# LegacyObject.java

    /*
    ** Module   : LegacyObject.java
    ** Abstract : Helper to transport serialized object instances over network.
    **
    ** Copyright (c) 2022-2024, Golden Code Development Corporation.
    **
    ** -#- -I- --Date-- ---------------------------------------Description----------------------------------------
    ** 001 CA  20220602 First version.
    **     SVL 20230113 Improved performance by replacing some "for-each" loops with indexed "for" loops.
    ** 002 GBB 20230512 Logging methods replaced by CentralLogger/ConversionStatus.
    ** 003 CA  20230915 Refactored to allow BDT array serialization and also allow non-BDT fields to be serialized
    **                  (only from internal FWD legacy classes).
    ** 004 CA  20230929 Javadoc fixes.
    ** 005 AP  20240802 Improved support for TableWrapper objects being sent as parameters to remote procedures
    **                  inside the same JVM.
    ** 006 DDF 20240211 Added an additional parameter for avoiding execution of the constructor method during
    **                  the object initialization.
    ** 007 CA  20240911 Fixed deserialization of dyanmic extent fields.  HANDLE fields are not serialized.
    */

    /*
    ** 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 java.io.*;
    import java.lang.reflect.*;
    import java.util.*;
    import java.util.logging.*;

    import com.goldencode.p2j.oo.lang.*;
    import com.goldencode.p2j.persist.*;
    import com.goldencode.p2j.util.logging.*;

    /**
     * Provides a transport mechanism of {@link object} instances over the network, for i.e. appserver calls.
     */
    public class LegacyObject
    implements Externalizable
    {
       /** Logger */
       private static final CentralLogger LOG = CentralLogger.get(LegacyObject.class);

       /** The legacy type being transported. */
       private String legacyClass;

       /** Flag indicating if this is an unknown instance. */
       private boolean unknown;

       /** The converted type of the object being transported. */
       private Class<? extends _BaseObject_> type;

       /** Serialization of each instance field. */
       private LinkedHashMap<Field, Object> serialized = new LinkedHashMap<>();

       /** Flag indicating whether the appserver, which sent the object, is running in the same
        *  JVM as the requester.
        */
       private boolean local = false;

       /**
        * Default c'tor, used for deserialization.
        */
       public LegacyObject()
       {
       }

       /**
        * Calls {@link #serialize} in order to prepare the object to be transported over network.
        *
        * @param    o
        *           The instance.
        * @param    local
        *           Flag indicating if the object is being transported in the same JVM.
        */
       public LegacyObject(object<? extends _BaseObject_> o, boolean local)
       {
          this.local = local;
          serialize(o);
       }

       /**
        * Calls {@link #serialize} in order to prepare the object to be transported over network.
        *
        * @param    o
        *           The instance.
        */
       public LegacyObject(object<? extends _BaseObject_> o)
       {
          serialize(o);
       }

       /**
        * Write the state of this instance to the specified stream.
        *
        * @param    out
        *           The stream where the state of this instance will be sent.
        */
       @Override
       public void writeExternal(ObjectOutput out)
       throws IOException
       {
          out.writeUTF(legacyClass);
          out.writeBoolean(unknown);

          if (unknown)
          {
             return;
          }

          out.writeInt(serialized.size());
          for (Map.Entry<Field, Object> entry : serialized.entrySet())
          {
             Field f = entry.getKey();
             Object ser = entry.getValue();

             out.writeUTF(f.getDeclaringClass().getName());
             out.writeUTF(f.getName());
             out.writeObject(ser);
          }
       }

       /**
        * Initialize this instance by reading its state from the specified stream.
        *
        * @param    in
        *           The stream from where the state of this instance will be read.
        */
       @Override
       public void readExternal(ObjectInput in)
       throws IOException,
              ClassNotFoundException
       {
          this.legacyClass = in.readUTF();
          this.unknown = in.readBoolean();
          this.type = ObjectOps.resolveClass(legacyClass);

          if (unknown)
          {
             return;
          }

          serialized.clear();
          int numFields = in.readInt();
          for (int i = 0; i < numFields; i++)
          {
             String fclass = in.readUTF();
             String fname = in.readUTF();
             Object val = in.readObject();
             try
             {
                Field field = Class.forName(fclass).getDeclaredField(fname);
                serialized.put(field, val);
             }
             catch (NoSuchFieldException |
                    SecurityException    |
                    ClassNotFoundException e)
             {
                LOG.severe("", e);
             }
          }
       }

