package k8s

import (
	"context"
	"fmt"
	"strings"
	"time"

	spclient "github.com/linkerd/linkerd2/controller/gen/client/clientset/versioned"
	sp "github.com/linkerd/linkerd2/controller/gen/client/informers/externalversions"
	spinformers "github.com/linkerd/linkerd2/controller/gen/client/informers/externalversions/serviceprofile/v1alpha1"
	"github.com/linkerd/linkerd2/pkg/k8s"
	log "github.com/sirupsen/logrus"
	"google.golang.org/grpc/codes"
	"google.golang.org/grpc/status"
	appsv1 "k8s.io/api/apps/v1"
	appsv1beta2 "k8s.io/api/apps/v1beta2"
	apiv1 "k8s.io/api/core/v1"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/apimachinery/pkg/labels"
	"k8s.io/apimachinery/pkg/runtime"
	"k8s.io/client-go/informers"
	arinformers "k8s.io/client-go/informers/admissionregistration/v1beta1"
	appv1informers "k8s.io/client-go/informers/apps/v1"
	appv1beta2informers "k8s.io/client-go/informers/apps/v1beta2"
	coreinformers "k8s.io/client-go/informers/core/v1"
	"k8s.io/client-go/kubernetes"
	"k8s.io/client-go/tools/cache"
)

// APIResource is an enum for Kubernetes API resource types, for use when
// initializing a K8s API, to describe which resource types to interact with.
type APIResource int

// These constants enumerate Kubernetes resource types.
const (
	CM APIResource = iota
	Deploy
	DS
	Endpoint
	MWC // mutating webhook configuration
	Pod
	RC
	RS
	SP
	Svc
)

// API provides shared informers for all Kubernetes objects
type API struct {
	Client kubernetes.Interface

	cm       coreinformers.ConfigMapInformer
	deploy   appv1beta2informers.DeploymentInformer
	ds       appv1informers.DaemonSetInformer
	endpoint coreinformers.EndpointsInformer
	mwc      arinformers.MutatingWebhookConfigurationInformer
	pod      coreinformers.PodInformer
	rc       coreinformers.ReplicationControllerInformer
	rs       appv1beta2informers.ReplicaSetInformer
	sp       spinformers.ServiceProfileInformer
	svc      coreinformers.ServiceInformer

	syncChecks        []cache.InformerSynced
	sharedInformers   informers.SharedInformerFactory
	spSharedInformers sp.SharedInformerFactory
	namespace         string
}

// NewAPI takes a Kubernetes client and returns an initialized API
func NewAPI(k8sClient kubernetes.Interface, spClient spclient.Interface, namespace string, resources ...APIResource) *API {
	var sharedInformers informers.SharedInformerFactory
	var spSharedInformers sp.SharedInformerFactory
	if namespace == "" {
		sharedInformers = informers.NewSharedInformerFactory(k8sClient, 10*time.Minute)
		spSharedInformers = sp.NewSharedInformerFactory(spClient, 10*time.Minute)
	} else {
		sharedInformers = informers.NewFilteredSharedInformerFactory(
			k8sClient,
			10*time.Minute,
			namespace,
			nil,
		)
		spSharedInformers = sp.NewFilteredSharedInformerFactory(
			spClient,
			10*time.Minute,
			namespace,
			nil,
		)
	}

	api := &API{
		Client:            k8sClient,
		syncChecks:        make([]cache.InformerSynced, 0),
		sharedInformers:   sharedInformers,
		spSharedInformers: spSharedInformers,
		namespace:         namespace,
	}

