package main

import (
	corev1 "k8s.io/api/core/v1"
	"k8s.io/apimachinery/pkg/fields"
	"k8s.io/client-go/kubernetes"
	"k8s.io/client-go/tools/cache"
	"k8s.io/klog/v2"
)

type Watcher struct {
}

func (watcher *Watcher) WatchPods(
	clientset *kubernetes.Clientset,
	namespace string) {

	watchlist := cache.NewListWatchFromClient(
		clientset.CoreV1().RESTClient(),
		"pods",
		namespace,
		fields.Everything(),
	)

	addOrUpdate := func(obj interface{}) {
		pod := watcher.getPod(obj)
		klog.Infof("Added/updated %s/%s\n", pod.Namespace, pod.Name)
	}

	options := cache.InformerOptions{
		ListerWatcher: watchlist,
		ObjectType:    &corev1.Pod{},
		Handler: cache.ResourceEventHandlerFuncs{
			AddFunc: addOrUpdate,
			UpdateFunc: func(_ any, obj any) {
				addOrUpdate(obj)
			},
			DeleteFunc: func(obj any) {
				pod := watcher.getPod(obj)
				klog.Infof("Delete %s/%s\n", pod.Namespace, pod.Name)
			},
		},
		ResyncPeriod: 0,
	}

	_, controller := cache.NewInformerWithOptions(options)
	stop := make(chan struct{})
	defer close(stop)
	go controller.Run(stop)
	select {}
}

func (watcher *Watcher) getPod(obj any) *corev1.Pod {
	k8spod, ok := obj.(*corev1.Pod)
	if !ok {
		klog.Fatalf("Object of wrong type: %v", obj)
	}
	return k8spod
}