// Licensed to the Apache Software Foundation (ASF) under one or more
// contributor license agreements.  See the NOTICE file distributed with
// this work for additional information regarding copyright ownership.
// The ASF licenses this file to You under the Apache License, Version 2.0
// (the "License"); you may not use this file except in compliance with
// the License.  You may obtain a copy of the License at
//
//	http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package providers

import (
	"context"
	"fmt"
	"os"
	"time"

	"go.uber.org/zap"
	v1 "k8s.io/api/core/v1"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/apimachinery/pkg/runtime"
	utilruntime "k8s.io/apimachinery/pkg/util/runtime"
	"k8s.io/client-go/kubernetes/scheme"
	typedcorev1 "k8s.io/client-go/kubernetes/typed/core/v1"
	extensionsv1beta1 "k8s.io/client-go/listers/extensions/v1beta1"
	networkingv1 "k8s.io/client-go/listers/networking/v1"
	networkingv1beta1 "k8s.io/client-go/listers/networking/v1beta1"
	"k8s.io/client-go/tools/cache"
	"k8s.io/client-go/tools/leaderelection"
	"k8s.io/client-go/tools/leaderelection/resourcelock"
	"k8s.io/client-go/tools/record"

	"github.com/apache/apisix-ingress-controller/pkg/api"
	"github.com/apache/apisix-ingress-controller/pkg/apisix"
	"github.com/apache/apisix-ingress-controller/pkg/config"
	"github.com/apache/apisix-ingress-controller/pkg/kube"
	apisixscheme "github.com/apache/apisix-ingress-controller/pkg/kube/apisix/client/clientset/versioned/scheme"
	v2 "github.com/apache/apisix-ingress-controller/pkg/kube/apisix/client/listers/config/v2"
	"github.com/apache/apisix-ingress-controller/pkg/kube/apisix/client/listers/config/v2beta3"
	"github.com/apache/apisix-ingress-controller/pkg/log"
	"github.com/apache/apisix-ingress-controller/pkg/metrics"
	apisixprovider "github.com/apache/apisix-ingress-controller/pkg/providers/apisix"
	apisixtranslation "github.com/apache/apisix-ingress-controller/pkg/providers/apisix/translation"
	"github.com/apache/apisix-ingress-controller/pkg/providers/gateway"
	ingressprovider "github.com/apache/apisix-ingress-controller/pkg/providers/ingress"
	"github.com/apache/apisix-ingress-controller/pkg/providers/k8s"
	"github.com/apache/apisix-ingress-controller/pkg/providers/k8s/namespace"
	"github.com/apache/apisix-ingress-controller/pkg/providers/k8s/pod"
	"github.com/apache/apisix-ingress-controller/pkg/providers/translation"
	providertypes "github.com/apache/apisix-ingress-controller/pkg/providers/types"
	"github.com/apache/apisix-ingress-controller/pkg/providers/utils"
)

const (
	// _component is used for event component
	_component = "ApisixIngress"
	// minimum interval for ingress sync to APISIX
	_mininumApisixResourceSyncInterval = 60 * time.Second
)

// Controller is the ingress apisix controller object.
type Controller struct {
	name             string
	namespace        string
	cfg              *config.Config
	apisix           apisix.APISIX
	apiServer        *api.Server
	MetricsCollector metrics.Collector
	kubeClient       *kube.KubeClient
	// recorder event
	recorder record.EventRecorder

	// leaderContextCancelFunc will be called when apisix-ingress-controller
	// decides to give up its leader role.
	leaderContextCancelFunc context.CancelFunc

	translator       translation.Translator
	apisixTranslator apisixtranslation.ApisixTranslator

	informers *providertypes.ListerInformer

	namespaceProvider namespace.WatchingNamespaceProvider
	podProvider       pod.Provider
	kubeProvider      k8s.Provider
	gatewayProvider   *gateway.Provider
	apisixProvider    apisixprovider.Provider
	ingressProvider   ingressprovider.Provider
}

