/*
 * Copyright 1999-2018 Alibaba Group Holding Ltd.
 *
 * 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.alibaba.druid.util;

public class ServletPathMatcher implements PatternMatcher {
    private static final ServletPathMatcher INSTANCE = new ServletPathMatcher();

    public static ServletPathMatcher getInstance() {
        return INSTANCE;
    }

    private ServletPathMatcher() {
    }

    /**
     * <p>
     * three type: endsWithMatch(eg. /xxx*=/xxx/xyz), startsWithMatch(eg.
     * *.xxx=abc.xxx), equals(eg. /xxx=/xxx).
     * </p>
     * <b>Notice</b>: *xxx* will match *xxxyyyy. endsWithMatch first.
     */
    @Override
    public boolean matches(String pattern, String source) {
        if (pattern == null || source == null) {
            return false;
        }
        pattern = pattern.trim();
        source = source.trim();
        if (pattern.endsWith("*")) {
            // pattern: /druid* source:/druid/index.html
            int length = pattern.length() - 1;
            if (source.length() >= length) {
                if (pattern.substring(0, length).equals(
                        source.substring(0, length))) {
                    return true;
                }
            }
        } else if (pattern.startsWith("*")) {
            // pattern: *.html source:/xx/xx.html
            int length = pattern.length() - 1;
            if (source.length() >= length
                    && source.endsWith(pattern.substring(1))) {
                return true;
            }
        } else if (pattern.contains("*")) {
            // pattern:  /druid/*/index.html source:/druid/admin/index.html
            int start = pattern.indexOf("*");
            int end = pattern.lastIndexOf("*");
            if (source.startsWith(pattern.substring(0, start))
                    && source.endsWith(pattern.substring(end + 1))) {
                return true;
            }
        } else {
            // pattern: /druid/index.html source:/druid/index.html
            if (pattern.equals(source)) {
                return true;
            }
        }
        return false;
    }

}
