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Utility classes for Jetty
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//
// ========================================================================
// Copyright (c) 1995 Mort Bay Consulting Pty Ltd and others.
//
// This program and the accompanying materials are made available under the
// terms of the Eclipse Public License v. 2.0 which is available at
// https://www.eclipse.org/legal/epl-2.0, or the Apache License, Version 2.0
// which is available at https://www.apache.org/licenses/LICENSE-2.0.
//
// SPDX-License-Identifier: EPL-2.0 OR Apache-2.0
// ========================================================================
//

package org.eclipse.jetty.util;

import java.io.Closeable;
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.util.Objects;
import java.util.stream.Stream;

import org.eclipse.jetty.util.resource.Resource;
import org.eclipse.jetty.util.resource.ResourceFactory;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * Utility class to handle a Multi Release Jar file
 */
public class MultiReleaseJarFile implements Closeable
{
    private static final Logger LOG = LoggerFactory.getLogger(MultiReleaseJarFile.class);

    private final Path jarFile;
    private final Resource jarResource;
    private final ResourceFactory.Closeable resourceFactory;

    /**
     * Construct a multi release jar file for the current JVM version, ignoring directories.
     *
     * @param jarFile The file to open
     */
    public MultiReleaseJarFile(Path jarFile)
    {
        Objects.requireNonNull(jarFile, "Jar File");

        if (!Files.exists(jarFile))
            throw new IllegalArgumentException("File does not exist: " + jarFile);

        if (!Files.isRegularFile(jarFile))
            throw new IllegalArgumentException("Not a file: " + jarFile);

        if (!FileID.isJavaArchive(jarFile))
            throw new IllegalArgumentException("Not a Jar: " + jarFile);

        if (!Files.isReadable(jarFile))
            throw new IllegalArgumentException("Unable to read Jar file: " + jarFile);

        this.jarFile = jarFile;

        this.resourceFactory = ResourceFactory.closeable();
        this.jarResource = resourceFactory.newJarFileResource(jarFile.toUri());
        if (LOG.isDebugEnabled())
            LOG.debug("mounting {}", jarResource);
    }

    /**
     * @return A stream of versioned entries from the jar, excluding {@code META-INF/versions} entries.
     */
    @SuppressWarnings("resource")
    public Stream stream() throws IOException
    {
        Path rootPath = this.jarResource.getPath();

        return Files.walk(rootPath)
            // skip the entire META-INF/versions tree
            .filter(FileID::isNotMetaInfVersions);
    }

    @Override
    public void close() throws IOException
    {
        if (LOG.isDebugEnabled())
            LOG.debug("Closing {}", jarResource);
        this.resourceFactory.close();
    }

    @Override
    public String toString()
    {
        return jarFile.toString();
    }
}