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    /*
 * Fabric3
 * Copyright (c) 2009-2015 Metaform Systems
 *
 * 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.
 *
 * Portions originally based on Apache Tuscany 2007
 * licensed under the Apache 2.0 license.
 */
package org.fabric3.implementation.system.singleton;

import javax.xml.namespace.QName;
import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Member;
import java.lang.reflect.Method;
import java.net.URI;
import java.util.Collection;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.atomic.AtomicBoolean;

import org.fabric3.api.annotation.monitor.MonitorLevel;
import org.fabric3.implementation.pojo.objectfactory.ArrayMultiplicityObjectFactory;
import org.fabric3.implementation.pojo.objectfactory.ListMultiplicityObjectFactory;
import org.fabric3.implementation.pojo.objectfactory.MapMultiplicityObjectFactory;
import org.fabric3.implementation.pojo.objectfactory.MultiplicityObjectFactory;
import org.fabric3.implementation.pojo.objectfactory.SetMultiplicityObjectFactory;
import org.fabric3.spi.container.component.InstanceDestructionException;
import org.fabric3.spi.container.component.InstanceInitException;
import org.fabric3.spi.container.component.InstanceLifecycleException;
import org.fabric3.spi.container.component.ScopedComponent;
import org.fabric3.spi.model.type.java.FieldInjectionSite;
import org.fabric3.api.model.type.java.Injectable;
import org.fabric3.api.model.type.java.InjectableType;
import org.fabric3.api.model.type.java.InjectionSite;
import org.fabric3.spi.model.type.java.MethodInjectionSite;
import org.fabric3.spi.container.objectfactory.InjectionAttributes;
import org.fabric3.spi.container.objectfactory.ObjectCreationException;
import org.fabric3.spi.container.objectfactory.ObjectFactory;
import org.fabric3.spi.container.objectfactory.SingletonObjectFactory;

/**
 * Wraps an object intended to serve as a system component provided to the Fabric3 runtime by the host environment.
 */
public class SingletonComponent implements ScopedComponent {
    private final URI uri;
    private Object instance;
    private Map sites;
    private Map reinjectionMappings;
    private URI classLoaderId;
    private MonitorLevel level = MonitorLevel.INFO;
    private AtomicBoolean started = new AtomicBoolean(false);

    public SingletonComponent(URI componentId, Object instance, Map mappings) {
        this.uri = componentId;
        this.instance = instance;
        this.reinjectionMappings = new HashMap<>();
        initializeInjectionSites(instance, mappings);
    }

    public URI getClassLoaderId() {
        return classLoaderId;
    }

    public void setClassLoaderId(URI classLoaderId) {
        this.classLoaderId = classLoaderId;
    }

    public String getKey() {
        return null;
    }

    public URI getUri() {
        return uri;
    }

    public void start() {
        started.set(true);
    }

    public void stop() {
        started.set(false);
    }

    public void startUpdate() {
        for (ObjectFactory factory : reinjectionMappings.keySet()) {
            if (factory instanceof MultiplicityObjectFactory) {
                ((MultiplicityObjectFactory) factory).startUpdate();
            }
        }
    }

    public void endUpdate() {
        for (ObjectFactory factory : reinjectionMappings.keySet()) {
            if (factory instanceof MultiplicityObjectFactory) {
                ((MultiplicityObjectFactory) factory).endUpdate();
            }
        }
    }

    public QName getDeployable() {
        return null;
    }

    public boolean isEagerInit() {
        return true;
    }

    public Object createInstance() throws ObjectCreationException {
        return instance;
    }

    public void releaseInstance(Object instance) {
        // no-op
    }

    public ObjectFactory createObjectFactory() {
        return new SingletonObjectFactory<>(instance);
    }

    public Object getInstance() {
        return instance;
    }

    public String getName() {
        return uri.toString();
    }

    public MonitorLevel getLevel() {
        return level;
    }

    public void setLevel(MonitorLevel level) {
        this.level = level;
    }

    public void startInstance(Object instance) throws InstanceInitException {
        // no-op
    }

    public void stopInstance(Object instance) throws InstanceDestructionException {
        // no-op
    }

    public void reinject(Object instance) throws InstanceLifecycleException {
        for (Map.Entry entry : reinjectionMappings.entrySet()) {
            try {
                inject(entry.getValue(), entry.getKey());
            } catch (ObjectCreationException e) {
                throw new AssertionError(e);
            }
        }
        reinjectionMappings.clear();
    }

    /**
     * Adds an ObjectFactory to be reinjected. Note only String keys are supported for singleton components to avoid a requirement on the transformer
     * infrastructure.
     *
     * @param injectable    the InjectableAttribute describing the site to reinject
     * @param objectFactory the object factory responsible for supplying a value to reinject
     * @param attributes    the injection attributes
     */
    public void addObjectFactory(Injectable injectable, ObjectFactory objectFactory, InjectionAttributes attributes) {
        if (InjectableType.REFERENCE == injectable.getType()) {
            setFactory(injectable, objectFactory, attributes);
        } else {
            // the factory corresponds to a property or context, which will override previous values if reinjected
            reinjectionMappings.put(objectFactory, injectable);
        }
    }

    public void removeObjectFactory(Injectable injectable) {
        for (Iterator> iterator = reinjectionMappings.entrySet().iterator(); iterator.hasNext(); ) {
            Map.Entry entry = iterator.next();
            if (injectable.equals(entry.getValue())) {
                iterator.remove();
                break;
            }
        }
    }

    public String toString() {
        return "[" + uri.toString() + "] in state [" + super.toString() + ']';
    }

