feat: add avatar cropping with Cropper.js and server-side resize

handlers/profile.go

@@ -1,7 +1,10 @@
 package handlers
 
 import (
+	"bytes"
 	"fmt"
+	"image"
+	"image/jpeg"
 	"io"
 	"net/http"
 	"os"
@@ -13,6 +16,9 @@ import (
 	"github.com/gin-gonic/gin"
 	"gorm.io/gorm"
 
+	xdraw "golang.org/x/image/draw"
+	_ "golang.org/x/image/webp"
+
 	"go_blog/models"
 )
 
@@ -147,3 +153,92 @@ func UpdateProfile(db *gorm.DB, storagePath string) gin.HandlerFunc {
 		c.Redirect(http.StatusFound, "/profile?saved=1")
 	}
 }
+
+// UploadAvatar handles AJAX avatar upload with cropping.
+func UploadAvatar(db *gorm.DB, storagePath string) gin.HandlerFunc {
+	return func(c *gin.Context) {
+		session := sessions.Default(c)
+		userID := session.Get("user_id")
+
+		var user models.User
+		if err := db.First(&user, userID).Error; err != nil {
+			c.JSON(http.StatusBadRequest, gin.H{"error": "User not found"})
+			return
+		}
+
+		file, header, err := c.Request.FormFile("avatar")
+		if err != nil {
+			c.JSON(http.StatusBadRequest, gin.H{"error": "No file provided"})
+			return
+		}
+		defer file.Close()
+
+		// Validate extension.
+		ext := strings.ToLower(filepath.Ext(header.Filename))
+		if ext == "" || (ext != ".jpg" && ext != ".jpeg" && ext != ".png" && ext != ".gif" && ext != ".webp") {
+			ext = ".jpg"
+		}
+
+		// Read file bytes for image processing.
+		imgBytes, err := io.ReadAll(file)
+		if err != nil {
+			c.JSON(http.StatusInternalServerError, gin.H{"error": "Failed to read file"})
+			return
+		}
+
+		// Decode, resize, and re-encode the image.
+		processedBytes, finalExt, err := processAvatar(imgBytes, ext)
+		if err != nil {
+			// Fall back to saving raw bytes if processing fails.
+			processedBytes = imgBytes
+			finalExt = ext
+		}
+
+		// Ensure avatar directory exists.
+		avatarDir := filepath.Join(storagePath, "avatars")
+		os.MkdirAll(avatarDir, 0755)
+
+		// Remove old avatar file.
+		if user.Avatar != "" {
+			oldPath := filepath.Join(avatarDir, user.Avatar)
+			os.Remove(oldPath)
+		}
+
+		// Save processed avatar.
+		savedName := fmt.Sprintf("%d%s", user.ID, finalExt)
+		savedPath := filepath.Join(avatarDir, savedName)
+		if err := os.WriteFile(savedPath, processedBytes, 0644); err != nil {
+			c.JSON(http.StatusInternalServerError, gin.H{"error": "Failed to save avatar"})
+			return
+		}
+
+		// Update user record.
+		user.Avatar = savedName
+		db.Save(&user)
+
+		// Update session.
+		session.Set("avatar", savedName)
+		session.Save()
+
+		c.JSON(http.StatusOK, gin.H{"avatar": savedName})
+	}
+}
+
+// processAvatar decodes, resizes to 256x256, and re-encodes an avatar image as JPEG.
+func processAvatar(imgBytes []byte, ext string) ([]byte, string, error) {
+	src, _, err := image.Decode(bytes.NewReader(imgBytes))
+	if err != nil {
+		return nil, "", err
+	}
+
+	const targetSize = 256
+	dst := image.NewRGBA(image.Rect(0, 0, targetSize, targetSize))
+	xdraw.CatmullRom.Scale(dst, dst.Bounds(), src, src.Bounds(), xdraw.Src, nil)
+
+	var buf bytes.Buffer
+	if err := jpeg.Encode(&buf, dst, &jpeg.Options{Quality: 85}); err != nil {
+		return nil, "", err
+	}
+
+	return buf.Bytes(), ".jpg", nil
+}