/*
 *  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
 *
 *      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 org.apache.tools.ant.util;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Iterator;
import java.util.List;

/**
 * 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}. */
    public String[] mapFileName(String sourceFileName) {
        List inputs = new ArrayList();
        List results = new ArrayList();
        // we do this 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.
        results.add(sourceFileName);
        FileNameMapper mapper = null;

        for (Iterator mIter = getMappers().iterator(); mIter.hasNext();) {
            mapper = (FileNameMapper) (mIter.next());
            if (mapper != null) {
                inputs.clear();
                inputs.addAll(results);
                results.clear();

                for (Iterator it = inputs.iterator(); it.hasNext();) {
                    String[] mapped = mapper.mapFileName((String) (it.next()));
                    if (mapped != null) {
                        results.addAll(Arrays.asList(mapped));
                    }
                }
            }
        }
        return (results.size() == 0) ? null
            : (String[]) results.toArray(new String[results.size()]);
    }
}

