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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;

import static com.google.common.base.Strings.isNullOrEmpty;

public class RegexReplaceExtractor extends Extractor {
    private static final String CONFIG_REGEX = "regex";
    private static final String CONFIG_REPLACEMENT = "replacement";
    private static final String CONFIG_REPLACE_ALL = "replace_all";
    private static final String DEFAULT_REPLACE_VALUE = "$1";

    private final Pattern pattern;
    private final String replacement;
    private final boolean replaceAll;

    public RegexReplaceExtractor(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_REPLACE, cursorStrategy, sourceField, targetField, extractorConfig, creatorUserId, converters, conditionType, conditionValue);

        if (extractorConfig == null || extractorConfig.isEmpty()) {
            throw new ConfigurationException("Missing configuration");
        }

        final Object configRegexValue = extractorConfig.get(CONFIG_REGEX);
        if (!(configRegexValue instanceof String) || ((String) configRegexValue).isEmpty()) {
            throw new ConfigurationException("Missing configuration field: " + CONFIG_REGEX);
        }

        final Object configReplaceValue = extractorConfig.get(CONFIG_REPLACEMENT);
        if (configReplaceValue != null && !(configReplaceValue instanceof String)) {
            throw new ConfigurationException("Missing configuration field: " + CONFIG_REPLACEMENT);
        }

        final Object configReplaceAll = extractorConfig.get(CONFIG_REPLACE_ALL);
        if (configReplaceAll != null && !(configReplaceAll instanceof Boolean)) {
            throw new ConfigurationException("Missing configuration field: " + CONFIG_REPLACE_ALL);
        }

        this.pattern = Pattern.compile((String) configRegexValue, Pattern.DOTALL);
        this.replacement = isNullOrEmpty((String) configReplaceValue) ? DEFAULT_REPLACE_VALUE : (String) configReplaceValue;
        this.replaceAll = configReplaceAll == null ? false : (boolean) configReplaceAll;
    }

    @Override
    protected Result[] run(String value) {
        final Result result = runExtractor(value);
        return result == null ? null : new Result[]{result};
    }

    public Result runExtractor(String value) {
        final Matcher matcher = pattern.matcher(value);

        final boolean found = matcher.find();
        if (!found) {
            return null;
        }

        final int start = matcher.groupCount() > 0 ? matcher.start(1) : -1;
        final int end = matcher.groupCount() > 0 ? matcher.end(1) : -1;

        final String s;
        try {
            s = replaceAll ? matcher.replaceAll(replacement) : matcher.replaceFirst(replacement);
        } catch (Exception e) {
            throw new RuntimeException("Error while trying to replace string", e);
        }

        return new Result(s, start, end);
    }

}