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

namespace Biff8Excel.Excel
{
    internal class ExcelBinaryWriter : BinaryWriter, IDisposable
    {
        //static int tmp ;     //用于tmp文件不重覆
        string m_FileName;

        public ExcelBinaryWriter()
        {
            //m_FileName = "btw" + tmp.ToString() + ".tmp";
            //tmp++;
            //生成一临时文件
            m_FileName = Path.GetTempFileName();
            FileInfo myFileInfo = new FileInfo(m_FileName);
            myFileInfo.Attributes = FileAttributes.Temporary;
        }

        public long Length
        {
            get
            {
                //StreamWriter myWriter = File.AppendText(m_FileName);

                if (!OutStream.CanRead)
                    OutStream = File.Open(m_FileName, FileMode.Open);

                return this.OutStream.Length;
            }
        }

        public long Position
        {
            get
            {
                if (OutStream.CanRead)
                    return OutStream.Position;

                return 0;
            }
            set
            {
                if (!OutStream.CanWrite)
                    OutStream = File.Open(m_FileName, FileMode.Open);

                OutStream.Position = value;
            }
        }

        public byte[] Stream
        {
            get
            {
                if (OutStream == System.IO.Stream.Null)
                    return null;

                if ( !OutStream.CanRead )
                    OutStream = File.Open(m_FileName, FileMode.Open);

                int rdlen = (int)this.OutStream.Length;
                byte[] b = new byte[rdlen];
                this.OutStream.Seek(0, SeekOrigin.Begin);
                this.OutStream.Read(b, 0, rdlen);
                return b;
            }
        }

        public override void Write(byte[] buffer)
        {
            if (buffer == null)
                return;

            int len = buffer.Length;

            if (len == 0)
                return;

            //if (OutStream == System.IO.Stream.Null)
            //    OutStream = File.Create(fn);

            if ( OutStream == System.IO.Stream.Null)
                OutStream = File.Open(m_FileName, FileMode.Truncate);
           
            OutStream.Write(buffer, 0, len);
            //OutStream.Flush();
        }

        internal void clear()
        {
            //删除临时文件
            OutStream.Close();
            if (File.Exists(m_FileName))
                File.Delete(m_FileName);
            m_FileName = string.Empty;
        }

        /// <summary>
        /// 删除临时文件
        /// </summary>
        ~ExcelBinaryWriter()
        {
            clear();
        }
    }
}