package main

import (
        "os"
	"log"

	"github.com/fsnotify/fsnotify"
        "gopkg.in/natefinch/lumberjack.v2"
)

func main() {
	myFile := "/var/log/x.log"
	file := &lumberjack.Logger{
		Filename: myFile,
	}
        file.Write([]byte{})
        file.Close()
	watcher, err := fsnotify.NewWatcher()
	if err != nil {
		log.Println(err)
	}
	defer watcher.Close()

	done := make(chan bool)
	go func() {
		for {
			select {
			case event, ok := <-watcher.Events:
                                log.Println("ok:", ok)
				if !ok {
					return
				}
				log.Println("event:", event)
                                if event.Op&fsnotify.Chmod == fsnotify.Chmod {
					file.Close()
				} else if event.Op&fsnotify.Rename == fsnotify.Rename || event.Op&fsnotify.Remove == fsnotify.Remove {
					file.Write([]byte{})
					log.Println("modified file:", event.Name)
					if err := watcher.Add(event.Name); err != nil {
						log.Println("Unable to watch file: ", event.Name, " ", err)
						os.Exit(1)
					}
					log.Println("started watching file: ", event.Name)
				}
			case err, ok := <-watcher.Errors:
                                log.Println("err ok:", ok)
				if !ok {
					return
				}
				log.Println("error:", err)
			}
		}
	}()

	err = watcher.Add(myFile)
	if err != nil {
		log.Println(err)
	}
	<-done
}