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package media
import (
"fmt"
"io"
"net/http"
"os"
"path/filepath"
"strconv"
"strings"
"github.com/gin-gonic/gin"
"github.com/google/uuid"
)
const (
maxUploadSize = 20 << 20 // 20 MB
maxWidth = 3000
)
// allowedMIMEs maps detected content types to canonical file extensions.
var allowedMIMEs = map[string]string{
"image/jpeg": ".jpg",
"image/png": ".png",
"image/gif": ".gif",
"image/webp": ".webp",
}
// MediaHandler handles image uploads and on-the-fly image serving.
type MediaHandler struct {
StorageDir string
}
// NewMediaHandler returns a MediaHandler that stores files in storageDir.
func NewMediaHandler(storageDir string) *MediaHandler {
return &MediaHandler{StorageDir: storageDir}
}
// HandleUpload handles POST /admin/upload/image.
// Expects multipart/form-data with an "image" field.
// Returns EditorJS-compatible JSON: {"success":1,"file":{"url":"/media/<uuid>.webp"}}
func (h *MediaHandler) HandleUpload(c *gin.Context) {
c.Request.Body = http.MaxBytesReader(c.Writer, c.Request.Body, maxUploadSize)
file, _, err := c.Request.FormFile("image")
if err != nil {
c.JSON(http.StatusBadRequest, gin.H{"success": 0, "error": err.Error()})
return
}
defer file.Close()
// Sniff MIME type from first 512 bytes
sniff := make([]byte, 512)
n, _ := file.Read(sniff)
mimeType := http.DetectContentType(sniff[:n])
ext, ok := allowedMIMEs[mimeType]
if !ok {
c.JSON(http.StatusBadRequest, gin.H{"success": 0, "error": "unsupported image type: " + mimeType})
return
}
// Rewind so the full file is copied to disk
if seeker, ok := file.(io.Seeker); ok {
if _, err := seeker.Seek(0, io.SeekStart); err != nil {
c.JSON(http.StatusInternalServerError, gin.H{"success": 0, "error": "seek error"})
return
}
}
if err := os.MkdirAll(h.StorageDir, 0755); err != nil {
c.JSON(http.StatusInternalServerError, gin.H{"success": 0, "error": "storage error"})
return
}
id := uuid.New().String()
destPath := filepath.Join(h.StorageDir, id+ext)
out, err := os.Create(destPath)
if err != nil {
c.JSON(http.StatusInternalServerError, gin.H{"success": 0, "error": "storage error"})
return
}
defer out.Close()
if _, err := io.Copy(out, file); err != nil {
c.JSON(http.StatusInternalServerError, gin.H{"success": 0, "error": "write error"})
return
}
c.JSON(http.StatusOK, gin.H{
"success": 1,
"file": gin.H{"url": "/media/" + id + ".webp"},
})
}
// HandleServe handles GET /media/*filepath.
// Format is determined by the file extension (.webp or .jpg/.jpeg).
// The optional ?w=<pixels> query param resizes the image (clamped to 3000; error if <= 0).
func (h *MediaHandler) HandleServe(c *gin.Context) {
filename := strings.TrimPrefix(c.Param("filepath"), "/")
ext := strings.ToLower(filepath.Ext(filename))
base := strings.TrimSuffix(filename, filepath.Ext(filename))
var format, contentType string
switch ext {
case ".webp":
format, contentType = "webp", "image/webp"
case ".jpg", ".jpeg":
format, contentType = "jpeg", "image/jpeg"
default:
c.AbortWithStatus(http.StatusNotFound)
return
}
width := 0
if wStr := c.Query("w"); wStr != "" {
w, err := strconv.Atoi(wStr)
if err != nil || w <= 0 {
c.AbortWithStatus(http.StatusBadRequest)
return
}
if w > maxWidth {
w = maxWidth
}
width = w
}
cacheName := cacheKey(base, width, format)
cachePath := filepath.Join(h.StorageDir, cacheName)
// Cache hit: serve the existing variant directly
if f, err := os.Open(cachePath); err == nil {
defer f.Close()
info, _ := os.Stat(cachePath)
c.Header("Content-Type", contentType)
http.ServeContent(c.Writer, c.Request, cacheName, info.ModTime(), f)
return
}
origPath, err := findOriginal(h.StorageDir, base)
if err != nil {
c.AbortWithStatus(http.StatusNotFound)
return
}
// Skip processing if format matches original and no resize is requested
origExt := strings.ToLower(filepath.Ext(origPath))
sameFormat := origExt == ext ||
(origExt == ".jpg" && ext == ".jpeg") ||
(origExt == ".jpeg" && ext == ".jpg")
if width == 0 && sameFormat {
f, err := os.Open(origPath)
if err != nil {
c.AbortWithStatus(http.StatusInternalServerError)
return
}
defer f.Close()
info, _ := os.Stat(origPath)
c.Header("Content-Type", contentType)
http.ServeContent(c.Writer, c.Request, filename, info.ModTime(), f)
return
}
result, err := ConvertAndResize(origPath, width, format)
if err != nil {
c.AbortWithStatus(http.StatusInternalServerError)
return
}
// Atomic cache write — concurrent writers are harmless (last rename wins)
tmp := cachePath + ".tmp"
if err := os.WriteFile(tmp, result, 0644); err == nil {
_ = os.Rename(tmp, cachePath)
}
c.Header("Content-Type", contentType)
c.Data(http.StatusOK, contentType, result)
}
// cacheKey returns the filename for a processed image variant.
// - No width: "<base>.webp" / "<base>.jpg"
// - With width: "<base>_<width>w.webp" / "<base>_<width>w.jpg"
func cacheKey(base string, width int, format string) string {
ext := ".webp"
if format == "jpeg" {
ext = ".jpg"
}
if width > 0 {
return fmt.Sprintf("%s_%dw%s", base, width, ext)
}
return base + ext
}
// findOriginal finds the original upload file for a given UUID base name.
// Cache variants (which contain '_' before the extension) are excluded.
func findOriginal(dir, base string) (string, error) {
matches, err := filepath.Glob(filepath.Join(dir, base+".*"))
if err != nil {
return "", err
}
for _, m := range matches {
name := filepath.Base(m)
nameBase := strings.TrimSuffix(name, filepath.Ext(name))
if !strings.Contains(nameBase, "_") {
return m, nil
}
}
return "", fmt.Errorf("original not found for %q in %s", base, dir)
}
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