	for _, resource := range resources {
		switch resource {
		case CM:
			api.cm = sharedInformers.Core().V1().ConfigMaps()
			api.syncChecks = append(api.syncChecks, api.cm.Informer().HasSynced)
		case Deploy:
			api.deploy = sharedInformers.Apps().V1beta2().Deployments()
			api.syncChecks = append(api.syncChecks, api.deploy.Informer().HasSynced)
		case DS:
			api.ds = sharedInformers.Apps().V1().DaemonSets()
			api.syncChecks = append(api.syncChecks, api.ds.Informer().HasSynced)
		case Endpoint:
			api.endpoint = sharedInformers.Core().V1().Endpoints()
			api.syncChecks = append(api.syncChecks, api.endpoint.Informer().HasSynced)
		case MWC:
			api.mwc = sharedInformers.Admissionregistration().V1beta1().MutatingWebhookConfigurations()
			api.syncChecks = append(api.syncChecks, api.mwc.Informer().HasSynced)
		case Pod:
			api.pod = sharedInformers.Core().V1().Pods()
			api.syncChecks = append(api.syncChecks, api.pod.Informer().HasSynced)
		case RC:
			api.rc = sharedInformers.Core().V1().ReplicationControllers()
			api.syncChecks = append(api.syncChecks, api.rc.Informer().HasSynced)
		case RS:
			api.rs = sharedInformers.Apps().V1beta2().ReplicaSets()
			api.syncChecks = append(api.syncChecks, api.rs.Informer().HasSynced)
		case SP:
			api.sp = spSharedInformers.Linkerd().V1alpha1().ServiceProfiles()
			api.syncChecks = append(api.syncChecks, api.sp.Informer().HasSynced)
		case Svc:
			api.svc = sharedInformers.Core().V1().Services()
			api.syncChecks = append(api.syncChecks, api.svc.Informer().HasSynced)
		}
	}

	return api
}

// Sync waits for all informers to be synced.
func (api *API) Sync() {
	api.sharedInformers.Start(nil)
	api.spSharedInformers.Start(nil)

	ctx, cancel := context.WithTimeout(context.Background(), 60*time.Second)
	defer cancel()

	log.Infof("waiting for caches to sync")
	if !cache.WaitForCacheSync(ctx.Done(), api.syncChecks...) {
		log.Fatal("failed to sync caches")
	}
	log.Infof("caches synced")
}

// Deploy provides access to a shared informer and lister for Deployments.
func (api *API) Deploy() appv1beta2informers.DeploymentInformer {
	if api.deploy == nil {
		panic("Deploy informer not configured")
	}
	return api.deploy
}

// DS provides access to a shared informer and lister for Daemonsets.
func (api *API) DS() appv1informers.DaemonSetInformer {
	if api.ds == nil {
		panic("DS informer not configured")
	}
	return api.ds
}

// RS provides access to a shared informer and lister for ReplicaSets.
func (api *API) RS() appv1beta2informers.ReplicaSetInformer {
	if api.rs == nil {
		panic("RS informer not configured")
	}
	return api.rs
}

// Pod provides access to a shared informer and lister for Pods.
func (api *API) Pod() coreinformers.PodInformer {
	if api.pod == nil {
		panic("Pod informer not configured")
	}
	return api.pod
}

// RC provides access to a shared informer and lister for
// ReplicationControllers.
func (api *API) RC() coreinformers.ReplicationControllerInformer {
	if api.rc == nil {
		panic("RC informer not configured")
	}
	return api.rc
}

// Svc provides access to a shared informer and lister for Services.
func (api *API) Svc() coreinformers.ServiceInformer {
	if api.svc == nil {
		panic("Svc informer not configured")
	}
	return api.svc
}

// Endpoint provides access to a shared informer and lister for Endpoints.
func (api *API) Endpoint() coreinformers.EndpointsInformer {
	if api.endpoint == nil {
		panic("Endpoint informer not configured")
	}
	return api.endpoint
}

// CM provides access to a shared informer and lister for ConfigMaps.
func (api *API) CM() coreinformers.ConfigMapInformer {
	if api.cm == nil {
		panic("CM informer not configured")
	}
	return api.cm
}

// SP provides access to a shared informer and lister for ServiceProfiles.
func (api *API) SP() spinformers.ServiceProfileInformer {
	if api.sp == nil {
		panic("SP informer not configured")
	}
	return api.sp
}

