package main

import (
	"log"

	"git.k6n.net/mats/go-cart-actor/pkg/discovery"
	v1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/client-go/kubernetes"
	"k8s.io/client-go/rest"
)

// GetDiscovery returns the k8s pod-watcher that finds peer profile replicas, or
// nil when POD_IP is unset (single-node / local dev — clustering disabled). The
// watch is scoped to this pod's own namespace so it only needs a namespaced Role
// (pods: get/list/watch), not a cluster-wide role.
func GetDiscovery() discovery.Discovery {
	if podIp == "" {
		return nil
	}

	config, kerr := rest.InClusterConfig()
	if kerr != nil {
		log.Fatalf("Error creating kubernetes client: %v\n", kerr)
	}
	client, err := kubernetes.NewForConfig(config)
	if err != nil {
		log.Fatalf("Error creating client: %v\n", err)
	}
	timeout := int64(30)
	return discovery.NewK8sDiscoveryInNamespace(client, discovery.InClusterNamespace(), v1.ListOptions{
		LabelSelector:  "actor-pool=profile",
		TimeoutSeconds: &timeout,
	})
}

// UseDiscovery starts the watch loop that adds/removes peer hosts from the pool
// as profile replicas become ready or go away. A nil discovery (POD_IP unset)
// logs and returns, leaving the pool in single-node mode.
func UseDiscovery(pool discovery.DiscoveryTarget) {
	go func(hw discovery.Discovery) {
		if hw == nil {
			log.Print("No discovery service available")
			return
		}
		ch, err := hw.Watch()
		if err != nil {
			log.Printf("Discovery error: %v", err)
			return
		}
		for evt := range ch {
			if evt.Host == "" {
				continue
			}
			switch evt.IsReady {
			case false:
				if pool.IsKnown(evt.Host) {
					log.Printf("Host %s is not ready, removing", evt.Host)
					pool.RemoveHost(evt.Host)
				}
			default:
				if !pool.IsKnown(evt.Host) {
					log.Printf("Discovered host %s", evt.Host)
					pool.AddRemoteHost(evt.Host)
				}
			}
		}
	}(GetDiscovery())
}