feat: add govips ConvertAndResize wrapper

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

1 files changed, 46 insertions, 0 deletions

diff --git a/internal/media/process.go b/internal/media/process.go
new file mode 100644
index 0000000..bb3ac89
--- /dev/null
+++ b/internal/media/process.go
@@ -0,0 +1,46 @@
+package media
+
+import (
+	"fmt"
+
+	"github.com/davidbyttow/govips/v2/vips"
+)
+
+// ConvertAndResize loads the image at src, optionally resizes it to width pixels
+// wide (maintaining aspect ratio), and exports it in the requested format.
+//
+// width <= 0 means no resize. format must be "webp" or "jpeg".
+func ConvertAndResize(src string, width int, format string) ([]byte, error) {
+	if format != "webp" && format != "jpeg" {
+		return nil, fmt.Errorf("unsupported format %q: must be webp or jpeg", format)
+	}
+
+	img, err := vips.NewImageFromFile(src)
+	if err != nil {
+		return nil, fmt.Errorf("load image %s: %w", src, err)
+	}
+	defer img.Close()
+
+	if width > 0 && width < img.Width() {
+		scale := float64(width) / float64(img.Width())
+		if err := img.Resize(scale, vips.KernelLanczos3); err != nil {
+			return nil, fmt.Errorf("resize: %w", err)
+		}
+	}
+
+	switch format {
+	case "webp":
+		buf, _, err := img.ExportWebp(vips.NewWebpExportParams())
+		if err != nil {
+			return nil, fmt.Errorf("export webp: %w", err)
+		}
+		return buf, nil
+	case "jpeg":
+		buf, _, err := img.ExportJpeg(vips.NewJpegExportParams())
+		if err != nil {
+			return nil, fmt.Errorf("export jpeg: %w", err)
+		}
+		return buf, nil
+	}
+	return nil, fmt.Errorf("unsupported format %q", format)
+}