/*****************************************************************
 *   Licensed to the Apache Software Foundation (ASF) under one
 *  or more contributor license agreements.  See the NOTICE file
 *  distributed with this work for additional information
 *  regarding copyright ownership.  The ASF licenses this file
 *  to you under the Apache License, Version 2.0 (the
 *  "License"); you may not use this file except in compliance
 *  with the License.  You may obtain a copy of the License at
 *
 *    https://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing,
 *  software distributed under the License is distributed on an
 *  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 *  KIND, either express or implied.  See the License for the
 *  specific language governing permissions and limitations
 *  under the License.
 ****************************************************************/

package org.apache.cayenne.access;

import org.apache.cayenne.CayenneRuntimeException;
import org.apache.cayenne.DataRow;
import org.apache.cayenne.EmbeddableObject;
import org.apache.cayenne.ObjectContext;
import org.apache.cayenne.ObjectId;
import org.apache.cayenne.Persistent;
import org.apache.cayenne.QueryResponse;
import org.apache.cayenne.ResultIterator;
import org.apache.cayenne.cache.QueryCache;
import org.apache.cayenne.cache.QueryCacheEntryFactory;
import org.apache.cayenne.di.AdhocObjectFactory;
import org.apache.cayenne.map.DataMap;
import org.apache.cayenne.map.DbEntity;
import org.apache.cayenne.map.DbRelationship;
import org.apache.cayenne.map.Embeddable;
import org.apache.cayenne.map.EntityInheritanceTree;
import org.apache.cayenne.map.LifecycleEvent;
import org.apache.cayenne.map.ObjRelationship;
import org.apache.cayenne.query.EmbeddableResultSegment;
import org.apache.cayenne.query.EntityResultSegment;
import org.apache.cayenne.query.ObjectIdQuery;
import org.apache.cayenne.query.PrefetchSelectQuery;
import org.apache.cayenne.query.PrefetchTreeNode;
import org.apache.cayenne.query.Query;
import org.apache.cayenne.query.QueryCacheStrategy;
import org.apache.cayenne.query.QueryMetadata;
import org.apache.cayenne.query.QueryRouter;
import org.apache.cayenne.query.RefreshQuery;
import org.apache.cayenne.query.RelationshipQuery;
import org.apache.cayenne.reflect.ClassDescriptor;
import org.apache.cayenne.reflect.LifecycleCallbackRegistry;
import org.apache.cayenne.util.GenericResponse;
import org.apache.cayenne.util.ListResponse;
import org.apache.cayenne.util.Util;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.function.Function;

/**
 * Performs query routing and execution. During execution phase intercepts
 * callbacks to the OperationObserver, remapping results to the original
 * pre-routed queries.
 * 
 * @since 1.2
 */
class DataDomainQueryAction implements QueryRouter, OperationObserver {

    static final boolean DONE = true;

    final DataContext context;
    final DataDomain domain;
    final Query query;
    final QueryMetadata metadata;
    final AdhocObjectFactory objectFactory;

    DataRowStore cache;
    QueryResponse response;
    GenericResponse fullResponse;
    Map<String, List<?>> prefetchResultsByPath;
    Map<QueryEngine, Collection<Query>> queriesByNode;
    Map<Query, Query> queriesByExecutedQueries;
    boolean noObjectConversion;

    /*
     * A constructor for the "new" way of performing a query via 'execute' with
     * QueryResponse created internally.
     */
    DataDomainQueryAction(ObjectContext context, DataDomain domain, Query query) {
        if (context != null && !(context instanceof DataContext)) {
            throw new IllegalArgumentException("DataDomain can only work with DataContext. "
                    + "Unsupported context type: " + context);
        }

        this.domain = domain;
        this.query = query;
        this.metadata = query.getMetaData(domain.getEntityResolver());
        this.context = (DataContext) context;
        this.objectFactory = domain.getObjectFactory();

