/*
    *  Java HTML Tidy - JTidy
    *  HTML parser and pretty printer
    *
    *  Copyright (c) 1998-2000 World Wide Web Consortium (Massachusetts
    *  Institute of Technology, Institut National de Recherche en
    *  Informatique et en Automatique, Keio University). All Rights
    *  Reserved.
    *
   *  Contributing Author(s):
   *
   *     Dave Raggett <dsr@w3.org>
   *     Andy Quick <ac.quick@sympatico.ca> (translation to Java)
   *     Gary L Peskin <garyp@firstech.com> (Java development)
   *     Sami Lempinen <sami@lempinen.net> (release management)
   *     Fabrizio Giustina <fgiust at users.sourceforge.net>
   *
   *  The contributing author(s) would like to thank all those who
   *  helped with testing, bug fixes, and patience.  This wouldn't
   *  have been possible without all of you.
   *
   *  COPYRIGHT NOTICE:
   * 
   *  This software and documentation is provided "as is," and
   *  the copyright holders and contributing author(s) make no
   *  representations or warranties, express or implied, including
   *  but not limited to, warranties of merchantability or fitness
   *  for any particular purpose or that the use of the software or
   *  documentation will not infringe any third party patents,
   *  copyrights, trademarks or other rights. 
   *
   *  The copyright holders and contributing author(s) will not be
   *  liable for any direct, indirect, special or consequential damages
   *  arising out of any use of the software or documentation, even if
   *  advised of the possibility of such damage.
   *
   *  Permission is hereby granted to use, copy, modify, and distribute
   *  this source code, or portions hereof, documentation and executables,
   *  for any purpose, without fee, subject to the following restrictions:
   *
   *  1. The origin of this source code must not be misrepresented.
   *  2. Altered versions must be plainly marked as such and must
   *     not be misrepresented as being the original source.
   *  3. This Copyright notice may not be removed or altered from any
   *     source or altered source distribution.
   * 
   *  The copyright holders and contributing author(s) specifically
   *  permit, without fee, and encourage the use of this source code
   *  as a component for supporting the Hypertext Markup Language in
   *  commercial products. If you use this source code in a product,
   *  acknowledgment is not required but would be appreciated.
   *
   */
  package org.w3c.tidy;
  
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.InputStreamReader;
  import java.io.Reader;
  import java.io.UnsupportedEncodingException;
  
  
  /**
   * StreamIn Implementation using java writers.
   * @author Fabrizio Giustina
   * @version $Revision: 807 $ ($Author: fgiust $)
   */
  public class StreamInJavaImpl implements StreamIn
  {
  
      /**
       * number of characters kept in buffer.
       */
      private static final int CHARBUF_SIZE = 5;
  
      /**
       * character buffer.
       */
      private int[] charbuf = new int[CHARBUF_SIZE];
  
      /**
       * actual position in buffer.
       */
      private int bufpos;
  
      /**
       * Java input stream reader.
       */
      private Reader reader;
  
      /**
       * has end of stream been reached?
       */
      private boolean endOfStream;
  
      /**
       * Is char pushed?
       */
      private boolean pushed;
 
     /**
      * current column number.
      */
     private int curcol;
 
     /**
      * last column.
      */
     private int lastcol;
 
     /**
      * current line number.
      */
     private int curline;
 
     /**
      * tab size in chars.
      */
     private int tabsize;
 
     private int tabs;
 
     /**
      * Instantiates a new StreamInJavaImpl.
      * @param stream
      * @param encoding
      * @param tabsize
      * @throws UnsupportedEncodingException
      */
     protected StreamInJavaImpl(InputStream stream, String encoding, int tabsize) throws UnsupportedEncodingException
     {
         reader = new InputStreamReader(stream, encoding);
         this.pushed = false;
         this.tabsize = tabsize;
         this.curline = 1;
         this.curcol = 1;
         this.endOfStream = false;
     }
 
     /**
      * Instantiates a new StreamInJavaImpl.
      * @param stream
      * @param encoding
      * @param tabsize
      */
     protected StreamInJavaImpl(Reader reader, int tabsize)
     {
         this.reader = reader;
         this.pushed = false;
         this.tabsize = tabsize;
         this.curline = 1;
         this.curcol = 1;
         this.endOfStream = false;
     }
 
     /**
      * @see org.w3c.tidy.StreamIn#readCharFromStream()
      */
     public int readCharFromStream()
     {
         int c;
         try
         {
             c = reader.read();
             if (c < 0)
             {
                 endOfStream = true;
             }
 
         }
         catch (IOException e)
         {
             // @todo how to handle?
             endOfStream = true;
             return END_OF_STREAM;
         }
 
         return c;
     }
 
     /**
      * @see org.w3c.tidy.StreamIn#readChar()
      */
     public int readChar()
     {
         int c;
 
         if (this.pushed)
         {
             c = this.charbuf[--(this.bufpos)];
             if ((this.bufpos) == 0)
             {
                 this.pushed = false;
             }
 
             if (c == '\n')
             {
                 this.curcol = 1;
                 this.curline++;
                 return c;
             }
 
             this.curcol++;
             return c;
         }
 
         this.lastcol = this.curcol;
 
         if (this.tabs > 0)
         {
             this.curcol++;
             this.tabs--;
             return ' ';
         }
 
         c = readCharFromStream();
 
         if (c < 0)
         {
             endOfStream = true;
             return END_OF_STREAM;
         }
 
         if (c == '\n')
         {
             this.curcol = 1;
             this.curline++;
             return c;
         }
         else if (c == '\r') // \r\n
         {
             c = readCharFromStream();
             if (c != '\n')
             {
                 if (c != END_OF_STREAM)
                 {
                     ungetChar(c);
                 }
                 c = '\n';
             }
             this.curcol = 1;
             this.curline++;
             return c;
         }
 
         if (c == '\t')
         {
             this.tabs = this.tabsize - ((this.curcol - 1) % this.tabsize) - 1;
             this.curcol++;
             c = ' ';
             return c;
         }
 
         this.curcol++;
 
         return c;
     }
 
     /**
      * @see org.w3c.tidy.StreamIn#ungetChar(int)
      */
     public void ungetChar(int c)
     {
         this.pushed = true;
         if (this.bufpos >= CHARBUF_SIZE)
         {
             // pop last element
             System.arraycopy(this.charbuf, 0, this.charbuf, 1, CHARBUF_SIZE - 1);
             this.bufpos--;
         }
         this.charbuf[(this.bufpos)++] = c;
 
         if (c == '\n')
         {
             --this.curline;
         }
 
         this.curcol = this.lastcol;
     }
 
     /**
      * @see org.w3c.tidy.StreamIn#isEndOfStream()
      */
     public boolean isEndOfStream()
     {
         return endOfStream;
     }
 
     /**
      * Getter for <code>curcol</code>.
      * @return Returns the curcol.
      */
     public int getCurcol()
     {
         return this.curcol;
     }
 
     /**
      * Getter for <code>curline</code>.
      * @return Returns the curline.
      */
     public int getCurline()
     {
         return this.curline;
     }
 
     /**
      * @see org.w3c.tidy.StreamIn#setLexer(org.w3c.tidy.Lexer)
      */
     public void setLexer(Lexer lexer)
     {
         // unused in the java implementation
     }
 
 }