rings: introduce RegionID, ZoneID and NodeID

and a Valid() method to check if their value is within the
valid range.

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

pkg/rings/rings.go

@@ -1,3 +1,37 @@
 // Package rings provides logic to work with the four rings
 // of a cluster
 package rings
+
+const (
+	// RegionMax indicates the highest number that can be used for a [RegionID].
+	RegionMax = (1 << 4) - 1
+	// ZoneMax indicates the highest number that can be used for a [ZoneID].
+	ZoneMax = (1 << 4) - 1
+	// NodeMax indicates the highest number that can be used for a [NodeID].
+	NodeMax = (1 << 12) - 1
+	// NodeZeroMax indicates the highest number that can be used for a [NodeID]
+	// when its a gateway connected to Ring 0 (backbone).
+	NodeZeroMax = (1 << 8) - 1
+)
+
+// RegionID is the identifier of a region, valid between 1 and [RegionMax].
+type RegionID int
+
+// Valid tells a [RegionID] is within the valid range.
+func (n RegionID) Valid() bool { return n > 0 && n <= RegionMax }
+
+// 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 }
+
+// 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
+
+// Valid tells a [NodeID] is within the valid range.
+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 }