split functions to different files. Build and run, please use package mode, example:

`go run .`
`go build .`
`go run . --prefetch`

encoder.go

@@ -0,0 +1,68 @@
+package main
+
+import (
+	"bytes"
+	"errors"
+	"fmt"
+	"github.com/chai2010/webp"
+	"golang.org/x/image/bmp"
+	"image"
+	"image/gif"
+	"image/jpeg"
+	"image/png"
+	"io/ioutil"
+	"log"
+	"path"
+	"strings"
+)
+
+func WebpEncoder(p1, p2 string, quality float32, Log bool, c chan int) (err error) {
+	// if convert fails, return error; success nil
+	var buf bytes.Buffer
+	var img image.Image
+
+	data, err := ioutil.ReadFile(p1)
+	if err != nil {
+		ChanErr(c)
+		return
+	}
+
+	contentType := GetFileContentType(data[:512])
+	if strings.Contains(contentType, "jpeg") {
+		img, _ = jpeg.Decode(bytes.NewReader(data))
+	} else if strings.Contains(contentType, "png") {
+		img, _ = png.Decode(bytes.NewReader(data))
+	} else if strings.Contains(contentType, "bmp") {
+		img, _ = bmp.Decode(bytes.NewReader(data))
+	} else if strings.Contains(contentType, "gif") {
+		// TODO: need to support animated webp
+		img, _ = gif.Decode(bytes.NewReader(data))
+	}
+
+	if img == nil {
+		msg := "image file " + path.Base(p1) + " is corrupted or not supported"
+		log.Println(msg)
+		err = errors.New(msg)
+		ChanErr(c)
+		return
+	}
+
+	if err = webp.Encode(&buf, img, &webp.Options{Lossless: false, Quality: quality}); err != nil {
+		log.Println(err)
+		ChanErr(c)
+		return
+	}
+	if err = ioutil.WriteFile(p2, buf.Bytes(), 0755); err != nil {
+		log.Println(err)
+		ChanErr(c)
+		return
+	}
+
+	if Log {
+		fmt.Printf("Save to %s ok\n", p2)
+	}
+
+	ChanErr(c)
+
+	return nil
+}

helper.go

@@ -0,0 +1,59 @@
+package main
+
+import (
+	"fmt"
+	"net/http"
+	"os"
+	"path"
+	"path/filepath"
+)
+
+func ChanErr(ccc chan int) {
+	if ccc != nil {
+		ccc <- 1
+	}
+}
+
+func GetFileContentType(buffer []byte) string {
+	// Use the net/http package's handy DectectContentType function. Always returns a valid
+	// content-type by returning "application/octet-stream" if no others seemed to match.
+	contentType := http.DetectContentType(buffer)
+	return contentType
+}
+
+func FileCount(dir string) int {
+	count := 0
+	_ = filepath.Walk(dir,
+		func(path string, info os.FileInfo, err error) error {
+			if !info.IsDir() {
+				count += 1
+			}
+			return nil
+		})
+	return count
+}
+
+func ImageExists(filename string) bool {
+	info, err := os.Stat(filename)
+	if os.IsNotExist(err) {
+		return false
+	}
+	return !info.IsDir()
+}
+
+func GenWebpAbs(RawImagePath string, ExhaustPath string, ImgFilename string, reqURI string) (string, string) {
+	// get file mod time
+	STAT, err := os.Stat(RawImagePath)
+	if err != nil {
+		fmt.Println(err.Error())
+	}
+	ModifiedTime := STAT.ModTime().Unix()
+	// webpFilename: abc.jpg.png -> abc.jpg.png1582558990.webp
+	var WebpFilename = fmt.Sprintf("%s.%d.webp", ImgFilename, ModifiedTime)
+	cwd, _ := os.Getwd()
+
+	// /home/webp_server/exhaust/path/to/tsuki.jpg.1582558990.webp
+	// Custom Exhaust: /path/to/exhaust/web_path/web_to/tsuki.jpg.1582558990.webp
+	WebpAbsolutePath := path.Clean(path.Join(ExhaustPath, path.Dir(reqURI), WebpFilename))
+	return cwd, WebpAbsolutePath
+}