// NewController creates an ingress apisix controller object.
func NewController(cfg *config.Config) (*Controller, error) {
	podName := os.Getenv("POD_NAME")
	podNamespace := os.Getenv("POD_NAMESPACE")
	if podNamespace == "" {
		podNamespace = "default"
	}
	client, err := apisix.NewClient(cfg.APISIX.AdminAPIVersion)
	if err != nil {
		return nil, err
	}

	kubeClient, err := kube.NewKubeClient(cfg)
	if err != nil {
		return nil, err
	}

	apiSrv, err := api.NewServer(cfg)
	if err != nil {
		return nil, err
	}

	// recorder
	utilruntime.Must(apisixscheme.AddToScheme(scheme.Scheme))
	eventBroadcaster := record.NewBroadcaster()
	eventBroadcaster.StartRecordingToSink(&typedcorev1.EventSinkImpl{Interface: kubeClient.Client.CoreV1().Events("")})

	c := &Controller{
		name:             podName,
		namespace:        podNamespace,
		cfg:              cfg,
		apiServer:        apiSrv,
		apisix:           client,
		MetricsCollector: metrics.NewPrometheusCollector(),
		kubeClient:       kubeClient,
		recorder:         eventBroadcaster.NewRecorder(scheme.Scheme, v1.EventSource{Component: _component}),
	}
	return c, nil
}

// Eventf implements the resourcelock.EventRecorder interface.
func (c *Controller) Eventf(_ runtime.Object, eventType string, reason string, message string, _ ...interface{}) {
	log.Infow(reason, zap.String("message", message), zap.String("event_type", eventType))
}

// Run launches the controller.
func (c *Controller) Run(stop chan struct{}) error {
	rootCtx, rootCancel := context.WithCancel(context.Background())
	defer rootCancel()
	go func() {
		<-stop
		rootCancel()
	}()
	c.MetricsCollector.ResetLeader(false)

	go func() {
		if err := c.apiServer.Run(rootCtx.Done()); err != nil {
			log.Errorf("failed to launch API Server: %s", err)
		}
	}()

	lock := &resourcelock.LeaseLock{
		LeaseMeta: metav1.ObjectMeta{
			Namespace: c.namespace,
			Name:      c.cfg.Kubernetes.ElectionID,
		},
		Client: c.kubeClient.Client.CoordinationV1(),
		LockConfig: resourcelock.ResourceLockConfig{
			Identity:      c.name,
			EventRecorder: c,
		},
	}
	cfg := leaderelection.LeaderElectionConfig{
		Lock:          lock,
		LeaseDuration: 15 * time.Second,
		RenewDeadline: 5 * time.Second,
		RetryPeriod:   2 * time.Second,
		Callbacks: leaderelection.LeaderCallbacks{
			OnStartedLeading: c.run,
			OnNewLeader: func(identity string) {
				log.Warnf("found a new leader %s", identity)
				if identity != c.name {
					log.Infow("controller now is running as a candidate",
						zap.String("namespace", c.namespace),
						zap.String("pod", c.name),
					)
					c.MetricsCollector.ResetLeader(false)
					// delete the old APISIX cluster, so that the cached state
					// like synchronization won't be used next time the candidate
					// becomes the leader again.
					c.apisix.DeleteCluster(c.cfg.APISIX.DefaultClusterName)
				}
			},
			OnStoppedLeading: func() {
				log.Infow("controller now is running as a candidate",
					zap.String("namespace", c.namespace),
					zap.String("pod", c.name),
				)
				c.MetricsCollector.ResetLeader(false)
				// delete the old APISIX cluster, so that the cached state
				// like synchronization won't be used next time the candidate
				// becomes the leader again.
				c.apisix.DeleteCluster(c.cfg.APISIX.DefaultClusterName)
			},
		},
		ReleaseOnCancel: true,
		Name:            "ingress-apisix",
	}
	elector, err := leaderelection.NewLeaderElector(cfg)
	if err != nil {
		log.Errorf("failed to create leader elector: %s", err.Error())
		return err
	}

