/*
Copyright 2022 The Kubernetes Authors.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package utils

import (
	"os"
	"strings"

	restclient "k8s.io/client-go/rest"
	"k8s.io/client-go/tools/clientcmd"
)

var nodeName string

// NodeName returns the name of the k8s node we're running on.
func NodeName() string {
	if nodeName == "" {
		nodeName = os.Getenv("NODE_NAME")
	}
	return nodeName
}

// GetKubernetesNamespace returns the kubernetes namespace we're running under,
// or an empty string if the namespace cannot be determined.
func GetKubernetesNamespace() string {
	const kubernetesNamespaceFilePath = "/var/run/secrets/kubernetes.io/serviceaccount/namespace"
	if _, err := os.Stat(kubernetesNamespaceFilePath); err == nil {
		data, err := os.ReadFile(kubernetesNamespaceFilePath)
		if err == nil {
			return strings.TrimSpace(string(data))
		}
	}
	return os.Getenv("KUBERNETES_NAMESPACE")
}

// GetKubeconfig returns the kubeconfig for the cluster
func GetKubeconfig(path string) (*restclient.Config, error) {
	if path == "" {
		return restclient.InClusterConfig()
	}
	return clientcmd.BuildConfigFromFlags("", path)
}