package internal

import (
	"fmt"
	"strings"
	"time"

	log "github.com/sirupsen/logrus"
	v1 "k8s.io/api/coordination/v1"
	"k8s.io/client-go/informers"
	"k8s.io/client-go/tools/cache"
)

// StartLeaseInformer starts a long-running informer watching Lease objects in the kube-system namespace.
// It will react to Add/Update events for leases whose name starts with "cilium-l2announce" and label
// the corresponding node.
func StartLeaseInformer(cfg *Config, stopCh <-chan struct{}) error {
	log.WithFields(log.Fields{"Caller": "StartLeaseInformer"}).Info("Starting lease informer")

	client, err := generateClient()
	if err != nil {
		return fmt.Errorf("Could not generate client for informer: %s", err.Error())
	}

	factory := informers.NewSharedInformerFactoryWithOptions(&client, 0, informers.WithNamespace("kube-system"))
	leaseInformer := factory.Coordination().V1().Leases().Informer()

	leaseInformer.AddEventHandler(cache.ResourceEventHandlerFuncs{
		AddFunc: func(obj interface{}) {
			handleLease(obj, cfg)
		},
		UpdateFunc: func(oldObj, newObj interface{}) {
			handleLease(newObj, cfg)
		},
		DeleteFunc: func(obj interface{}) {
			// nothing to do on delete for now
		},
	})

	factory.Start(stopCh)

	// wait for cache sync with timeout
	synced := make(chan struct{})
	go func() {
		if !cache.WaitForCacheSync(stopCh, leaseInformer.HasSynced) {
			close(synced)
			return
		}
		close(synced)
	}()

	select {
	case <-synced:
		// proceed
	case <-time.After(15 * time.Second):
		return fmt.Errorf("timed out waiting for informer cache sync")
	}

	log.WithFields(log.Fields{"Caller": "StartLeaseInformer"}).Info("Lease informer running")
	return nil
}

func handleLease(obj interface{}, cfg *Config) {
	lease, ok := obj.(*v1.Lease)
	if !ok {
		log.WithFields(log.Fields{"Caller": "handleLease"}).Warn("Could not cast object to Lease")
		return
	}

	if lease == nil {
		return
	}

	if lease.Name == "" || len(lease.Name) < 1 {
		return
	}

	if !strings.HasPrefix(lease.Name, "cilium-l2announce") {
		return
	}

	node, err := GetNodeNameFromLease(*lease)
	if err != nil {
		log.WithFields(log.Fields{"Caller": "handleLease", "Lease": lease.Name}).Errorf("Error parsing lease: %s", err.Error())
		return
	}

	if cfg.DryRun {
		log.WithFields(log.Fields{"Caller": "handleLease"}).Infof("Dry run: would label node %s with %s=true (lease %s)", node, cfg.CiliumLabel, lease.Name)
		return
	}

	err = LabelNode(node, lease.Name, cfg)
	if err != nil {
		log.WithFields(log.Fields{"Caller": "handleLease", "Node": node, "Lease": lease.Name}).Errorf("Error labeling node: %s", err.Error())
	}
}