        // cache may be shared or unique for the ObjectContext
        if (context != null) {
            this.cache = this.context.getObjectStore().getDataRowCache();
        }

        if (this.cache == null) {
            this.cache = domain.getSharedSnapshotCache();
        }
    }

    QueryResponse execute() {

        // run chain...
        if (interceptOIDQuery() != DONE) {
            if (interceptRelationshipQuery() != DONE) {
                if (interceptRefreshQuery() != DONE) {
                    if (interceptSharedCache() != DONE) {
                        if (interceptDataDomainQuery() != DONE) {
                            runQueryInTransaction();
                        }
                    }
                }
            }
        }

        if (!noObjectConversion) {
            interceptObjectConversion();
        }

        return response;
    }

    private boolean interceptDataDomainQuery() {
        if (query instanceof DataDomainQuery) {
            response = new ListResponse(domain);
            return DONE;
        }

        return !DONE;
    }

    private boolean interceptOIDQuery() {
        if (query instanceof ObjectIdQuery) {

            ObjectIdQuery oidQuery = (ObjectIdQuery) query;
            ObjectId oid = oidQuery.getObjectId();

            // special handling of temp ids... Return an empty list immediately
            // so that
            // upstream code could throw FaultFailureException, etc. Don't
            // attempt to
            // translate and run the query. See for instance CAY-1651
            if (oid.isTemporary() && !oid.isReplacementIdAttached()) {
                response = new ListResponse();
                return DONE;
            }

            DataRow row = null;

			if (cache != null && !oidQuery.isFetchMandatory()) {
				row = polymorphicRowFromCache(oid);
			}

            // refresh is forced or not found in cache
            if (row == null) {

                if (oidQuery.isFetchAllowed()) {

                    runQueryInTransaction();
                } else {
                    response = new ListResponse();
                }
            } else {
                response = new ListResponse(row);
            }

            return DONE;
        }

        return !DONE;
    }
    
	private DataRow polymorphicRowFromCache(ObjectId superOid) {
		DataRow row = cache.getCachedSnapshot(superOid);
		if (row != null) {
			return row;
		}

		EntityInheritanceTree inheritanceTree = domain.getEntityResolver().getInheritanceTree(superOid.getEntityName());
		if (!inheritanceTree.getChildren().isEmpty()) {
			row = polymorphicRowFromCache(inheritanceTree, superOid);
		}

		return row;
	}
    
	private DataRow polymorphicRowFromCache(EntityInheritanceTree superNode, ObjectId superOid) {

		for (EntityInheritanceTree child : superNode.getChildren()) {
			ObjectId id = ObjectId.of(child.getEntity().getName(), superOid);
			DataRow row = cache.getCachedSnapshot(id);
			if (row != null) {
				return row;
			}
			
			row = polymorphicRowFromCache(child, superOid);
			if (row != null) {
				return row;
			}
		}

		return null;
	}

    private boolean interceptRelationshipQuery() {

        if (query instanceof RelationshipQuery) {

            RelationshipQuery relationshipQuery = (RelationshipQuery) query;
            if (relationshipQuery.isRefreshing()) {
                return !DONE;
            }

            ObjRelationship relationship = relationshipQuery.getRelationship(domain.getEntityResolver());

            // check if we can derive target PK from FK...
            if (relationship.isSourceIndependentFromTargetChange()) {
                return !DONE;
            }

            // we can assume that there is one and only one DbRelationship as
            // we previously checked that "!isSourceIndependentFromTargetChange"
            DbRelationship dbRelationship = relationship.getDbRelationships().get(0);

            // FK pointing to a unique field that is a 'fake' PK (CAY-1755)...
            // It is not sufficient to generate target ObjectId.
            DbEntity targetEntity = dbRelationship.getTargetEntity();
            if (dbRelationship.getJoins().size() < targetEntity.getPrimaryKeys().size()) {
                return !DONE;
            }

            if (cache == null) {
                return !DONE;
            }

            DataRow sourceRow = cache.getCachedSnapshot(relationshipQuery.getObjectId());
            if (sourceRow == null) {
                return !DONE;
            }

