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/*
 * Copyright (c) 2024 Contributors to Eclipse Foundation.
 * Copyright (c) 2023 Payara Foundation and/or its affiliates. All rights reserved.
 * Copyright (c) 2012, 2018 Oracle and/or its affiliates. All rights reserved.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v. 2.0, which is available at
 * http://www.eclipse.org/legal/epl-2.0.
 *
 * This Source Code may also be made available under the following Secondary
 * Licenses when the conditions for such availability set forth in the
 * Eclipse Public License v. 2.0 are satisfied: GNU General Public License,
 * version 2 with the GNU Classpath Exception, which is available at
 * https://www.gnu.org/software/classpath/license.html.
 *
 * SPDX-License-Identifier: EPL-2.0 OR GPL-2.0 WITH Classpath-exception-2.0
 */

package org.glassfish.hk2.internal;

import jakarta.inject.Singleton;

import java.lang.annotation.Annotation;
import java.security.AccessController;
import java.security.PrivilegedAction;
import java.util.HashMap;
import java.util.Map;

import org.glassfish.hk2.api.ActiveDescriptor;
import org.glassfish.hk2.api.Context;
import org.glassfish.hk2.api.DescriptorVisibility;
import org.glassfish.hk2.api.PerThread;
import org.glassfish.hk2.api.ServiceHandle;
import org.glassfish.hk2.api.Visibility;
import org.glassfish.hk2.utilities.CleanerFactory;
import org.glassfish.hk2.utilities.general.Hk2ThreadLocal;
import org.glassfish.hk2.utilities.reflection.Logger;

/**
 * @author jwells
 */
@Singleton @Visibility(DescriptorVisibility.LOCAL)
public class PerThreadContext implements Context {

    private final static boolean LOG_THREAD_DESTRUCTION = AccessController.doPrivileged(
            (PrivilegedAction) () -> Boolean.getBoolean("org.hk2.debug.perthreadcontext.log"));
    
    private final Hk2ThreadLocal threadMap =
            new Hk2ThreadLocal<>() {

                @Override
                public PerThreadContextWrapper initialValue() {
                    return new PerThreadContextWrapper();
                }
            };

    /* (non-Javadoc)
     * @see org.glassfish.hk2.api.Context#getScope()
     */
    @Override
    public Class getScope() {
        return PerThread.class;
    }

    /* (non-Javadoc)
     * @see org.glassfish.hk2.api.Context#findOrCreate(org.glassfish.hk2.api.ActiveDescriptor, org.glassfish.hk2.api.ServiceHandle)
     */
    @SuppressWarnings("unchecked")
    @Override
    public  U findOrCreate(ActiveDescriptor activeDescriptor, ServiceHandle root) {
        U retVal = (U) threadMap.get().get(activeDescriptor);
        if (retVal == null) {
            retVal = activeDescriptor.create(root);
            threadMap.get().put(activeDescriptor, retVal);
        }
        return retVal;
    }

    /* (non-Javadoc)
     * @see org.glassfish.hk2.api.Context#find(org.glassfish.hk2.api.ActiveDescriptor)
     */
    @Override
    public boolean containsKey(ActiveDescriptor descriptor) {
        return threadMap.get().has(descriptor);
    }

    /* (non-Javadoc)
     * @see org.glassfish.hk2.api.Context#isActive()
     */
    @Override
    public boolean isActive() {
        return true;
    }

    /* (non-Javadoc)
     * @see org.glassfish.hk2.api.Context#supportsNullCreation()
     */
    @Override
    public boolean supportsNullCreation() {
        return false;
    }

    /* (non-Javadoc)
     * @see org.glassfish.hk2.api.Context#supportsNullCreation()
     */
    @Override
    public void shutdown() {
        threadMap.removeAll();
    }

    @Override
    public void destroyOne(ActiveDescriptor descriptor) {
        // per-thread instances live for the life of the thread,
        // so we will ignore any request to destroy a descriptor
    }
    
    private static class PerThreadContextWrapper {

        private final CleanableContext context = new CleanableContext();

        public PerThreadContextWrapper() {
            registerStopEvent();
        }
                
        public boolean has(ActiveDescriptor descriptor) {
            return context.has(descriptor);
        }
        
        public Object get(ActiveDescriptor descriptor) {
            return context.get(descriptor);
        }
        
        public void put(ActiveDescriptor descriptor, Object value) {
            context.put(descriptor, value);
        }
        
        public final void registerStopEvent() {
            CleanerFactory.create().register(this, context);
        }
    }

    private static final class CleanableContext implements Runnable {

        private final Map, Object> instances = new HashMap<>();

        private final long id = Thread.currentThread().getId();

        public boolean has(ActiveDescriptor descriptor) {
            return instances.containsKey(descriptor);
        }

        public Object get(ActiveDescriptor descriptor) {
            return instances.get(descriptor);
        }

        public void put(ActiveDescriptor descriptor, Object value) {
            instances.put(descriptor, value);
        }

        @Override
        public void run() {
            instances.clear();

            if (LOG_THREAD_DESTRUCTION) {
                Logger.getLogger().debug("Removing PerThreadContext data for thread " + id);
            }
        }
    }
}