NGINX Ingress Provider

Co-authored-by: Kevin Pollet <pollet.kevin@gmail.com>

pkg/provider/kubernetes/ingress-nginx/convert.go

@@ -0,0 +1,69 @@
+package ingressnginx
+
+import (
+	"errors"
+
+	corev1 "k8s.io/api/core/v1"
+	netv1 "k8s.io/api/networking/v1"
+)
+
+type marshaler interface {
+	Marshal() ([]byte, error)
+}
+
+type unmarshaler interface {
+	Unmarshal(data []byte) error
+}
+
+type LoadBalancerIngress interface {
+	corev1.LoadBalancerIngress | netv1.IngressLoadBalancerIngress
+}
+
+// convertSlice converts slice of LoadBalancerIngress to slice of LoadBalancerIngress.
+// O (Bar), I (Foo) => []Bar.
+func convertSlice[O LoadBalancerIngress, I LoadBalancerIngress](loadBalancerIngresses []I) ([]O, error) {
+	var results []O
+
+	for _, loadBalancerIngress := range loadBalancerIngresses {
+		mar, ok := any(&loadBalancerIngress).(marshaler)
+		if !ok {
+			// All the pointer of types related to the interface LoadBalancerIngress are compatible with the interface marshaler.
+			continue
+		}
+
+		um, err := convert[O](mar)
+		if err != nil {
+			return nil, err
+		}
+
+		v, ok := any(*um).(O)
+		if !ok {
+			continue
+		}
+
+		results = append(results, v)
+	}
+
+	return results, nil
+}
+
+// convert must only be used with unmarshaler and marshaler compatible types.
+func convert[T any](input marshaler) (*T, error) {
+	data, err := input.Marshal()
+	if err != nil {
+		return nil, err
+	}
+
+	var output T
+	um, ok := any(&output).(unmarshaler)
+	if !ok {
+		return nil, errors.New("the output type doesn't implement unmarshaler interface")
+	}
+
+	err = um.Unmarshal(data)
+	if err != nil {
+		return nil, err
+	}
+
+	return &output, nil
+}