/**
*
* 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.airavata.service.security.authzcache;

import java.util.LinkedHashMap;
import java.util.Map;
import org.apache.airavata.common.exception.ApplicationSettingsException;
import org.apache.airavata.common.utils.ServerSettings;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class AuthzCache extends LinkedHashMap<AuthzCacheIndex, AuthzCacheEntry> {

    private static int MAX_SIZE;
    private static final Logger logger = LoggerFactory.getLogger(AuthzCache.class);

    private static AuthzCache authzCache = null;

    public static AuthzCache getInstance() throws ApplicationSettingsException {
        if (authzCache == null) {
            synchronized (AuthzCache.class) {
                if (authzCache == null) {
                    authzCache = new AuthzCache(ServerSettings.getCacheSize());
                }
            }
        }
        return authzCache;
    }

    private AuthzCache(int initialCapacity) {
        super(initialCapacity);
        MAX_SIZE = initialCapacity;
    }

    @Override
    protected boolean removeEldestEntry(Map.Entry<AuthzCacheIndex, AuthzCacheEntry> eldest) {
        if (size() > MAX_SIZE) {
            logger.info("Authz cache max size exceeded. Removing the old entries.");
        }
        return size() > MAX_SIZE;
    }
}
