/*
 * Copyright 2015, The Querydsl Team (http://www.querydsl.com/team)
 *
 * Licensed 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
 * http://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 com.querydsl.jpa;

import java.io.Closeable;
import java.io.IOException;
import java.util.Iterator;

import javax.persistence.Query;

import org.eclipse.persistence.config.QueryHints;
import org.eclipse.persistence.config.ResultSetType;
import org.eclipse.persistence.jpa.JpaQuery;
import org.eclipse.persistence.queries.Cursor;

import com.mysema.commons.lang.CloseableIterator;
import com.mysema.commons.lang.IteratorAdapter;
import com.querydsl.core.types.FactoryExpression;

/**
 * {@code EclipseLinkHandler} is the {@link QueryHandler} implementation for EclipseLink
 *
 * @author tiwe
 *
 */
class EclipseLinkHandler implements QueryHandler {

    @Override
    public void addEntity(Query query, String alias, Class<?> type) {
        // do nothing
    }

    @Override
    public void addScalar(Query query, String alias, Class<?> type) {
        // do nothing
    }

    @Override
    public boolean createNativeQueryTyped() {
        return true;
    }

    @SuppressWarnings("unchecked")
    @Override
    public <T> CloseableIterator<T> iterate(Query query, FactoryExpression<?> projection) {
        Iterator<T> iterator = null;
        Closeable closeable = null;
        if (query instanceof JpaQuery) {
            JpaQuery<T> elQuery = (JpaQuery<T>) query;
            elQuery.setHint(QueryHints.RESULT_SET_TYPE, ResultSetType.ForwardOnly);
            elQuery.setHint(QueryHints.SCROLLABLE_CURSOR, true);
            final Cursor cursor = elQuery.getResultCursor();
            closeable = new Closeable() {
                @Override
                public void close() throws IOException {
                    cursor.close();
                }
            };
            iterator = cursor;
        } else {
            iterator = query.getResultList().iterator();
        }
        if (projection != null) {
            return new TransformingIterator<T>(iterator, closeable, projection);
        } else {
            return new IteratorAdapter<T>(iterator, closeable);
        }
    }

    @Override
    public boolean transform(Query query, FactoryExpression<?> projection) {
        return false;
    }

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

}

@@ -721,24 +721,71 @@
 .Iterator;%0A%0A
+import javax.persistence.PersistenceException;%0A
 import javax
@@ -843,25 +843,25 @@
 .config.
-QueryHint
+HintValue
 s;%0Aimpor
@@ -893,29 +893,26 @@
 .config.
-ResultSetType
+QueryHints
 ;%0Aimport
@@ -1785,90 +1785,104 @@
     
-Iterator%3CT%3E iterator = null;%0A        Closeable closeable = null;%0A        if (query
+boolean canUseCursor = false;%0A        try %7B%0A            canUseCursor = query.unwrap(Query.class)
  ins
@@ -1897,19 +1897,17 @@
 JpaQuery
-) %7B
+;
 %0A       
@@ -1911,138 +1911,188 @@
     
-    JpaQuery%3CT%3E elQuery = (JpaQuery%3CT%3E) query;%0A            elQuery.setHint(QueryHints.RESULT_SET_TYPE, ResultSetType.ForwardOnly);
+%7D catch (PersistenceException e) %7B%7D // can't unwrap, just ignore the exception%0A%0A        Iterator%3CT%3E iterator = null;%0A        Closeable closeable = null;%0A        if (canUseCursor) %7B
 %0A   
@@ -2100,19 +2100,17 @@
         
-elQ
+q
 uery.set
@@ -2129,31 +2129,31 @@
 nts.
-SCROLLABLE_CURSOR, true
+CURSOR, HintValues.TRUE
 );%0A 
@@ -2189,31 +2189,93 @@
 r = 
-elQuery.getResultCursor
+(Cursor) query.getSingleResult();%0A            final int pageSize = cursor.getPageSize
 ();%0A
@@ -2491,22 +2491,545 @@
 rator = 
-cursor
+new Iterator%3CT%3E() %7B%0A                private int rowsSinceLastClear = 0;%0A                %0A                @Override%0A                public boolean hasNext() %7B%0A                    return cursor.hasNext();%0A                %7D%0A%0A                @Override%0A                public T next() %7B%0A                    if (rowsSinceLastClear++ == pageSize) %7B%0A                        rowsSinceLastClear = 0;%0A                        cursor.clear();%0A                    %7D%0A                    return (T) cursor.next();%0A                %7D%0A            %7D
 ;%0A      

Fix bugs when using a cursor with EclipseLink: