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/*******************************************************************************
 * Copyright (c) 2015 LegSem.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the GNU Lesser Public License v2.1
 * which accompanies this distribution, and is available at
 * http://www.gnu.org/licenses/old-licenses/gpl-2.0.html
 * 
 * Contributors:
 *     LegSem - initial API and implementation
 ******************************************************************************/
package com.legstar.coxb.transform;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import com.legstar.coxb.CobolContext;
import com.legstar.coxb.CobolElementVisitor;
import com.legstar.coxb.ICobolComplexBinding;
import com.legstar.coxb.host.HostException;

/**
 * Generic methods to transform host data to java.
 * 
 * Implementing classes should inherit from AbstractHostToJavaTransformer and
 * implement the getBinding method.
 * 

 * This is sample code with dynamic binding:
 * 
 * 
 * public class HostToJavaLsfileaeTransformer extends
 *         AbstractHostToJavaTransformer {
 *     public ICobolComplexBinding getBinding() throws BindingException {
 *         try {
 *             CComplexReflectBinding binding = new CComplexReflectBinding(
 *                     new com.legstar.test.coxb.lsfileae.ObjectFactory(),
 *                     com.legstar.test.coxb.lsfileae.Dfhcommarea.class);
 *             return binding;
 *         } catch (ReflectBindingException e) {
 *             throw new BindingException(e);
 *         }
 *     }
 * }
 * 
 * 
 * This is sample code with static binding:
 * 
 * 
 * public class HostToJavaLsfileaeTransformer extends
 *         AbstractHostToJavaTransformer {
 *     public ICobolComplexBinding getBinding() throws BindingException {
 *         return new com.legstar.test.coxb.lsfileae.DfhcommareaBinding();
 *     }
 * }
 * 
 */
public abstract class AbstractHostToJavaTransformer extends AbstractTransformer
        implements IHostToJavaTransformer {

    /** Logger. */
    private final Log _log = LogFactory
            .getLog(AbstractHostToJavaTransformer.class);

    /**
     * Create a Host to Java transformer using default COBOL parameters.
     */
    public AbstractHostToJavaTransformer() {
        super();
    }

    /**
     * Create a Host to Java transformer using a specific host character set
     * while other COBOL parameters are set by default.
     * 
     * @param hostCharset the host character set
     */
    public AbstractHostToJavaTransformer(final String hostCharset) {
        super(hostCharset);
    }

    /**
     * Create a Host to Java transformer using a specific COBOL parameters set.
     * 
     * @param cobolContext the COBOL parameters set.
     */
    public AbstractHostToJavaTransformer(final CobolContext cobolContext) {
        super(cobolContext);
    }

    /**
     * Transforms host data to java data object.
     * 
     * @param  the bound object type
     * @param hostData a byte array containing host data
     * @return a Java value object
     * @throws HostTransformException if transformation fails
     */
    @SuppressWarnings("unchecked")
    public  T transform(final byte[] hostData) throws HostTransformException {
        return (T) transform(hostData, 0);
    }

    /**
     * Transforms host data to java data object.
     * 
     * @param  the bound object type
     * @param hostData a byte array containing host data
     * @param offset index of first byte to process in hostData
     * @return a Java value object
     * @throws HostTransformException if transformation fails
     */
    @SuppressWarnings("unchecked")
    public  T transform(final byte[] hostData, final int offset)
            throws HostTransformException {
        return (T) transform(hostData, offset, (String) null);
    }

    /**
     * Transforms host data to java data object with a specific host character
     * set.
     * 
     * @param  the bound object type
     * @param hostData a byte array containing host data
     * @param hostCharset the host character set
     * @return a Java value object
     * @throws HostTransformException if transformation fails
     */
    @SuppressWarnings("unchecked")
    public  T transform(final byte[] hostData, final String hostCharset)
            throws HostTransformException {
        return (T) transform(hostData, 0, hostCharset);
    }