// MWC provides access to a shared informer and lister for MutatingWebhookConfigurations.
func (api *API) MWC() arinformers.MutatingWebhookConfigurationInformer {
	if api.mwc == nil {
		panic("MWC informer not configured")
	}
	return api.mwc
}

// GetObjects returns a list of Kubernetes objects, given a namespace, type, and name.
// If namespace is an empty string, match objects in all namespaces.
// If name is an empty string, match all objects of the given type.
func (api *API) GetObjects(namespace, restype, name string) ([]runtime.Object, error) {
	switch restype {
	case k8s.Namespace:
		return api.getNamespaces(name)
	case k8s.DaemonSet:
		return api.getDaemonsets(namespace, name)
	case k8s.Deployment:
		return api.getDeployments(namespace, name)
	case k8s.Pod:
		return api.getPods(namespace, name)
	case k8s.ReplicationController:
		return api.getRCs(namespace, name)
	case k8s.Service:
		return api.getServices(namespace, name)
	default:
		// TODO: ReplicaSet
		return nil, status.Errorf(codes.Unimplemented, "unimplemented resource type: %s", restype)
	}
}

// GetOwnerKindAndName returns the pod owner's kind and name, using owner
// references from the Kubernetes API. The kind is represented as the Kubernetes
// singular resource type (e.g. deployment, daemonset, job, etc.)
func (api *API) GetOwnerKindAndName(pod *apiv1.Pod) (string, string) {
	if len(pod.GetOwnerReferences()) != 1 {
		return "pod", pod.Name
	}

	parent := pod.GetOwnerReferences()[0]
	if parent.Kind == "ReplicaSet" {
		rs, err := api.RS().Lister().ReplicaSets(pod.Namespace).Get(parent.Name)
		if err != nil || len(rs.GetOwnerReferences()) != 1 {
			return strings.ToLower(parent.Kind), parent.Name
		}
		rsParent := rs.GetOwnerReferences()[0]
		return strings.ToLower(rsParent.Kind), rsParent.Name
	}

	return strings.ToLower(parent.Kind), parent.Name
}

// GetPodsFor returns all running and pending Pods associated with a given
// Kubernetes object. Use includeFailed to also get failed Pods
func (api *API) GetPodsFor(obj runtime.Object, includeFailed bool) ([]*apiv1.Pod, error) {
	var namespace string
	var selector labels.Selector
	var pods []*apiv1.Pod
	var err error

	switch typed := obj.(type) {
	case *apiv1.Namespace:
		namespace = typed.Name
		selector = labels.Everything()

	case *appsv1.DaemonSet:
		namespace = typed.Namespace
		selector = labels.Set(typed.Spec.Selector.MatchLabels).AsSelector()

	case *appsv1beta2.Deployment:
		namespace = typed.Namespace
		selector = labels.Set(typed.Spec.Selector.MatchLabels).AsSelector()

	case *appsv1beta2.ReplicaSet:
		namespace = typed.Namespace
		selector = labels.Set(typed.Spec.Selector.MatchLabels).AsSelector()

	case *apiv1.ReplicationController:
		namespace = typed.Namespace
		selector = labels.Set(typed.Spec.Selector).AsSelector()

	case *apiv1.Service:
		namespace = typed.Namespace
		selector = labels.Set(typed.Spec.Selector).AsSelector()

	case *apiv1.Pod:
		// Special case for pods:
		// GetPodsFor a pod should just return the pod itself
		namespace = typed.Namespace
		pod, err := api.Pod().Lister().Pods(typed.Namespace).Get(typed.Name)
		if err != nil {
			return nil, err
		}
		pods = []*apiv1.Pod{pod}

	default:
		return nil, fmt.Errorf("Cannot get object selector: %v", obj)
	}

	// if obj.(type) is Pod, we've already retrieved it and put it in pods
	// for the other types, pods will still be empty
	if len(pods) == 0 {
		pods, err = api.Pod().Lister().Pods(namespace).List(selector)
		if err != nil {
			return nil, err
		}
	}

	allPods := []*apiv1.Pod{}
	for _, pod := range pods {
		if isPendingOrRunning(pod) || (includeFailed && isFailed(pod)) {
			allPods = append(allPods, pod)
		}
	}

