feat: image variants per image

internal/infrastructure/useCases/ServeVariantGenerate.go

@@ -0,0 +1,33 @@
+package useCases
+
+import (
+	"RenewCMS/internal/domain/image"
+	"context"
+)
+
+func (u *ServeVariantUseCase) Generate(ctx context.Context, variant image.Variant, storedName string) (image.VariantFile, error) {
+	source, err := u.storage.Open(storedName)
+	if err != nil {
+		return image.VariantFile{}, err
+	}
+	defer source.Content.Close()
+
+	if servedAsIs(storedName, source.Content) {
+		return image.VariantFile{}, image.ErrVariantSourceUnsupported
+	}
+	if source.Size > u.maxSourceBytes {
+		return image.VariantFile{}, image.ErrSourceTooLarge
+	}
+
+	settings := variant.Settings()
+	fingerprint := settings.Fingerprint()
+	served, existing, hit, err := u.lookupCached(variant.Name, storedName, fingerprint, image.VariantETag(settings, storedName))
+	if err != nil {
+		return image.VariantFile{}, err
+	}
+	if hit {
+		_ = served.Content.Close()
+		return existing, nil
+	}
+	return u.generated(ctx, variant, storedName, fingerprint, existing)
+}