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/*
 *  ******************************************************************************
 *  *
 *  *
 *  * This program and the accompanying materials are made available under the
 *  * terms of the Apache License, Version 2.0 which is available at
 *  * https://www.apache.org/licenses/LICENSE-2.0.
 *  *
 *  *  See the NOTICE file distributed with this work for additional
 *  *  information regarding copyright ownership.
 *  * 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.
 *  *
 *  * SPDX-License-Identifier: Apache-2.0
 *  *****************************************************************************
 */

package org.datavec.api.util;

import org.datavec.api.conf.Configurable;
import org.datavec.api.conf.Configuration;
import org.datavec.api.io.DataInputBuffer;
import org.datavec.api.io.DataOutputBuffer;
import org.datavec.api.io.serializers.Deserializer;
import org.datavec.api.io.serializers.SerializationFactory;
import org.datavec.api.io.serializers.Serializer;

import java.io.IOException;
import java.lang.reflect.Method;

@Deprecated
public class ReflectionUtils {

    private static final Class[] EMPTY_ARRAY = new Class[] {};
    private static SerializationFactory serialFactory = null;

    private ReflectionUtils() {
    }

    /** Create an object for the given class and initialize it from conf
     *
     * @param theClass class of which an object is created
     * @param conf Configuration
     * @return a new object
     */
    @SuppressWarnings("unchecked")
    public static  T newInstance(Class theClass, Configuration conf) {
        T result = org.nd4j.common.io.ReflectionUtils.newInstance(theClass);
        setConf(result, conf);
        return result;
    }

    /**
     * Check and set 'configuration' if necessary.
     *
     * @param theObject object for which to set configuration
     * @param conf Configuration
     */
    public static void setConf(Object theObject, Configuration conf) {
        if (conf != null) {
            if (theObject instanceof Configurable) {
                ((Configurable) theObject).setConf(conf);
            }
            setJobConf(theObject, conf);
        }
    }

    /**
     * This code is to support backward compatibility and break the compile
     * time dependency of core on mapred.
     * This should be made deprecated along with the mapred package HADOOP-1230.
     * Should be removed when mapred package is removed.
     */
    private static void setJobConf(Object theObject, Configuration conf) {
        //If JobConf and JobConfigurable are in classpath, AND
        //theObject is of type JobConfigurable AND
        //conf is of type JobConf then
        //invoke configure on theObject
        try {
            Class jobConfClass = conf.getClassByName("org.apache.hadoop.mapred.JobConf");
            Class jobConfigurableClass = conf.getClassByName("org.apache.hadoop.mapred.JobConfigurable");
            if (jobConfClass.isAssignableFrom(conf.getClass())
                    && jobConfigurableClass.isAssignableFrom(theObject.getClass())) {
                Method configureMethod = jobConfigurableClass.getMethod("configure", jobConfClass);
                configureMethod.invoke(theObject, conf);
            }
        } catch (ClassNotFoundException e) {
            //JobConf/JobConfigurable not in classpath. no need to configure
        } catch (Exception e) {
            throw new RuntimeException("Error in configuring object", e);
        }
    }


    /**
     * A pair of input/output buffers that we use to clone writables.
     */
    private static class CopyInCopyOutBuffer {
        DataOutputBuffer outBuffer = new DataOutputBuffer();
        DataInputBuffer inBuffer = new DataInputBuffer();

        /**
         * Move the data from the output buffer to the input buffer.
         */
        void moveData() {
            inBuffer.reset(outBuffer.getData(), outBuffer.getLength());
        }
    }

    /**
     * Allocate a buffer for each thread that tries to clone objects.
     */
    private static ThreadLocal cloneBuffers = new ThreadLocal() {
        protected synchronized CopyInCopyOutBuffer initialValue() {
            return new CopyInCopyOutBuffer();
        }
    };

    private static SerializationFactory getFactory(Configuration conf) {
        if (serialFactory == null) {
            serialFactory = new SerializationFactory(conf);
        }
        return serialFactory;
    }

    /**
     * Make a copy of the writable object using serialization to a buffer
     * @param dst the object to copy from
     * @param src the object to copy into, which is destroyed
     * @throws IOException
     */
    @SuppressWarnings("unchecked")
    public static  T copy(Configuration conf, T src, T dst) throws IOException {
        CopyInCopyOutBuffer buffer = cloneBuffers.get();
        buffer.outBuffer.reset();
        SerializationFactory factory = getFactory(conf);
        Class cls = (Class) src.getClass();
        Serializer serializer = factory.getSerializer(cls);
        serializer.open(buffer.outBuffer);
        serializer.serialize(src);
        buffer.moveData();
        Deserializer deserializer = factory.getDeserializer(cls);
        deserializer.open(buffer.inBuffer);
        dst = deserializer.deserialize(dst);
        return dst;
    }
}