	return allPods, nil
}

// GetNameAndNamespaceOf returns the name and namespace of the given object.
func GetNameAndNamespaceOf(obj runtime.Object) (string, string, error) {
	switch typed := obj.(type) {
	case *apiv1.Namespace:
		return typed.Name, typed.Name, nil

	case *appsv1.DaemonSet:
		return typed.Name, typed.Namespace, nil

	case *appsv1beta2.Deployment:
		return typed.Name, typed.Namespace, nil

	case *appsv1beta2.ReplicaSet:
		return typed.Name, typed.Namespace, nil

	case *apiv1.ReplicationController:
		return typed.Name, typed.Namespace, nil

	case *apiv1.Service:
		return typed.Name, typed.Namespace, nil

	case *apiv1.Pod:
		return typed.Name, typed.Namespace, nil

	default:
		return "", "", fmt.Errorf("Cannot determine object type: %v", obj)
	}
}

// GetNameOf returns the name of the given object.
func GetNameOf(obj runtime.Object) (string, error) {
	name, _, err := GetNameAndNamespaceOf(obj)
	if err != nil {
		return "", err
	}
	return name, nil
}

// GetNamespaceOf returns the namespace of the given object.
func GetNamespaceOf(obj runtime.Object) (string, error) {
	_, namespace, err := GetNameAndNamespaceOf(obj)
	if err != nil {
		return "", err
	}
	return namespace, nil
}

// getNamespaces returns the namespace matching the specified name. If no name
// is given, it returns all namespaces, unless the API was configured to only
// work with a single namespace, in which case it returns that namespace. Note
// that namespace reads are not cached.
func (api *API) getNamespaces(name string) ([]runtime.Object, error) {
	namespaces := make([]*apiv1.Namespace, 0)

	if name == "" && api.namespace != "" {
		name = api.namespace
	}

	if name == "" {
		namespaceList, err := api.Client.CoreV1().Namespaces().List(metav1.ListOptions{})
		if err != nil {
			return nil, err
		}
		for _, item := range namespaceList.Items {
			ns := item // must create separate var in order to get unique pointers
			namespaces = append(namespaces, &ns)
		}
	} else {
		namespace, err := api.Client.CoreV1().Namespaces().Get(name, metav1.GetOptions{})
		if err != nil {
			return nil, err
		}
		namespaces = []*apiv1.Namespace{namespace}
	}

	objects := []runtime.Object{}
	for _, ns := range namespaces {
		objects = append(objects, ns)
	}

	return objects, nil
}

func (api *API) getDeployments(namespace, name string) ([]runtime.Object, error) {
	var err error
	var deploys []*appsv1beta2.Deployment

	if namespace == "" {
		deploys, err = api.Deploy().Lister().List(labels.Everything())
	} else if name == "" {
		deploys, err = api.Deploy().Lister().Deployments(namespace).List(labels.Everything())
	} else {
		var deploy *appsv1beta2.Deployment
		deploy, err = api.Deploy().Lister().Deployments(namespace).Get(name)
		deploys = []*appsv1beta2.Deployment{deploy}
	}

	if err != nil {
		return nil, err
	}

	objects := []runtime.Object{}
	for _, deploy := range deploys {
		objects = append(objects, deploy)
	}

	return objects, nil
}

func (api *API) getPods(namespace, name string) ([]runtime.Object, error) {
	var err error
	var pods []*apiv1.Pod

	if namespace == "" {
		pods, err = api.Pod().Lister().List(labels.Everything())
	} else if name == "" {
		pods, err = api.Pod().Lister().Pods(namespace).List(labels.Everything())
	} else {
		var pod *apiv1.Pod
		pod, err = api.Pod().Lister().Pods(namespace).Get(name)
		pods = []*apiv1.Pod{pod}
	}

	if err != nil {
		return nil, err
	}

	objects := []runtime.Object{}
	for _, pod := range pods {
		if !isPendingOrRunning(pod) {
			continue
		}
		objects = append(objects, pod)
	}