       /**
        * Get the object's {@link #type}.
        *
        * @return   See above.
        */
       public Class<? extends _BaseObject_> getType()
       {
          return type;
       }

       public void assign(LegacyObject ref)
       {
          this.legacyClass = ref.legacyClass;
          this.type = ref.type;
          this.unknown = ref.unknown;
          this.serialized.clear();
          this.serialized.putAll(ref.serialized);
       }

       /**
        * Create a new instance and set its state from the {@link #serialized} information.
        *
        * @return   See above.
        */
       public _BaseObject_ restore()
       {
          return restore(false);
       }

       /**
        * Create a new instance and set its state from the {@link #serialized} information.
        *
        * @param    local
        *           Flag indicating if the object is being transported in the same JVM.
        *
        * @return   See above.
        */
       _BaseObject_ restore(boolean local)
       {
          if (unknown)
          {
             return null;
          }

          if (local)
          {
             // a quirk for in-JVM appserver calls: emulate network transport, otherwise TableWrapper can't be
             // deserialized
             try
             {
                ByteArrayOutputStream baos = new ByteArrayOutputStream();
                ObjectOutputStream out = new ObjectOutputStream(baos);
                this.writeExternal(out);
                out.close();

                ByteArrayInputStream bais = new ByteArrayInputStream(baos.toByteArray());
                ObjectInputStream in = new ObjectInputStream(bais);
                this.readExternal(in);
                in.close();
             }
             catch (IOException |
                    ClassNotFoundException e)
             {
                LOG.severe("", e);
             }
          }

          object<?> ref = ObjectOps.newInstance(type, true);
          ObjectOps.pendingAssign(ref.ref);

          if (!ref._isValid())
          {
             LOG.log(Level.SEVERE, "An instance of type " + type + " could not be created.");
             return null;
          }

          for (Map.Entry<Field, Object> entry : serialized.entrySet())
          {
             Field f = entry.getKey();
             Object ser = entry.getValue();

             try
             {
                restoreField(f, ref.ref, ser);
             }
             catch (IllegalArgumentException |
                    IllegalAccessException e)
             {
                LOG.severe("", e);
             }
          }

          return ref.ref;
       }

       /**
        * Serialize the given {@link object} reference, and save it, to be transported over network.
        *
        * @param o
        */
       private void serialize(object<? extends _BaseObject_> o)
       {
          unknown = o.ref == null;
          type = (unknown ? o.type() : o.ref.getClass());
          legacyClass = type == null ? "Progress.Lang.Object" : ObjectOps.getLegacyName(type);

          save(o.ref);
       }

       /**
        * Serialize the given reference.
        *
        * @param    ref
        *           The reference to serialize.
        */
       private void save(_BaseObject_ ref)
       {
          if (unknown)
          {
             return;
          }

          // TODO: check type to have LegacySerializable annotation

          ArrayList<Field> fields = collectInstanceFields(ref);

          for (int i = 0; i < fields.size(); i++)
          {
             Field f = fields.get(i);
             try
             {
                Object ser = serializeField(ref, f);
                serialized.put(f, ser);
             }
             catch (IllegalArgumentException |
                    IllegalAccessException e)
             {
                LOG.severe("", e);
             }
          }
       }

