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/*
 * 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.mysema.query.jpa;

import javax.persistence.Entity;

import com.mysema.query.support.CollectionAnyVisitor;
import com.mysema.query.support.Context;
import com.mysema.query.types.*;
import com.mysema.query.types.path.EntityPathBase;
import com.mysema.query.types.path.ListPath;
import com.mysema.query.types.path.SimplePath;

/**
 * JPACollectionAnyVisitor extends the {@link CollectionAnyVisitor} class with module specific
 * extensions
 *
 * @author tiwe
 *
 */
public final class JPACollectionAnyVisitor extends CollectionAnyVisitor {

    public static final JPACollectionAnyVisitor DEFAULT = new JPACollectionAnyVisitor();

    @SuppressWarnings("unchecked")
    @Override
    protected Predicate exists(Context c, Predicate condition) {
        JPASubQuery query = new JPASubQuery();
        for (int i = 0; i < c.paths.size(); i++) {
            Path child = c.paths.get(i).getMetadata().getParent();
            EntityPath replacement = (EntityPath) c.replacements.get(i);
            if (c.paths.get(i).getType().isAnnotationPresent(Entity.class)) {
                if (i == 0) {
                    query.from(new ListPath(c.paths.get(i).getType(), SimplePath.class, child.getMetadata()), replacement);
                } else {
                    query.innerJoin(new ListPath(c.paths.get(i).getType(), SimplePath.class, child.getMetadata()), replacement);
                }
            } else {
                // join via parent
                Path parent = child.getMetadata().getParent();
                EntityPathBase newParent = new EntityPathBase(parent.getType(),
                        ExpressionUtils.createRootVariable(parent));
                EntityPath newChild = new EntityPathBase(child.getType(),
                        PathMetadataFactory.forProperty(newParent, child.getMetadata().getName()));
                query.from(newParent).innerJoin(newChild, replacement);
                query.where(ExpressionUtils.eq(newParent, parent));
            }
        }
        c.clear();
        query.where(condition);
        return query.exists();
    }

    private JPACollectionAnyVisitor() {}

}