/**
 * Redistribution and use of this software and associated documentation ("Software"), with or
 * without modification, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain copyright statements and notices. Redistributions
 * must also contain a copy of this document.
 *
 * 2. Redistributions in binary form must reproduce the above copyright notice, this list of
 * conditions and the following disclaimer in the documentation and/or other materials provided with
 * the distribution.
 *
 * 3. The name "Exolab" must not be used to endorse or promote products derived from this Software
 * without prior written permission of Intalio, Inc. For written permission, please contact
 * info@exolab.org.
 *
 * 4. Products derived from this Software may not be called "Exolab" nor may "Exolab" appear in
 * their names without prior written permission of Intalio, Inc. Exolab is a registered trademark of
 * Intalio, Inc.
 *
 * 5. Due credit should be given to the Exolab Project (http://www.exolab.org/).
 *
 * THIS SOFTWARE IS PROVIDED BY INTALIO, INC. AND CONTRIBUTORS ``AS IS'' AND ANY EXPRESSED OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
 * FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL INTALIO, INC. OR ITS
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY
 * WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * Copyright 2000 (C) Intalio Inc. All Rights Reserved.
 *
 * $Id$
 */

package org.exolab.castor.xml.dtd.parser;

/**
 * An implementation of interface {@link org.exolab.castor.xml.dtd.parser.CharStream CharStream}.
 * Implements input character stream that maintains line and column number positions of the
 * characters. It also has the capability to backup the stream to some extent.<br>
 * The object of this class is constructed using {@link java.io.Reader java.io.Reader}
 * <tt>reader</tt> and it is left to constructor of the <tt>reader</tt> to set up character encoding
 * correctly. This means that method <u><font color="blue">read</font></u> of the <tt>reader</tt> is
 * used to get next characters, assuming it returns appropriate values. It is recommended to use
 * class {@link java.io.InputStreamReader java.io.InputStreamReader} as a <tt>reader</tt>, which
 * allows to set desired character encoding. This class is an intermediate component between input
 * character reader and the parser.<br>
 * The code of this class is based on the class <b>ASCII_CharStream</b> - implementation of
 * interface {@link org.exolab.castor.xml.dtd.parser.CharStream CharStream}, that JavaCC would have
 * generated with the following options set in a JavaCC grammar file:
 * 
 * <pre>
 * JAVA_UNICODE_ESCAPE = false;
 * UNICODE_INPUT = false;
 * USER_CHAR_STREAM = false;
 * </pre>
 * 
 * Note that this class is not fully JavaCC generated.<br>
 * 
 * @author <b>JavaCC</b>, <a href="mailto:totok@intalio.com">Alexander Totok</a>
 * @version $Revision$ $Date: 2003-03-03 00:05:44 -0700 (Mon, 03 Mar 2003) $
 */
public final class InputCharStream implements CharStream {

  public static final boolean staticFlag = false;
  int bufsize;
  int available;
  int tokenBegin;
  public int bufpos = -1;
  private int bufline[];
  private int bufcolumn[];

  private int column = 0;
  private int line = 1;

  private boolean prevCharIsCR = false;
  private boolean prevCharIsLF = false;

  private java.io.Reader inputStream;

  private char[] buffer;
  private int maxNextCharInd = 0;
  private int inBuf = 0;

  private final void ExpandBuff(boolean wrapAround) {

    char[] newbuffer = new char[bufsize + 2048];
    int newbufline[] = new int[bufsize + 2048];
    int newbufcolumn[] = new int[bufsize + 2048];

    try {
      if (wrapAround) {
        System.arraycopy(buffer, tokenBegin, newbuffer, 0, bufsize - tokenBegin);
        System.arraycopy(buffer, 0, newbuffer, bufsize - tokenBegin, bufpos);
        buffer = newbuffer;

        System.arraycopy(bufline, tokenBegin, newbufline, 0, bufsize - tokenBegin);
        System.arraycopy(bufline, 0, newbufline, bufsize - tokenBegin, bufpos);
        bufline = newbufline;

        System.arraycopy(bufcolumn, tokenBegin, newbufcolumn, 0, bufsize - tokenBegin);
        System.arraycopy(bufcolumn, 0, newbufcolumn, bufsize - tokenBegin, bufpos);
        bufcolumn = newbufcolumn;

        maxNextCharInd = (bufpos += (bufsize - tokenBegin));

