rings: add String() to RegionID, ZoneID, NodeID

Signed-off-by: Alejandro Mery <amery@jpi.io>

pkg/rings/rings.go

@@ -3,6 +3,8 @@
 package rings
 
 import (
+	"fmt"
+	"strconv"
 	"syscall"
 
 	"darvaza.org/core"
@@ -37,12 +39,20 @@ type RegionID int
 // Valid tells a [RegionID] is within the valid range.
 func (n RegionID) Valid() bool { return n > 0 && n <= RegionMax }
 
+func (n RegionID) String() string {
+	return idString(n)
+}
+
 // ZoneID is the identifier of a zone within a region, valid between 1 and [ZoneMax].
 type ZoneID int
 
 // Valid tells a [ZoneID] is within the valid range.
 func (n ZoneID) Valid() bool { return n > 0 && n <= ZoneMax }
 
+func (n ZoneID) String() string {
+	return idString(n)
+}
+
 // NodeID is the identifier of a machine within a zone of a region, valid between
 // 1 and [NodeMax], but between 1 and [NodeZeroMax] if it will be a zone gateway.
 type NodeID int
@@ -53,8 +63,28 @@ func (n NodeID) Valid() bool { return n > 0 && n <= NodeMax }
 // ValidZero tells a [NodeID] is within the valid range for a gateway.
 func (n NodeID) ValidZero() bool { return n > 0 && n <= NodeZeroMax }
 
+func (n NodeID) String() string {
+	return idString(n)
+}
+
 // ErrOutOfRange is an error indicating the value of a field
 // is out of range.
 func ErrOutOfRange[T ~int | ~uint32](value T, field string) error {
 	return core.Wrap(syscall.EINVAL, "%s out of range (%v)", field, value)
 }
+
+type intID interface {
+	~int
+	Valid() bool
+}
+
+func idString[T intID](p T) string {
+	switch {
+	case p == 0:
+		return "unspecified"
+	case p.Valid():
+		return strconv.Itoa(int(p))
+	default:
+		return fmt.Sprintf("invalid (%v)", int(p))
+	}
+}