# PresortCompoundQuery.java

    /*
    ** Module   : PresortCompoundQuery.java
    ** Abstract : Implementation of a presorting, multi-table query
    **
    ** Copyright (c) 2004-2024, Golden Code Development Corporation.
    **
    ** -#- -I- --Date-- --JPRM-- ----------------------------Description-----------------------------
    ** 001 ECF 20080112   @36991 Created initial version. Implementation of a
    **                           presorting, multi-table query which does not
    **                           perform its table join(s) on the database
    **                           server.
    ** 002 ECF 20090313   @41602 Forced full-records mode. Added overridden
    **                           addComponent() method which calls
    **                           setFullRecords().
    ** 003 SVL 20090723   @43343 Changes due to Sorter API change.
    ** 004 SIY 20100303   @44700 Added support for proper accumulator handling.
    ** 005 SVL 20111111          Make the class implement PresortDelegate.
    ** 006 ECF 20131028          Import change.
    ** 007 ECF 20150327          Javadoc fix.
    ** 008 OM  20150727          Synchronized the cursors for first/next/prev/last methods.
    ** 009 ECF 20150806          Re-ordered some methods to comply with coding standards.
    ** 010 SVL 20160526          Removed sorted result set (second). All sorted data is now stored in
    **                           the cursor.
    ** 011 GES 20160919          All initialization is now done with a default constructor followed
    **                           by a call to initialize(). This enables query instance members in
    **                           converted code to be local variables that are effectively final.
    **                           This is needed to support lambdas without moving queries to be
    **                           instance members. Queries as instance members breaks recursion
    **                           use cases.
    ** 012 OM  20180620          Added support for dynamically configured sort criteria.
    ** 013 ECF 20181106          Added runtime support for {FIRST|LAST}-OF methods.
    ** 014 ECF 20200906          New ORM implementation.
    ** 015 IAS 20230717          Added 'initialize' with two arguments.
    ** 016 IAS 20230921          Added initializa2f() method.
    ** 017 ES  20240404          Overridden isPesort method.
    ** 018 CA  20240422          Allow the query to be reset to its initialization state, so the same instance can
    **                           be used to execute child buffer FILL operations.
    ** 019 AL2 20240926          Adapted CursorResults to new signature of get.
    ** 020 LS  20241101          Adapted Presorter to new signature of createSortedResults.
    */

    /*
    ** 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 com.goldencode.p2j.persist.lock.*;
    import com.goldencode.p2j.util.*;

    /**
     * PresortCompoundQuery is used when it is necessary to presort the results
     * of a multi-table join, where the join cannot be performed at the database
     * server.  This is necessary when tables are being joined across databases,
     * for example, though there may be other circumstances which could drive
     * this requirement.
     * <p>
     * Upon the first request for a record, this query preselects all of its
     * results in the order prescribed by each of its individual query components.
     * It then sorts these results according to the sort criteria provided by one
     * of the <code>addSortCriterion()</code> method variants.  These results are
     * cached.  The appropriate record is returned for the original request, and
     * thereafter, the cache is accessed for all subsequent record retrieval
     * requests.  The cache contains only primary key ID values;  the actual
     * records associated with these are retrieved on demand.
     */
    public final class PresortCompoundQuery
    extends CompoundQuery
    implements Presortable,
               PresortDelegate
    {
       /** Helper which sorts preselected, unsorted results */
       private Presorter sorter;

       /** The cached results stored in the cursor, wrapped by {@link Results} interface. */
       private CursorResults cursorResults = null;

       /**
        * Default constructor. Initialization is deferred until <code>initialize()</code> is
        * called.
        */
       public PresortCompoundQuery()
       {
       }

       /**
        * Clear the current results from the query, so the same query instance can be executed again, without
        * having to {@link #open() re-open} it.
        */
       @Override
       public void clearResults()
       {
          super.clearResults();

          this.cursorResults = null;
          this.sorter = null;
       }

       /**
        * Initialization logic.
        * <p>
        * This code is intentionally separated from the constructor. The purpose of this separation
        * is to allow construction to occur in the prior scope while initialization can still occur
        * within a method or lambda that is inside the next block's scope.
        *
        * @param    resolveOnce
        *           {@code true} to resolve arguments once, up front, or on every loop cycle.
        * @param    preselect
        *           {@code true} to force preselection of all results; {@code false} otherwise.
        * @return   This query instance.
        */
       public PresortCompoundQuery initialize(boolean resolveOnce, boolean preselect)
       {
          // Resolve args once up front and preselect results.
          super.initialize(resolveOnce, preselect);

          sorter = new Presorter(this);

          setScrolling(); // we need cursor in any case, so set the query scrolling even if it
                          // backs a cycle

          return this;
       }
       /**
        * Initialization logic.
        * <p>
        * This code is intentionally separated from the constructor. The purpose of this separation
        * is to allow construction to occur in the prior scope while initialization can still occur
        * within a method or lambda that is inside the next block's scope.
        *
        * @return   This query instance.
        */
       public PresortCompoundQuery initialize()
       {
          return initialize(true, true);
       }