            ObjectId targetId = sourceRow.createTargetObjectId(relationship.getTargetEntityName(), dbRelationship);

            // null id means that FK is null...
            if (targetId == null) {
                this.response = new GenericResponse(Collections.EMPTY_LIST);
                return DONE;
            }

            // target id resolution (unlike source) should be polymorphic
            DataRow targetRow = polymorphicRowFromCache(targetId);

            if (targetRow != null) {
                this.response = new GenericResponse(Collections.singletonList(targetRow));
                return DONE;
            }

            // check whether a non-null FK is enough to assume non-null target,
            // and if so,
            // create a fault
            if (context != null && relationship.isSourceDefiningTargetPrecenseAndType(domain.getEntityResolver())) {

                // prevent passing partial snapshots to ObjectResolver per
                // CAY-724.
                // Create a hollow object right here and skip object conversion
                // downstream
                this.noObjectConversion = true;
                Object object = context.findOrCreateObject(targetId);

                this.response = new GenericResponse(Collections.singletonList(object));
                return DONE;
            }
        }

        return !DONE;
    }

    /**
     * @since 3.0
     */
    private boolean interceptRefreshQuery() {

        if (query instanceof RefreshQuery) {
            RefreshQuery refreshQuery = (RefreshQuery) query;

            if (refreshQuery.isRefreshAll()) {

                // not sending any events - peer contexts will not get refreshed
                if (domain.getSharedSnapshotCache() != null) {
                    domain.getSharedSnapshotCache().clear();
                } else {
                    // remove snapshots from local ObjectStore only
                    context.getObjectStore().getDataRowCache().clear();
                }
                context.getQueryCache().clear();

                GenericResponse response = new GenericResponse();
                response.addUpdateCount(1);
                this.response = response;
                return DONE;
            }

            @SuppressWarnings("unchecked")
            Collection<Persistent> objects = (Collection<Persistent>) refreshQuery.getObjects();
            if (objects != null && !objects.isEmpty()) {

                Collection<ObjectId> ids = new ArrayList<>(objects.size());
                for (final Persistent object : objects) {
                    ids.add(object.getObjectId());
                }

                if (domain.getSharedSnapshotCache() != null) {
                    // send an event for removed snapshots
                    domain.getSharedSnapshotCache().processSnapshotChanges(context.getObjectStore(),
                            Collections.emptyMap(), Collections.emptyList(), ids, Collections.emptyList());
                } else {
                    // remove snapshots from local ObjectStore only
                    context.getObjectStore()
                            .getDataRowCache()
                            .processSnapshotChanges(context.getObjectStore(), Collections.emptyMap(),
                                    Collections.emptyList(), ids, Collections.emptyList());
                }

                GenericResponse response = new GenericResponse();
                response.addUpdateCount(1);
                this.response = response;
                return DONE;
            }

            // 3. refresh query - this shouldn't normally happen as child
            // datacontext
            // usually does a cascading refresh
            if (refreshQuery.getQuery() != null) {
                Query cachedQuery = refreshQuery.getQuery();

                String cacheKey = cachedQuery.getMetaData(context.getEntityResolver()).getCacheKey();
                context.getQueryCache().remove(cacheKey);

                this.response = domain.onQuery(context, cachedQuery);
                return DONE;
            }

            // 4. refresh groups...
            if (refreshQuery.getGroupKeys() != null && refreshQuery.getGroupKeys().length > 0) {

                String[] groups = refreshQuery.getGroupKeys();
                for (String group : groups) {
                    domain.getQueryCache().removeGroup(group);
                }

