/*

 * 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;

import java.util.Arrays;

import java.util.Collections;

import java.util.EnumSet;

/**

 * Translate XML numeric entities of the form &#[xX]?\d+;? to

 * the specific codepoint.

 *

 * Note that the semi-colon is optional.

 *

 * @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/NumericEntityUnescaper.html">

 * NumericEntityUnescaper</a> instead

 */

@Deprecated

public class NumericEntityUnescaper extends CharSequenceTranslator {

    public enum OPTION {

        semiColonRequired, semiColonOptional, errorIfNoSemiColon

    }

    // TODO?: Create an OptionsSet class to hide some of the conditional logic below

    private final EnumSet<OPTION> options;

    /**

     * Create a UnicodeUnescaper.

     *

     * The constructor takes a list of options, only one type of which is currently

     * available (whether to allow, error or ignore the semi-colon on the end of a

     * numeric entity to being missing).

     *

     * For example, to support numeric entities without a ';':

     *    new NumericEntityUnescaper(NumericEntityUnescaper.OPTION.semiColonOptional)

     * and to throw an IllegalArgumentException when they're missing:

     *    new NumericEntityUnescaper(NumericEntityUnescaper.OPTION.errorIfNoSemiColon)

     *

     * Note that the default behavior is to ignore them.

     *

     * @param options to apply to this unescaper

     */

    public NumericEntityUnescaper(final OPTION... options) {

        if (options.length > 0) {

            this.options = EnumSet.copyOf(Arrays.asList(options));

        } else {

            this.options = EnumSet.copyOf(Collections.singletonList(OPTION.semiColonRequired));

        }

    }

    /**

     * Whether the passed in option is currently set.

     *

     * @param option to check state of

     * @return whether the option is set

     */

    public boolean isSet(final OPTION option) {

        return options != null && options.contains(option);

    }

    /**

     * {@inheritDoc}

     */

    @Override

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

        final int seqEnd = input.length();

        // Uses -2 to ensure there is something after the &#

        if (input.charAt(index) == '&' && index < seqEnd - 2 && input.charAt(index + 1) == '#') {

            int start = index + 2;

            boolean isHex = false;

            final char firstChar = input.charAt(start);

            if (firstChar == 'x' || firstChar == 'X') {

                start++;

                isHex = true;

                // Check there's more than just an x after the &#

                if (start == seqEnd) {

                    return 0;

                }

            }

            int end = start;

            // Note that this supports character codes without a ; on the end

            while (end < seqEnd && ( input.charAt(end) >= '0' && input.charAt(end) <= '9' ||

                                    input.charAt(end) >= 'a' && input.charAt(end) <= 'f' ||

                                    input.charAt(end) >= 'A' && input.charAt(end) <= 'F' ) ) {

                end++;

            }

            final boolean semiNext = end != seqEnd && input.charAt(end) == ';';

            if (!semiNext) {

                if (isSet(OPTION.semiColonRequired)) {

                    return 0;

                } else

                if (isSet(OPTION.errorIfNoSemiColon)) {

                    throw new IllegalArgumentException("Semi-colon required at end of numeric entity");

                }

            }

            int entityValue;

            try {

                if (isHex) {

                    entityValue = Integer.parseInt(input.subSequence(start, end).toString(), 16);

                } else {

                    entityValue = Integer.parseInt(input.subSequence(start, end).toString(), 10);

                }

            } catch(final NumberFormatException nfe) {

                return 0;

            }

            if (entityValue > 0xFFFF) {

                final char[] chars = Character.toChars(entityValue);

                out.write(chars[0]);

                out.write(chars[1]);

            } else {

                out.write(entityValue);

            }

            return 2 + end - start + (isHex ? 1 : 0) + (semiNext ? 1 : 0);

        }

        return 0;

    }

}