       /**
        * Initialization logic.
        * <p>
        * This code is intentionally separated from the constructor. The purpose of this separation
        * is to allow construction to occur in the prior scope while initialization can still occur
        * within a method or lambda that is inside the next block's scope.
        *
        * @return   This query instance.
        */
       public PresortCompoundQuery initialize2f()
       {
          return initialize(false, false);
       }

       /**
        * Add a joinable query to the compound query, and specify the nature of
        * the iteration which will be performed (first, last, next, etc.) on that
        * component, when the compound query is iterated.  If this is not the
        * first component to be added to the query, the type of join performed
        * with the immediately previous component is determined by the value of
        * <code>outer</code>.
        *
        * @param   query
        *          Query which will perform the fundamental work for this
        *          component when the compound query is iterated.
        * @param   iteration
        *          A {@link QueryConstants constant} indicating the type of work
        *          to be performed upon an iteration of the compound query.  This
        *          parameter determines whether the underlying query will be asked
        *          to perform a first, last, next, previous, or unique record
        *          retrieval.
        * @param   outer
        *          <code>true</code> if this component should be joined to the
        *          previously added component via a left outer join;
        *          <code>false</code> if an inner join is required.  Note that
        *          adding an inner join component will cause any previously added
        *          components added as outer joins to be reset to inner joins.
        *
        * @throws  IllegalStateException
        *          if this method is invoked during an iteration cycle.
        *
        * @see     #iterate
        */
       public void addComponent(Joinable query, int iteration, boolean outer)
       {
          query.setFullRecords();

          super.addComponent(query, iteration, outer);
       }

       /**
        * Access the record buffers manipulated by this query, in order from
        * left-most (outermost) table of the query's join (if any) to right-most
        * (innermost) table.
        *
        * @return  Array of one or more record buffers.
        */
       public RecordBuffer[] getRecordBuffers()
       {
          RecordBuffer[] buffers = new RecordBuffer[getTableCount()];
          Iterator<RecordBuffer> iter = recordBuffers();
          for (int i = 0; iter.hasNext(); i++)
          {
             buffers[i] = iter.next();
          }

          return buffers;
       }

       /**
        * Add a single sort criterion, in the form of a <code>Resolvable</code>
        * object which is resolved at sort time.  It is the value of the resolved
        * result which is used for the sort.
        * <p>
        * The sort is ascending, from lowest resolved value to highest.
        *
        * @param   sort
        *          A resolvable object whose resolved result is used for sorting.
        */
       public void addSortCriterion(Resolvable sort)
       {
          sorter.addSortCriterion(sort);
       }

       /**
        * Add a single sort criterion, in the form of a <code>Resolvable</code>
        * object which is resolved at runtime.  It is the value of the resolved
        * result which is used for the sort.
        *
        * @param   sort
        *          A resolvable object whose resolved result is used for sorting.
        * @param   descending
        *          if <code>true</code>, the sort is descending, from highest
        *          resolved value to lowest;  otherwise, the sort is ascending.
        */
       public void addSortCriterion(Resolvable sort, boolean descending)
       {
          sorter.addSortCriterion(sort, descending);
       }

       /**
        * Add a single dynamic sort criterion, in the form of a {@code Resolvable} object which is
        * resolved at runtime.  It is the value of the resolved result which is used for the sort.
        * <p>
        * Unlike {@link #addSortCriterion} methods, the criterion is added with higher priority.
        *
        * @param   sort
        *          A resolvable object whose resolved result is used for sorting.
        * @param   ascending
        *          if {@code true}, the sort is ascending, from lowest resolved value to highest;
        *          otherwise, the sort is descending.
        */
       @Override
       public void addDynamicSortCriterion(Resolvable sort, boolean ascending)
       {
          sorter.addDynamicSortCriterion(sort, ascending);
       }

       /**
        * Clears all sort criteria added dynamically.
        */
       @Override
       public void clearDynamicSortCriteria()
       {
          sorter.clearDynamicSortCriteria();
       }

