/*
 * Licensed to CRATE Technology GmbH ("Crate") under one or more contributor
 * license agreements.  See the NOTICE file distributed with this work for
 * additional information regarding copyright ownership.  Crate 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
 *
 *     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.
 *
 * However, if you have executed another commercial license agreement
 * with Crate these terms will supersede the license and you may use the
 * software solely pursuant to the terms of the relevant commercial agreement.
 */

package io.crate.executor.transport.task.elasticsearch;

import com.google.common.base.Function;
import io.crate.metadata.Scalar;
import io.crate.data.Input;

import java.util.List;

public class FunctionExtractor<T> implements Function<T, Object> {

    private final Scalar scalar;
    private final List<Function<T, Object>> subExtractors;

    public FunctionExtractor(Scalar scalar, List<Function<T, Object>> subExtractors) {
        this.scalar = scalar;
        this.subExtractors = subExtractors;
    }

    @Override
    public Object apply(final T response) {
        Input[] inputs = new Input[subExtractors.size()];
        int idx = 0;
        for (final Function<T, Object> subExtractor : subExtractors) {
            inputs[idx] = new Input() {
                @Override
                public Object value() {
                    return subExtractor.apply(response);
                }
            };
            idx++;
        }
        //noinspection unchecked
        return scalar.evaluate(inputs);
    }
}