watchtower/wtwire/error_code: add human-readable descriptors

watchtower/wtwire/error_code.go

@@ -1,5 +1,7 @@
 package wtwire
 
+import "fmt"
+
 // ErrorCode represents a generic error code used when replying to watchtower
 // clients. Specific reply messages may extend the ErrorCode primitive and add
 // custom codes, so long as they don't collide with the generic error codes..
@@ -18,3 +20,33 @@ const (
 	// permanently failed, and further communication should be avoided.
 	CodePermanentFailure ErrorCode = 50
 )
+
+// String returns a human-readable description of an ErrorCode.
+func (c ErrorCode) String() string {
+	switch c {
+	case CodeOK:
+		return "CodeOK"
+	case CodeTemporaryFailure:
+		return "CodeTemporaryFailure"
+	case CodePermanentFailure:
+		return "CodePermanentFailure"
+	case CreateSessionCodeAlreadyExists:
+		return "CreateSessionCodeAlreadyExists"
+	case CreateSessionCodeRejectMaxUpdates:
+		return "CreateSessionCodeRejectMaxUpdates"
+	case CreateSessionCodeRejectRewardRate:
+		return "CreateSessionCodeRejectRewardRate"
+	case CreateSessionCodeRejectSweepFeeRate:
+		return "CreateSessionCodeRejectSweepFeeRate"
+	case CreateSessionCodeRejectBlobType:
+		return "CreateSessionCodeRejectBlobType"
+	case StateUpdateCodeClientBehind:
+		return "StateUpdateCodeClientBehind"
+	case StateUpdateCodeMaxUpdatesExceeded:
+		return "StateUpdateCodeMaxUpdatesExceeded"
+	case StateUpdateCodeSeqNumOutOfOrder:
+		return "StateUpdateCodeSeqNumOutOfOrder"
+	default:
+		return fmt.Sprintf("UnknownErrorCode: %d", c)
+	}
+}