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 * and Distribution License("CDDL") (collectively, the "License").  You
 * may not use this file except in compliance with the License.  You can
 * obtain a copy of the License at
 * http://glassfish.java.net/public/CDDL+GPL_1_1.html
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 * GPL Classpath Exception:
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package org.glassfish.jersey.servlet.internal;

import java.lang.reflect.Proxy;
import java.util.Enumeration;
import java.util.Map;

import javax.inject.Inject;
import javax.inject.Singleton;
import javax.persistence.EntityManagerFactory;
import javax.persistence.PersistenceUnit;
import javax.servlet.ServletConfig;

import org.glassfish.hk2.utilities.binding.AbstractBinder;
import org.glassfish.jersey.server.ContainerException;

import org.glassfish.hk2.api.Injectee;
import org.glassfish.hk2.api.InjectionResolver;
import org.glassfish.hk2.api.ServiceHandle;
import org.glassfish.hk2.api.ServiceLocator;
import org.glassfish.hk2.api.TypeLiteral;

import com.google.common.collect.Maps;

/**
 * {@link PersistenceUnit Persistence unit} injection binder.
 *
 * @author Michal Gajdos (michal.gajdos at oracle.com)
 */
public class PersistenceUnitBinder extends AbstractBinder {

    /**
     * Prefix of the persistence unit init param.
     */
    public final static String PERSISTENCE_UNIT_PREFIX = "unit:";

    @Singleton
    private static class PersistenceUnitInjectionResolver implements InjectionResolver<PersistenceUnit> {

        private final Map<String, String> persistenceUnits = Maps.newHashMap();

        @Inject
        private PersistenceUnitInjectionResolver(final ServiceLocator locator) {
            // Look for persistence units.
            final ServletConfig servletConfig = locator.getService(ServletConfig.class);

            for (final Enumeration parameterNames = servletConfig.getInitParameterNames(); parameterNames.hasMoreElements(); ) {
                final String key = (String) parameterNames.nextElement();

                if (key.startsWith(PERSISTENCE_UNIT_PREFIX)) {
                    persistenceUnits.put(key.substring(PERSISTENCE_UNIT_PREFIX.length()),
                            "java:comp/env/" + servletConfig.getInitParameter(key));
                }
            }
        }

        @Override
        public Object resolve(final Injectee injectee, final ServiceHandle<?> root) {
            if (!injectee.getRequiredType().equals(EntityManagerFactory.class)) {
                return null;
            }

            final PersistenceUnit annotation = injectee.getParent().getAnnotation(PersistenceUnit.class);
            final String unitName = annotation.unitName();

            if (!persistenceUnits.containsKey(unitName)) {
                throw new ContainerException(LocalizationMessages.PERSISTENCE_UNIT_NOT_CONFIGURED(unitName));
            }

            return Proxy.newProxyInstance(
                    this.getClass().getClassLoader(),
                    new Class[]{EntityManagerFactory.class},
                    new ThreadLocalNamedInvoker<EntityManagerFactory>(persistenceUnits.get(unitName)));
        }

        @Override
        public boolean isConstructorParameterIndicator() {
            return false;
        }

        @Override
        public boolean isMethodParameterIndicator() {
            return false;
        }
    }

    @Override
    protected void configure() {
        bind(PersistenceUnitInjectionResolver.class)
                .to(new TypeLiteral<InjectionResolver<PersistenceUnit>>() {})
                .in(Singleton.class);
    }
}
