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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.querydsl.sql;

import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;

import com.querydsl.core.types.*;
import com.querydsl.core.util.ArrayUtils;
import com.querydsl.core.util.CollectionUtils;

/**
 * Expression used to project a list of beans
 *
 * @author luis
 */
public class QBeans extends FactoryExpressionBase {

    private static final long serialVersionUID = -4411839816134215923L;

    private final Map, QBean> qBeans;

    private final List> expressions;

    @SuppressWarnings("unchecked")
    public QBeans(RelationalPath... beanPaths) {
        super(Beans.class);
        try {
            final List> listBuilder = new ArrayList<>();
            final Map, QBean> mapBuilder = new HashMap<>();
            for (RelationalPath path : beanPaths) {
                Map> bindings = new LinkedHashMap>();
                for (Path column : path.getColumns()) {
                    bindings.put(column.getMetadata().getName(), column);
                    listBuilder.add(column);
                }
                mapBuilder.put(path, Projections.bean((Class) path.getType(), bindings));
            }
            expressions = CollectionUtils.unmodifiableList(listBuilder);
            qBeans = Collections.unmodifiableMap(mapBuilder);
        } catch (Exception e) {
            throw new IllegalStateException(e);
        }
    }

    @Override
    public  R accept(Visitor v, C context) {
        return v.visit(this, context);
    }

    @Override
    public List> getArgs() {
        return expressions;
    }

    @Override
    public Beans newInstance(Object... args) {
        int offset = 0;
        Map, Object> beans = new HashMap, Object>();
        for (Map.Entry, QBean> entry : qBeans.entrySet()) {
            RelationalPath path = entry.getKey();
            QBean qBean = entry.getValue();
            int argsSize = qBean.getArgs().size();
            Object[] subArgs = ArrayUtils.subarray(args, offset, offset + argsSize);
            beans.put(path, qBean.newInstance(subArgs));
            offset += argsSize;
        }
        return new Beans(beans);
    }

}