Simple blogging system written in Go https://goblog.app
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package main
import (
"context"
"crypto/sha256"
"errors"
"fmt"
"image/png"
"io"
"log"
"net/http"
"github.com/carlmjohnson/requests"
"github.com/disintegration/imaging"
"go.goblog.app/app/pkgs/bufferpool"
)
const defaultCompressionWidth = 2000
const defaultCompressionHeight = 3000
type mediaCompression interface {
compress(url string, save mediaStorageSaveFunc, hc *http.Client) (location string, err error)
}
func (a *goBlog) compressMediaFile(url string) (location string, err error) {
// Init compressors
a.compressorsInit.Do(a.initMediaCompressors)
// Try all compressors until success
for _, c := range a.compressors {
location, err = c.compress(url, a.saveMediaFile, a.httpClient)
if location != "" && err == nil {
break
}
}
// Return result
return location, err
}
func (a *goBlog) initMediaCompressors() {
if a.cfg.Micropub == nil || a.cfg.Micropub.MediaStorage == nil {
return
}
config := a.cfg.Micropub.MediaStorage
if key := config.TinifyKey; key != "" {
a.compressors = append(a.compressors, &tinify{key})
}
if config.CloudflareCompressionEnabled {
a.compressors = append(a.compressors, &cloudflare{})
}
if config.LocalCompressionEnabled {
a.compressors = append(a.compressors, &localMediaCompressor{})
}
}
type tinify struct {
key string
}
func (tf *tinify) compress(url string, upload mediaStorageSaveFunc, hc *http.Client) (string, error) {
tinifyErr := errors.New("failed to compress image using tinify")
// Check url
fileExtension, allowed := urlHasExt(url, "jpg", "jpeg", "png")
if !allowed {
return "", nil
}
// Compress
headers := http.Header{}
err := requests.
URL("https://api.tinify.com/shrink").
Client(hc).
Method(http.MethodPost).
BasicAuth("api", tf.key).
BodyJSON(map[string]any{
"source": map[string]any{
"url": url,
},
}).
ToHeaders(headers).
Fetch(context.Background())
if err != nil {
log.Println("Tinify error:", err.Error())
return "", tinifyErr
}
compressedLocation := headers.Get("Location")
if compressedLocation == "" {
log.Println("Tinify error: location header missing")
return "", tinifyErr
}
// Resize and download image
imgBuffer := bufferpool.Get()
defer bufferpool.Put(imgBuffer)
err = requests.
URL(compressedLocation).
Client(hc).
Method(http.MethodPost).
BasicAuth("api", tf.key).
BodyJSON(map[string]any{
"resize": map[string]any{
"method": "fit",
"width": defaultCompressionWidth,
"height": defaultCompressionHeight,
},
}).
ToBytesBuffer(imgBuffer).
Fetch(context.Background())
if err != nil {
log.Println("Tinify error:", err.Error())
return "", tinifyErr
}
// Upload compressed file
return uploadCompressedFile(fileExtension, imgBuffer, upload)
}
type cloudflare struct{}
func (*cloudflare) compress(url string, upload mediaStorageSaveFunc, hc *http.Client) (string, error) {
// Check url
if _, allowed := urlHasExt(url, "jpg", "jpeg", "png"); !allowed {
return "", nil
}
// Force jpeg
fileExtension := "jpeg"
// Compress
imgBuffer := bufferpool.Get()
defer bufferpool.Put(imgBuffer)
err := requests.
URL(fmt.Sprintf("https://www.cloudflare.com/cdn-cgi/image/f=jpeg,q=75,metadata=none,fit=scale-down,w=%d,h=%d/%s", defaultCompressionWidth, defaultCompressionHeight, url)).
Client(hc).
ToBytesBuffer(imgBuffer).
Fetch(context.Background())
if err != nil {
log.Println("Cloudflare error:", err.Error())
return "", errors.New("failed to compress image using cloudflare")
}
// Upload compressed file
return uploadCompressedFile(fileExtension, imgBuffer, upload)
}
type localMediaCompressor struct{}
func (*localMediaCompressor) compress(url string, upload mediaStorageSaveFunc, hc *http.Client) (string, error) {
// Check url
fileExtension, allowed := urlHasExt(url, "jpg", "jpeg", "png")
if !allowed {
return "", nil
}
// Download image
imgBuffer := bufferpool.Get()
defer bufferpool.Put(imgBuffer)
err := requests.
URL(url).
Client(hc).
ToBytesBuffer(imgBuffer).
Fetch(context.Background())
if err != nil {
log.Println("Local compressor error:", err.Error())
return "", errors.New("failed to download image using local compressor")
}
// Decode image
img, err := imaging.Decode(imgBuffer, imaging.AutoOrientation(true))
if err != nil {
log.Println("Local compressor error:", err.Error())
return "", errors.New("failed to compress image using local compressor")
}
// Resize image
resizedImage := imaging.Fit(img, defaultCompressionWidth, defaultCompressionHeight, imaging.Lanczos)
// Encode image
resizedBuffer := bufferpool.Get()
defer bufferpool.Put(resizedBuffer)
switch fileExtension {
case "jpg", "jpeg":
err = imaging.Encode(resizedBuffer, resizedImage, imaging.JPEG, imaging.JPEGQuality(75))
case "png":
err = imaging.Encode(resizedBuffer, resizedImage, imaging.PNG, imaging.PNGCompressionLevel(png.BestCompression))
}
if err != nil {
log.Println("Local compressor error:", err.Error())
return "", errors.New("failed to compress image using local compressor")
}
// Upload compressed file
return uploadCompressedFile(fileExtension, resizedBuffer, upload)
}
func uploadCompressedFile(fileExtension string, r io.Reader, upload mediaStorageSaveFunc) (string, error) {
// Copy file to temporary buffer to generate hash and filename
hash := sha256.New()
tempBuffer := bufferpool.Get()
defer bufferpool.Put(tempBuffer)
_, _ = io.Copy(io.MultiWriter(tempBuffer, hash), r)
// Upload buffer
return upload(fmt.Sprintf("%x.%s", hash.Sum(nil), fileExtension), tempBuffer)
}