                GenericResponse response = new GenericResponse();
                response.addUpdateCount(1);
                this.response = response;
                return DONE;
            }
        }

        return !DONE;
    }

    /*
     * Wraps execution in shared cache checks
     */
    private boolean interceptSharedCache() {

        if (metadata.getCacheKey() == null) {
            return !DONE;
        }

        boolean cache = QueryCacheStrategy.SHARED_CACHE == metadata.getCacheStrategy();
        boolean cacheOrCacheRefresh = cache || QueryCacheStrategy.SHARED_CACHE_REFRESH == metadata.getCacheStrategy();

        if (!cacheOrCacheRefresh) {
            return !DONE;
        }

        QueryCache queryCache = domain.getQueryCache();
        QueryCacheEntryFactory factory = getCacheObjectFactory();

        if (cache) {
            boolean wasResponseNull = (response == null);
            List cachedResults = queryCache.get(metadata, factory);

            // response may already be initialized by the factory above ... it
            // is null if
            // there was a preexisting cache entry
            if (response == null || wasResponseNull) {
                response = new ListResponse(cachedResults);
            }

            if (cachedResults instanceof ListWithPrefetches) {
                this.prefetchResultsByPath = ((ListWithPrefetches) cachedResults).getPrefetchResultsByPath();
            }
        } else {
            // on cache-refresh request, fetch without blocking and fill the
            // cache
            queryCache.put(metadata, factory.createObject());
        }

        return DONE;
    }

    private QueryCacheEntryFactory getCacheObjectFactory() {
        return () -> {
            runQueryInTransaction();

            List<?> list = response.firstList();
            if (list != null) {

                // make an immutable list to make sure callers don't mess it up
                list = Collections.unmodifiableList(list);

                // include prefetches in the cached result
                if (prefetchResultsByPath != null) {
                    list = new ListWithPrefetches(list, prefetchResultsByPath);
                }
            }

            return list;
        };
    }

    /*
     * Gets response from the underlying DataNodes.
     */
    void runQueryInTransaction() {
        domain.getTransactionManager().performInTransaction(() -> {
            runQuery();
            return null;
        });
    }

    private void runQuery() {
        // reset
        this.fullResponse = new GenericResponse();
        this.response = this.fullResponse;
        this.queriesByNode = null;
        this.queriesByExecutedQueries = null;

        // whether this is null or not will driver further decisions on how to process prefetched rows
        this.prefetchResultsByPath = metadata.getPrefetchTree() != null && !metadata.isFetchingDataRows()
                ? new HashMap<>() : null;

        // categorize queries by node and by "executable" query...
        query.route(this, domain.getEntityResolver(), null);

        // run categorized queries
        if (queriesByNode != null) {
            for (Map.Entry<QueryEngine, Collection<Query>> entry : queriesByNode.entrySet()) {
                QueryEngine nextNode = entry.getKey();
                Collection<Query> nodeQueries = entry.getValue();
                nextNode.performQueries(nodeQueries, this);
            }
        }
    }

    @SuppressWarnings("unchecked")
    private void interceptObjectConversion() {

        if (context != null) {
            List mainRows = response.firstList(); // List<DataRow> or List<Object[]>
            if (mainRows != null && !mainRows.isEmpty()) {

                ObjectConversionStrategy<?> converter;

                if(metadata.isFetchingDataRows()) {
                    converter = new IdentityConversionStrategy();
                } else {
                    List<Object> rsMapping = metadata.getResultSetMapping();
                    if (rsMapping == null) {
                        converter = new SingleObjectConversionStrategy();
                    } else {
                        if (metadata.isSingleResultSetMapping()) {
                            if (rsMapping.get(0) instanceof EntityResultSegment) {
                                converter = new SingleObjectConversionStrategy();
                        } else if(rsMapping.get(0) instanceof EmbeddableResultSegment) {
                            converter = new SingleEmbeddableConversionStrategy();
                            } else {
                                converter = new SingleScalarConversionStrategy();
                            }
                        } else {
                            converter = new MixedConversionStrategy();
                        }
                    }
                }

                if(metadata.getResultMapper() != null) {
                    converter = new MapperConversionStrategy(converter);
                }

                converter.convert(mainRows);
                // rewind response after firstList() call
                response.reset();
            }
        }
    }

    @Override
    public void route(QueryEngine engine, Query query, Query substitutedQuery) {

