/*

 * This file is part of libbluray

 * Copyright (C) 2014  Petri Hintukainen <phintuka@users.sourceforge.net>

 *

 * This library is free software; you can redistribute it and/or

 * modify it under the terms of the GNU Lesser General Public

 * License as published by the Free Software Foundation; either

 * version 2.1 of the License, or (at your option) any later version.

 *

 * This library 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

 * Lesser General Public License for more details.

 *

 * You should have received a copy of the GNU Lesser General Public

 * License along with this library. If not, see

 * <http://www.gnu.org/licenses/>.

 */

package org.videolan;

import java.io.IOException;

import java.io.RandomAccessFile;

class LockFile {

    private LockFile(RandomAccessFile lockFile) {

        this.lockFile = lockFile;

    }

    public static LockFile create(String path) {

        RandomAccessFile os = null;

        try {

            os = new RandomAccessFile(path, "rw");

            if (os.getChannel().tryLock() != null) {

                /* Test if locking works: second tryLock() should fail */

                try {

                    if (os.getChannel().tryLock() != null) {

                        try {

                            os.close();

                        } catch (Exception e) {

                        }

                        logger.error("File locking is unreliable !");

                        return null;

                    }

                } catch (Exception e) {

                }

                return new LockFile(os);

            } else {

                os.close();

                logger.info("Failed locking " + path);

            }

        } catch (Exception e) {

            if (os != null) {

                try {

                    os.close();

                } catch (IOException e1) {

                    e1.printStackTrace();

                }

            }

            logger.error("Failed creating lock file: " + e);

        }

        return null;

    }

    public void release() {

        try {

            if (lockFile != null) {

                lockFile.close();

            }

        } catch (Exception e) {

        }

    }

    private RandomAccessFile lockFile;

    private static final Logger logger = Logger.getLogger(LockFile.class.getName());

}