package main

// https://medium.com/@skdomino/watch-this-file-watching-in-go-5b5a247cf71f

import (
	"fmt"
	"os"
	"path/filepath"

	"github.com/fsnotify/fsnotify"
	"time"
)

//
var watcher *fsnotify.Watcher

// main
func main() {
	var err error

	// creates a new file watcher
	watcher, err = fsnotify.NewWatcher()
	if err != nil {
		panic(err)
	}
	defer watcher.Close()

	rootPath := os.Getenv("RP")
	if rootPath == "" {
		panic("rootpath is null, please pass RP=..., even if it's just RP=.")
	}

	filePath := os.Getenv("FP")
	if filePath == "" {
		panic("FP is null, please pass FP=....")
	}

	// starting at the root of the project, walk each file/directory searching for
	// directories
	if err := filepath.Walk(rootPath, watchDir); err != nil {
		fmt.Println("ERROR", err)
		panic(err)
	}

	//
	done := make(chan bool)

	//
	go func() {
		for {
			select {
			// watch for events
			case event := <-watcher.Events:
				fmt.Printf("%s EVENT! %#v\n", time.Now().String(), event)

				// watch for errors
			case err := <-watcher.Errors:
				fmt.Printf("%s ERROR %s\n", time.Now().String(), err.Error())
			}
		}
	}()

	<-done
}

// watchDir gets run as a walk func, searching for directories to add watchers to
func watchDir(path string, fi os.FileInfo, err error) error {

	// since fsnotify can watch all the files in a directory, watchers only need
	// to be added to each nested directory
	if fi != nil && fi.Mode().IsDir() {
		return watcher.Add(path)
	}

	return nil
}