        Collection<Query> queries = null;
        if (queriesByNode == null) {
            queriesByNode = new HashMap<>();
        } else {
            queries = queriesByNode.get(engine);
        }

        if (queries == null) {
            queries = new ArrayList<>(5);
            queriesByNode.put(engine, queries);
        }

        queries.add(query);

        // handle case when routing resulted in an "executable" query different
        // from the
        // original query.
        if (substitutedQuery != null && substitutedQuery != query) {

            if (queriesByExecutedQueries == null) {
                queriesByExecutedQueries = new HashMap<>();
            }

            queriesByExecutedQueries.put(query, substitutedQuery);
        }
    }

    @Override
    public QueryEngine engineForDataMap(DataMap map) {
        if (map == null) {
            throw new NullPointerException("Null DataMap, can't determine DataNode.");
        }

        QueryEngine node = domain.lookupDataNode(map);

        if (node == null) {
            throw new CayenneRuntimeException("No DataNode exists for DataMap %s", map);
        }

        return node;
    }

    /**
     * @since 4.0
     */
    @Override
    public QueryEngine engineForName(String name) {

        QueryEngine node;

        if (name != null) {
            node = domain.getDataNode(name);
            if (node == null) {
                throw new CayenneRuntimeException("No DataNode exists for name %s", name);
            }
        } else {
            node = domain.getDefaultNode();
            if (node == null) {
                throw new CayenneRuntimeException("No default DataNode exists.");
            }
        }

        return node;
    }

    @Override
    public void nextCount(Query query, int resultCount) {
        fullResponse.addUpdateCount(resultCount);
    }

    @Override
    public void nextBatchCount(Query query, int[] resultCount) {
        fullResponse.addBatchUpdateCount(resultCount);
    }

    @Override
    public void nextRows(Query query, List<?> dataRows) {

        // exclude prefetched rows in the main result
        if (prefetchResultsByPath != null && query instanceof PrefetchSelectQuery) {
            PrefetchSelectQuery prefetchQuery = (PrefetchSelectQuery) query;
            prefetchResultsByPath.put(prefetchQuery.getPrefetchPath(), dataRows);
        } else {
            fullResponse.addResultList(dataRows);
        }
    }

    @Override
    public void nextRows(Query q, ResultIterator<?> it) {
        throw new CayenneRuntimeException("Invalid attempt to fetch a cursor.");
    }

    @Override
    public void nextGeneratedRows(Query query, ResultIterator<?> keys, List<ObjectId> idsToUpdate) {
        if (keys != null) {
            try {
                nextRows(query, keys.allRows());
            } finally {
                keys.close();
            }
        }
    }

    @Override
    public void nextQueryException(Query query, Exception ex) {
        throw new CayenneRuntimeException("Query exception.", Util.unwindException(ex));
    }

    @Override
    public void nextGlobalException(Exception e) {
        throw new CayenneRuntimeException("Global exception.", Util.unwindException(e));
    }

    @Override
    public boolean isIteratedResult() {
        return false;
    }

    abstract class ObjectConversionStrategy<T> {

        abstract void convert(List<T> mainRows);

        protected PrefetchProcessorNode toResultsTree(ClassDescriptor descriptor, PrefetchTreeNode prefetchTree,
                List<DataRow> normalizedRows) {

            // take a shortcut when no prefetches exist...
            if (prefetchTree == null) {
                return new ObjectResolver(context, descriptor, metadata.isRefreshingObjects())
                        .synchronizedRootResultNodeFromDataRows(normalizedRows);
            } else {
                HierarchicalObjectResolver resolver = new HierarchicalObjectResolver(context, metadata);
                return resolver.synchronizedRootResultNodeFromDataRows(prefetchTree, normalizedRows,
                        prefetchResultsByPath);
            }
        }

        protected void updateResponse(List sourceObjects, List targetObjects) {
            if (response instanceof GenericResponse) {
                ((GenericResponse) response).replaceResult(sourceObjects, targetObjects);
            } else if (response instanceof ListResponse) {
                response = new ListResponse(targetObjects);
            } else {
                throw new IllegalStateException("Unknown response object: " + response);
            }
        }

        protected void performPostLoadCallbacks(PrefetchProcessorNode node, LifecycleCallbackRegistry callbackRegistry) {

            if (node.hasChildren()) {
                for (PrefetchTreeNode child : node.getChildren()) {
                    performPostLoadCallbacks((PrefetchProcessorNode) child, callbackRegistry);
                }
            }