      } else {

        System.arraycopy(buffer, tokenBegin, newbuffer, 0, bufsize - tokenBegin);
        buffer = newbuffer;

        System.arraycopy(bufline, tokenBegin, newbufline, 0, bufsize - tokenBegin);
        bufline = newbufline;

        System.arraycopy(bufcolumn, tokenBegin, newbufcolumn, 0, bufsize - tokenBegin);
        bufcolumn = newbufcolumn;

        maxNextCharInd = (bufpos -= tokenBegin);
      }
    } catch (Throwable t) {
      throw new Error(t.getMessage());
    }

    bufsize += 2048;
    available = bufsize;
    tokenBegin = 0;
  }

  private final void FillBuff() throws java.io.IOException {
    if (maxNextCharInd == available) {
      if (available == bufsize) {
        if (tokenBegin > 2048) {
          bufpos = maxNextCharInd = 0;
          available = tokenBegin;
        } else if (tokenBegin < 0)
          bufpos = maxNextCharInd = 0;
        else
          ExpandBuff(false);
      } else if (available > tokenBegin)
        available = bufsize;
      else if ((tokenBegin - available) < 2048)
        ExpandBuff(true);
      else
        available = tokenBegin;
    }

    int i;

    try {
      if ((i = inputStream.read(buffer, maxNextCharInd, available - maxNextCharInd)) == -1) {
        inputStream.close();
        throw new java.io.IOException();
      }
      maxNextCharInd += i;
      return;
    } catch (java.io.IOException e) {
      --bufpos;
      backup(0);
      if (tokenBegin == -1)
        tokenBegin = bufpos;
      throw e;
    }
  }

  public final char BeginToken() throws java.io.IOException {

    tokenBegin = -1;
    char c = readChar();
    tokenBegin = bufpos;
    return c;
  }

  private final void UpdateLineColumn(char c) {

    column++;
    if (prevCharIsLF) {
      prevCharIsLF = false;
      line += (column = 1);
    } else if (prevCharIsCR) {
      prevCharIsCR = false;
      if (c == '\n')
        prevCharIsLF = true;
      else
        line += (column = 1);
    }

    switch (c) {
      case '\r':
        prevCharIsCR = true;
        break;
      case '\n':
        prevCharIsLF = true;
        break;
      case '\t':
        column--;
        column += (8 - (column & 07));
        break;
      default:
        break;
    }

    bufline[bufpos] = line;
    bufcolumn[bufpos] = column;
  }

  /**
   * Returns the next character from the input stream. The only method whose implementation is
   * different from its original in the ASCII_CharStream class.
   */
  public final char readChar() throws java.io.IOException {

    if (inBuf > 0) {
      --inBuf;

      // ----------------------------------------------------------------------
      // the next line was changed, the original line generated by JavaCC was:
      // return (char)((char)0xff & buffer[(bufpos == bufsize - 1) ? (bufpos = 0) : ++bufpos]);
      // ----------------------------------------------------------------------
      return buffer[(bufpos == bufsize - 1) ? (bufpos = 0) : ++bufpos];
    }
    if (++bufpos >= maxNextCharInd)
      FillBuff();

    // ----------------------------------------------------------------------
    // the next line was changed, the original line generated by JavaCC was:
    // char c = (char)((char)0xff & buffer[bufpos]);
    // ----------------------------------------------------------------------
    char c = buffer[bufpos];

    UpdateLineColumn(c);
    return (c);
  }

  /**
   * @deprecated
   * @see #getEndColumn
   */
  public final int getColumn() {
    return bufcolumn[bufpos];
  }

  /**
   * @deprecated
   * @see #getEndLine
   */
  public final int getLine() {
    return bufline[bufpos];
  }

  public final int getEndColumn() {
    return bufcolumn[bufpos];
  }

  public final int getEndLine() {
    return bufline[bufpos];
  }

  public final int getBeginColumn() {
    return bufcolumn[tokenBegin];
  }

  public final int getBeginLine() {
    return bufline[tokenBegin];
  }

  public final void backup(int amount) {
    inBuf += amount;
    if ((bufpos -= amount) < 0)
      bufpos += bufsize;
  }

