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/*
 * Copyright 2006-2023 Prowide
 *
 * 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.prowidesoftware.swift.model.mx;

import jakarta.xml.bind.JAXBContext;
import jakarta.xml.bind.JAXBException;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;

/**
 * Simple cache based on {@link ConcurrentHashMap} without eviction. This implementation is aimed to avoid additional
 * third party dependencies. For a more robust solution You can easily implement your own cache with Guava, Ecache,
 * Caffeine or any other cache library. See some code references in the {@link JaxbContextCache} interface.
 *
 * @since 9.0
 */
public class JaxbContextCacheImpl implements JaxbContextCache {

    private Map cachedMap;

    /**
     * Gets a context from the static cache. If the context for the specific message type is not present,
     * a new context is initialized with the given classes or messageClass and stored in the cache.
     *
     * @param messageClass class of the message to be read or written
     * @param classes      comprehensive list of classes for the context, null or empty to create a context with the messageClass
     * @return the cached or created context for the specific message type
     */
    public JAXBContext get(final Class messageClass, final Class[] classes) throws JAXBException {
        if (cachedMap == null) {
            cachedMap = new ConcurrentHashMap<>();
        }

        JAXBContext context = cachedMap.get(messageClass);
        if (context == null) {
            if (classes != null && classes.length != 0) {
                context = JAXBContext.newInstance(classes);
            } else {
                context = JAXBContext.newInstance(messageClass);
            }
            cachedMap.put(messageClass, context);
        }
        return context;
    }

    /**
     * Drops all cached contexts
     */
    public void clear() {
        cachedMap = null;
    }

    /**
     * Drops the cached context for the specific MX implementation class
     *
     * @return the remove context, if it was present, or null otherwise
     */
    public JAXBContext clear(Class clazz) {
        if (cachedMap != null) {
            return cachedMap.remove(clazz);
        }
        return null;
    }

    /**
     * @return the number of cached contexts
     */
    public int size() {
        if (cachedMap != null) {
            return cachedMap.size();
        }
        return 0;
    }
}