prefetch.go

@@ -0,0 +1,51 @@
+package main
+
+import (
+	"bufio"
+	"fmt"
+	"log"
+	"os"
+	"path"
+	"path/filepath"
+	"strconv"
+	"strings"
+)
+
+func PrefetchImages(confImgPath string, ExhaustPath string, QUALITY string) {
+	fmt.Println(`Prefetch will convert all your images to webp, it may take some time and consume a lot of CPU resource. Do you want to proceed(Y/n)`)
+	reader := bufio.NewReader(os.Stdin)
+	char, _, _ := reader.ReadRune() //y Y enter
+	// maximum ongoing prefetch is depending on your core of CPU
+	log.Printf("Prefetching using %d cores", jobs)
+	var finishChan = make(chan int, jobs)
+	for i := 0; i < jobs; i++ {
+		finishChan <- 0
+	}
+	if char == 121 || char == 10 || char == 89 {
+		//prefetch, recursive through the dir
+		all := FileCount(confImgPath)
+		count := 0
+		err := filepath.Walk(confImgPath,
+			func(picAbsPath string, info os.FileInfo, err error) error {
+				if err != nil {
+					return err
+				}
+				// RawImagePath string, ImgFilename string, reqURI string
+				proposedURI := strings.Replace(picAbsPath, confImgPath, "", 1)
+				_, p2 := GenWebpAbs(picAbsPath, ExhaustPath, info.Name(), proposedURI)
+				q, _ := strconv.ParseFloat(QUALITY, 32)
+				_ = os.MkdirAll(path.Dir(p2), 0755)
+				go WebpEncoder(picAbsPath, p2, float32(q), false, finishChan)
+				count += <-finishChan
+				//progress bar
+				_, _ = fmt.Fprintf(os.Stdout, "[Webp Server started] - convert in progress: %d/%d\r", count, all)
+				return nil
+			})
+		if err != nil {
+			log.Println(err)
+		}
+	}
+
+	_, _ = fmt.Fprintf(os.Stdout, "Prefetch completeY(^_^)Y\n\n")
+
+}

router.go

@@ -0,0 +1,91 @@
+package main
+
+import (
+	"fmt"
+	"github.com/gofiber/fiber"
+	"os"
+	"path"
+	"path/filepath"
+	"strconv"
+	"strings"
+)
+
+func Convert(ImgPath string, ExhaustPath string, AllowedTypes []string, QUALITY string) func(c *fiber.Ctx) {
+	return func(c *fiber.Ctx) {
+		//basic vars
+		var reqURI = c.Path()                        // mypic/123.jpg
+		var RawImageAbs = path.Join(ImgPath, reqURI) // /home/xxx/mypic/123.jpg
+		var ImgFilename = path.Base(reqURI)          // pure filename, 123.jpg
+		var finalFile string                         // We'll only need one c.sendFile()
+		// Check for Safari users. If they're Safari, just simply ignore everything.
+		UA := c.Get("User-Agent")
+		if strings.Contains(UA, "Safari") && !strings.Contains(UA, "Chrome") &&
+			!strings.Contains(UA, "Firefox") {
+			c.SendFile(RawImageAbs)
+			return
+		}
+
+		// check ext
+		// TODO: may remove this function. Check in Nginx.
+		var allowed = false
+		for _, ext := range AllowedTypes {
+			haystack := strings.ToLower(ImgFilename)
+			needle := strings.ToLower("." + ext)
+			if strings.HasSuffix(haystack, needle) {
+				allowed = true
+				break
+			} else {
+				allowed = false
+			}
+		}
+		if !allowed {
+			c.Send("File extension not allowed!")
+			c.SendStatus(403)
+			return
+		}
+
+		// Check the original image for existence,
+		if !ImageExists(RawImageAbs) {
+			c.Send("Image not found!")
+			c.SendStatus(404)
+			return
+		}
+
+		cwd, WebpAbsPath := GenWebpAbs(RawImageAbs, ExhaustPath, ImgFilename, reqURI)
+
+		if ImageExists(WebpAbsPath) {
+			finalFile = WebpAbsPath
+		} else {
+			// we don't have abc.jpg.png1582558990.webp
+			// delete the old pic and convert a new one.
+			// /home/webp_server/exhaust/path/to/tsuki.jpg.1582558990.webp
+			destHalfFile := path.Clean(path.Join(cwd, "exhaust", path.Dir(reqURI), ImgFilename))
+			matches, err := filepath.Glob(destHalfFile + "*")
+			if err != nil {
+				fmt.Println(err.Error())
+			} else {
+				// /home/webp_server/exhaust/path/to/tsuki.jpg.1582558100.webp <- older ones will be removed
+				// /home/webp_server/exhaust/path/to/tsuki.jpg.1582558990.webp <- keep the latest one
+				for _, p := range matches {
+					if strings.Compare(destHalfFile, p) != 0 {
+						_ = os.Remove(p)
+					}
+				}
+			}
+
+			//for webp, we need to create dir first
+			_ = os.MkdirAll(path.Dir(WebpAbsPath), 0755)
+			q, _ := strconv.ParseFloat(QUALITY, 32)
+			err = WebpEncoder(RawImageAbs, WebpAbsPath, float32(q), true, nil)
+
+			if err != nil {
+				fmt.Println(err)
+				c.SendStatus(400)
+				c.Send("Bad file!")
+				return
+			}
+			finalFile = WebpAbsPath
+		}
+		c.SendFile(finalFile)
+	}
+}

