fix(scanner): prevent infinite recursion in pid configuration

closes #4920

Signed-off-by: Deluan <deluan@navidrome.org>

model/metadata/persistent_ids.go

@@ -8,6 +8,7 @@ import (
 
 	"github.com/navidrome/navidrome/conf"
 	"github.com/navidrome/navidrome/consts"
+	"github.com/navidrome/navidrome/log"
 	"github.com/navidrome/navidrome/model"
 	"github.com/navidrome/navidrome/model/id"
 	"github.com/navidrome/navidrome/utils"
@@ -26,10 +27,14 @@ type getPIDFunc = func(mf model.MediaFile, md Metadata, spec string, prependLibI
 
 func createGetPID(hash hashFunc) getPIDFunc {
 	var getPID getPIDFunc
-	getAttr := func(mf model.MediaFile, md Metadata, attr string, prependLibId bool) string {
+	getAttr := func(mf model.MediaFile, md Metadata, attr string, prependLibId bool, spec string) string {
 		attr = strings.TrimSpace(strings.ToLower(attr))
 		switch attr {
 		case "albumid":
+			if spec == conf.Server.PID.Album {
+				log.Error("Recursive PID definition detected, ignoring `albumid`", "spec", spec)
+				return ""
+			}
 			return getPID(mf, md, conf.Server.PID.Album, prependLibId)
 		case "folder":
 			return filepath.Dir(mf.Path)
@@ -49,7 +54,7 @@ func createGetPID(hash hashFunc) getPIDFunc {
 			attributes := strings.Split(field, ",")
 			hasValue := false
 			values := slice.Map(attributes, func(attr string) string {
-				v := getAttr(mf, md, attr, prependLibId)
+				v := getAttr(mf, md, attr, prependLibId, spec)
 				if v != "" {
 					hasValue = true
 				}

model/metadata/persistent_ids_test.go

@@ -114,6 +114,24 @@ var _ = Describe("getPID", func() {
 				Expect(getPID(mf, md, spec, false)).To(Equal("(album name)"))
 			})
 		})
+
+		When("albumid configuration refers to albumid recursively", func() {
+			It("should avoid infinite recursion", func() {
+				// Reproduce the issue from #4920
+				conf.Server.PID.Album = "albumid,album,albumversion,releasedate"
+				spec := conf.Server.PID.Album
+				md.tags = map[model.TagName][]string{
+					"album":        {"Album Name"},
+					"albumversion": {"Version"},
+					"releasedate":  {"2022"},
+				}
+				// Should not panic and return a valid PID ignoring the recursive "albumid"
+				Expect(func() {
+					pid := getPID(mf, md, spec, false)
+					Expect(pid).To(Equal("(\\album name\\Version\\2022)"))
+				}).To(Not(Panic()))
+			})
+		})
 	})
 
 	Context("edge cases", func() {