Fix tests and lint errors, plus a bit of refactor

server/public/encode_id.go

@@ -0,0 +1,71 @@
+package public
+
+import (
+	"context"
+	"errors"
+	"net/http"
+	"net/url"
+	"path/filepath"
+	"strconv"
+
+	"github.com/lestrrat-go/jwx/v2/jwt"
+	"github.com/navidrome/navidrome/consts"
+	"github.com/navidrome/navidrome/core/auth"
+	"github.com/navidrome/navidrome/model"
+	"github.com/navidrome/navidrome/server"
+)
+
+func ImageURL(r *http.Request, artID model.ArtworkID, size int) string {
+	link := encodeArtworkID(artID)
+	path := filepath.Join(consts.URLPathPublicImages, link)
+	params := url.Values{}
+	if size > 0 {
+		params.Add("size", strconv.Itoa(size))
+	}
+	return server.AbsoluteURL(r, path, params)
+}
+
+func encodeArtworkID(artID model.ArtworkID) string {
+	token, _ := auth.CreatePublicToken(map[string]any{"id": artID.String()})
+	return token
+}
+
+func decodeArtworkID(tokenString string) (model.ArtworkID, error) {
+	token, err := auth.TokenAuth.Decode(tokenString)
+	if err != nil {
+		return model.ArtworkID{}, err
+	}
+	if token == nil {
+		return model.ArtworkID{}, errors.New("unauthorized")
+	}
+	err = jwt.Validate(token, jwt.WithRequiredClaim("id"))
+	if err != nil {
+		return model.ArtworkID{}, err
+	}
+	claims, err := token.AsMap(context.Background())
+	if err != nil {
+		return model.ArtworkID{}, err
+	}
+	id, ok := claims["id"].(string)
+	if !ok {
+		return model.ArtworkID{}, errors.New("invalid id type")
+	}
+	artID, err := model.ParseArtworkID(id)
+	if err == nil {
+		return artID, nil
+	}
+	// Try to default to mediafile artworkId (if used with a mediafileShare token)
+	return model.ParseArtworkID("mf-" + id)
+}
+
+func encodeMediafileShare(s model.Share, id string) string {
+	claims := map[string]any{"id": id}
+	if s.Format != "" {
+		claims["f"] = s.Format
+	}
+	if s.MaxBitRate != 0 {
+		claims["b"] = s.MaxBitRate
+	}
+	token, _ := auth.CreateExpiringPublicToken(s.ExpiresAt, claims)
+	return token
+}