	return objects, nil
}

func (api *API) getRCs(namespace, name string) ([]runtime.Object, error) {
	var err error
	var rcs []*apiv1.ReplicationController

	if namespace == "" {
		rcs, err = api.RC().Lister().List(labels.Everything())
	} else if name == "" {
		rcs, err = api.RC().Lister().ReplicationControllers(namespace).List(labels.Everything())
	} else {
		var rc *apiv1.ReplicationController
		rc, err = api.RC().Lister().ReplicationControllers(namespace).Get(name)
		rcs = []*apiv1.ReplicationController{rc}
	}

	if err != nil {
		return nil, err
	}

	objects := []runtime.Object{}
	for _, rc := range rcs {
		objects = append(objects, rc)
	}

	return objects, nil
}

func (api *API) getDaemonsets(namespace, name string) ([]runtime.Object, error) {
	var err error
	var daemonsets []*appsv1.DaemonSet

	if namespace == "" {
		daemonsets, err = api.DS().Lister().List(labels.Everything())
	} else if name == "" {
		daemonsets, err = api.DS().Lister().DaemonSets(namespace).List(labels.Everything())
	} else {
		var ds *appsv1.DaemonSet
		ds, err = api.DS().Lister().DaemonSets(namespace).Get(name)
		daemonsets = []*appsv1.DaemonSet{ds}
	}

	if err != nil {
		return nil, err
	}

	objects := []runtime.Object{}
	for _, ds := range daemonsets {
		objects = append(objects, ds)
	}

	return objects, nil
}

func (api *API) getServices(namespace, name string) ([]runtime.Object, error) {
	services, err := api.GetServices(namespace, name)

	if err != nil {
		return nil, err
	}

	objects := []runtime.Object{}
	for _, svc := range services {
		objects = append(objects, svc)
	}

	return objects, nil
}

// GetServices returns a list of Service resources, based on input namespace and
// name.
func (api *API) GetServices(namespace, name string) ([]*apiv1.Service, error) {
	var err error
	var services []*apiv1.Service

	if namespace == "" {
		services, err = api.Svc().Lister().List(labels.Everything())
	} else if name == "" {
		services, err = api.Svc().Lister().Services(namespace).List(labels.Everything())
	} else {
		var svc *apiv1.Service
		svc, err = api.Svc().Lister().Services(namespace).Get(name)
		services = []*apiv1.Service{svc}
	}

	return services, err
}

// GetServicesFor returns all Service resources which include a pod of the given
// resource object.  In other words, it returns all Services of which the given
// resource object is a part of.
func (api *API) GetServicesFor(obj runtime.Object, includeFailed bool) ([]*apiv1.Service, error) {
	if svc, ok := obj.(*apiv1.Service); ok {
		return []*apiv1.Service{svc}, nil
	}

	pods, err := api.GetPodsFor(obj, includeFailed)
	if err != nil {
		return nil, err
	}
	namespace, err := GetNamespaceOf(obj)
	if err != nil {
		return nil, err
	}
	allServices, err := api.GetServices(namespace, "")
	if err != nil {
		return nil, err
	}
	services := make([]*apiv1.Service, 0)
	for _, svc := range allServices {
		svcPods, err := api.GetPodsFor(svc, includeFailed)
		if err != nil {
			return nil, err
		}
		if hasOverlap(pods, svcPods) {
			services = append(services, svc)
		}
	}
	return services, nil
}

func hasOverlap(as, bs []*apiv1.Pod) bool {
	for _, a := range as {
		for _, b := range bs {
			if a.Name == b.Name {
				return true
			}
		}
	}
	return false
}

func isPendingOrRunning(pod *apiv1.Pod) bool {
	pending := pod.Status.Phase == apiv1.PodPending
	running := pod.Status.Phase == apiv1.PodRunning
	terminating := pod.DeletionTimestamp != nil
	return (pending || running) && !terminating
}

func isFailed(pod *apiv1.Pod) bool {
	return pod.Status.Phase == apiv1.PodFailed
}