            List<Persistent> objects = node.getObjects();
            if (objects != null) {
                callbackRegistry.performCallbacks(LifecycleEvent.POST_LOAD, objects);
            }
        }
    }

    class SingleObjectConversionStrategy extends ObjectConversionStrategy<DataRow> {

        @Override
        void convert(List<DataRow> mainRows) {

            PrefetchTreeNode prefetchTree = metadata.getPrefetchTree();

            List<Object> rsMapping = metadata.getResultSetMapping();
            EntityResultSegment resultSegment = null;
            if(rsMapping != null && !rsMapping.isEmpty()) {
                resultSegment = (EntityResultSegment)rsMapping.get(0);
            }

            ClassDescriptor descriptor = resultSegment == null
                    ? metadata.getClassDescriptor()
                    : resultSegment.getClassDescriptor();

            PrefetchProcessorNode node = toResultsTree(descriptor, prefetchTree, mainRows);
            List<Persistent> objects = node.getObjects();
            updateResponse(mainRows, objects != null ? objects : new ArrayList<>(1));

            // apply POST_LOAD callback
            LifecycleCallbackRegistry callbackRegistry = context.getEntityResolver().getCallbackRegistry();

            if (!callbackRegistry.isEmpty(LifecycleEvent.POST_LOAD)) {
                performPostLoadCallbacks(node, callbackRegistry);
            }
        }
    }

    class SingleScalarConversionStrategy extends ObjectConversionStrategy<Object> {

        @Override
        void convert(List<Object> mainRows) {
            // noop... scalars require no further processing
        }
    }

    class SingleEmbeddableConversionStrategy extends ObjectConversionStrategy<DataRow> {

        @Override
        void convert(List<DataRow> mainRows) {
            EmbeddableResultSegment resultSegment = (EmbeddableResultSegment)metadata.getResultSetMapping().get(0);
            Embeddable embeddable = resultSegment.getEmbeddable();
            Class<?> embeddableClass = objectFactory.getJavaClass(embeddable.getClassName());
            List<EmbeddableObject> result = new ArrayList<>(mainRows.size());
            mainRows.forEach(dataRow -> {
                EmbeddableObject eo;
                try {
                    eo = (EmbeddableObject)embeddableClass.getDeclaredConstructor().newInstance();
                } catch (Exception e) {
                    throw new CayenneRuntimeException("Unable to materialize embeddable '%s'", e, embeddable.getClassName());
                }
                dataRow.forEach(eo::writePropertyDirectly);
                result.add(eo);
            });
            updateResponse(mainRows, result);
        }
    }

    class MixedConversionStrategy extends ObjectConversionStrategy<Object[]> {

        protected PrefetchProcessorNode toResultsTree(ClassDescriptor descriptor, PrefetchTreeNode prefetchTree,
                List<Object[]> rows, int position) {

            List<DataRow> rowsColumn = new ArrayList<>(rows.size());
            for (Object[] row : rows) {
                rowsColumn.add((DataRow) row[position]);
            }

            if (prefetchTree != null) {
                PrefetchTreeNode prefetchTreeNode = null;
                for (PrefetchTreeNode prefetch : prefetchTree.getChildren()) {
                    if (descriptor.getEntity().getName().equals(prefetch.getEntityName())) {
                        if (prefetchTreeNode == null) {
                            prefetchTreeNode = new PrefetchTreeNode();
                        }
                        PrefetchTreeNode addPath = prefetchTreeNode.addPath(prefetch.getPath());
                        addPath.setSemantics(prefetch.getSemantics());
                        addPath.setPhantom(false);
                    }
                }
                prefetchTree = prefetchTreeNode;
            }

