using System;
using System.IO;

namespace SharpCompress.Compressor.LZMA.Utilites
{
    internal class CrcBuilderStream : Stream
    {
        private long mProcessed;
        private Stream mTarget;
        private uint mCRC;
        private bool mFinished;

        public CrcBuilderStream(Stream target)
        {
            mTarget = target;
            mCRC = CRC.kInitCRC;
        }

        public long Processed
        {
            get { return mProcessed; }
        }

        public uint Finish()
        {
            if (!mFinished)
            {
                mFinished = true;
                mCRC = CRC.Finish(mCRC);
            }

            return mCRC;
        }

        public override bool CanRead
        {
            get { return false; }
        }

        public override bool CanSeek
        {
            get { return false; }
        }

        public override bool CanWrite
        {
            get { return true; }
        }

        public override void Flush()
        {
        }

        public override long Length
        {
            get { throw new NotSupportedException(); }
        }

        public override long Position
        {
            get { throw new NotSupportedException(); }
            set { throw new NotSupportedException(); }
        }

        public override int Read(byte[] buffer, int offset, int count)
        {
            throw new InvalidOperationException();
        }

        public override long Seek(long offset, SeekOrigin origin)
        {
            throw new NotSupportedException();
        }

        public override void SetLength(long value)
        {
            throw new NotSupportedException();
        }

        public override void Write(byte[] buffer, int offset, int count)
        {
            if (mFinished)
                throw new InvalidOperationException("CRC calculation has been finished.");

            mProcessed += count;
            mCRC = CRC.Update(mCRC, buffer, offset, count);
            mTarget.Write(buffer, offset, count);
        }
    }

    internal class ReadingCrcBuilderStream : Stream
    {
        private long mProcessed;
        private Stream mSource;
        private uint mCRC;
        private bool mFinished;

        public ReadingCrcBuilderStream(Stream source)
        {
            mSource = source;
            mCRC = CRC.kInitCRC;
        }

        protected override void Dispose(bool disposing)
        {
            try
            {
                if (disposing)
                    mSource.Dispose();
            }
            finally
            {
                base.Dispose(disposing);
            }
        }

        public long Processed
        {
            get { return mProcessed; }
        }

        public uint Finish()
        {
            if (!mFinished)
            {
                mFinished = true;
                mCRC = CRC.Finish(mCRC);
            }

            return mCRC;
        }

        public override bool CanRead
        {
            get { return mSource.CanRead; }
        }

        public override bool CanSeek
        {
            get { return false; }
        }

        public override bool CanWrite
        {
            get { return false; }
        }

        public override void Flush()
        {
            throw new NotImplementedException();
        }

        public override long Length
        {
            get { throw new NotImplementedException(); }
        }

        public override long Position
        {
            get { throw new NotImplementedException(); }
            set { throw new NotImplementedException(); }
        }

        public override int Read(byte[] buffer, int offset, int count)
        {
            if (count > 0 && !mFinished)
            {
                int read = mSource.Read(buffer, offset, count);
                if (read > 0)
                {
                    mProcessed += read;
                    mCRC = CRC.Update(mCRC, buffer, offset, read);
                    return read;
                }

                Finish();
            }

            return 0;
        }

        public override long Seek(long offset, SeekOrigin origin)
        {
            throw new NotImplementedException();
        }

        public override void SetLength(long value)
        {
            throw new NotImplementedException();
        }

        public override void Write(byte[] buffer, int offset, int count)
        {
            throw new NotImplementedException();
        }
    }
}