/**
 * 
 */

import java.io.IOException;
import java.nio.file.FileSystems;
import java.nio.file.Paths;
import java.nio.file.StandardWatchEventKinds;
import java.nio.file.WatchEvent;
import java.nio.file.WatchKey;
import java.nio.file.WatchService;
import java.util.Objects;
import java.util.Properties;

import org.springframework.core.io.ClassPathResource;
import org.springframework.core.io.Resource;
import org.springframework.core.io.support.PropertiesLoaderUtils;

/**
 * @description 
 * @author Abel.li
 * @version 
 */
public class PropertiesUtil {

	private static Properties properties;
	
	static {
		try {
			final WatchService watchService = FileSystems.getDefault().newWatchService();
			final String fileName = "abel.properties";
			final Resource resource = new ClassPathResource(fileName);
			Paths.get(resource.getFile().getParent()).register(watchService, 
					StandardWatchEventKinds.ENTRY_MODIFY,
					StandardWatchEventKinds.ENTRY_DELETE,
					StandardWatchEventKinds.ENTRY_CREATE);
			properties = PropertiesLoaderUtils.loadProperties(resource);
			
			Thread watchThread = new Thread(new Runnable() {
				public void run() {
					while(true){
						try {
							WatchKey watchKey = watchService.take();
							watchLoop:for(WatchEvent<?> event : watchKey.pollEvents()){
								if(Objects.equals(event.context().toString(), fileName)){
									properties = PropertiesLoaderUtils.loadProperties(resource);
									break watchLoop;
								}
							}
						} catch (Exception e) {
							e.printStackTrace();
						}
					}
				}
			});
			watchThread.setDaemon(true);
			watchThread.start();
			
			Runtime.getRuntime().addShutdownHook(new Thread(new Runnable() {
				public void run() {
					try {
						watchService.close();
					} catch (IOException e) {
						e.printStackTrace();
					}
				}
			}));
		} catch (Exception e) {
			e.printStackTrace();
		}
	}
	
	public static String getValue(String key){
		return properties.getProperty(key);
	}
}