  /**
   * Constructor, allowing to specify start line and start column of the char stream, and buffer
   * size as well.
   */
  public InputCharStream(java.io.Reader dstream, int startline, int startcolumn, int buffersize) {
    inputStream = dstream;
    line = startline;
    column = startcolumn - 1;
    available = bufsize = buffersize;
    buffer = new char[buffersize];
    bufline = new int[buffersize];
    bufcolumn = new int[buffersize];
  }

  /**
   * Constructor, allowing to specify start line and start column of the char stream.
   */
  public InputCharStream(java.io.Reader dstream, int startline, int startcolumn) {
    this(dstream, startline, startcolumn, 4096);
  }

  /**
   * Constructor, instantiating the char stream to begin at 1-st line and 1-st column of
   * <tt>dstream</tt>.
   */
  public InputCharStream(java.io.Reader dstream) {
    this(dstream, 1, 1);
  }

  /**
   * Reinitialization of the char stream, allowing to specify start line and start column of the
   * char stream, and buffer size as well.
   */
  public void ReInit(java.io.Reader dstream, int startline, int startcolumn, int buffersize) {
    inputStream = dstream;
    line = startline;
    column = startcolumn - 1;

    if (buffer == null || buffersize != buffer.length) {
      available = bufsize = buffersize;
      buffer = new char[buffersize];
      bufline = new int[buffersize];
      bufcolumn = new int[buffersize];
    }
    prevCharIsLF = prevCharIsCR = false;
    tokenBegin = inBuf = maxNextCharInd = 0;
    bufpos = -1;
  }

  /**
   * Reinitialization of the char stream, allowing to specify start line and start column of the
   * char stream.
   */
  public void ReInit(java.io.Reader dstream, int startline, int startcolumn) {
    ReInit(dstream, startline, startcolumn, 4096);
  }

  /**
   * Reinitialization of the char stream, instantiating the char stream to begin at 1-st line and
   * 1-st column of <tt>dstream</tt>.
   */
  public void ReInit(java.io.Reader dstream) {
    ReInit(dstream, 1, 1);
  }

  public final String GetImage() {
    if (bufpos >= tokenBegin) {
      return new String(buffer, tokenBegin, bufpos - tokenBegin + 1);
    }
    return new String(buffer, tokenBegin, bufsize - tokenBegin) + new String(buffer, 0, bufpos + 1);
  }

  public final char[] GetSuffix(int len) {
    char[] ret = new char[len];

    if ((bufpos + 1) >= len)
      System.arraycopy(buffer, bufpos - len + 1, ret, 0, len);
    else {
      System.arraycopy(buffer, bufsize - (len - bufpos - 1), ret, 0, len - bufpos - 1);
      System.arraycopy(buffer, 0, ret, len - bufpos - 1, bufpos + 1);
    }
    return ret;
  }

  public void Done() {
    buffer = null;
    bufline = null;
    bufcolumn = null;
  }

  /**
   * Method to adjust line and column numbers for the start of a token.
   */
  public void adjustBeginLineColumn(int newLine, int newCol) {
    int start = tokenBegin;
    int len;

    if (bufpos >= tokenBegin) {
      len = bufpos - tokenBegin + inBuf + 1;
    } else {
      len = bufsize - tokenBegin + bufpos + 1 + inBuf;
    }

    int i = 0, j = 0, k = 0;
    int nextColDiff = 0, columnDiff = 0;

    while (i < len && bufline[j = start % bufsize] == bufline[k = ++start % bufsize]) {
      bufline[j] = newLine;
      nextColDiff = columnDiff + bufcolumn[k] - bufcolumn[j];
      bufcolumn[j] = newCol + columnDiff;
      columnDiff = nextColDiff;
      i++;
    }

    if (i < len) {
      bufline[j] = newLine++;
      bufcolumn[j] = newCol + columnDiff;

      while (i++ < len) {
        if (bufline[j = start % bufsize] != bufline[++start % bufsize])
          bufline[j] = newLine++;
        else
          bufline[j] = newLine;
      }
    }

    line = bufline[j];
    column = bufcolumn[j];
  }
}
