package service;

import config.Config;
import java.io.IOException;
import java.nio.file.*;
import java.util.List;
import java.util.concurrent.TimeUnit;

public class WatchDirService {
  private WatchService watchService;
  private boolean notDone = true;

  public WatchDirService(String dirPath){
    init(dirPath);
  }

  private void init(String dirPath) {
    Path path = Paths.get(dirPath);
    try {
      watchService = FileSystems.getDefault().newWatchService(); //創建watchService
      path.register(watchService, 
      StandardWatchEventKinds.ENTRY_CREATE,
      StandardWatchEventKinds.ENTRY_MODIFY,
      StandardWatchEventKinds.ENTRY_DELETE); //注冊需要監控的事件,ENTRY_CREATE 文件創建,ENTRY_MODIFY 文件修改,ENTRY_MODIFY 文件刪除
    } catch (IOException e) {
      e.printStackTrace();
    }
  }

  public void start(){
    System.out.print("watch...");
    while (notDone){
      try {
        WatchKey watchKey = watchService.poll(Config.POLL_TIME_OUT, TimeUnit.SECONDS); //此處將處于等待狀態,等待檢測到文件夾下得文件發生改變,返回WatchKey對象
        if(watchKey != null){
          List<WatchEvent<&#63;>> events = watchKey.pollEvents(); //獲取所有得事件
          for (WatchEvent event : events){
            WatchEvent.Kind<&#63;> kind = event.kind(); 
            if (kind == StandardWatchEventKinds.OVERFLOW){
              //當前磁盤不可用
              continue;
            }
            WatchEvent<Path> ev = event;
            Path path = ev.context();
            if(kind == StandardWatchEventKinds.ENTRY_CREATE){
              System.out.println("create " + path.getFileName());
            }else if(kind == StandardWatchEventKinds.ENTRY_MODIFY){
              System.out.println("modify " + path.getFileName());
            }else if(kind == StandardWatchEventKinds.ENTRY_DELETE){
              System.out.println("delete " + path.getFileName());
            }
          }
          if(!watchKey.reset()){ 
            //已經關閉了進程
            System.out.println("exit watch server");
            break;
          }
        }
      } catch (InterruptedException e) {
        e.printStackTrace();
        return;
      }
    }
  }
}