# ExportField.java

    /*
    ** Module   : ExportField.java
    ** Abstract : handle export data fields for I/O helpers
    **
    ** Copyright (c) 2006-2022, Golden Code Development Corporation.
    **
    ** -#- -I- --Date-- --JPRM-- ---------------------------Description----------------------------
    ** 001 GES 20060925   @29901 Created initial version to export data fields for I/O helpers.
    ** 002 SIY 20071001   @35319 Made class suitable for network transfers. Ref: #35314
    ** 003 SIY 20071003   @35350 Added default constructor. Header cleanup. Fixed NPE during
    **                           serialization. Ref: #35347.
    ** 004 GES 20160530          Use lambdas instead of Resolvable instances.
    ** 005 IAS 20200908          Rework (de)serialization.
    **     EVL 20221222          Adding LOB fields export service methods to simplify processing.
    */
    /*
    ** This program is free software: you can redistribute it and/or modify
    ** it under the terms of the GNU Affero General Public License as
    ** published by the Free Software Foundation, either version 3 of the
    ** License, or (at your option) any later version.
    **
    ** This program 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 Affero General Public License for more details.
    **
    ** You may find a copy of the GNU Affero GPL version 3 at the following
    ** location: https://www.gnu.org/licenses/agpl-3.0.en.html
    **
    ** Additional terms under GNU Affero GPL version 3 section 7:
    **
    **   Under Section 7 of the GNU Affero GPL version 3, the following additional
    **   terms apply to the works covered under the License.  These additional terms
    **   are non-permissive additional terms allowed under Section 7 of the GNU
    **   Affero GPL version 3 and may not be removed by you.
    **
    **   0. Attribution Requirement.
    **
    **     You must preserve all legal notices or author attributions in the covered
    **     work or Appropriate Legal Notices displayed by works containing the covered
    **     work.  You may not remove from the covered work any author or developer
    **     credit already included within the covered work.
    **
    **   1. No License To Use Trademarks.
    **
    **     This license does not grant any license or rights to use the trademarks
    **     Golden Code, FWD, any Golden Code or FWD logo, or any other trademarks
    **     of Golden Code Development Corporation. You are not authorized to use the
    **     name Golden Code, FWD, or the names of any author or contributor, for
    **     publicity purposes without written authorization.
    **
    **   2. No Misrepresentation of Affiliation.
    **
    **     You may not represent yourself as Golden Code Development Corporation or FWD.
    **
    **     You may not represent yourself for publicity purposes as associated with
    **     Golden Code Development Corporation, FWD, or any author or contributor to
    **     the covered work, without written authorization.
    **
    **   3. No Misrepresentation of Source or Origin.
    **
    **     You may not represent the covered work as solely your work.  All modified
    **     versions of the covered work must be marked in a reasonable way to make it
    **     clear that the modified work is not originating from Golden Code Development
    **     Corporation or FWD.  All modified versions must contain the notices of
    **     attribution required in this license.
    */

    package com.goldencode.p2j.util;

    import static com.goldencode.util.NativeTypeSerializer.*;
    import java.io.*;
    import java.lang.management.*;
    import java.util.concurrent.atomic.*;
    import java.util.function.*;

    /**
     * Handles export formatted output of data fields for I/O helpers.
     */
    public class ExportField
    extends FieldEntry
    {
       /** Unique number for next LOB related file export operation. */
       private static AtomicLong nextFSId = new AtomicLong(0);

       /** The PID associated with current JVM instance. */
       private static final String jvmPId;

       /** The data to output to the stream. */
       private Supplier<BaseDataType> data = null;

       /** Resolved variable value. */
       private BaseDataType savedVar = null;

       /** Getting the current PID. */
       static
       {
          String jvmName = ManagementFactory.getRuntimeMXBean().getName();
          int pNdx = jvmName.indexOf("@");
          jvmPId = jvmName.substring(0, pNdx);
       }

