Move rule target builders into the correct locations.

internal/mappingrules/init_rules.go

@@ -3,6 +3,7 @@ package mappingrules
 import (
 	"errors"
 	"fmt"
+	"slices"
 	"strings"
 
 	"git.annabunches.net/annabunches/joyful/internal/configparser"
@@ -60,3 +61,19 @@ func NewRule(config configparser.RuleConfig, pDevs map[string]Device, vDevs map[
 
 	return newRule, nil
 }
+
+// validateModes checks the provided modes against a larger subset of modes (usually all defined ones)
+// and returns false if any of the modes are not defined.
+func validateModes(modes []string, allModes []string) bool {
+	if len(modes) == 0 {
+		return true
+	}
+
+	for _, mode := range modes {
+		if !slices.Contains(allModes, mode) {
+			return false
+		}
+	}
+
+	return true
+}