src/main/java/org/apache/maven/plugins/assembly/filter/SimpleAggregatingDescriptorHandler.java

/*
 * 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.maven.plugins.assembly.filter;

import javax.inject.Named;

import java.io.File;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.Reader;
import java.io.StringWriter;
import java.io.Writer;
import java.nio.charset.StandardCharsets;
import java.nio.file.Files;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Date;
import java.util.List;

import org.apache.commons.io.IOUtils;
import org.apache.maven.plugins.assembly.utils.AssemblyFileUtils;
import org.codehaus.plexus.archiver.Archiver;
import org.codehaus.plexus.archiver.ArchiverException;
import org.codehaus.plexus.archiver.UnArchiver;
import org.codehaus.plexus.components.io.fileselectors.FileInfo;

/**
 * <code>file-aggregator</code>: Generic aggregating handler, configured with filePattern and outputPath.
 */
@Named("file-aggregator")
public class SimpleAggregatingDescriptorHandler implements ContainerDescriptorHandler {
    // component configuration.

    @SuppressWarnings("FieldCanBeLocal")
    private final String commentChars = "#";

    private final StringWriter aggregateWriter = new StringWriter();

    private final List<String> filenames = new ArrayList<>();

    // calculated, temporary values.

    private String filePattern;

    private String outputPath;

    private boolean overrideFilterAction;

    @Override
    public void finalizeArchiveCreation(final Archiver archiver) {
        checkConfig();

        if (outputPath.endsWith("/")) {
            throw new ArchiverException("Cannot write aggregated properties to a directory. "
                    + "You must specify a file name in the outputPath configuration for this"
                    + " handler. (handler: " + getClass().getName());
        }

        if (outputPath.startsWith("/")) {
            outputPath = outputPath.substring(1);
        }

        final File temp = writePropertiesFile();

        overrideFilterAction = true;

        archiver.addFile(temp, outputPath);

        overrideFilterAction = false;
    }

    private File writePropertiesFile() {
        File f;
        try {
            f = Files.createTempFile("maven-assembly-plugin", "tmp").toFile();
            f.deleteOnExit();

            try (Writer writer = getWriter(f)) {
                writer.write(commentChars + " Aggregated on " + new Date() + " from: ");

                for (final String filename : filenames) {
                    writer.write("\n" + commentChars + " " + filename);
                }

                writer.write("\n\n");
                writer.write(aggregateWriter.toString());
            }
        } catch (final IOException e) {
            throw new ArchiverException(
                    "Error adding aggregated properties to finalize archive creation. Reason: " + e.getMessage(), e);
        }

        return f;
    }

    private Writer getWriter(File f) throws IOException {
        Writer writer;
        writer = AssemblyFileUtils.isPropertyFile(f)
                ? new OutputStreamWriter(Files.newOutputStream(f.toPath()), StandardCharsets.ISO_8859_1)
                : new OutputStreamWriter(Files.newOutputStream(f.toPath())); // Still platform encoding
        return writer;
    }

    @Override
    public void finalizeArchiveExtraction(final UnArchiver unarchiver) {}

    @Override
    public List<String> getVirtualFiles() {
        checkConfig();

        return Collections.singletonList(outputPath);
    }

    @Override
    public boolean isSelected(final FileInfo fileInfo) throws IOException {
        checkConfig();

        if (overrideFilterAction) {
            return true;
        }

        String name = AssemblyFileUtils.normalizeFileInfo(fileInfo);

        if (fileInfo.isFile() && name.matches(filePattern)) {
            readProperties(fileInfo);
            filenames.add(name);

            return false;
        }

        return true;
    }

    private void checkConfig() {
        if (filePattern == null || outputPath == null) {
            throw new IllegalStateException(
                    "You must configure filePattern and outputPath in your containerDescriptorHandler declaration.");
        }
    }

    private void readProperties(final FileInfo fileInfo) throws IOException {
        try (StringWriter writer = new StringWriter();
                Reader reader = AssemblyFileUtils.isPropertyFile(fileInfo.getName())
                        ? new InputStreamReader(fileInfo.getContents(), StandardCharsets.ISO_8859_1)
                        : new InputStreamReader(fileInfo.getContents())) // platform encoding
        {
            IOUtils.copy(reader, writer);
            final String content = writer.toString();
            aggregateWriter.write("\n");
            aggregateWriter.write(content);
        }
    }

    @SuppressWarnings("UnusedDeclaration")
    public String getFilePattern() {
        return filePattern;
    }

    @SuppressWarnings("UnusedDeclaration")
    public void setFilePattern(final String filePattern) {
        this.filePattern = filePattern;
    }

    @SuppressWarnings("UnusedDeclaration")
    public String getOutputPath() {
        return outputPath;
    }

    @SuppressWarnings("UnusedDeclaration")
    public void setOutputPath(final String outputPath) {
        this.outputPath = outputPath;
    }
}