       /**
        * Default constructor which is necessary to restores instance when it is transferred via
        * the network.
        */
       public ExportField()
       {
       }

       /**
        * Generate output formatted using the <code>toStringExport</code> method of the associated
        * type.
        *
        * @param    val
        *           The value to be output.
        */
       public ExportField(int val)
       {
          this(new integer(val));
       }

       /**
        * Generate output formatted using the <code>toStringExport</code> method of the associated
        * type.
        *
        * @param    val
        *           The value to be output.
        */
       public ExportField(double val)
       {
          this(new decimal(val));
       }

       /**
        * Generate output formatted using the <code>toStringExport</code> method of the associated
        * type.
        *
        * @param    val
        *           The value to be output.
        */
       public ExportField(boolean val)
       {
          this(new logical(val));
       }

       /**
        * Generate output formatted using the <code>toStringExport</code> method of the associated
        * type.
        *
        * @param    val
        *           The value to be output.
        */
       public ExportField(String val)
       {
          this(new character(val));
       }

       /**
        * Generate output formatted using the <code>toStringExport</code> method of the associated
        * type.
        *
        * @param    val
        *           The value to be output.
        */
       public ExportField(final BaseDataType val)
       {
          this.data = () -> val;
       }

       /**
        * Generate output formatted using the <code>toStringExport</code> method of the associated
        * type.  This form is used for field references.
        *
        * @param    val
        *           The value to be output.
        */
       public ExportField(final Resolvable val)
       {
          this.data = () -> val.resolve();
       }

       /**
        * Generate output formatted using the <code>toStringExport</code> method of the associated
        * type.  This form is used for complex expressions whose evaluation bmust be deferred.
        *
        * @param    val
        *           The function which supplies the value to be output.
        */
       public ExportField(Supplier<BaseDataType> val)
       {
          this.data = val;
       }

      /**
        * Renders the contained field definition to the given stream.
        *
        * @param    out
        *           The stream to which the field should be rendered.
        * @throws ErrorConditionException
        */
       public void output(Stream out)
       throws ErrorConditionException
       {
          BaseDataType bdt = data.get();

          // use different methods for different data types
          if (bdt instanceof memptr)
          {
             out.writeBlock((BinaryData) bdt);
          }
          else if (bdt instanceof blob)
          {
             out.writeBlob((blob) bdt);
          }
          else if (bdt instanceof clob)
          {
             out.writeClob((clob) bdt);
          }
          else
          {
             out.writeField(bdt);
          }
       }

       /**
        * Notify instance that it is about to be transferred so all resolvable data should be
        * resolved and prepared for sending via network.
        */
       public void resolveData()
       {
          savedVar = data.get();
       }

       /**
        * Replacement for the default object reading method. The latest state is read from the
        * input source.
        *
        * @param    in
        *           The input source from which fields will be restored.
        *
        * @throws   IOException
        *           In case of I/O errors.
        * @throws   ClassNotFoundException
        *           If payload can't be instantiated.
        */
       public void readExternal(ObjectInput in)
       throws IOException,
              ClassNotFoundException
       {
          final BaseDataType data = readBaseDataType(in);

          this.data = () -> data;
       }

       /**
        * Replacement for the default object writing method. The latest state is written to the
        * output destination.
        *
        * @param    out
        *           The output destination to which fields will be saved.
        *
        * @throws   IOException
        *           In case of I/O errors.
        */
       public void writeExternal(ObjectOutput out)
       throws IOException
       {
          writeBaseDataType(out, savedVar);
       }

       /**
        * Gets the next unique integer number per JVM running instance to be used in file name reconstruction.
        *
        * @return   The next number for separate export operation into file system.
        */
       public static long getNextFSId()
       {
          return nextFSId.incrementAndGet();
       }

       /**
        * Gets the current process ID for data exporting process.
        *
        * @return   The current process ID as string value.
        */
       public static String getJavaPId()
       {
          return jvmPId;
       }
    }