Make AtLeastAsSafeAs a function of SafetyLevel

op-supervisor/supervisor/backend/backend.go

@@ -171,34 +171,16 @@ func (su *SupervisorBackend) CheckMessages(
 		if err != nil {
 			return fmt.Errorf("failed to check message: %w", err)
 		}
-		if !atLeastAsSafe(safety, minSafety) {
-			return fmt.Errorf("message %v is not safe: %v", identifier, safety)
+		if !safety.AtLeastAsSafe(minSafety) {
+			return fmt.Errorf("message %v (safety level: %v) does not meet the minimum safety %v",
+				identifier,
+				safety,
+				minSafety)
 		}
 	}
 	return nil
 }
 
-// TODO: Really this should be a method on types.SafetyLevel
-// for now it's easy to do this calculation here
-func atLeastAsSafe(safety, minSafety types.SafetyLevel) bool {
-	switch minSafety {
-	// If for some reason the minimum safety level is invalid, then nothing is unsafe by comparison
-	case types.Invalid:
-		return true
-	// Unsafe is the lowest safety level, so it is safe so long as it isn't invalid
-	case types.Unsafe:
-		return safety != types.Invalid
-	// Safe is satisfied by Safe or Finalized
-	case types.Safe:
-		return safety == types.Safe || safety == types.Finalized
-	// Finalized is only satisfied by Finalized
-	case types.Finalized:
-		return safety == types.Finalized
-	default:
-		return false
-	}
-}
-
 // CheckBlock checks if the block is safe according to the safety level
 // The block is considered safe if all logs in the block are safe
 // this is decided by finding the last log in the block and

op-supervisor/supervisor/types/types.go

@@ -83,6 +83,22 @@ func (lvl *SafetyLevel) UnmarshalText(text []byte) error {
 	return nil
 }
 
+// AtLeastAsSafe returns true if the receiver is at least as safe as the other SafetyLevel.
+func (lvl *SafetyLevel) AtLeastAsSafe(other SafetyLevel) bool {
+	switch *lvl {
+	case Invalid:
+		return true
+	case Unsafe:
+		return other != Invalid
+	case Safe:
+		return other == Safe || other == Finalized
+	case Finalized:
+		return other == Finalized
+	default:
+		return false
+	}
+}
+
 const (
 	CrossFinalized SafetyLevel = "cross-finalized"
 	Finalized      SafetyLevel = "finalized"