/*

 * Copyright 2008-2009 Sun Microsystems, Inc.  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.  Sun designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

 * CA 95054 USA or visit www.sun.com if you need additional information or

 * have any questions.

 */

package sun.nio.fs;

import java.nio.file.*;

import java.util.Iterator;

import java.util.ConcurrentModificationException;

import java.util.NoSuchElementException;

import java.io.IOException;

import static sun.nio.fs.WindowsNativeDispatcher.*;

import static sun.nio.fs.WindowsConstants.*;

/**

 * Windows implementation of DirectoryStream

 */

class WindowsDirectoryStream

    implements DirectoryStream<Path>

{

    private final WindowsPath dir;

    private final DirectoryStream.Filter<? super Path> filter;

    // handle to directory

    private final long handle;

    // first entry in the directory

    private final String firstName;

    private final Object closeLock = new Object();

    // need closeLock to access these

    private boolean isOpen = true;

    private Iterator<Path> iterator;

    WindowsDirectoryStream(WindowsPath dir, DirectoryStream.Filter<? super Path> filter)

        throws IOException

    {

        this.dir = dir;

        this.filter = filter;

        try {

            // Need to append * or \* to match entries in directory.

            String search = dir.getPathForWin32Calls();

            char last = search.charAt(search.length() -1);

            if (last == ':' || last == '\\') {

                search += "*";

            } else {

                search += "\\*";

            }

            FirstFile first = FindFirstFile(search);

            this.handle = first.handle();

            this.firstName = first.name();

        } catch (WindowsException x) {

            if (x.lastError() == ERROR_DIRECTORY) {

                throw new NotDirectoryException(dir.getPathForExceptionMessage());

            }

            x.rethrowAsIOException(dir);

            // keep compiler happy

            throw new AssertionError();

        }

    }

    @Override

    public void close()

        throws IOException

    {

        synchronized (closeLock) {

            if (!isOpen)

                return;

            isOpen = false;

        }

        try {

            FindClose(handle);

        } catch (WindowsException x) {

            x.rethrowAsIOException(dir);

        }

    }

    @Override

    public Iterator<Path> iterator() {

        if (!isOpen) {

            throw new IllegalStateException("Directory stream is closed");

        }

        synchronized (this) {

            if (iterator != null)

                throw new IllegalStateException("Iterator already obtained");

            iterator = new WindowsDirectoryIterator(firstName);

            return iterator;

        }

    }

    private static void throwAsConcurrentModificationException(Throwable t) {

        ConcurrentModificationException cme = new ConcurrentModificationException();

        cme.initCause(t);

        throw cme;

    }

    private class WindowsDirectoryIterator implements Iterator<Path> {

        private boolean atEof;

        private String first;

        private Path nextEntry;

        private Path prevEntry;

        WindowsDirectoryIterator(String first) {

            atEof = false;

            this.first = first;

        }

        // applies filter and also ignores "." and ".."

        private Path acceptEntry(String s) {

            if (s.equals(".") || s.equals(".."))

                return null;

            Path entry = WindowsPath

                .createFromNormalizedPath(dir.getFileSystem(), dir + "\\" + s);

            if (filter.accept(entry)) {

                return entry;

            } else {

                return null;

            }

        }

        // reads next directory entry

        private Path readNextEntry() {

            // handle first element returned by search

            if (first != null) {

                nextEntry = acceptEntry(first);

                first = null;

                if (nextEntry != null)

                    return nextEntry;

            }

            String name = null;

            for (;;) {

                // synchronize on closeLock to prevent close while reading

                synchronized (closeLock) {

                    if (!isOpen)

                        throwAsConcurrentModificationException(new

                            IllegalStateException("Directory stream is closed"));

                    try {

                        name = FindNextFile(handle);

                    } catch (WindowsException x) {

                        try {

                            x.rethrowAsIOException(dir);

                        } catch (IOException ioe) {

                            throwAsConcurrentModificationException(ioe);

                        }

                    }

                }

                // EOF

                if (name == null)

                    return null;

                Path entry = acceptEntry(name);

                if (entry != null)

                    return entry;

            }

        }

        @Override

        public synchronized boolean hasNext() {

            if (nextEntry == null && !atEof) {

                nextEntry = readNextEntry();

                atEof = (nextEntry == null);

            }

            return nextEntry != null;

        }

        @Override

        public synchronized Path next() {

            if (nextEntry == null) {

                if (!atEof) {

                    nextEntry = readNextEntry();

                }

                if (nextEntry == null) {

                    atEof = true;

                    throw new NoSuchElementException();

                }

            }

            prevEntry = nextEntry;

            nextEntry = null;

            return prevEntry;

        }

        @Override

        public void remove() {

            if (!isOpen) {

                throw new IllegalStateException("Directory stream is closed");

            }

            Path entry;

            synchronized (this) {

                if (prevEntry == null)

                    throw new IllegalStateException("no last element");

                entry = prevEntry;

                prevEntry = null;

            }

            try {

                entry.delete(true);

            } catch (IOException ioe) {

                throwAsConcurrentModificationException(ioe);

            } catch (SecurityException se) {

                throwAsConcurrentModificationException(se);

            }

        }

    }

}