/*
 *  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.tools.ant.util;

import java.util.Objects;
import java.util.stream.Stream;

A ContainerMapper that chains the results of the first
nested FileNameMappers into sourcefiles for the second,
the second to the third, and so on, returning the resulting mapped
filenames from the last nested FileNameMapper.
/**
 * A <code>ContainerMapper</code> that chains the results of the first
 * nested <code>FileNameMapper</code>s into sourcefiles for the second,
 * the second to the third, and so on, returning the resulting mapped
 * filenames from the last nested <code>FileNameMapper</code>.
 */
public class ChainedMapper extends ContainerMapper {

    
{@inheritDoc}. /** {@inheritDoc}. */
    @Override
    public String[] mapFileName(String sourceFileName) {
        // we invoke the chain even if the sourceFileName is null. Some
        // resources have a null name and users may use a mapper like
        // MergeMapper to provide a name for it.
        String[] result = getMappers().stream()
            .filter(Objects::nonNull)
            .reduce(new String[] { sourceFileName }, (i, m) -> Stream.of(i)
                .map(m::mapFileName).filter(Objects::nonNull).flatMap(Stream::of).toArray(String[]::new),
                (i, o) -> o);
        return result == null || result.length == 0 ? null : result;
    }
}