       /**
        * Restore the given field from its serialized state.
        *
        * @param    f
        *           The field to restore.
        * @param    ref
        *           The reference where the field needs to be set.
        * @param    ser
        *           The field's new value, which will either be assigned or set directly.
        */
       private void restoreField(Field f, _BaseObject_ ref, Object ser)
       throws IllegalArgumentException,
              IllegalAccessException
       {
          Class<?> ftype = f.getType();
          f.setAccessible(true);
          Object dest = f.get(ref);

          if (ser instanceof LegacyArray)
          {
             LegacyArray arr = (LegacyArray) ser;
             int size = Array.getLength(dest);
             if (size == 0)
             {
                size = Array.getLength(arr.val);
                if (size == 0)
                {
                   // nothing else to do, just an empty array
                   return;
                }

                dest = ArrayAssigner.resizeField((BaseDataType[]) dest, size, ref);
                f.set(ref, dest);
             }
             Class<?> elType = ftype.getComponentType();
             for (int i = 0; i < size; i++)
             {
                Externalizable elSer = (Externalizable) Array.get(arr.val, i);
                Object destEl = Array.get(dest, i);
                if (!deserializeObject(elType, destEl, elSer))
                {
                   // if this is not a FWD type, then just set the element.
                   Array.set(dest, i, elSer);
                }
             }
          }
          else
          {
             if (!deserializeObject(ftype, dest, ser))
             {
                f.set(ref, ser);
             }
          }
       }

       /**
        * Restore the state of a field using the received (serialized) value.
        *
        * @param    ftype
        *           The field's type.
        * @param    dest
        *           The field's current value.
        * @param    ser
        *           The field's value to be assigned.
        *
        * @return   <code>true</code> if the field was updated.
        */
       private boolean deserializeObject(Class<?> ftype, Object dest, Object ser)
       {
          if (object.class.isAssignableFrom(ftype))
          {
             deserializeObject(dest, (LegacyObject) ser);
             return true;
          }

          if (memptr.class.isAssignableFrom(ftype))
          {
             deserializeMemptr(dest, (MemoryBuffer) ser);
             return true;
          }

          if (DataSet.class.isAssignableFrom(ftype))
          {
             deserializeDataSet(dest, (longchar) ser);
             return true;
          }

          if (Buffer.class.isAssignableFrom(ftype))
          {
             deserializeTable(dest, (TableWrapper) ser);
             return true;
          }

          if (BaseDataType.class.isAssignableFrom(ftype))
          {
             deserialize(dest, (BaseDataType) ser);
             return true;
          }

          return false;
       }

       /**
        * Restore the given field from its serialized state.
        *
        * @param    dest
        *           The reference where the field needs to be set.
        * @param    ser
        *           The serialized state.
        */
       private void deserialize(Object dest, BaseDataType ser)
       {
          ((BaseDataType) dest).assign(ser);
       }

       /**
        * Restore the given table field from its serialized state.
        *
        * @param    dest
        *           The reference where the field needs to be set.
        * @param    ser
        *           The serialized state.
        */
       private void deserializeTable(Object dest, TableWrapper ser)
       {
          Buffer buffer = (Buffer) dest;
          Temporary dmo = TemporaryBuffer.getDefaultBuffer(buffer.tableHandle());
          TemporaryBuffer.insertAllRows(ser, dmo, false, TemporaryBuffer.CopyTableMode.INPUT_PARAM_MODE, -1);
       }

       /**
        * Restore the given {@link DataSet} field from its serialized state.
        *
        * @param    dest
        *           The reference where the field needs to be set.
        * @param    ser
        *           The serialized state.
        */
       private void deserializeDataSet(Object dest, longchar ser)
       {
          DataSet ds = (DataSet) dest;
          ds.readXml(new SourceData("longchar", ser), new character("empty"), new character(), new logical());
       }

       /**
        * Restore the given {@link memptr} field from its serialized state.
        *
        * @param    dest
        *           The reference where the field needs to be set.
        * @param    ser
        *           The serialized state.
        */
       private void deserializeMemptr(Object dest, MemoryBuffer ser)
       {
          memptr m = (memptr) dest;
          m.assign(ser.getValue());
       }

       /**
        * Restore the given {@link object} field from its serialized state.
        *
        * @param    dest
        *           The reference where the field needs to be set.
        * @param    ser
        *           The serialized state.
        */
       private void deserializeObject(Object dest, LegacyObject ser)
       {
          object o = (object) dest;
          o.assign(ser.restore());
       }

