# ForeignResolver.java

    /*
    ** Module   : ForeignResolver.java
    ** Abstract : Helper object for foreign relation joins
    **
    ** Copyright (c) 2006-2023, Golden Code Development Corporation.
    **
    ** -#- -I- --Date-- -JPRM-- -----------------------------------Description-----------------------------------
    ** 001 ECF 20060302  @25012 Created initial version. Resolves foreign
    **                          records using legacy keys.
    ** 002 ECF 20060713  @28045 Use new DBUtils class.
    ** 003 ECF 20061114  @31137 Modified to support expanded foreign
    **                          association synchronization. Also embedded
    **                          rtrim() function into character queries to
    **                          match database indices.
    ** 004 ECF 20070629  @35298 Minor optimization. Replaced StringBuffer
    **                          with StringBuilder.
    ** 005 CA  20080819  @39460 Support API change in FieldReference.
    ** 006 SVL 20140210         Use HQLExpression instead of HQL string.
    ** 007 ECF 20160202         Replaced Apache commons logging with J2SE logging.
    ** 008 OM  20160603         Fixed rtrimming to space character only.
    ** 009 ECF 20200906         New ORM implementation.
    **     OM  20221103         New class names for FQLPreprocessor, FQLExpression, FQLBundle, and FQLCache.
    ** 010 SR  20230510         Matched persistence.list() new signature.
    ** 011 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;

    import java.util.*;
    import java.util.logging.*;

    import com.goldencode.p2j.persist.orm.*;
    import com.goldencode.p2j.util.logging.*;

    /**
     * Resolves records on either end of a foreign key association, based upon
     * the values of one or more properties in a DMO, where those properties
     * represent the legacy "foreign key" in the pre-conversion application.
     * This allows a record's foreign key to be kept in synch with changes to
     * these legacy key properties.  This is necessary because a true foreign key
     * is only added to a table as part of the conversion process;  the legacy
     * application knows nothing of these new keys, so the runtime must keep them
     * in synch as the legacy key values change.
     */
    final class ForeignResolver
    {
       /** Logger */
       private static final CentralLogger LOG = CentralLogger.get(ForeignResolver.class.getName());

       /** Information about the primary/foreign key relation */
       private final RelationInfo info;

       /** FQL query statement */
       private final String fql;

       /** Field references used to retrieve query substitution values */
       private final ArrayList<FieldReference> fieldRefs = new ArrayList<>();

       /** Does resolver walk the foreign key association from the foreign end? */
       private final boolean inverse;

       /** The associated database */
       private final Database database;

       /**
        * Constructor.
        *
        * @param   info
        *          Descriptor of the relation between the local and foreign DMOs.
        * @param   buffer
        *          A record buffer which represents the "local" (i.e., referring)
        *          DMO if <code>inverse</code> is <code>false</code>, or which
        *          represents the foreign (i.e., referent) DMO if
        *          <code>inverse</code> is <code>true</code>.
        * @param   inverse
        *          <code>true</code> to construct an object which resolves the
        *          "local" (i.e., referring) DMO(s) given a foreign (i.e.,
        *          referent) DMO;  <code>false</code> to construct an object
        *          which resolves the foreign DMO given a local DMO.
        */
       ForeignResolver(RelationInfo info, RecordBuffer buffer, boolean inverse)
       {
          this.info = info;
          this.database = buffer.getDatabase(); // TODO: OM: caching Database obj?
          this.inverse = inverse;
          this.fql = generateFQL(info);
          Iterator<String> propIter = inverse
                               ? info.foreignProperties()
                               : info.localProperties();
          createFieldRefs(buffer.getDMOInterface(), propIter);
       }

       /**
        * Resolve a foreign record using the values of one or more legacy key
        * properties in <code>buffer</code>'s current record.
        *
        * @param   buffer
        *          The record buffer containing the current, local record for
        *          which a related, foreign record must be found.
        *
        * @return  The primary key ID of the foreign record associated with the
        *          current value(s) of the legacy key(s) in <code>buffer</code>'s
        *          current record, or <code>null</code> if none was found.
        *
        * @throws  PersistenceException
        *          if any error occurs querying the foreign record from the
        *          database.
        * @throws  IllegalStateException
        *          if the current record in the buffer is <code>null</code>, or
        *          if this object has been configured to retrieve the record for
        *          the inverse, foreign key association.
        */
       Long resolveForeign(RecordBuffer buffer)
       throws PersistenceException
       {
          if (inverse)
          {
             throw new IllegalStateException(
                "Resolver configured to resolve inverse foreign association");
          }

          Record local = buffer.getCurrentRecord();
          if (local == null)
          {
             throw new IllegalStateException("Cannot resolve foreign DMO for a null record");
          }

          Persistence persistence = buffer.getPersistence();
          Object[] args = getArguments(local);

          if (LOG.isLoggable(Level.FINE))
          {
             LOG.fine("FQL:  " + fql);

             StringBuilder buf = new StringBuilder("PARMS:  ");
             int len = args.length;
             if (len == 0)
             {
                buf.append("N/A");
             }

             for (int k = 0; k < len; k++)
             {
                if (k > 0)
                {
                   buf.append(", ");
                }
                buf.append(args[k]);
             }

             LOG.fine(buf.toString());

             buf.setLength(0);
             buf.append("LOCAL DMO:  ");
             buf.append(local);
             buf.append(" [");
             buf.append(local.primaryKey());
             buf.append("]");

