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This project contains some of the configurable modules used within the Heritrix application to crawl the web. The modules in this project can be used in applications other than Heritrix, however.

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/*
 *  This file is part of the Heritrix web crawler (crawler.archive.org).
 *
 *  Licensed to the Internet Archive (IA) by one or more individual 
 *  contributors. 
 *
 *  The IA 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.archive.modules.deciderules;

import java.util.regex.Matcher;

import org.archive.modules.CrawlURI;
import org.archive.util.TextUtils;


/**
 * Rule REJECTs any URI which contains an excessive number of identical, 
 * consecutive path-segments (eg http://example.com/a/a/a/boo.html == 3 '/a' 
 * segments)
 *
 * @author gojomo
 */
public class PathologicalPathDecideRule extends DecideRule {
    private static final long serialVersionUID = 3L;

    /**
     * Number of times the pattern should be allowed to occur. This rule returns
     * its decision (usually REJECT) if a path-segment is repeated more than
     * number of times.
     */
    {
        setMaxRepetitions(2);
    }
    public int getMaxRepetitions() {
        return (Integer) kp.get("maxRepetitions");
    }
    public void setMaxRepetitions(int maxRepetitions) {
        kp.put("maxRepetitions", maxRepetitions);
    }
    
    /** Constructs a new PathologicalPathFilter.
     */
    public PathologicalPathDecideRule() {
    }


    @Override
    protected DecideResult innerDecide(CrawlURI uri) {
        int maxRep = getMaxRepetitions();
//        Pattern p = getPattern(maxRep);
        Matcher m = TextUtils.getMatcher(constructRegex(maxRep), uri.getUURI().toString());
        try {
            if (m.matches()) {
                return DecideResult.REJECT;
            } else {
                return DecideResult.NONE;
            }
        } finally {
            TextUtils.recycleMatcher(m);
        }
    }
 
    protected String constructRegex(int rep) {
        return (rep == 0) ? null : ".*?/(.*?/)\\1{" + rep + ",}.*";
    }
}