PermissionTopicMatcher.java

/*
 * Copyright 2014 dc-square GmbH
 *
 * Licensed 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 com.hivemq.spi.topic;

import com.hivemq.spi.topic.exception.InvalidTopicException;
import org.apache.commons.lang3.StringUtils;

import static java.lang.Math.min;

/**
 * An implementation of a topic matcher which tokenizes topics to match wildcards.
 *
 * @author Dominik Obermaier
 * @since 1.4
 */

public class PermissionTopicMatcher implements TopicMatcher {

    PermissionTopicMatcher() {
        //decrease visibility
    }

    @Override
    public boolean matches(String permissionTopic, String actualTopic) throws InvalidTopicException {
        final String stripedPermissionTopic = StringUtils.stripEnd(permissionTopic, "/");
        final String[] splitPermissionTopic = StringUtils.splitPreserveAllTokens(stripedPermissionTopic, "/");
        final boolean nonWildCard = StringUtils.containsNone(stripedPermissionTopic, "#+");
        final boolean rootWildCard = stripedPermissionTopic.contains("#");
        final boolean endsWithWildCard = StringUtils.endsWith(stripedPermissionTopic, "/#");

        final String stripedActualTopic = StringUtils.stripEnd(actualTopic, "/");
        final String[] splitActualTopic = StringUtils.splitPreserveAllTokens(stripedActualTopic, "/");
        return matches(stripedPermissionTopic, splitPermissionTopic, nonWildCard, endsWithWildCard, rootWildCard, stripedActualTopic, splitActualTopic);
    }

    public boolean matches(final String permissionTopic, final String[] splitPermissionTopic, boolean nonWildCard, boolean endsWithWildCard, boolean rootWildCard, final String actualTopic, final String[] splitActualTopic) throws InvalidTopicException {
        if (nonWildCard) {

            return permissionTopic.equals(actualTopic);
        }
        return matchesWildcards(permissionTopic, splitPermissionTopic, endsWithWildCard, rootWildCard, splitActualTopic);
    }

    private static boolean matchesWildcards(final String permissionTopic, final String[] splitPermissionTopic, boolean endsWithWildCard, boolean rootWildCard, final String[] splitActualTopic) {

        if (rootWildCard) {
            if (!endsWithWildCard && permissionTopic.length() > 1) {
                return false;
            }
        }

        final int smallest = min(splitPermissionTopic.length, splitActualTopic.length);

        for (int i = 0; i < smallest; i++) {
            final String sub = splitPermissionTopic[i];
            final String t = splitActualTopic[i];

            if (!sub.equals(t)) {
                if (sub.equals("#")) {
                    return true;
                } else if (sub.equals("+")) {
                    //Matches Topic Level wildcard, so we can just ignore

                } else {
                    //Does not match a wildcard and is not equal to the topic token
                    return false;
                }
            }
        }
        //If the length is equal or the subscription token with the number x+1 (where x is the topic length) is a wildcard,
        //everything is alright.
        return splitPermissionTopic.length == splitActualTopic.length ||
                (splitPermissionTopic.length - splitActualTopic.length == 1 && (splitPermissionTopic[splitPermissionTopic.length - 1].equals("#")));
    }
}