/*
* $HeadURL$
* $Revision$
* $Date$
*
* ====================================================================
*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache 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.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
* ====================================================================
*
* This software consists of voluntary contributions made by many
* individuals on behalf of the Apache Software Foundation. For more
* information on the Apache Software Foundation, please see
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package org.apache.ogt.http.client.utils;
import java.util.StringTokenizer;
import org.apache.ogt.http.annotation.Immutable;
/**
* Implementation from pseudo code in RFC 3492.
*
* @since 4.0
*/
@Immutable
public class Rfc3492Idn implements Idn {
private static final int base = 36;
private static final int tmin = 1;
private static final int tmax = 26;
private static final int skew = 38;
private static final int damp = 700;
private static final int initial_bias = 72;
private static final int initial_n = 128;
private static final char delimiter = '-';
private static final String ACE_PREFIX = "xn--";
private int adapt(int delta, int numpoints, boolean firsttime) {
if (firsttime) delta = delta / damp;
else delta = delta / 2;
delta = delta + (delta / numpoints);
int k = 0;
while (delta > ((base - tmin) * tmax) / 2) {
delta = delta / (base - tmin);
k = k + base;
}
return k + (((base - tmin + 1) * delta) / (delta + skew));
}
private int digit(char c) {
if ((c >= 'A') && (c <= 'Z')) return (c - 'A');
if ((c >= 'a') && (c <= 'z')) return (c - 'a');
if ((c >= '0') && (c <= '9')) return (c - '0') + 26;
throw new IllegalArgumentException("illegal digit: "+ c);
}
public String toUnicode(String punycode) {
StringBuilder unicode = new StringBuilder(punycode.length());
StringTokenizer tok = new StringTokenizer(punycode, ".");
while (tok.hasMoreTokens()) {
String t = tok.nextToken();
if (unicode.length() > 0) unicode.append('.');
if (t.startsWith(ACE_PREFIX)) t = decode(t.substring(4));
unicode.append(t);
}
return unicode.toString();
}
protected String decode(String input) {
int n = initial_n;
int i = 0;
int bias = initial_bias;
StringBuilder output = new StringBuilder(input.length());
int lastdelim = input.lastIndexOf(delimiter);
if (lastdelim != -1) {
output.append(input.subSequence(0, lastdelim));
input = input.substring(lastdelim + 1);
}
while (input.length() > 0) {
int oldi = i;
int w = 1;
for (int k = base;; k += base) {
if (input.length() == 0) break;
char c = input.charAt(0);
input = input.substring(1);
int digit = digit(c);
i = i + digit * w; // FIXME fail on overflow
int t;
if (k <= bias + tmin) {
t = tmin;
} else if (k >= bias + tmax) {
t = tmax;
} else {
t = k - bias;
}
if (digit < t) break;
w = w * (base - t); // FIXME fail on overflow
}
bias = adapt(i - oldi, output.length() + 1, (oldi == 0));
n = n + i / (output.length() + 1); // FIXME fail on overflow
i = i % (output.length() + 1);
// {if n is a basic code point then fail}
output.insert(i, (char) n);
i++;
}
return output.toString();
}
}