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/**
 * This file is part of Graylog.
 *
 * Graylog 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 3 of the License, or
 * (at your option) any later version.
 *
 * Graylog 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 Graylog.  If not, see .
 */
package org.graylog2.inputs.extractors;

import com.codahale.metrics.MetricRegistry;
import org.graylog2.ConfigurationException;
import org.graylog2.plugin.inputs.Converter;
import org.graylog2.plugin.inputs.Extractor;

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

public class RegexExtractor extends Extractor {
    private static final String CONFIG_REGEX_VALUE = "regex_value".intern();

    private final Pattern pattern;

    public RegexExtractor(final MetricRegistry metricRegistry,
                          final String id,
                          final String title,
                          final long order,
                          final CursorStrategy cursorStrategy,
                          final String sourceField,
                          final String targetField,
                          final Map extractorConfig,
                          final String creatorUserId,
                          final List converters,
                          final ConditionType conditionType,
                          final String conditionValue) throws ReservedFieldException, ConfigurationException {
        super(metricRegistry, id, title, order, Type.REGEX, cursorStrategy, sourceField, targetField, extractorConfig, creatorUserId, converters, conditionType, conditionValue);

        if (extractorConfig == null || extractorConfig.get(CONFIG_REGEX_VALUE) == null || ((String) extractorConfig.get(CONFIG_REGEX_VALUE)).isEmpty()) {
            throw new ConfigurationException("Missing regex configuration field: regex_value");
        }

        pattern = Pattern.compile((String) extractorConfig.get(CONFIG_REGEX_VALUE), Pattern.DOTALL);
    }

    @Override
    protected Result[] run(String value) {
        final Matcher matcher = pattern.matcher(value);

        if (!matcher.find() || matcher.groupCount() == 0 || matcher.start(1) == -1 || matcher.end(1) == -1) {
            return null;
        }

        return new Result[] { new Result(value.substring(matcher.start(1), matcher.end(1)), matcher.start(1), matcher.end(1)) };
    }

}