/*

 * 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.

 */

package org.apache.commons.lang3.text.translate;

import java.io.IOException;

import java.io.Writer;

/**

 * Translates escaped Unicode values of the form \\u+\d\d\d\d back to

 * Unicode. It supports multiple 'u' characters and will work with or

 * without the +.

 *

 * @since 3.0

 * @deprecated as of 3.6, use commons-text

 * <a href="https://commons.apache.org/proper/commons-text/javadocs/api-release/org/apache/commons/text/translate/UnicodeUnescaper.html">

 * UnicodeUnescaper</a> instead

 */

@Deprecated

public class UnicodeUnescaper extends CharSequenceTranslator {

    /**

     * {@inheritDoc}

     */

    @Override

    public int translate(final CharSequence input, final int index, final Writer out) throws IOException {

        if (input.charAt(index) == '\\' && index + 1 < input.length() && input.charAt(index + 1) == 'u') {

            // consume optional additional 'u' chars

            int i = 2;

            while (index + i < input.length() && input.charAt(index + i) == 'u') {

                i++;

            }

            if (index + i < input.length() && input.charAt(index + i) == '+') {

                i++;

            }

            if (index + i + 4 <= input.length()) {

                // Get 4 hex digits

                final CharSequence unicode = input.subSequence(index + i, index + i + 4);

                try {

                    final int value = Integer.parseInt(unicode.toString(), 16);

                    out.write((char) value);

                } catch (final NumberFormatException nfe) {

                    throw new IllegalArgumentException("Unable to parse unicode value: " + unicode, nfe);

                }

                return i + 4;

            }

            throw new IllegalArgumentException("Less than 4 hex digits in unicode value: '" + input.subSequence(index, input.length())

                    + "' due to end of CharSequence");

        }

        return 0;

    }

}