    /**
     * Obtain the fields and methods for injection sites associated with the instance
     *
     * @param instance the instance this component wraps
     * @param mappings the mappings of injection sites
     */
    private void initializeInjectionSites(Object instance, Map mappings) {
        this.sites = new HashMap<>();
        for (Map.Entry entry : mappings.entrySet()) {
            InjectionSite site = entry.getKey();
            if (site instanceof FieldInjectionSite) {
                try {
                    Field field = getField(((FieldInjectionSite) site).getName());
                    sites.put(field, entry.getValue());
                } catch (NoSuchFieldException e) {
                    // programming error
                    throw new AssertionError(e);
                }
            } else if (site instanceof MethodInjectionSite) {
                MethodInjectionSite methodInjectionSite = (MethodInjectionSite) site;
                try {
                    Method method = methodInjectionSite.getSignature().getMethod(instance.getClass());
                    sites.put(method, entry.getValue());
                } catch (ClassNotFoundException | NoSuchMethodException e) {
                    // programming error
                    throw new AssertionError(e);
                }

            } else {
                // ignore other injection sites
            }
        }
    }

    private void setFactory(Injectable injectable, ObjectFactory objectFactory, InjectionAttributes attributes) {
        ObjectFactory factory = findFactory(injectable);
        if (factory == null) {
            Class type = getMemberType(injectable);
            if (Map.class.equals(type)) {
                MapMultiplicityObjectFactory mapFactory = new MapMultiplicityObjectFactory();
                mapFactory.startUpdate();
                mapFactory.addObjectFactory(objectFactory, attributes);
                reinjectionMappings.put(mapFactory, injectable);
            } else if (Set.class.equals(type)) {
                SetMultiplicityObjectFactory setFactory = new SetMultiplicityObjectFactory();
                setFactory.startUpdate();
                setFactory.addObjectFactory(objectFactory, attributes);
                reinjectionMappings.put(setFactory, injectable);
            } else if (List.class.equals(type)) {
                ListMultiplicityObjectFactory listFactory = new ListMultiplicityObjectFactory();
                listFactory.startUpdate();
                listFactory.addObjectFactory(objectFactory, attributes);
                reinjectionMappings.put(listFactory, injectable);
            } else if (Collection.class.equals(type)) {
                ListMultiplicityObjectFactory listFactory = new ListMultiplicityObjectFactory();
                listFactory.startUpdate();
                listFactory.addObjectFactory(objectFactory, attributes);
                reinjectionMappings.put(listFactory, injectable);
            } else if (type.isArray()) {
                ArrayMultiplicityObjectFactory arrayFactory = new ArrayMultiplicityObjectFactory(type.getComponentType());
                arrayFactory.startUpdate();
                arrayFactory.addObjectFactory(objectFactory, attributes);
                reinjectionMappings.put(arrayFactory, injectable);
            } else {
                reinjectionMappings.put(objectFactory, injectable);
            }
        } else if (factory instanceof MultiplicityObjectFactory) {
            MultiplicityObjectFactory multiplicityObjectFactory = (MultiplicityObjectFactory) factory;
            multiplicityObjectFactory.addObjectFactory(objectFactory, attributes);
        } else {
            //update or overwrite  the factory
            reinjectionMappings.put(objectFactory, injectable);
        }
    }

    /**
     * Finds the mapped object factory for the injectable.
     *
     * @param injectable the injectable
     * @return the object factory
     */
    private ObjectFactory findFactory(Injectable injectable) {
        ObjectFactory factory = null;
        for (Map.Entry entry : reinjectionMappings.entrySet()) {
            if (injectable.equals(entry.getValue())) {
                factory = entry.getKey();
                break;
            }
        }
        return factory;
    }

    /**
     * Returns the injectable type.
     *
     * @param injectable the injectable
     * @return the type
     */
    private Class getMemberType(Injectable injectable) {
        for (Map.Entry entry : sites.entrySet()) {
            if (injectable.equals(entry.getValue())) {
                Member member = entry.getKey();
                if (member instanceof Method) {
                    return ((Method) member).getParameterTypes()[0];
                } else if (member instanceof Field) {
                    return ((Field) member).getType();
                } else {
                    throw new AssertionError("Unsupported injection site type for singleton components");
                }
            }
        }
        return null;
    }

    private Field getField(String name) throws NoSuchFieldException {
        Class clazz = instance.getClass();
        while (clazz != null) {
            try {
                return clazz.getDeclaredField(name);
            } catch (NoSuchFieldException e) {
                clazz = clazz.getSuperclass();
            }
        }
        throw new NoSuchFieldException(name);
    }

    /**
     * Injects a new value on a field or method of the instance.
     *
     * @param attribute the InjectableAttribute defining the field or method
     * @param factory   the ObjectFactory that returns the value to inject
     * @throws ObjectCreationException if an error occurs during injection
     */
    private void inject(Injectable attribute, ObjectFactory factory) throws ObjectCreationException {
        for (Map.Entry entry : sites.entrySet()) {
            if (entry.getValue().equals(attribute)) {
                Member member = entry.getKey();
                if (member instanceof Field) {
                    try {
                        Object param = factory.getInstance();
                        ((Field) member).set(instance, param);
                    } catch (IllegalAccessException e) {
                        // should not happen as accessibility is already set
                        throw new ObjectCreationException(e);
                    }
                } else if (member instanceof Method) {
                    try {
                        Object param = factory.getInstance();
                        Method method = (Method) member;
                        method.invoke(instance, param);
                    } catch (IllegalAccessException | InvocationTargetException e) {
                        // should not happen as accessibility is already set
                        throw new ObjectCreationException(e);
                    }
                } else {
                    // programming error
                    throw new ObjectCreationException("Unsupported member type" + member);
                }
            }
        }
    }

}
    
    
    
    

    




    
    
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