package main

import (
	"errors"
	"flag"
	"fmt"
	"log"
	"os"
	"os/signal"
	"path/filepath"
	"time"

	"git.trj.tw/golang/go-watch-webp/module/config"
	"git.trj.tw/golang/go-watch-webp/module/image"
	"git.trj.tw/golang/go-watch-webp/module/option"
	"git.trj.tw/golang/utils"
	"gopkg.in/fsnotify.v1"
)

func init() {
	option.RegOptions()
}

func main() {
	fmt.Println("watch dir webp image")
	var err error
	lock := make(chan os.Signal, 1)
	signal.Notify(lock, os.Interrupt)

	opts := option.GetOptions()

	if opts.Help {
		flag.Usage()
		return
	}

	err = config.LoadConfig(opts.Config)
	if err != nil {
		log.Fatal(err)
	}

	conf := config.GetConfig()

	if exists := checkDirectory(conf.Src); !exists {
		log.Fatal(errors.New("source folder not exists"))
	}
	if exists := checkDirectory(conf.Dist); !exists {
		log.Fatal(errors.New("target folder not exists"))
	}

	watcher, err := fsnotify.NewWatcher()
	if err != nil {
		log.Fatal(err)
	}

	// watch fs notify
	go func() {
		for {
			select {
			case event, ok := <-watcher.Events:
				if !ok {
					return
				}
				log.Println("fs event :: ", event)
				if event.Op&fsnotify.Create == fsnotify.Create {
					log.Println("create file :: ", event.Name)
					go procFile(event.Name)
				}
			case err, ok := <-watcher.Errors:
				if !ok {
					return
				}
				log.Println("error: ", err)
			}
		}
	}()

	err = watcher.Add(conf.Src)
	if err != nil {
		log.Fatal(err)
	}

	<-lock
}

func procFile(loc string) {
	// only proc webp file
	if ext := filepath.Ext(loc); ext != ".webp" {
		return
	}
	go func(loc string) {
		defer func() {
			os.Remove(loc)
		}()
		fin := waitFile(loc)
		if fin {
			log.Println("file write ok")
			file, err := os.Open(loc)
			if err != nil {
				log.Println("err :: ", err)
			}
			defer file.Close()
			err = image.ConvertToPng(file)
			if err != nil {
				log.Println("err :: ", err)
			}
		}
	}(loc)
}

func waitFile(loc string) bool {
	if len(loc) == 0 {
		return false
	}

	for {
		// check file modify time
		t1, err := getFileModTime(loc)
		if err != nil {
			return false
		}
		time.Sleep(100 * time.Millisecond)
		t2, err := getFileModTime(loc)
		if err != nil {
			return false
		}

		if t1 == t2 {
			break
		}
	}
	return true
}

func getFileModTime(loc string) (int64, error) {
	file, err := os.Open(loc)
	if err != nil {
		return -1, err
	}
	defer file.Close()
	info, err := file.Stat()
	if err != nil {
		return -1, err
	}

	return info.ModTime().UnixNano(), nil
}

func checkDirectory(dir string) bool {
	if len(dir) == 0 {
		return false
	}

	dir = utils.ParsePath(dir)
	if exists := utils.CheckExists(dir, true); !exists {
		return false
	}
	if isDir := utils.IsDir(dir); !isDir {
		return false
	}
	return true
}