannels);
            writer.Write ((Int32) format.nSamplesPerSec);
            writer.Write ((Int32) format.nAvgBytesPerSec);
            writer.Write ((Int16) format.nBlockAlign);
            writer.Write ((Int16) format.wBitsPerSample);

            writer.Write (System.Text.Encoding.ASCII.GetBytes ("data".ToCharArray ()));

            writer.Write ((Int32) waveData.Length);

            waveData.Seek (0, SeekOrigin.Begin);
            byte[] b = new byte[waveData.Length];
            waveData.Read (b, 0, (int) waveData.Length);
            writer.Write (b);

            writer.Seek (0, SeekOrigin.Begin);
            return stream;
        }

        public WaveStream (Stream sourceStream, Stream destinationStream) {
            m_Stream = sourceStream;
            CopyHeader (destinationStream);
        }

        public WaveStream (Stream sourceStream) {
                m_Stream = sourceStream;
                ReadHeader ();
            }

            ~WaveStream () {
                Dispose ();
            }

        public new void Dispose () {
            base.Dispose ();
            GC.SuppressFinalize (this);
        }

        public override bool CanRead {
            get { return true; }
        }
        public override bool CanSeek {
            get { return true; }
        }
        public override bool CanWrite {
            get { return false; }
        }
        public override long Length {
            get { return m_Length; }
        }

        /// <summary>Length of the data (in samples)</summary>
        public long CountSamples {
            get { return (long) ((m_Length - m_DataPos) / (m_Format.wBitsPerSample / 8)); }
        }

        public override long Position {
            get { return m_Stream.Position - m_DataPos; }
            set { Seek (value, SeekOrigin.Begin); }
        }
        public override void Flush () { }
        public override void SetLength (long len) {
            throw new InvalidOperationException ();
        }
        public override long Seek (long pos, SeekOrigin o) {
            switch (o) {
                case SeekOrigin.Begin:
                    m_Stream.Position = pos + m_DataPos;
                    break;
                case SeekOrigin.Current:
                    m_Stream.Seek (pos, SeekOrigin.Current);
                    break;
                case SeekOrigin.End:
                    m_Stream.Position = m_DataPos + m_Length - pos;
                    break;
            }
            return this.Position;
        }

        public override int Read (byte[] buf, int ofs, int count) {
            int toread = (int) Math.Min (count, m_Length - Position);
            return m_Stream.Read (buf, ofs, toread);
        }

        /// <summary>Read - Changed to Copy</summary>
        /// <param name="buf">Buffer to receive the data</param>
        /// <param name="ofs">Offset</param>
        /// <param name="count">Count of bytes to read</param>
        /// <param name="destination">Where to copy the buffer</param>
        /// <returns>Count of bytes actually read</returns>
        public int Copy (byte[] buf, int ofs, int count, Stream destination) {
            int toread = (int) Math.Min (count, m_Length - Position);
            int read = m_Stream.Read (buf, ofs, toread);
            destination.Write (buf, ofs, read);

            if (m_Stream.Position != destination.Position) {
                Console.WriteLine ();
            }

            return read;
        }

        public override void Write (byte[] buf, int ofs, int count) {
            throw new InvalidOperationException ();
        }
    }
}