       /**
        * Enable all sort criteria set for this query to act as break group
        * categories.  When the query's results are presorted, the contents of
        * each break group are determined.
        */
       public void enableBreakGroups()
       {
          sorter.enableBreakGroups();
       }

       /**
        * Determine whether the query result row currently being visited is the
        * first row in the presorted results list.
        *
        * @return  <code>true</code> if the current result row is the first row,
        *          else <code>false</code>.
        */
       public logical isFirst()
       {
          return sorter.isFirst();
       }

       /**
        * Determine whether the query result row currently being visited is the
        * first row within a break group whose category is identified by the
        * specified resolvable object.
        *
        * @param   key
        *          Break group category key.  Must be the same object reference
        *          as was specified previously when invoking one of the
        *          <code>addSortCriterion</code> method variants.
        *
        * @return  <code>true</code> if break groups are enabled and current row
        *          is first in the specified break group;
        *          <code>false</code> if break groups have not been enabled or
        *          current row is not first in the specified break group.
        */
       public logical isFirstOfGroup(Resolvable key)
       {
          return sorter.isFirstOfGroup(key);
       }

       /**
        * Determine whether the query result row currently being visited is the first row of the
        * query's result set or the first row within a break group whose category is identified by
        * the specified BREAK-BY level.
        *
        * @param   level
        *          Break group level, where 0 is the whole query, 1 is the first BREAK-BY sort
        *          criterion, etc. Must not be negative or greater than the number of sort criteria.
        *
        * @return  {@code true} if the current row is first in the result set or within the specified
        *          break group; else {@code false}.
        */
       public logical isFirstOfGroup(integer level)
       {
          return sorter.isFirstOf(level);
       }

       /**
        * Determine whether the query result row currently being visited is the first row of the
        * query's result set or the first row within a break group whose category is identified by
        * the specified BREAK-BY level.
        *
        * @param   level
        *          Break group level, where 0 is the whole query, 1 is the first BREAK-BY sort
        *          criterion, etc. Must not be negative or greater than the number of sort criteria.
        *
        * @return  {@code true} if the current row is first in the result set or within the specified
        *          break group; else {@code false}.
        */
       public logical isFirstOfGroup(int level)
       {
          return isFirstOfGroup(new integer(level));
       }

       /**
        * Determine whether the query result row currently being visited is the
        * last row in the presorted results list.
        *
        * @return  <code>true</code> if the current result row is the last row,
        *          else <code>false</code>.
        */
       public logical isLast()
       {
          return sorter.isLast();
       }

       /**
        * Indicate whether the query is of presort type.
        *
        * @return  <code>true</code> if the query is of presort type..
        */
       @Override
       public boolean isPresort()
       {
          return true;
       }

       /**
        * Determine whether the query result row currently being visited is the
        * last row within a break group whose category is identified by the
        * specified resolvable object.
        *
        * @param   key
        *          Break group category key.  Must be the same object reference
        *          as was specified previously when invoking one of the
        *          <code>addSortCriterion</code> method variants.
        *
        * @return  <code>true</code> if break groups are enabled and current row
        *          is last in the specified break group;
        *          <code>false</code> if break groups have not been enabled or
        *          current row is not last in the specified break group.
        */
       public logical isLastOfGroup(Resolvable key)
       {
          return sorter.isLastOfGroup(key);
       }

       /**
        * Determine whether the query result row currently being visited is the last row of the
        * query's result set or the last row within a break group whose category is identified by
        * the specified BREAK-BY level.
        *
        * @param   level
        *          Break group level, where 0 is the whole query, 1 is the first BREAK-BY sort
        *          criterion, etc. Must not be negative or greater than the number of sort criteria.
        *          Must not be unknown value.
        *
        * @return  {@code true} if the current row is last in the result set or within the specified
        *          break group; else {@code false}.
        */
       public logical isLastOfGroup(integer level)
       {
          return sorter.isLastOf(level);
       }

       /**
        * Determine whether the query result row currently being visited is the last row of the
        * query's result set or the last row within a break group whose category is identified by
        * the specified BREAK-BY level.
        *
        * @param   level
        *          Break group level, where 0 is the whole query, 1 is the first BREAK-BY sort
        *          criterion, etc. Must not be negative or greater than the number of sort criteria.
        *
        * @return  {@code true} if the current row is last in the result set or within the specified
        *          break group; else {@code false}.
        */
       public logical isLastOfGroup(int level)
       {
          return isLastOfGroup(new integer(level));
       }