webp-server.go

@@ -1,29 +1,14 @@
 package main
 
 import (
-	"bufio"
-	"bytes"
 	"encoding/json"
-	"errors"
 	"flag"
 	"fmt"
-	"golang.org/x/image/bmp"
+	"github.com/gofiber/fiber"
-	"image"
-	"image/gif"
-	"image/jpeg"
-	"image/png"
-	"io/ioutil"
 	"log"
-	"net/http"
 	"os"
 	"path"
-	"path/filepath"
 	"runtime"
-	"strconv"
-	"strings"
-
-	"github.com/chai2010/webp"
-	"github.com/gofiber/fiber"
 )
 
 type Config struct {
@@ -74,7 +59,7 @@ RestartSec=3s
 WantedBy=multi-user.target
 `
 
-func loadConfig(path string) Config {
+func LoadConfig(path string) Config {
 	var config Config
 	jsonObject, err := os.Open(path)
 	if err != nil {
@@ -86,77 +71,6 @@ func loadConfig(path string) Config {
 	return config
 }
 
-func imageExists(filename string) bool {
-	info, err := os.Stat(filename)
-	if os.IsNotExist(err) {
-		return false
-	}
-	return !info.IsDir()
-}
-
-func GetFileContentType(buffer []byte) string {
-	// Use the net/http package's handy DectectContentType function. Always returns a valid
-	// content-type by returning "application/octet-stream" if no others seemed to match.
-	contentType := http.DetectContentType(buffer)
-	return contentType
-}
-
-func chanErr(ccc chan int) {
-	if ccc != nil {
-		ccc <- 1
-	}
-}
-func webpEncoder(p1, p2 string, quality float32, Log bool, c chan int) (err error) {
-	// if convert fails, return error; success nil
-	var buf bytes.Buffer
-	var img image.Image
-
-	data, err := ioutil.ReadFile(p1)
-	if err != nil {
-		chanErr(c)
-		return
-	}
-
-	contentType := GetFileContentType(data[:512])
-	if strings.Contains(contentType, "jpeg") {
-		img, _ = jpeg.Decode(bytes.NewReader(data))
-	} else if strings.Contains(contentType, "png") {
-		img, _ = png.Decode(bytes.NewReader(data))
-	} else if strings.Contains(contentType, "bmp") {
-		img, _ = bmp.Decode(bytes.NewReader(data))
-	} else if strings.Contains(contentType, "gif") {
-		// TODO: need to support animated webp
-		img, _ = gif.Decode(bytes.NewReader(data))
-	}
-
-	if img == nil {
-		msg := "image file " + path.Base(p1) + " is corrupted or not supported"
-		log.Println(msg)
-		err = errors.New(msg)
-		chanErr(c)
-		return
-	}
-
-	if err = webp.Encode(&buf, img, &webp.Options{Lossless: false, Quality: quality}); err != nil {
-		log.Println(err)
-		chanErr(c)
-		return
-	}
-	if err = ioutil.WriteFile(p2, buf.Bytes(), 0755); err != nil {
-		log.Println(err)
-		chanErr(c)
-		return
-	}
-
-	if Log {
-		fmt.Printf("Save to %s ok\n", p2)
-	}
-
-	chanErr(c)
-
-	return nil
-}
-
 func init() {
 	flag.StringVar(&configPath, "config", "config.json", "/path/to/config.json. (Default: ./config.json)")
 	flag.BoolVar(&prefetch, "prefetch", false, "Prefetch and convert image to webp")
@@ -166,156 +80,8 @@ func init() {
 	flag.Parse()
 }
 
