homebox/backend/app/api/handlers/v1/v1_ctrl_qrcode.go

package v1

import (
	"bytes"
	"image/png"
	"io"
	"net/http"

	"github.com/hay-kot/homebox/backend/internal/sys/validate"
	"github.com/hay-kot/homebox/backend/pkgs/server"
	"github.com/yeqown/go-qrcode/v2"
	"github.com/yeqown/go-qrcode/writer/standard"

	_ "embed"
)

//go:embed assets/QRIcon.png
var qrcodeLogo []byte

// HandleGenerateQRCode godoc
//
//	@Summary  Encode data into QRCode
//	@Tags     Items
//	@Produce  json
//	@Param    data      query    string   false "data to be encoded into qrcode"
//	@Success 200 {string} string "image/jpeg"
//	@Router   /v1/qrcode [GET]
//	@Security Bearer
func (ctrl *V1Controller) HandleGenerateQRCode() server.HandlerFunc {
	const MaxLength = 4_296 // assume alphanumeric characters only

	return func(w http.ResponseWriter, r *http.Request) error {
		data := r.URL.Query().Get("data")

		image, err := png.Decode(bytes.NewReader(qrcodeLogo))
		if err != nil {
			panic(err)
		}

		if len(data) > MaxLength {
			return validate.NewFieldErrors(validate.FieldError{
				Field: "data",
				Error: "max length is 4,296 characters exceeded",
			})
		}

		qrc, err := qrcode.New(data)
		if err != nil {
			return err
		}

		toWriteCloser := struct {
			io.Writer
			io.Closer
		}{
			Writer: w,
			Closer: io.NopCloser(nil),
		}

		qrwriter := standard.NewWithWriter(toWriteCloser, standard.WithLogoImage(image))

		// Return the QR code as a jpeg image
		w.Header().Set("Content-Type", "image/jpeg")
		w.Header().Set("Content-Disposition", "attachment; filename=qrcode.jpg")
		return qrc.Save(qrwriter)
	}
}