election:
	curCtx, cancel := context.WithCancel(rootCtx)
	c.leaderContextCancelFunc = cancel
	elector.Run(curCtx)
	select {
	case <-rootCtx.Done():
		return nil
	default:
		goto election
	}
}

func (c *Controller) initSharedInformers() *providertypes.ListerInformer {
	kubeFactory := c.kubeClient.NewSharedIndexInformerFactory()
	apisixFactory := c.kubeClient.NewAPISIXSharedIndexInformerFactory()

	var (
		ingressInformer cache.SharedIndexInformer

		ingressListerV1                networkingv1.IngressLister
		ingressListerV1beta1           networkingv1beta1.IngressLister
		ingressListerExtensionsV1beta1 extensionsv1beta1.IngressLister
	)

	var (
		apisixUpstreamInformer      cache.SharedIndexInformer
		apisixRouteInformer         cache.SharedIndexInformer
		apisixPluginConfigInformer  cache.SharedIndexInformer
		apisixConsumerInformer      cache.SharedIndexInformer
		apisixTlsInformer           cache.SharedIndexInformer
		apisixClusterConfigInformer cache.SharedIndexInformer

		apisixRouteListerV2beta3         v2beta3.ApisixRouteLister
		apisixUpstreamListerV2beta3      v2beta3.ApisixUpstreamLister
		apisixTlsListerV2beta3           v2beta3.ApisixTlsLister
		apisixClusterConfigListerV2beta3 v2beta3.ApisixClusterConfigLister
		apisixConsumerListerV2beta3      v2beta3.ApisixConsumerLister
		apisixPluginConfigListerV2beta3  v2beta3.ApisixPluginConfigLister

		apisixRouteListerV2         v2.ApisixRouteLister
		apisixUpstreamListerV2      v2.ApisixUpstreamLister
		apisixTlsListerV2           v2.ApisixTlsLister
		apisixClusterConfigListerV2 v2.ApisixClusterConfigLister
		apisixConsumerListerV2      v2.ApisixConsumerLister
		apisixPluginConfigListerV2  v2.ApisixPluginConfigLister
	)

	switch c.cfg.Kubernetes.APIVersion {
	case config.ApisixV2beta3:
		apisixRouteInformer = apisixFactory.Apisix().V2beta3().ApisixRoutes().Informer()
		apisixTlsInformer = apisixFactory.Apisix().V2beta3().ApisixTlses().Informer()
		apisixClusterConfigInformer = apisixFactory.Apisix().V2beta3().ApisixClusterConfigs().Informer()
		apisixConsumerInformer = apisixFactory.Apisix().V2beta3().ApisixConsumers().Informer()
		apisixPluginConfigInformer = apisixFactory.Apisix().V2beta3().ApisixPluginConfigs().Informer()
		apisixUpstreamInformer = apisixFactory.Apisix().V2beta3().ApisixUpstreams().Informer()

		apisixRouteListerV2beta3 = apisixFactory.Apisix().V2beta3().ApisixRoutes().Lister()
		apisixUpstreamListerV2beta3 = apisixFactory.Apisix().V2beta3().ApisixUpstreams().Lister()
		apisixTlsListerV2beta3 = apisixFactory.Apisix().V2beta3().ApisixTlses().Lister()
		apisixClusterConfigListerV2beta3 = apisixFactory.Apisix().V2beta3().ApisixClusterConfigs().Lister()
		apisixConsumerListerV2beta3 = apisixFactory.Apisix().V2beta3().ApisixConsumers().Lister()
		apisixPluginConfigListerV2beta3 = apisixFactory.Apisix().V2beta3().ApisixPluginConfigs().Lister()
	case config.ApisixV2:
		apisixRouteInformer = apisixFactory.Apisix().V2().ApisixRoutes().Informer()
		apisixTlsInformer = apisixFactory.Apisix().V2().ApisixTlses().Informer()
		apisixClusterConfigInformer = apisixFactory.Apisix().V2().ApisixClusterConfigs().Informer()
		apisixConsumerInformer = apisixFactory.Apisix().V2().ApisixConsumers().Informer()
		apisixPluginConfigInformer = apisixFactory.Apisix().V2().ApisixPluginConfigs().Informer()
		apisixUpstreamInformer = apisixFactory.Apisix().V2().ApisixUpstreams().Informer()