    /**
     * Transforms host data to java data object with a specific host character
     * set.
     * 
     * @param  the bound object type
     * @param hostData a byte array containing host data
     * @param offset index of first byte to process in hostData
     * @param hostCharset the host character set
     * @return a Java value object
     * @throws HostTransformException if transformation fails
     */
    @SuppressWarnings("unchecked")
    public  T transform(final byte[] hostData, final int offset,
            final String hostCharset) throws HostTransformException {
        return (T) transform(hostData, offset, hostCharset,
                new HostTransformStatus());
    }

    /**
     * Transforms host data to java data object with a specific host character
     * set.
     * 
     * @param  the bound object type
     * @param hostData a byte array containing host data
     * @param hostCharset the host character set
     * @param status will contain information on the transformation after it is
     *            executed
     * @return a Java value object
     * @throws HostTransformException if transformation fails
     */
    @SuppressWarnings("unchecked")
    public  T transform(final byte[] hostData, final String hostCharset,
            final HostTransformStatus status) throws HostTransformException {
        return (T) transform(hostData, 0, hostCharset, status);
    }

    /**
     * Transforms host data to java data object with a specific host character
     * set.
     * 
     * @param  the bound object type
     * @param hostData a byte array containing host data
     * @param offset index of first byte to process in hostData
     * @param hostCharset the host character set
     * @param status will contain information on the transformation after it is
     *            executed
     * @return a Java value object
     * @throws HostTransformException if transformation fails
     */
    @SuppressWarnings("unchecked")
    public  T transform(final byte[] hostData, final int offset,
            final String hostCharset, final HostTransformStatus status)
            throws HostTransformException {
        if (hostCharset != null && hostCharset.length() > 0) {
            getCobolConverters().getCobolContext().setHostCharsetName(
                    hostCharset);
        }
        return (T) transform(hostData, offset, status);
    }

    /**
     * Transforms host data to java data object.
     * 
     * @param  the bound object type
     * @param hostData a byte array containing host data
     * @param status will contain information on the transformation after it is
     *            executed
     * @return a Java value object
     * @throws HostTransformException if transformation fails
     */
    @SuppressWarnings("unchecked")
    public  T transform(final byte[] hostData,
            final HostTransformStatus status) throws HostTransformException {
        return (T) transform(hostData, 0, status);
    }

    /**
     * Transforms host data to java data object.
     * 
     * @param  the bound object type
     * @param hostData a byte array containing host data
     * @param offset index of first byte to process in hostData
     * @param status will contain information on the transformation after it is
     *            executed
     * @return a Java value object
     * @throws HostTransformException if transformation fails
     */
    @SuppressWarnings("unchecked")
    public  T transform(final byte[] hostData, final int offset,
            final HostTransformStatus status) throws HostTransformException {

        long start = System.currentTimeMillis();
        if (_log.isDebugEnabled()) {
            _log.debug("Host to Java transformation started");
        }

        if (hostData == null) {
            throw new HostTransformException(
                    "Host data is null. Unable to transform to java.");
        }

        try {
            /* Reuse binding if possible get a new one otherwise */
            CobolElementVisitor unmarshaler = getCobolBindingVisitorsFactory()
                    .createUnmarshalVisitor(hostData, offset,
                            getCobolConverters());

            /* Request a binding from concrete class */
            ICobolComplexBinding binding = getCachedBinding();

            /*
             * Traverse the object structure, visiting each node with the
             * visitor
             */
            binding.accept(unmarshaler);

            /* Get the actual bytes unmarshalled */
            int bytesUnmarshalled = unmarshaler.getOffset();

            if (_log.isDebugEnabled()) {
                long end = System.currentTimeMillis();
                _log.debug("Host to Java transformation ended Processed: "
                        + Integer.toString(bytesUnmarshalled) + " bytes "
                        + "elapse:" + Long.toString(end - start) + " ms");
            }

            status.setHostBytesProcessed(bytesUnmarshalled);
            status.setBinding(binding);

            return (T) binding.getObjectValue((Class < T >) binding
                    .getJaxbType());

        } catch (HostException he) {
            throw new HostTransformException(he);
        }
    }

}