            if (prefetchTree == null) {
                return new ObjectResolver(context, descriptor, metadata.isRefreshingObjects())
                        .synchronizedRootResultNodeFromDataRows(rowsColumn);
            } else {
                HierarchicalObjectResolver resolver = new HierarchicalObjectResolver(context, metadata, descriptor,
                        true);
                return resolver.synchronizedRootResultNodeFromDataRows(prefetchTree, rowsColumn, prefetchResultsByPath);
            }
        }

        @Override
        void convert(List<Object[]> mainRows) {

            int rowsLen = mainRows.size();

            List<Object> rsMapping = metadata.getResultSetMapping();
            int width = rsMapping.size();

            // no conversions needed for scalar positions;
            // reuse Object[]'s to fill them with resolved objects
            List<PrefetchProcessorNode> segmentNodes = new ArrayList<>(width);
            for (int i = 0; i < width; i++) {
                Object mapping = rsMapping.get(i);
                if (mapping instanceof EntityResultSegment) {
                    EntityResultSegment entitySegment = (EntityResultSegment) mapping;
                    PrefetchProcessorNode nextResult = toResultsTree(entitySegment.getClassDescriptor(),
                            metadata.getPrefetchTree(), mainRows, i);

                    segmentNodes.add(nextResult);

                    List<Persistent> objects = nextResult.getObjects();

                    for (int j = 0; j < rowsLen; j++) {
                        Object[] row = mainRows.get(j);
                        row[i] = objects.get(j);
                    }
                } else if (mapping instanceof EmbeddableResultSegment) {
                    EmbeddableResultSegment resultSegment = (EmbeddableResultSegment)mapping;
                    Embeddable embeddable = resultSegment.getEmbeddable();
                    Class<?> embeddableClass = objectFactory.getJavaClass(embeddable.getClassName());
                    try {
                        for(Object[] row : mainRows) {
                            DataRow dataRow = (DataRow)row[i];
                            EmbeddableObject eo = (EmbeddableObject)embeddableClass.getDeclaredConstructor().newInstance();
                            dataRow.forEach(eo::writePropertyDirectly);
                            row[i] = eo;
                        }
                    } catch (Exception e) {
                        throw new CayenneRuntimeException("Unable to materialize embeddable '%s'", e, embeddable.getClassName());
                    }
                }
            }

            if(!metadata.isSuppressingDistinct()) {
                Set<List<?>> seen = new HashSet<>(mainRows.size());
                mainRows.removeIf(objects -> !seen.add(Arrays.asList(objects)));
            }

            // invoke callbacks now that all objects are resolved...
            LifecycleCallbackRegistry callbackRegistry = context.getEntityResolver().getCallbackRegistry();

            if (!callbackRegistry.isEmpty(LifecycleEvent.POST_LOAD)) {
                for (PrefetchProcessorNode node : segmentNodes) {
                    performPostLoadCallbacks(node, callbackRegistry);
                }
            }
        }
    }

    private class IdentityConversionStrategy extends ObjectConversionStrategy<Object> {
        @Override
        void convert(List<Object> mainRows) {
        }
    }

    /**
     * Conversion strategy that uses mapper function to map raw result
     */
    private class MapperConversionStrategy extends ObjectConversionStrategy<Object> {

        private final Function<Object, ?> mapper;
        private final ObjectConversionStrategy<Object> parentStrategy;

        @SuppressWarnings({"unchecked", "rawtypes"})
        MapperConversionStrategy(ObjectConversionStrategy<?> parentStrategy) {
            this.mapper = (Function)metadata.getResultMapper();
            this.parentStrategy = (ObjectConversionStrategy)parentStrategy;
        }

        @Override
        void convert(List<Object> mainRows) {
            parentStrategy.convert(mainRows);
            mainRows.replaceAll(mapper::apply);
        }
    }

}