             LOG.fine(buf.toString());
          }

          List<Long> list = persistence.list(fql, args, 0, 0);
          Long id = list == null ? null : list.get(0);

          if (LOG.isLoggable(Level.FINE))
          {
             LOG.fine("FOREIGN DMO:  " + (id != null ? id : "N/A"));
          }

          return id;
       }

       /**
        * Resolve zero or more records which refer via foreign key association to
        * the record currently stored in {@code buffer}, using the values
        * of one or more legacy key properties in that record.
        *
        * @param   buffer
        *          The record buffer containing the current, foreign record for
        *          which one or more related, "local" records must be found.
        *
        * @return  A list of zero or more primary key IDs for the record(s), if
        *          any, associated with the current value(s) of the legacy key(s)
        *          in {@code buffer}'s current record.
        *
        * @throws  PersistenceException
        *          if any error occurs querying the database.
        * @throws  IllegalStateException
        *          if the current record in the buffer is {@code null}, or
        *          if this object has not been configured to retrieve the record
        *          for the inverse, foreign key association..
        */
       List<Long> resolveLocal(RecordBuffer buffer)
       throws PersistenceException
       {
          if (!inverse)
          {
             throw new IllegalStateException(
                "Resolver not configured to resolve inverse foreign association");
          }

          Record dmo = buffer.getCurrentRecord();
          if (dmo == null)
          {
             throw new IllegalStateException("Cannot resolve local DMO for a null record");
          }

          Persistence persistence = buffer.getPersistence();
          Object[] args = getArguments(dmo);

          if (LOG.isLoggable(Level.FINE))
          {
             LOG.fine("FQL:  " + fql);

             StringBuilder buf = new StringBuilder("PARMS:  ");
             int len = args.length;
             if (len == 0)
             {
                buf.append("N/A");
             }

             for (int k = 0; k < len; k++)
             {
                if (k > 0)
                {
                   buf.append(", ");
                }
                buf.append(args[k]);
             }

             LOG.fine(buf.toString());

             buf.setLength(0);
             buf.append("FOREIGN DMO:  ");
             buf.append(dmo);
             buf.append(" [");
             buf.append(dmo.primaryKey());
             buf.append("]");

             LOG.fine(buf.toString());
          }

          List<Long> list = persistence.list(fql, args, 0, 0);

          if (LOG.isLoggable(Level.FINE))
          {
             LOG.fine("LOCAL DMO(s):  " + list);
          }

          return list;
       }

       /**
        * Get the descriptor object which contains information about the relation
        * associated with this resolver.
        *
        * @return  Relation descriptor.
        */
       RelationInfo getInfo()
       {
          return info;
       }

       /**
        * Get the current values of all legacy key properties for this relation,
        * from the given record.  These will become query substitution values
        * when searching for the foreign record.
        *
        * @param   dmo
        *          Record currently stored in the record buffer.
        *
        * @return  Array of current, legacy key property values.
        */
       private Object[] getArguments(Record dmo)
       {
          Object[] args = new Object[fieldRefs.size()];

          Iterator<FieldReference> iter = fieldRefs.iterator();
          for (int i = 0; iter.hasNext(); i++)
          {
             FieldReference next = iter.next();
             args[i] = next.get(dmo);
          }

          return args;
       }

       /**
        * Generate the FQL statement which will be used for record resolution,
        * using the information stored in the relation descriptor.
        *
        * @param   info
        *          Relation descriptor.
        *
        * @return  FQL query statement.
        */
       private String generateFQL(RelationInfo info)
       {
          String alias = inverse ? info.getLocalAlias() : info.getForeignAlias();
          FQLExpression buf = new FQLExpression("select ");
          buf.append(alias);
          buf.append("." + Session.PK + " from ");
          buf.append(inverse ? info.getLocalClassName() : info.getForeignClassName());
          buf.append(" as ");
          buf.append(alias);
          buf.append(" where ");

          Iterator<String> iter = inverse
                           ? info.localProperties()
                           : info.foreignProperties();
          for (int i = 0; iter.hasNext(); i++)
          {
             if (i > 0)
             {
                buf.append(" and ");
             }

             String prop = iter.next();

             // TODO:  support computed columns
             if (info.isIgnoreCase(prop))
             {
                buf.append("upper(rtrim(");
                buf.append(alias);
                buf.append(".");
                buf.append(prop);
                buf.append(")) = upper(rtrim(", true);
                buf.append("))");
             }
             else
             {
                buf.append(alias);
                buf.append(".");
                buf.append(prop);
                buf.append(" = ", true);
             }
          }

          return buf.toFinalExpression();
       }

       /**
        * Construct one {@link FieldReference} object for each legacy key
        * property which will be used as a query substitution parameter during
        * record resolution.  Store these objects in a list for later access.
        *
        * @param   dmoIface
        *          Business interface which the field references will invoke to
        *          retrieve property values.
        * @param   propIter
        *          Iterator on the names of those DMO properties which form the
        *          legacy foreign key.
        */
       private void createFieldRefs(Class<? extends DataModelObject> dmoIface,
                                    Iterator<String> propIter)
       {
          while (propIter.hasNext())
          {
             String prop = propIter.next();
             fieldRefs.add(new FieldReference(database, dmoIface, prop));
          }

          fieldRefs.trimToSize();
       }
    }