BEGIN LICENSE BLOCK *****
Version: EPL 2.0/GPL 2.0/LGPL 2.1
The contents of this file are subject to the Eclipse Public
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.eclipse.org/legal/epl-v20.html
Software distributed under the License is distributed on an "AS
IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
implied. See the License for the specific language governing
rights and limitations under the License.
Copyright (C) 2002-2004 Jan Arne Petersen 
Copyright (C) 2002-2004 Anders Bengtsson 
Copyright (C) 2003-2004 Thomas E Enebo 
Copyright (C) 2004 Charles O Nutter 
Copyright (C) 2004 Stefan Matthias Aust 
Copyright (C) 2005 Derek Berner 
Copyright (C) 2006 Evan Buswell 
Copyright (C) 2007 Nick Sieger 
Copyright (C) 2009 Joseph LaFata 
Alternatively, the contents of this file may be used under the terms of
either of the GNU General Public License Version 2 or later (the "GPL"),
or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
in which case the provisions of the GPL or the LGPL are applicable instead
of those above. If you wish to allow use of your version of this file only
under the terms of either the GPL or the LGPL, and not to allow others to
use your version of this file under the terms of the EPL, indicate your
decision by deleting the provisions above and replace them with the notice
and other provisions required by the GPL or the LGPL. If you do not delete
the provisions above, a recipient may use your version of this file under
the terms of any one of the EPL, the GPL or the LGPL.
END LICENSE BLOCK /***** BEGIN LICENSE BLOCK *****
 * Version: EPL 2.0/GPL 2.0/LGPL 2.1
 *
 * The contents of this file are subject to the Eclipse Public
 * 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.eclipse.org/legal/epl-v20.html
 *
 * Software distributed under the License is distributed on an "AS
 * IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
 * implied. See the License for the specific language governing
 * rights and limitations under the License.
 *
 * Copyright (C) 2002-2004 Jan Arne Petersen <jpetersen@uni-bonn.de>
 * Copyright (C) 2002-2004 Anders Bengtsson <ndrsbngtssn@yahoo.se>
 * Copyright (C) 2003-2004 Thomas E Enebo <enebo@acm.org>
 * Copyright (C) 2004 Charles O Nutter <headius@headius.com>
 * Copyright (C) 2004 Stefan Matthias Aust <sma@3plus4.de>
 * Copyright (C) 2005 Derek Berner <derek.berner@state.nm.us>
 * Copyright (C) 2006 Evan Buswell <ebuswell@gmail.com>
 * Copyright (C) 2007 Nick Sieger <nicksieger@gmail.com>
 * Copyright (C) 2009 Joseph LaFata <joe@quibb.org>
 *
 * Alternatively, the contents of this file may be used under the terms of
 * either of the GNU General Public License Version 2 or later (the "GPL"),
 * or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
 * in which case the provisions of the GPL or the LGPL are applicable instead
 * of those above. If you wish to allow use of your version of this file only
 * under the terms of either the GPL or the LGPL, and not to allow others to
 * use your version of this file under the terms of the EPL, indicate your
 * decision by deleting the provisions above and replace them with the notice
 * and other provisions required by the GPL or the LGPL. If you do not delete
 * the provisions above, a recipient may use your version of this file under
 * the terms of any one of the EPL, the GPL or the LGPL.
 ***** END LICENSE BLOCK *****/

package org.jruby.util;

public class PackUtils {

    private static final byte[] hex_table;

    static {
        hex_table = ByteList.plain("0123456789ABCDEF");
    }

    
encodes a String with the Quoted printable, MIME encoding (see RFC2045).
appends the result of the encoding in a StringBuffer
Params:
io2Append – The StringBuffer which should receive the result
i2Encode – The String to encode
iLength – The max number of characters to encode
Returns:
the io2Append buffer/**
     * encodes a String with the Quoted printable, MIME encoding (see RFC2045).
     * appends the result of the encoding in a StringBuffer
     * @param io2Append The StringBuffer which should receive the result
     * @param i2Encode The String to encode
     * @param iLength The max number of characters to encode
     * @return the io2Append buffer
     **/
    public static ByteList qpencode(ByteList io2Append, ByteList i2Encode, int iLength) {
        io2Append.ensure(1024);
        int lCurLineLength = 0;
        int lPrevChar = -1;
        byte[] l2Encode = i2Encode.getUnsafeBytes();
        try {
            int end = i2Encode.getBegin() + i2Encode.getRealSize();
            for (int i = i2Encode.getBegin(); i < end; i++) {
                int lCurChar = l2Encode[i] & 0xff;
                if (lCurChar > 126 || (lCurChar < 32 && lCurChar != '\n' && lCurChar != '\t') || lCurChar == '=') {
                    io2Append.append('=');
                    io2Append.append(hex_table[lCurChar >>> 4]);
                    io2Append.append(hex_table[lCurChar & 0x0f]);
                    lCurLineLength += 3;
                    lPrevChar = -1;
                } else if (lCurChar == '\n') {
                    if (lPrevChar == ' ' || lPrevChar == '\t') {
                        io2Append.append('=');
                        io2Append.append(lCurChar);
                    }
                    io2Append.append(lCurChar);
                    lCurLineLength = 0;
                    lPrevChar = lCurChar;
                } else {
                    io2Append.append(lCurChar);
                    lCurLineLength++;
                    lPrevChar = lCurChar;
                }
                if (lCurLineLength > iLength) {
                    io2Append.append('=');
                    io2Append.append('\n');
                    lCurLineLength = 0;
                    lPrevChar = '\n';
                }
            }
        } catch (ArrayIndexOutOfBoundsException e) {
            //normal exit, this should be faster than a test at each iterations for string with more than
            //about 40 char
        }

        if (lCurLineLength > 0) {
            io2Append.append('=');
            io2Append.append('\n');
        }
        return io2Append;
    }
}