/*
 * Copyright (c) 2016 Cisco Systems, Inc. and others.  All rights reserved.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v1.0 which accompanies this distribution,
 * and is available at http://www.eclipse.org/legal/epl-v10.html
 */

package org.opendaylight.protocol.bgp.config.loader.impl;

import static java.nio.file.StandardWatchEventKinds.ENTRY_CREATE;
import static java.nio.file.StandardWatchEventKinds.OVERFLOW;

import java.io.File;
import java.io.IOException;
import java.nio.file.FileSystems;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.nio.file.WatchService;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public final class BGPFileWatcher implements FileWatcher, AutoCloseable {
    private static final Logger LOG = LoggerFactory.getLogger(BGPFileWatcher.class);
    private static final String INTERRUPTED = "InterruptedException";
    private static final String DEFAULT_APP_CONFIG_FILE_PATH = "etc" + File.separator + "opendaylight" + File.separator + "bgp";
    private static final Path PATH = Paths.get(DEFAULT_APP_CONFIG_FILE_PATH);
    private final WatchService watchService;

    public BGPFileWatcher() throws IOException {
        this.watchService = FileSystems.getDefault().newWatchService();
        Runtime.getRuntime().addShutdownHook(new Thread() {
            @Override
            public void run() {
                try {
                    BGPFileWatcher.this.watchService.close();
                } catch (final IOException e) {
                    LOG.warn(INTERRUPTED, e);
                }
            }
        });
        PATH.register(this.watchService, OVERFLOW, ENTRY_CREATE);
    }

    @Override
    public String getPathFile() {
        return DEFAULT_APP_CONFIG_FILE_PATH;
    }

    @Override
    public WatchService getWatchService() {
        return this.watchService;
    }

    @Override
    public synchronized void close() throws Exception {
        if (this.watchService != null) {
            this.watchService.close();
        }
    }
}