package cluster

import (
	"fmt"
	v1 "k8s.io/api/core/v1"
	"k8s.io/apimachinery/pkg/api/errors"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	utilruntime "k8s.io/apimachinery/pkg/util/runtime"
	"k8s.io/apimachinery/pkg/util/wait"
	"k8s.io/client-go/kubernetes"
	"k8s.io/client-go/kubernetes/scheme"
	v1core "k8s.io/client-go/kubernetes/typed/core/v1"
	"k8s.io/client-go/tools/cache"
	"k8s.io/client-go/tools/record"
	"k8s.io/client-go/util/retry"
	"k8s.io/client-go/util/workqueue"
	"k8s.io/klog"
	clusterv1alpha1 "kubesphere.io/kubesphere/pkg/apis/cluster/v1alpha1"
	clusterclient "kubesphere.io/kubesphere/pkg/client/clientset/versioned/typed/cluster/v1alpha1"
	clusterinformer "kubesphere.io/kubesphere/pkg/client/informers/externalversions/cluster/v1alpha1"
	clusterlister "kubesphere.io/kubesphere/pkg/client/listers/cluster/v1alpha1"
	"time"
)

const (
	// maxRetries is the number of times a service will be retried before it is dropped out of the queue.
	// With the current rate-limiter in use (5ms*2^(maxRetries-1)) the following numbers represent the
	// sequence of delays between successive queuings of a service.
	//
	// 5ms, 10ms, 20ms, 40ms, 80ms, 160ms, 320ms, 640ms, 1.3s, 2.6s, 5.1s, 10.2s, 20.4s, 41s, 82s
	maxRetries = 15
)

type ClusterController struct {
	eventBroadcaster record.EventBroadcaster
	eventRecorder    record.EventRecorder

	agentClient   clusterclient.AgentInterface
	clusterClient clusterclient.ClusterInterface

	agentLister    clusterlister.AgentLister
	agentHasSynced cache.InformerSynced

	clusterLister    clusterlister.ClusterLister
	clusterHasSynced cache.InformerSynced

	queue workqueue.RateLimitingInterface

	workerLoopPeriod time.Duration
}

func NewClusterController(
	client kubernetes.Interface,
	clusterInformer clusterinformer.ClusterInformer,
	agentInformer clusterinformer.AgentInformer,
	agentClient clusterclient.AgentInterface,
	clusterClient clusterclient.ClusterInterface,
) *ClusterController {

	broadcaster := record.NewBroadcaster()
	broadcaster.StartLogging(func(format string, args ...interface{}) {
		klog.Info(fmt.Sprintf(format, args))
	})
	broadcaster.StartRecordingToSink(&v1core.EventSinkImpl{Interface: client.CoreV1().Events("")})
	recorder := broadcaster.NewRecorder(scheme.Scheme, v1.EventSource{Component: "cluster-controller"})

	c := &ClusterController{
		eventBroadcaster: broadcaster,
		eventRecorder:    recorder,
		agentClient:      agentClient,
		clusterClient:    clusterClient,
		queue:            workqueue.NewNamedRateLimitingQueue(workqueue.DefaultControllerRateLimiter(), "cluster"),
		workerLoopPeriod: time.Second,
	}

	c.agentLister = agentInformer.Lister()
	c.agentHasSynced = agentInformer.Informer().HasSynced

	c.clusterLister = clusterInformer.Lister()
	c.clusterHasSynced = clusterInformer.Informer().HasSynced

	clusterInformer.Informer().AddEventHandler(cache.ResourceEventHandlerFuncs{
		AddFunc: c.addCluster,
		UpdateFunc: func(oldObj, newObj interface{}) {
			c.addCluster(newObj)
		},
		DeleteFunc: c.addCluster,
	})

	return c
}

func (c *ClusterController) Start(stopCh <-chan struct{}) error {
	return c.Run(5, stopCh)
}

func (c *ClusterController) Run(workers int, stopCh <-chan struct{}) error {
	defer utilruntime.HandleCrash()
	defer c.queue.ShutDown()

	klog.V(0).Info("starting cluster controller")
	defer klog.Info("shutting down cluster controller")

	if !cache.WaitForCacheSync(stopCh, c.clusterHasSynced, c.agentHasSynced) {
		return fmt.Errorf("failed to wait for caches to sync")
	}

	for i := 0; i < workers; i++ {
		go wait.Until(c.worker, c.workerLoopPeriod, stopCh)
	}

	<-stopCh
	return nil
}

func (c *ClusterController) worker() {
	for c.processNextItem() {
	}
}

func (c *ClusterController) processNextItem() bool {
	key, quit := c.queue.Get()
	if quit {
		return false
	}

	defer c.queue.Done(key)

	err := c.syncCluster(key.(string))
	c.handleErr(err, key)
	return true
}

func (c *ClusterController) syncCluster(key string) error {
	startTime := time.Now()

	_, name, err := cache.SplitMetaNamespaceKey(key)
	if err != nil {
		klog.Errorf("not a valid controller key %s, %#v", key, err)
		return err
	}

	defer func() {
		klog.V(4).Info("Finished syncing cluster.", "name", name, "duration", time.Since(startTime))
	}()

	cluster, err := c.clusterLister.Get(name)
	if err != nil {
		// cluster not found, possibly been deleted
		// need to do the cleanup
		if errors.IsNotFound(err) {
			_, err = c.agentLister.Get(name)
			if err != nil && errors.IsNotFound(err) {
				return nil
			}

			if err != nil {
				klog.Errorf("Failed to get cluster agent %s, %#v", name, err)
				return err
			}

			// do the real cleanup work
			err = c.agentClient.Delete(name, &metav1.DeleteOptions{})
			return err
		}

		klog.Errorf("Failed to get cluster with name %s, %#v", name, err)
		return err
	}

	newAgent := &clusterv1alpha1.Agent{
		ObjectMeta: metav1.ObjectMeta{
			Name: name,
			Labels: map[string]string{
				"app.kubernetes.io/name":     "tower",
				"cluster.kubesphere.io/name": name,
			},
		},
		Spec: clusterv1alpha1.AgentSpec{
			Token:                   "",
			KubeSphereAPIServerPort: 0,
			KubernetesAPIServerPort: 0,
			Proxy:                   "",
			Paused:                  !cluster.Spec.Active,
		},
	}

	agent, err := c.agentLister.Get(name)
	if err != nil && errors.IsNotFound(err) {
		agent, err = c.agentClient.Create(newAgent)
		if err != nil {
			klog.Errorf("Failed to create agent %s, %#v", name, err)
			return err
		}

		return nil
	}

	if err != nil {
		klog.Errorf("Failed to get agent %s, %#v", name, err)
		return err
	}

	if agent.Spec.Paused != newAgent.Spec.Paused {
		agent.Spec.Paused = newAgent.Spec.Paused
		return retry.RetryOnConflict(retry.DefaultBackoff, func() error {
			_, err = c.agentClient.Update(agent)
			return err
		})
	}

	return nil
}

func (c *ClusterController) addCluster(obj interface{}) {
	cluster := obj.(*clusterv1alpha1.Cluster)

	key, err := cache.MetaNamespaceKeyFunc(obj)
	if err != nil {
		utilruntime.HandleError(fmt.Errorf("get cluster key %s/%s failed", cluster.Namespace, cluster.Name))
		return
	}

	c.queue.Add(key)

}

func (c *ClusterController) handleErr(err error, key interface{}) {

}