       /**
        * Access the current, sorted results for this query.
        *
        * @return  <code>Results</code> object used to retrieve sorted results.
        */
       public Results getSortedResults()
       {
          return cursorAsResults();
       }

       /**
        * Retrieve the next virtual, composite row of results for the compound
        * query, overriding the lock type to apply to each underlying query.
        * <p>
        * This is a combination of records retrieved by each component query.  If
        * the compound query involves outer joins, some of the underlying buffers
        * may be empty when this method returns.
        *
        * @param   iterating
        *          <code>true</code> if this method is being invoked within the
        *          context of an iterating loop, which can only be exited by
        *          raising an end condition;  <code>false</code> if end condition
        *          should not be raised, even if no further advancement of the
        *          composite result is possible.
        * @param   lockType
        *          Lock type which should override that of any underlying query.
        *
        * @throws  QueryOffEndException
        *          if no more results were available in iterating mode.
        * @throws  ErrorConditionException
        *          if an underlying query triggers an error.
        */
       public boolean next(boolean iterating, LockType lockType)
       {
          boolean hasNext = super.next(iterating, lockType);

          accumulate();

          return hasNext;
       }

       /**
        * Determine whether the query result row currently being visited is the
        * last row within a break group whose category is identified by the
        * specified resolvable object.
        *
        * @param   key
        *          Break group category key.  Must be the same object reference
        *          as was specified previously when invoking one of the
        *          <code>addSortCriterion</code> method variants.
        *
        * @return  <code>true</code> if break groups are enabled and current row
        *          is last in the specified break group;
        *          <code>false</code> if break groups have not been enabled or
        *          current row is not last in the specified break group.
        */
       protected boolean isLastOfBreakGroup(Resolvable key)
       {
          return sorter.isLastOfBreakGroup(key);
       }

       /**
        * Determine whether the query result row currently being visited is the
        * first row within a break group whose category is identified by the
        * specified resolvable object.
        * <p>
        * This is the backing worker method for {@link #isFirstOfGroup} and is
        * used internally by the query to manage accumulators.
        *
        * @param   key
        *          Break group category key.  Must be the same object reference
        *          as was specified previously when invoking one of the
        *          <code>addSortCriterion</code> method variants.
        *
        * @return  <code>true</code> if current row is first in a break group;
        *          <code>false</code> if it is not;  unknown value if break groups
        *          have not been enabled.
        */
       protected boolean isNewBreakGroup(Resolvable key)
       {
          return sorter.isNewBreakGroup(key);
       }

       /**
        * Determines if the query is presorted, i.e. if the query is sorted up front in some special
        * way.
        *
        * @return <code>true</code> for this implementation.
        */
       protected boolean isPresorted()
       {
          return true;
       }

       /**
        * Get the cached results stored in the cursor, wrapped by {@link Results} interface.
        *
        * @return the cached results stored in the cursor, wrapped by {@link Results} interface.
        */
       protected CursorResults cursorAsResults()
       {
          if (cursorResults == null)
          {
             cursorResults = new CursorResults(cursor);
          }

          return cursorResults;
       }

       /**
        * Presort the results stored in the cursor.
        */
       protected void presort()
       {
          try
          {
             if (hasAccumulators())
             {
                postponeAccumulation();
             }

             // reset cursor's position, the sorter processes rows from this position
             cursor.beforeFirst();

             // sort them
             SimpleResults sorted = (SimpleResults) sorter.createSortedResults(cursorAsResults(), true);

             // discard unsorted cursor results and set sorted instead
             cursor.setResults(sorted.getRows());
          }
          catch (PersistenceException exc)
          {
             ErrorManager.recordOrThrowError(exc);
          }
          finally
          {
             if (hasAccumulators())
             {
                restoreAccumulation();
             }
          }
       }

       /**
        * An implementation of the <code>Results</code> interface which is backed
        * by a dynamic {@link Cursor} object.
        * <p>
        * Only those methods which are required by the {@link Presorter} to sort
        * the results managed by the cursor are implemented.

