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/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF 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.apache.camel.support;

import java.util.HashSet;
import java.util.Locale;
import java.util.Map;
import java.util.Set;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import java.util.regex.PatternSyntaxException;

public final class PatternHelper {

    private PatternHelper() {
        //Utility Class
    }

    /**
     * Matches the name with the given pattern (case insensitive).
     * 
     * The match rules are applied in this order:
     * 

     * exact match, returns true
     * wildcard match (pattern ends with a * and the name starts with the pattern), returns true
     * regular expression match, returns true
     * otherwise returns false
     * 
     *
     * @param  name    the name
     * @param  pattern a pattern to match
     * @return         true if match, false otherwise.
     */
    public static boolean matchPattern(String name, String pattern) {
        if (name == null || pattern == null) {
            return false;
        }

        if (name.equalsIgnoreCase(pattern)) {
            // exact match
            return true;
        }

        if (matchWildcard(name, pattern)) {
            return true;
        }

        if (matchRegex(name, pattern)) {
            return true;
        }

        // no match
        return false;
    }

    /**
     * Matches the name with the given patterns (case insensitive).
     *
     * @param  name     the name
     * @param  patterns pattern(s) to match
     * @return          true if match, false otherwise.
     * @see             #matchPattern(String, String)
     */
    public static boolean matchPatterns(String name, String[] patterns) {
        for (String pattern : patterns) {
            if (PatternHelper.matchPattern(name, pattern)) {
                return true;
            }
        }
        return false;
    }

    /**
     * Matches the name with the given pattern (case insensitive).
     * 
     * The match rules are applied in this order:
     * 

     * wildcard match (pattern ends with a * and the name starts with the pattern), returns true
     * otherwise returns false
     * 
     *
     * @param  name    the name
     * @param  pattern a pattern to match
     * @return         true if match, false otherwise.
     */
    private static boolean matchWildcard(String name, String pattern) {
        // we have wildcard support in that hence you can match with: file* to match any file endpoints
        if (pattern.endsWith("*")) {
            String text = pattern.substring(0, pattern.length() - 1);
            return name.toLowerCase(Locale.ENGLISH).startsWith(text.toLowerCase(Locale.ENGLISH));
        }
        return false;
    }

    /**
     * Matches the name with the given pattern (case insensitive).
     * 
     * The match rules are applied in this order:
     * 

     * regular expression match, returns true
     * otherwise returns false
     * 
     *
     * @param  name    the name
     * @param  pattern a pattern to match
     * @return         true if match, false otherwise.
     */
    public static boolean matchRegex(String name, String pattern) {
        // match by regular expression
        try {
            Pattern compiled = Pattern.compile(pattern, Pattern.CASE_INSENSITIVE);
            Matcher matcher = compiled.matcher(name);
            return matcher.matches();
        } catch (PatternSyntaxException e) {
            // ignore
        }
        return false;
    }

    public static boolean isExcludePatternMatch(String key, String... excludePatterns) {
        for (String pattern : excludePatterns) {
            if (matchPattern(key, pattern)) {
                return true;
            }
        }
        return false;
    }

    /**
     * Given a map, creates a set of all keys matching a pattern (except if explicitly excluded). This is usually used
     * to collect matching keys and properties for removal
     *
     * @param  map             A map
     * @param  pattern         The pattern to test
     * @param  excludePatterns An exclusion pattern that prevents a matching key to be added to the returned set
     * @return                 A {@link java.util.Set Set} instance with all the matching keys
     */
    public static Set matchingSet(Map map, String pattern, String[] excludePatterns) {
        Set toBeRemoved = null;
        // must use a set to store the keys to remove as we cannot walk using entrySet and remove at the same time
        // due concurrent modification error
        for (String key : map.keySet()) {
            if (PatternHelper.matchPattern(key, pattern)) {
                if (excludePatterns != null && PatternHelper.isExcludePatternMatch(key, excludePatterns)) {
                    continue;
                }
                if (toBeRemoved == null) {
                    toBeRemoved = new HashSet<>();
                }
                toBeRemoved.add(key);
            }
        }
        return toBeRemoved;
    }
}