-func Convert(ImgPath string, ExhaustPath string, AllowedTypes []string, QUALITY string) func(c *fiber.Ctx) {
-	return func(c *fiber.Ctx) {
-		//basic vars
-		var reqURI = c.Path()                        // mypic/123.jpg
-		var RawImageAbs = path.Join(ImgPath, reqURI) // /home/xxx/mypic/123.jpg
-		var ImgFilename = path.Base(reqURI)          // pure filename, 123.jpg
-		var finalFile string                         // We'll only need one c.sendFile()
-		// Check for Safari users. If they're Safari, just simply ignore everything.
-		UA := c.Get("User-Agent")
-		if strings.Contains(UA, "Safari") && !strings.Contains(UA, "Chrome") &&
-			!strings.Contains(UA, "Firefox") {
-			c.SendFile(RawImageAbs)
-			return
-		}
-
-		// check ext
-		// TODO: may remove this function. Check in Nginx.
-		var allowed = false
-		for _, ext := range AllowedTypes {
-			haystack := strings.ToLower(ImgFilename)
-			needle := strings.ToLower("." + ext)
-			if strings.HasSuffix(haystack, needle) {
-				allowed = true
-				break
-			} else {
-				allowed = false
-			}
-		}
-		if !allowed {
-			c.Send("File extension not allowed!")
-			c.SendStatus(403)
-			return
-		}
-
-		// Check the original image for existence,
-		if !imageExists(RawImageAbs) {
-			c.Send("Image not found!")
-			c.SendStatus(404)
-			return
-		}
-
-		cwd, WebpAbsPath := genWebpAbs(RawImageAbs, ExhaustPath, ImgFilename, reqURI)
-
-		if imageExists(WebpAbsPath) {
-			finalFile = WebpAbsPath
-		} else {
-			// we don't have abc.jpg.png1582558990.webp
-			// delete the old pic and convert a new one.
-			// /home/webp_server/exhaust/path/to/tsuki.jpg.1582558990.webp
-			destHalfFile := path.Clean(path.Join(cwd, "exhaust", path.Dir(reqURI), ImgFilename))
-			matches, err := filepath.Glob(destHalfFile + "*")
-			if err != nil {
-				fmt.Println(err.Error())
-			} else {
-				// /home/webp_server/exhaust/path/to/tsuki.jpg.1582558100.webp <- older ones will be removed
-				// /home/webp_server/exhaust/path/to/tsuki.jpg.1582558990.webp <- keep the latest one
-				for _, p := range matches {
-					if strings.Compare(destHalfFile, p) != 0 {
-						_ = os.Remove(p)
-					}
-				}
-			}
-
-			//for webp, we need to create dir first
-			_ = os.MkdirAll(path.Dir(WebpAbsPath), 0755)
-			q, _ := strconv.ParseFloat(QUALITY, 32)
-			err = webpEncoder(RawImageAbs, WebpAbsPath, float32(q), true, nil)
-
-			if err != nil {
-				fmt.Println(err)
-				c.SendStatus(400)
-				c.Send("Bad file!")
-				return
-			}
-			finalFile = WebpAbsPath
-		}
-		c.SendFile(finalFile)
-	}
-}
-
-func fileCount(dir string) int {
-	count := 0
-	_ = filepath.Walk(dir,
-		func(path string, info os.FileInfo, err error) error {
