/*
 * Licensed to Crate under one or more contributor license agreements.
 * See the NOTICE file distributed with this work for additional
 * information regarding copyright ownership.  Crate 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.
 *
 * However, if you have executed another commercial license agreement
 * with Crate these terms will supersede the license and you may use the
 * software solely pursuant to the terms of the relevant commercial
 * agreement.
 */

package io.crate.lucene.match;

import org.apache.lucene.util.BytesRef;
import org.apache.lucene.util.CharsRefBuilder;

import java.util.regex.Matcher;
import java.util.regex.Pattern;

/**
 * An implementation tying Java's built-in java.util.regex to {@link CrateRegexQuery}.
 */
public final class CrateRegexCapabilities {

    public static final int FLAG_UNICODE_CASE = Pattern.UNICODE_CASE;
    public static final int FLAG_CASE_INSENSITIVE = Pattern.CASE_INSENSITIVE;

    static JavaUtilRegexMatcher compile(String regex, int flags) {
        return new CrateRegexCapabilities.JavaUtilRegexMatcher(regex, flags);
    }

    static class JavaUtilRegexMatcher {
        private final Pattern pattern;
        private final Matcher matcher;
        private final CharsRefBuilder utf16 = new CharsRefBuilder();

        JavaUtilRegexMatcher(String regex, int flags) {
            this.pattern = Pattern.compile(regex, flags);
            this.matcher = this.pattern.matcher(utf16.get());
        }

        boolean match(BytesRef term) {
            utf16.copyUTF8Bytes(term);
            utf16.get();
            return matcher.reset().matches();
        }
    }
}