/*

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

package com.sun.xml.internal.bind.v2;

import java.lang.reflect.Constructor;

import java.lang.reflect.InvocationTargetException;

import java.lang.reflect.Method;

import java.lang.reflect.Modifier;

import java.lang.ref.WeakReference;

import java.util.Map;

import java.util.WeakHashMap;

import java.util.logging.Level;

import java.util.logging.Logger;

import com.sun.xml.internal.bind.Util;

/**

 * Creates new instances of classes.

 *

 * <p>

 * This code handles the case where the class is not public or the constructor is

 * not public.

 *

 * @since 2.0

 * @author Kohsuke Kawaguchi

 */

public final class ClassFactory {

    private static final Class[] emptyClass = new Class[0];

    private static final Object[] emptyObject = new Object[0];

    private static final Logger logger = Util.getClassLogger();

    /**

     * Cache from a class to its default constructor.

     *

     * To avoid synchronization among threads, we use {@link ThreadLocal}.

     */

    private static final ThreadLocal<Map<Class, WeakReference<Constructor>>> tls = new ThreadLocal<Map<Class,WeakReference<Constructor>>>() {

        @Override

        public Map<Class,WeakReference<Constructor>> initialValue() {

            return new WeakHashMap<Class,WeakReference<Constructor>>();

        }

    };

    public static void cleanCache() {

        if (tls != null) {

            try {

                tls.remove();

            } catch (Exception e) {

                logger.log(Level.WARNING, "Unable to clean Thread Local cache of classes used in Unmarshaller: {0}", e.getLocalizedMessage());

            }

        }

    }

    /**

     * Creates a new instance of the class but throw exceptions without catching it.

     */

    public static <T> T create0( final Class<T> clazz ) throws IllegalAccessException, InvocationTargetException, InstantiationException {

        Map<Class,WeakReference<Constructor>> m = tls.get();

        Constructor<T> cons = null;

        WeakReference<Constructor> consRef = m.get(clazz);

        if(consRef!=null)

            cons = consRef.get();

        if(cons==null) {

                }

            int classMod = clazz.getModifiers();

            if(!Modifier.isPublic(classMod) || !Modifier.isPublic(cons.getModifiers())) {

                // attempt to make it work even if the constructor is not accessible

                try {

                    cons.setAccessible(true);

                } catch(SecurityException e) {

                    // but if we don't have a permission to do so, work gracefully.

                    logger.log(Level.FINE,"Unable to make the constructor of "+clazz+" accessible",e);

                    throw e;

                }

            }

            m.put(clazz,new WeakReference<Constructor>(cons));

        }

        return cons.newInstance(emptyObject);

    }

    /**

     * The same as {@link #create0} but with an error handling to make

     * the instantiation error fatal.

     */

    public static <T> T create( Class<T> clazz ) {

        try {

            return create0(clazz);

        } catch (InstantiationException e) {

            logger.log(Level.INFO,"failed to create a new instance of "+clazz,e);

            throw new InstantiationError(e.toString());

        } catch (IllegalAccessException e) {

            logger.log(Level.INFO,"failed to create a new instance of "+clazz,e);

            throw new IllegalAccessError(e.toString());

        } catch (InvocationTargetException e) {

            Throwable target = e.getTargetException();

            // most likely an error on the user's code.

            // just let it through for the ease of debugging

            if(target instanceof RuntimeException)

                throw (RuntimeException)target;

            // error. just forward it for the ease of debugging

            if(target instanceof Error)

                throw (Error)target;

            // a checked exception.

            // not sure how we should report this error,

            // but for now we just forward it by wrapping it into a runtime exception

            throw new IllegalStateException(target);

        }

    }

    /**

     *  Call a method in the factory class to get the object.

     */

    public static Object create(Method method) {

        Throwable errorMsg;

        try {

            return method.invoke(null, emptyObject);

        } catch (InvocationTargetException ive) {

            Throwable target = ive.getTargetException();

            if(target instanceof RuntimeException)

                throw (RuntimeException)target;

            if(target instanceof Error)

                throw (Error)target;

            throw new IllegalStateException(target);

        } catch (IllegalAccessException e) {

            logger.log(Level.INFO,"failed to create a new instance of "+method.getReturnType().getName(),e);

            throw new IllegalAccessError(e.toString());

        } catch (IllegalArgumentException iae){

            logger.log(Level.INFO,"failed to create a new instance of "+method.getReturnType().getName(),iae);

            errorMsg = iae;

        } catch (NullPointerException npe){

            logger.log(Level.INFO,"failed to create a new instance of "+method.getReturnType().getName(),npe);

            errorMsg = npe;

        } catch (ExceptionInInitializerError eie){

            logger.log(Level.INFO,"failed to create a new instance of "+method.getReturnType().getName(),eie);

            errorMsg = eie;

        }

        NoSuchMethodError exp;

        exp = new NoSuchMethodError(errorMsg.getMessage());

        exp.initCause(errorMsg);

        throw exp;

    }

    /**

     * Infers the instanciable implementation class that can be assigned to the given field type.

     *

     * @return null

     *      if inference fails.

     */

    public static <T> Class<? extends T> inferImplClass(Class<T> fieldType, Class[] knownImplClasses) {

        if(!fieldType.isInterface())

            return fieldType;

        for( Class<?> impl : knownImplClasses ) {

            if(fieldType.isAssignableFrom(impl))

                return impl.asSubclass(fieldType);

        }

        // if we can't find an implementation class,

        // let's just hope that we will never need to create a new object,

        // and returns null

        return null;

    }

}