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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.net;

import java.io.Serializable;
import java.util.concurrent.ConcurrentSkipListSet;

import org.archive.bdb.AutoKryo;

import com.esotericsoftware.kryo.serialize.ReferenceFieldSerializer;

/**
 * Represents the directives that apply to a user-agent (or set of
 * user-agents)
 */
public class RobotsDirectives implements Serializable {
    private static final long serialVersionUID = 5386542759286155383L;
    
    protected ConcurrentSkipListSet disallows = new ConcurrentSkipListSet();
    protected ConcurrentSkipListSet allows = new ConcurrentSkipListSet();
    protected float crawlDelay = -1; 
    public transient boolean hasDirectives = false;

    public boolean allows(String path) {
        return !(longestPrefixLength(disallows, path) > longestPrefixLength(allows, path));
    }

    /**
     * @param prefixSet
     * @param str
     * @return length of longest entry in {@code prefixSet} that prefixes {@code str}, or zero
     *         if no entry prefixes {@code str}
     */
    protected int longestPrefixLength(ConcurrentSkipListSet prefixSet,
            String str) {
        String possiblePrefix = prefixSet.floor(str);
        if (possiblePrefix != null && str.startsWith(possiblePrefix)) {
            return possiblePrefix.length();
        } else {
            return 0;
        }
    }

    public void addDisallow(String path) {
        hasDirectives = true;
        if(path.length()==0) {
            // ignore empty-string disallows 
            // (they really mean allow, when alone)
            return;
        }
        disallows.add(path);
    }

    public void addAllow(String path) {
        hasDirectives = true;
        allows.add(path);
    }

    public void setCrawlDelay(float i) {
        hasDirectives = true;
        crawlDelay=i;
    }

    public float getCrawlDelay() {
        return crawlDelay;
    }
    
    // Kryo support
    public static void autoregisterTo(AutoKryo kryo) {
        kryo.register(RobotsDirectives.class, new ReferenceFieldSerializer(kryo, RobotsDirectives.class));
        kryo.autoregister(ConcurrentSkipListSet.class); // now used instead of PrefixSet in RobotsDirectives
        kryo.setRegistrationOptional(true); 
    }

}