       /**
        * Get the field's serialized state.
        *
        * @param    ref
        *           The reference from where the field is read.
        * @param    f
        *           The field to read.
        *
        * @return   See above.
        */
       private Object serializeField(_BaseObject_ ref, Field f)
       throws IllegalArgumentException,
              IllegalAccessException
       {
          Class<?> ftype = f.getType();
          f.setAccessible(true);
          Object val = f.get(ref);
          if (ftype.isArray())
          {
             return new LegacyArray(val);
          }

          return serializeField(ftype, val, local);
       }

       /**
        * Get the field's value using a serializable instance, assuming that
        * the sent object is not being transported in the same JVM.
        *
        * @param    ftype
        *           The field's type.
        * @param    val
        *           The field's value.
        *
        * @return   The serializable instance of this value or the actual value.
        */
       private static Object serializeField(Class<?> ftype, Object val)
       {
         return serializeField(ftype, val, false);
       }

       /**
        * Get the field's value using a serializable instance.
        *
        * @param    ftype
        *           The field's type.
        * @param    val
        *           The field's value.
        * @param    local
        *           Flag indicating if the object is being transported in the same JVM.
        *
        * @return   The serializable instance of this value or the actual value.
        */
       private static Object serializeField(Class<?> ftype, Object val, boolean local)
       {
          if (object.class.isAssignableFrom(ftype))
          {
             return serializeObject((object) val);
          }
          else if (memptr.class.isAssignableFrom(ftype))
          {
             return serializeMemptr((memptr) val);
          }
          else if (DataSet.class.isAssignableFrom(ftype))
          {
             return serializeDataSet((DataSet) val);
          }
          else if (Buffer.class.isAssignableFrom(ftype))
          {
             return serializeTable((Buffer) val, local);
          }
          else if (BaseDataType.class.isAssignableFrom(ftype))
          {
             return serialize((BaseDataType) val);
          }
          else if (val == null || val instanceof Serializable)
          {
             return val;
          }
          else
          {
             // this will abend when the data is transferred via serialization,  so lets log the stack trace here,
             // but do not completely abend
             Class<?> type = val.getClass();
             LOG.log(Level.SEVERE, "Value " + type + " is not serializable.", new NotSerializableException());
             ErrorManager.recordOrThrowError(17315,
                                            "Object of class type `" + type +
                                            "` is not allowed to be marshaled remotely",
                                            false);
             return null;
          }
       }

       /**
        * Get the field's serialized state.
        *
        * @param    ref
        *           The field's value.
        *
        * @return   See above.
        */
       private static  Externalizable serialize(BaseDataType ref)
       {
          return ref;
       }

       /**
        * Get the field's serialized state.
        *
        * @param    buffer
        *           The field's value.
        *
        * @return   See above.
        */
       private static  Externalizable serializeTable(Buffer buffer, boolean local)
       {
          Temporary dmo = TemporaryBuffer.getDefaultBuffer(buffer.tableHandle());
          TempTableResultSet resultSet = new TempTableResultSet(dmo, true, true, false, true);
          TableWrapper tw = new TableWrapper(resultSet);

          if(local)
          {
             tw = preProcessTable(tw);
          }

          return tw;
       }

       /**
        * This method emulates as if {@link TableWrapper} was sent over the network.
        *
        * @param tableWrapper
        *        The {@link TableWrapper} object which has to be serialized.
        */
       private static TableWrapper preProcessTable(TableWrapper tableWrapper)
       {
          try
          {
             ByteArrayOutputStream baos = new ByteArrayOutputStream();
             ObjectOutputStream out = new ObjectOutputStream(baos);
             tableWrapper.writeExternal(out);
             out.close();

             tableWrapper = new TableWrapper();
             ByteArrayInputStream bais = new ByteArrayInputStream(baos.toByteArray());
             ObjectInputStream in = new ObjectInputStream(bais);
             tableWrapper.readExternal(in);
             in.close();

             return tableWrapper;
          }
          catch (Throwable t)
          {
             throw new RuntimeException(t);
          }
       }

       /**
        * Get the field's serialized state.
        *
        * @param    dataSet
        *           The field's value.
        *
        * @return   See above.
        */
       private static Externalizable serializeDataSet(DataSet dataSet)
       {
          longchar lc = new longchar("");
          dataSet.writeXml(new TargetData(TargetData.TYPE_LONGCHAR, lc), new logical(true));
          return lc;
       }

