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/*
 * Copyright (C) 2020 Graylog, Inc.
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the Server Side Public License, version 1,
 * as published by MongoDB, Inc.
 *
 * This program 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
 * Server Side Public License for more details.
 *
 * You should have received a copy of the Server Side Public License
 * along with this program. 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)) };
    }

}