# StreamJsonSerializer.java

    /*
    ** Module   : StreamJsonSerializer.java
    ** Abstract : Json stream serialization.
    **
    ** Copyright (c) 2019-2023, Golden Code Development Corporation.
    **
    ** -#- -I- --Date-- ----------------------------------------Description---------------------------------------
    ** 001 HC  20190707 Initial version.
    **     OM  20190709 The backing stream can now be flushed and closed. Fixed decimal formatting.
    ** 002 CA  20190724 Fixed rawDecimalValue - it needs to write a value, and not 'raw'.
    **     CA  20190812 rawDecimalValue - removed the '.0' - not clear why this was added in the first
    **                  place.
    ** 003 CA  20210709 Force non-scientific format for BigDecimal numbers.
    ** 004 GBB 20230512 Logging methods replaced by CentralLogger/ConversionStatus.
    */

    /*
    ** 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.persist.serial;

    import com.fasterxml.jackson.core.*;
    import com.fasterxml.jackson.core.JsonGenerator.Feature;
    import com.fasterxml.jackson.core.util.*;
    import com.fasterxml.jackson.databind.*;
    import com.goldencode.p2j.util.logging.*;

    import java.io.*;
    import java.math.*;

    /**
     * Serializes json structure to a stream.
     */
    public class StreamJsonSerializer
    implements JsonStructureCallback
    {
       /** Logger */
       private static final CentralLogger LOG = CentralLogger.get(StreamJsonSerializer.class);

       /** Jackson json generator */
       private JsonGenerator gen;

       /**
        * Constructor.
        *
        * @param   out
        *          Output stream.
        * @param   encoding
        *          Character encoding.
        * @param   pretty
        *          Pretty print flag.
        *
        * @throws  IOException
        *          when IO error occurs.
        */
       public StreamJsonSerializer(OutputStream out, JsonEncoding encoding, boolean pretty)
       throws IOException
       {
          ObjectMapper mapper = new ObjectMapper();
          mapper.configure(Feature.WRITE_BIGDECIMAL_AS_PLAIN, true);
          JsonFactory factory = mapper.getFactory();
          gen = factory.createGenerator(out, encoding);
          if (pretty)
          {
             // The way 4GL formats JSON is really strange. This small change makes it a bit easy to
             // spot changes allowing at least records on consecutive lines to be identically as 4GL
             gen.setPrettyPrinter(new DefaultPrettyPrinter()
             {
                /**
                 * Method called after an object field has been output, but before the value is
                 * output.
                 */
                public void writeObjectFieldValueSeparator(JsonGenerator jg)
                throws IOException
                {
                   jg.writeRaw(": ");
                }
             });
          }
          else
          {
             gen.setPrettyPrinter(new MinimalPrettyPrinter());
          }
       }

       /**
        * Close the stream. Closes the internal stream.
        *
        * @throws  IOException
        *          when IO error occurs.
        */
       public void closeStream()
       throws IOException
       {
          gen.close();
       }

       /**
        * Called when json object start is encountered.
        */
       @Override
       public void startObject()
       {
          try
          {
             gen.writeStartObject();
          }
          catch (IOException e)
          {
             LOG.info("", e);
          }
       }

       /**
        * Called when json object end is encountered.
        */
       @Override
       public void endObject()
       {
          try
          {
             gen.writeEndObject();
          }
          catch (IOException e)
          {
             LOG.info("", e);
          }
       }

       /**
        * Called when json array start is encountered.
        */
       @Override
       public void startArray()
       {
          try
          {
             gen.writeStartArray();
          }
          catch (IOException e)
          {
             LOG.info("", e);
          }
       }

       /**
        * Called when json array end is encountered.
        */
       @Override
       public void endArray()
       {
          try
          {
             gen.writeEndArray();
          }
          catch (IOException e)
          {
             LOG.info("", e);
          }
       }

       /**
        * Called when json field is encountered.
        *
        * @param   name
        *          Field name.
        */
       @Override
       public void fieldName(String name)
       {
          try
          {
             gen.writeFieldName(name);
          }
          catch (IOException e)
          {
             LOG.info("", e);
          }
       }

       /**
        * Called when json boolean value is encountered.
        *
        * @param   value
        *          The value.
        */
       @Override
       public void booleanValue(boolean value)
       {
          try
          {
             gen.writeBoolean(value);
          }
          catch (IOException e)
          {
             LOG.info("", e);
          }
       }

       /**
        * Called when json string value is encountered.
        *
        * @param   value
        *          The value.
        */
       @Override
       public void stringValue(String value)
       {
          try
          {
             gen.writeString(value);
          }
          catch (IOException e)
          {
             LOG.info("", e);
          }
       }

       /**
        * Called when json number value is encountered.
        *
        * @param   value
        *          The value.
        */
       @Override
       public void numberValue(Number value)
       {
          try
          {
             if (value == null)
             {
                gen.writeNull();
             }
             else if (value instanceof Short)
             {
                gen.writeNumber((Short) value);
             }
             else if (value instanceof Integer)
             {
                gen.writeNumber((Integer) value);
             }
             else if (value instanceof Long)
             {
                gen.writeNumber((Long) value);
             }
             else if (value instanceof Double)
             {
                gen.writeNumber((Double) value);
             }
             else if (value instanceof Float)
             {
                gen.writeNumber((Float) value);
             }
             else if (value instanceof BigInteger)
             {
                gen.writeNumber((BigInteger) value);
             }
             else if (value instanceof BigDecimal)
             {
                gen.writeNumber((BigDecimal) value);
             }
             else
             {
                throw new RuntimeException("Unsupported number type " + value.getClass());
             }
          }
          catch (IOException e)
          {
             LOG.info("", e);
          }
       }

       /**
        * Called when json null value is encountered.
        */
       @Override
       public void nullValue()
       {
          try
          {
             gen.writeNull();
          }
          catch (IOException e)
          {
             LOG.severe("", e);
          }
       }

       /**
        * Called when json raw decimal value is encountered.
        *
        * @param   value
        *          The value.
        */
       @Override
       public void rawDecimalValue(String value)
       {
          try
          {
             if (value.indexOf('.') == -1)
             {
                // CA: why is this here? what specific case does this solve?
                // OM: the decimal numbers serialize by ABL always have the decimal point '.' (Ex: "42.0").
                //     the [BigDecimal] that we use will drop it if the decimals are null (Ex: "42").
                value += ".0";
             }

             gen.writeRawValue(value);
          }
          catch (IOException e)
          {
             LOG.info("", e);
          }
       }
    }