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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.deltaspike.proxy.spi;

import java.util.List;
import org.apache.deltaspike.core.util.ServiceUtils;

// TODO it would be great if we could just rewrite it to an AppScoped bean
public class DeltaSpikeProxyClassGeneratorHolder
{
    private static DeltaSpikeProxyClassGenerator generator;

    /**
     * Setter invoked by OSGi Service Component Runtime.
     *
     * @param generator generator service
     */
    public void setGenerator(DeltaSpikeProxyClassGenerator generator)
    {
        this.generator = generator;
    }
    
    /**
     * Looks up a unique service implementation.
     *
     * @return ProxyClassGenerator service
     */
    public static DeltaSpikeProxyClassGenerator lookup()
    {
        if (generator == null)
        {
            List proxyClassGeneratorList =
                    ServiceUtils.loadServiceImplementations(DeltaSpikeProxyClassGenerator.class);

            if (proxyClassGeneratorList.size() != 1)
            {
                throw new IllegalStateException(proxyClassGeneratorList.size()
                    + " implementations of " + DeltaSpikeProxyClassGenerator.class.getName()
                    + " found. Expected exactly one implementation.");
            }

            generator = proxyClassGeneratorList.get(0);
        }

        return generator;
    }
}