        */
       private static class CursorResults
       implements Results
       {
          /** Backing cursor */
          private final Cursor cursor;

          /** Array of records which represents the current, virtual row */
          private Object[] row = null;

          /**
           * Constructor which accepts the backing cursor object.
           *
           * @param   cursor
           *          Cursor which backs this <code>Results</code> object.
           */
          CursorResults(Cursor cursor)
          {
             this.cursor = cursor;
          }

          /**
           * Move cursor to the first results row.
           *
           * @return  <code>true</code> if there are any results.
           */
          public boolean first()
          {
             row = cursor.getFirst();

             return (row != null);
          }

          /**
           * Move cursor to the last results row.
           *
           * @return  <code>true</code> if there are any results.
           */
          public boolean last()
          {
             row = cursor.getLast();

             return (row != null);
          }

          /**
           * Move cursor to the next results row.
           *
           * @return  <code>true</code> if there is a result under the cursor
           *          under the move.
           */
          public boolean next()
          {
             row = cursor.getNext();

             return (row != null);
          }

          /**
           * Move cursor to the previous results row.
           *
           * @return  <code>true</code> if there is a result under the cursor
           *          under the move.
           */
          public boolean previous()
          {
             row = cursor.getPrevious();

             return (row != null);
          }

          /**
           * Is the cursor on the first row in the results set?
           *
           * @return  <code>true</code> if the cursor is on the first row.
           */
          public boolean isFirst()
          {
             return getRowNumber() == 0;
          }

          /**
           * Is the cursor on the last row in the results set?
           *
           * @return  <code>true</code> if the cursor is on the first row.
           */
          public boolean isLast()
          {
             return cursor.size().intValue() == getRowNumber() + 1;
          }

          /**
           * Returns the row at the current position. It can be either only an array of PK or
           * an array of DMOs.
           *
           * @param   forceOnlyId
           *          Indicates whether it's only the primary keys that must be returned,
           *          or original data found is returned (either PK or DMO).
           *
           * @return  Object array or {@code null}.
           */
          @Override
          public Object[] get(boolean forceOnlyId)
          {
             if (!forceOnlyId)
             {
                return row;
             }

             Object[] newRow = new Object[row.length];
             for (int i = 0; i < row.length; i++)
             {
                if (row[i] instanceof Record)
                {
                   newRow[i] = ((Record) row[i]).primaryKey();
                }
                else
                {
                   newRow[i] = row[i];
                }
             }

             return newRow;
          }

          /**
           * Get the object at the current result row, at the specified column.
           *
           * @param   column
           *          Zero-based index column of the desired object.
           *
           * @return  Object at <code>column</code> or <code>null</code>.
           */
          public Object get(int column)
          {
             return (row == null ? null : row[column]);
          }

          /**
           * Get the primary key ID at the current result row, at the specified
           * column.
           *
           * @param   column
           *          Zero-based index column of the desired ID.
           *
           * @return  ID of the record or <code>null</code>.
           */
          public Long getID(int column)
          {
             Object datum = get(column);

             if (datum instanceof Record)
             {
                return ((Record) datum).primaryKey();
             }

             return ((Long) datum);
          }

          /**
           * Get the row number currently under the cursor.
           *
           * @return  Zero-based index of the current row, or <code>-1</code>
           *          if the cursor is not currently on a result.
           */
          public int getRowNumber()
          {
             integer position = cursor.currentRow();
             if (position.isUnknown())
             {
                return -1;
             }

             return position.intValue() - 1;
          }

          /**
           * Set the row number currently under the cursor.
           *
           * @param   row
           *          Zero-based index of the row to be set as the current row.
           *
           * @return  <code>true</code> if there is a row at the specified row
           *          number;  else <code>false</code>.
           *
           * @throws  UnsupportedOperationException
           *          always;  this method is not needed to sort results.
           */
          public boolean setRowNumber(int row)
          {
             throw new UnsupportedOperationException();
          }

          /**
           * Scroll the cursor ahead by the specified number of rows.  If the
           * number is negative, the cursor is moved backward.  This may put the
           * cursor off the end (either end) of the query's results.
           *
           * @param   rows
           *          Number of rows to jump ahead or back.
           *
           * @return  <code>true</code> if there is a row at the new location;
           *          else <code>false</code>.
           *
           * @throws  UnsupportedOperationException
           *          always;  this method is not needed to sort results.
           */
          public boolean scroll(int rows)
          {
             throw new UnsupportedOperationException();
          }

          /**
           * Reset the cursor to its natural starting position, before the first
           * result row.
           */
          public void reset()
          {
             cursor.beforeFirst();
          }

          /**
           * Invoked when the current Hibernate session is about to close.  Gives
           * the implementation an opportunity to perform appropriate processing
           * in response to this event.
           * <p>
           * This implementation does nothing.
           */
          public void sessionClosing()
          {
          }

          /**
           * Clean up and release any resources which this object is holding, such
           * as open result sets.
           * <p>
           * This implementation does nothing.
           */
          public void cleanup()
          {
          }
       }
    }