/*
* Created on 21-Jun-2004
* Created by Paul Gardner
* Copyright (C) 2004, 2005, 2006 Aelitis, All Rights Reserved.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*
* AELITIS, SAS au capital de 46,603.30 euros
* 8 Allee Lenotre, La Grille Royale, 78600 Le Mesnil le Roi, France.
*
*/
package org.gudy.azureus2.core3.internat;
import java.io.File;
import java.io.UnsupportedEncodingException;
import org.gudy.azureus2.core3.util.*;
/**
* @author parg
*
*/
public class
LocaleUtilDecoderFallback
implements LocaleUtilDecoder
{
public static String NAME = "Fallback";
private static volatile int max_ok_name_length = 64;
private static volatile boolean max_ok_name_length_determined;
// don't change these, it'll stuff up people with torrents that are using the
// fallback encoding
private static final String VALID_CHARS = "abcdefghijklmnopqrstuvwxyz1234567890_-.";
private int index;
protected
LocaleUtilDecoderFallback(
int _index )
{
index = _index;
}
public String
getName()
{
return( NAME );
}
public int
getIndex()
{
return( index );
}
public String
tryDecode(
byte[] bytes,
boolean lax )
{
return( decode( bytes ));
}
public String
decodeString(
byte[] bytes )
throws UnsupportedEncodingException
{
return( decode( bytes ));
}
protected String
decode(
byte[] data )
{
if ( data == null ){
return( null );
}
StringBuffer res = new StringBuffer( data.length*2 );
for (int i=0;i<data.length;i++){
byte c = data[i];
if ( VALID_CHARS.indexOf( Character.toLowerCase((char)c)) != -1 ){
res.append((char)c);
}else{
res.append( "_" );
res.append( ByteFormatter.nicePrint(c));
}
}
// more often that not these decoded values are used for filenames. Windows has a limit
// of 250 (ish) chars, so we do something sensible with longer values
int len = res.length();
if ( len > max_ok_name_length ){
// could be a file system out there that supports arbitarily long names, so
// we can't pre-calculate the max
if ( ( !max_ok_name_length_determined )&&
fileLengthOK( len )){
// this length is ok, bump up the known limit
max_ok_name_length = len;
}else{
// won't fit
if ( !max_ok_name_length_determined ){
for (int i=max_ok_name_length+16;i<len;i+=16 ){
if ( fileLengthOK( i )){
max_ok_name_length = i;
}else{
break;
}
}
max_ok_name_length_determined = true;
}
// try and preserve extension
String extension = null;
int pos = res.lastIndexOf(".");
if ( pos != -1 ){
// include the "."
extension = res.substring( pos );
if ( extension.length() == 1 || extension.length() > 4 ){
extension = null;
}
}
// replace the end of the string with a hash value to ensure uniqueness
byte[] hash = new SHA1Hasher().calculateHash( data );
String hash_str = ByteFormatter.nicePrint( hash, true );
res = new StringBuffer(res.substring(
0,
max_ok_name_length - hash_str.length() - (extension == null?0:extension.length())));
res.append( hash_str );
if ( extension != null ){
res.append( extension );
}
}
}
return( res.toString());
}
protected boolean
fileLengthOK(
int len )
{
StringBuffer n = new StringBuffer( len );
for (int i=0;i<len;i++){
n.append( "A" );
}
try{
File f = File.createTempFile( n.toString(), "" );
f.delete();
return( true );
}catch( Throwable e ){
return( false );
}
}
}