-			if !info.IsDir() {
-				count += 1
-			}
-			return nil
-		})
-	return count
-}
-
-func genWebpAbs(RawImagePath string, ExhaustPath string, ImgFilename string, reqURI string) (string, string) {
-	// get file mod time
-	STAT, err := os.Stat(RawImagePath)
-	if err != nil {
-		fmt.Println(err.Error())
-	}
-	ModifiedTime := STAT.ModTime().Unix()
-	// webpFilename: abc.jpg.png -> abc.jpg.png1582558990.webp
-	var WebpFilename = fmt.Sprintf("%s.%d.webp", ImgFilename, ModifiedTime)
-	cwd, _ := os.Getwd()
-
-	// /home/webp_server/exhaust/path/to/tsuki.jpg.1582558990.webp
-	// Custom Exhaust: /path/to/exhaust/web_path/web_to/tsuki.jpg.1582558990.webp
-	WebpAbsolutePath := path.Clean(path.Join(ExhaustPath, path.Dir(reqURI), WebpFilename))
-	return cwd, WebpAbsolutePath
-}
-
-func prefetchImages(confImgPath string, ExhaustPath string, QUALITY string) {
-	fmt.Println(`Prefetch will convert all your images to webp, it may take some time and consume a lot of CPU resource. Do you want to proceed(Y/n)`)
-	reader := bufio.NewReader(os.Stdin)
-	char, _, _ := reader.ReadRune() //y Y enter
-	// maximum ongoing prefetch is depending on your core of CPU
-	log.Printf("Prefetching using %d cores", jobs)
-	var finishChan = make(chan int, jobs)
-	for i := 0; i < jobs; i++ {
-		finishChan <- 0
-	}
-	if char == 121 || char == 10 || char == 89 {
-		//prefetch, recursive through the dir
-		all := fileCount(confImgPath)
-		count := 0
-		err := filepath.Walk(confImgPath,
-			func(picAbsPath string, info os.FileInfo, err error) error {
-				if err != nil {
-					return err
-				}
-				// RawImagePath string, ImgFilename string, reqURI string
-				proposedURI := strings.Replace(picAbsPath, confImgPath, "", 1)
-				_, p2 := genWebpAbs(picAbsPath, ExhaustPath, info.Name(), proposedURI)
-				q, _ := strconv.ParseFloat(QUALITY, 32)
-				_ = os.MkdirAll(path.Dir(p2), 0755)
-				go webpEncoder(picAbsPath, p2, float32(q), false, finishChan)
-				count += <-finishChan
-				//progress bar
-				_, _ = fmt.Fprintf(os.Stdout, "[Webp Server started] - convert in progress: %d/%d\r", count, all)
-				return nil
-			})
-		if err != nil {
-			log.Println(err)
-		}
-	}
-
-	_, _ = fmt.Fprintf(os.Stdout, "Prefetch completeY(^_^)Y\n\n")
-
-}
-
 func main() {
-	config := loadConfig(configPath)
+	config := LoadConfig(configPath)
 
 	HOST := config.HOST
 	PORT := config.PORT
@@ -336,13 +102,11 @@ func main() {
 	}
 	if dumpSystemd {
 		fmt.Println(sampleSystemd)
-
 		os.Exit(0)
-
 	}
 
 	if prefetch {
-		go prefetchImages(confImgPath, ExhaustPath, QUALITY)
+		go PrefetchImages(confImgPath, ExhaustPath, QUALITY)
 	}
 
 	app := fiber.New()