/*
 * Copyright (c) 2014, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
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 */
package jdk.internal.jrtfs;

import java.nio.file.DirectoryStream;
import java.nio.file.ClosedDirectoryStreamException;
import java.nio.file.DirectoryIteratorException;
import java.nio.file.NotDirectoryException;
import java.nio.file.Path;
import java.util.Iterator;
import java.util.Objects;
import java.util.NoSuchElementException;
import java.io.IOException;

/**
 * DirectoryStream implementation for jrt file system implementations.
 *
 * @implNote This class needs to maintain JDK 8 source compatibility.
 *
 * It is used internally in the JDK to implement jimage/jrtfs access,
 * but also compiled and delivered as part of the jrtfs.jar to support access
 * to the jimage file provided by the shipped JDK by tools running on JDK 8.
 */
final class JrtDirectoryStream implements DirectoryStream<Path> {

    private final JrtPath dir;
    private final DirectoryStream.Filter<? super Path> filter;
    private volatile boolean isClosed;
    private volatile Iterator<Path> itr;

    JrtDirectoryStream(JrtPath dir,
            DirectoryStream.Filter<? super java.nio.file.Path> filter)
            throws IOException
    {
        this.dir = dir;
        if (!dir.jrtfs.isDirectory(dir, true)) {  // sanity check
            throw new NotDirectoryException(dir.toString());
        }
        this.filter = filter;
    }

    @Override
    public synchronized Iterator<Path> iterator() {
        if (isClosed)
            throw new ClosedDirectoryStreamException();
        if (itr != null)
            throw new IllegalStateException("Iterator has already been returned");
        try {
            itr = dir.jrtfs.iteratorOf(dir, filter);
        } catch (IOException e) {
            throw new IllegalStateException(e);
        }
        return new Iterator<Path>() {
            private Path next;
            @Override
            public synchronized boolean hasNext() {
                if (isClosed)
                    return false;
                return itr.hasNext();
            }

            @Override
            public synchronized Path next() {
                if (isClosed)
                    throw new NoSuchElementException();
                return itr.next();
            }

            @Override
            public void remove() {
                throw new UnsupportedOperationException();
            }
        };
    }

    @Override
    public synchronized void close() throws IOException {
        isClosed = true;
    }
}