       /**
        * Get the field's serialized state.
        *
        * @param    ref
        *           The field's value.
        *
        * @return   See above.
        */
       private static Externalizable serializeMemptr(memptr ref)
       {
          return new MemoryBuffer(ref.getByteArray());
       }

       /**
        * Get the field's serialized state.
        *
        * @param    ref
        *           The field's value.
        *
        * @return   See above.
        */
       private static Externalizable serializeObject(object ref)
       {
          // TODO: circular references....

          return new LegacyObject(ref);
       }

       /**
        * Collect all instance fields defined in the reference's type.
        *
        * @param    ref
        *           The reference.
        *
        * @return   See above.
        */
       private ArrayList<Field> collectInstanceFields(_BaseObject_ ref)
       {
          // TODO: cache this.

          ArrayList<Field> res = new ArrayList<>();

          Class<? extends _BaseObject_> parent = type;
          while (parent != BaseObject.class)
          {
             // internal FWD types allow presence of non-BDT fields - these will be serialized directly
             boolean internalType = parent.isAnnotationPresent(LegacyResource.class);

             Field[] fields = parent.getDeclaredFields();
             for (Field f : fields)
             {
                int mods = f.getModifiers();
                if (Modifier.isStatic(mods))
                {
                   continue;
                }

                // TODO: omit NOT-SERIALIZABLE fields

                Class<?> ftype = f.getType();

                LegacySignature ls = f.getAnnotation(LegacySignature.class);
                // check to be a dataset or temp-table
                if (ls == null    &&
                    !internalType &&
                    !(ftype == DataSet.class || TempTableBuffer.class.isAssignableFrom(ftype)))
                {
                   LOG.log(Level.WARNING,
                           "Omitting field " + f.toString() + " when serializing type " +  ref.getClass());
                   continue;
                }

                if (ftype == handle.class || (ftype.isArray() && ftype.getComponentType() == handle.class))
                {
                   LOG.log(Level.FINE, "HANDLE fields can not be serialized: " + f.toString());
                   continue;
                }

                try
                {
                   f.setAccessible(true);
                   Object val = f.get(ref);

                   if (val instanceof Buffer)
                   {
                      // TODO: check to be the default buffer for an actual temp-table and not an explicit buffer
                   }

                   res.add(f);
                }
                catch (IllegalArgumentException |
                       IllegalAccessException e)
                {
                   LOG.severe("", e);
                }
             }

             parent = (Class<? extends _BaseObject_>) parent.getSuperclass();
          }

          return res;
       }

       /**
        * Serializable storage of a BDT array associated with a field.
        */
       public static class LegacyArray
       implements Externalizable
       {
          /** The field's value. */
          private Object val;

          /**
           * Default constructor, for deserialization purposes.
           */
          public LegacyArray()
          {
          }

          /**
           * Create a new instance to serialize the given array.
           *
           * @param   val
           *          The array to serialize.
           */
          public LegacyArray(Object val)
          {
             this.val = val;
          }

          /**
           * Serialize the {@link #val value}.  Relies on {@link LegacyObject#serializeField} to get the
           * serialized representation of the array elements.
           */
          @Override
          public void writeExternal(ObjectOutput out)
          throws IOException
          {
             Class<?> type = val == null ? Object.class : val.getClass().getComponentType();
             int size = val == null ? 0 : Array.getLength(val);
             out.writeInt(size);
             for (int i = 0; i < size; i++)
             {
                Object valEl = Array.get(val, i);
                Object el = serializeField(type, valEl);
                out.writeObject(el);
             }
          }

          /**
           * Deserialize the {@link #val value}.
           */
          @Override
          public void readExternal(ObjectInput in)
          throws IOException,
                 ClassNotFoundException
          {
             int size = in.readInt();
             val = Array.newInstance(Externalizable.class, size);
             for (int i = 0; i < size; i++)
             {
                Externalizable extEl = (Externalizable) in.readObject();
                Array.set(val,  i, extEl);
             }
          }
       }
    }