/* ====================================================================
   Licensed to the Apache Software Foundation (ASF) under one or more
   contributor license agreements.  See the NOTICE file distributed with
   this work for Additional information regarding copyright ownership.
   The ASF licenses this file to You under the Apache License, Version 2.0
   (the "License"); you may not use this file except in compliance with
   the License.  You may obtain a copy of the License at

       http://www.apache.org/licenses/LICENSE-2.0

   Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS,
   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   See the License for the specific language governing permissions and
   limitations under the License.
==================================================================== */

/* ================================================================
 * About NPOI
 * Author: Tony Qu 
 * Author's email: tonyqus (at) gmail.com 
 * Author's Blog: tonyqus.wordpress.com.cn (wp.tonyqus.cn)
 * HomePage: http://www.codeplex.com/npoi
 * Contributors:
 * 
 * ==============================================================*/

using System;
using System.Collections.Generic;
using System.Text;
using System.IO;

using HH.WMS.Utils.NPOI.POIFS.Common;
using HH.WMS.Utils.NPOI.Util;


namespace HH.WMS.Utils.NPOI.POIFS.Storage
{
    /// <summary>
    /// A big block created from an InputStream, holding the raw data
    /// @author Marc Johnson (mjohnson at apache dot org
    /// </summary>
    public class RawDataBlock : ListManagedBlock
    {
        private byte[] _data;
        private bool _eof;
        private bool _hasData;
        private static POILogger log = POILogFactory.GetLogger(typeof(RawDataBlock));

        /// <summary>
        /// Constructor RawDataBlock
        /// </summary>
        /// <param name="stream">the Stream from which the data will be read</param>
        public RawDataBlock(Stream stream)
            : this(stream, POIFSConstants.SMALLER_BIG_BLOCK_SIZE)
        {

        }
        /// <summary>
        /// Initializes a new instance of the <see cref="RawDataBlock"/> class.
        /// </summary>
        /// <param name="stream">the Stream from which the data will be read</param>
        /// <param name="blockSize">the size of the POIFS blocks, normally 512 bytes {@link POIFSConstants#BIG_BLOCK_SIZE}</param>
        public RawDataBlock(Stream stream, int blockSize)
        {
            _data = new byte[blockSize];
            int count = IOUtils.ReadFully(stream, _data);
            _hasData = (count > 0);

            if (count == -1)
            {
                _eof = true;
            }
            else if (count != blockSize)
            {
                // IOUtils.readFully will always read the
                //  requested number of bytes, unless it hits
                //  an EOF
                _eof = true;
                String type = " byte" + ((count == 1) ? ("")
                                                      : ("s"));

                log.Log(POILogger.ERROR,
                        "Unable to read entire block; " + count
                         + type + " read before EOF; expected "
                         + blockSize + " bytes. Your document "
                         + "was either written by software that "
                         + "ignores the spec, or has been truncated!"
                );
            }
            else
            {
                _eof = false;
            }
        }

        /// <summary>
        /// When we read the data, did we hit end of file?
        /// </summary>
        /// <value><c>true</c> if the EoF was hit during this block, or; otherwise, <c>false</c>if not. If you have a dodgy short last block, then
        /// it's possible to both have data, and also hit EoF...</value>
        public bool EOF
        {
            get { return _eof; }
        }
        /// <summary>
        /// Did we actually find any data to read? It's possible,
        /// in the event of a short last block, to both have hit
        /// the EoF, but also to have data
        /// </summary>
        /// <value><c>true</c> if this instance has data; otherwise, <c>false</c>.</value>
        public bool HasData
        {
            get { return _hasData; }
        }

        /// <summary>
        /// Get the data from the block
        /// </summary>
        /// <value>the block's data as a byte array</value>
        public byte[] Data
        {
            get
            {
                if (!HasData)
                {
                    // TODO return null instead of raising an unexpected exception (CA1065)
                    //return null;
                    throw new IOException("Cannot return empty data");
                }
                return _data;
            }
        }

        public override string ToString()
        {
            return "RawDataBlock of size " + _data.Length;
        }

        public int BigBlockSize
        {
            get { return _data.Length; }
        }
    }
}