first commit

pkg/utils/image_processor.go

@@ -0,0 +1,137 @@
+package utils
+
+import (
+	"fmt"
+	"image"
+	"image/jpeg"
+	"image/png"
+	"mime/multipart"
+	"os"
+	"path/filepath"
+	"strings"
+	"time"
+
+	"gauth-central/config"
+
+	"github.com/chai2010/webp"
+	"github.com/disintegration/imaging"
+)
+
+type ImageOptions struct {
+	Width   int
+	Height  int
+	Quality float32 // 1-100 (WebP uses float32)
+	Format  string  // "webp", "jpg", "png"
+	Mode    string  // "cover", "contain", "resize"
+}
+
+// SaveOptimizedImage processes and saves an image
+// Returns the relative path to the saved file (e.g., "/uploads/avatars/filename.webp")
+func SaveOptimizedImage(fileHeader *multipart.FileHeader, uploadDir string, userID string, opts *ImageOptions) (string, error) {
+	// If opts is nil, use defaults from config
+	if opts == nil {
+		opts = &ImageOptions{
+			Width:   config.AppConfig.AvatarWidth,
+			Height:  config.AppConfig.AvatarHeight,
+			Quality: float32(config.AppConfig.AvatarQuality),
+			Format:  config.AppConfig.AvatarFormat,
+			Mode:    config.AppConfig.AvatarMode,
+		}
+	}
+
+	// Open the file
+	srcFile, err := fileHeader.Open()
+	if err != nil {
+		return "", fmt.Errorf("failed to open file: %v", err)
+	}
+	defer srcFile.Close()
+
+	// Decode image
+	img, _, err := image.Decode(srcFile)
+	if err != nil {
+		return "", fmt.Errorf("failed to decode image: %v", err)
+	}
+
+	// Resize logic
+	if opts.Width > 0 || opts.Height > 0 {
+		switch strings.ToLower(opts.Mode) {
+		case "cover":
+			// Fill requires both dimensions to be effective for cropping.
+			// If one is missing, we fall back to Resize which preserves aspect ratio.
+			if opts.Width > 0 && opts.Height > 0 {
+				img = imaging.Fill(img, opts.Width, opts.Height, imaging.Center, imaging.Lanczos)
+			} else {
+				img = imaging.Resize(img, opts.Width, opts.Height, imaging.Lanczos)
+			}
+		case "contain":
+			// Fit fits the image within the box, preserving aspect ratio.
+			// If one dimension is 0, Fit might behave like Resize(w, h) if implementation allows,
+			// but imaging.Fit usually expects a box.
+			// If one is 0, we assume the user wants to limit the other dimension.
+			if opts.Width > 0 && opts.Height > 0 {
+				img = imaging.Fit(img, opts.Width, opts.Height, imaging.Lanczos)
+			} else {
+				img = imaging.Resize(img, opts.Width, opts.Height, imaging.Lanczos)
+			}
+		default:
+			// "resize" or empty: Resize preserves aspect ratio if one arg is 0.
+			// If both are provided, it stretches unless we use Fill/Fit.
+			// imaging.Resize stretches if both are non-zero.
+			img = imaging.Resize(img, opts.Width, opts.Height, imaging.Lanczos)
+		}
+	}
+
+	// Determine output format and filename
+	ext := "." + strings.ToLower(opts.Format)
+	if opts.Format == "" {
+		ext = ".webp" // Default to WebP
+		opts.Format = "webp"
+	}
+
+	// Generate filename
+	filename := fmt.Sprintf("%s_%d%s", userID, time.Now().UnixNano(), ext)
+
+	// Ensure directory exists
+	if err := os.MkdirAll(uploadDir, 0755); err != nil {
+		return "", fmt.Errorf("failed to create directory: %v", err)
+	}
+
+	fullPath := filepath.Join(uploadDir, filename)
+	outFile, err := os.Create(fullPath)
+	if err != nil {
+		return "", fmt.Errorf("failed to create output file: %v", err)
+	}
+	defer outFile.Close()
+
+	// Encode
+	switch strings.ToLower(opts.Format) {
+	case "jpg", "jpeg":
+		quality := int(opts.Quality)
+		if quality < 1 || quality > 100 {
+			quality = 90
+		}
+		err = jpeg.Encode(outFile, img, &jpeg.Options{Quality: quality})
+	case "png":
+		err = png.Encode(outFile, img) // PNG is lossless
+	case "webp", "":
+		err = webp.Encode(outFile, img, &webp.Options{Lossless: false, Quality: opts.Quality})
+	default:
+		// Fallback to WebP
+		err = webp.Encode(outFile, img, &webp.Options{Lossless: false, Quality: opts.Quality})
+	}
+
+	if err != nil {
+		return "", fmt.Errorf("failed to encode image: %v", err)
+	}
+
+	// Return relative path
+	relPath := filepath.Join(uploadDir, filename)
+	if strings.HasPrefix(relPath, ".") {
+		relPath = relPath[1:]
+	}
+	if !strings.HasPrefix(relPath, "/") {
+		relPath = "/" + relPath
+	}
+
+	return relPath, nil
+}