		apisixRouteListerV2 = apisixFactory.Apisix().V2().ApisixRoutes().Lister()
		apisixUpstreamListerV2 = apisixFactory.Apisix().V2().ApisixUpstreams().Lister()
		apisixTlsListerV2 = apisixFactory.Apisix().V2().ApisixTlses().Lister()
		apisixClusterConfigListerV2 = apisixFactory.Apisix().V2().ApisixClusterConfigs().Lister()
		apisixConsumerListerV2 = apisixFactory.Apisix().V2().ApisixConsumers().Lister()
		apisixPluginConfigListerV2 = apisixFactory.Apisix().V2().ApisixPluginConfigs().Lister()
	default:
		panic(fmt.Errorf("unsupported API version %v", c.cfg.Kubernetes.APIVersion))
	}

	apisixUpstreamLister := kube.NewApisixUpstreamLister(apisixUpstreamListerV2beta3, apisixUpstreamListerV2)
	apisixRouteLister := kube.NewApisixRouteLister(apisixRouteListerV2beta3, apisixRouteListerV2)
	apisixTlsLister := kube.NewApisixTlsLister(apisixTlsListerV2beta3, apisixTlsListerV2)
	apisixClusterConfigLister := kube.NewApisixClusterConfigLister(apisixClusterConfigListerV2beta3, apisixClusterConfigListerV2)
	apisixConsumerLister := kube.NewApisixConsumerLister(apisixConsumerListerV2beta3, apisixConsumerListerV2)
	apisixPluginConfigLister := kube.NewApisixPluginConfigLister(apisixPluginConfigListerV2beta3, apisixPluginConfigListerV2)

	epLister, epInformer := kube.NewEndpointListerAndInformer(kubeFactory, c.cfg.Kubernetes.WatchEndpointSlices)
	svcInformer := kubeFactory.Core().V1().Services().Informer()
	svcLister := kubeFactory.Core().V1().Services().Lister()

	podInformer := kubeFactory.Core().V1().Pods().Informer()
	podLister := kubeFactory.Core().V1().Pods().Lister()

	secretInformer := kubeFactory.Core().V1().Secrets().Informer()
	secretLister := kubeFactory.Core().V1().Secrets().Lister()

	configmapInformer := kubeFactory.Core().V1().ConfigMaps().Informer()
	configmapLister := kubeFactory.Core().V1().ConfigMaps().Lister()

	switch c.cfg.Kubernetes.IngressVersion {
	case config.IngressNetworkingV1:
		ingressInformer = kubeFactory.Networking().V1().Ingresses().Informer()
		ingressListerV1 = kubeFactory.Networking().V1().Ingresses().Lister()
	case config.IngressNetworkingV1beta1:
		ingressInformer = kubeFactory.Networking().V1beta1().Ingresses().Informer()
		ingressListerV1beta1 = kubeFactory.Networking().V1beta1().Ingresses().Lister()
	default:
		ingressInformer = kubeFactory.Extensions().V1beta1().Ingresses().Informer()
		ingressListerExtensionsV1beta1 = kubeFactory.Extensions().V1beta1().Ingresses().Lister()
	}

	ingressLister := kube.NewIngressLister(ingressListerV1, ingressListerV1beta1, ingressListerExtensionsV1beta1)

	listerInformer := &providertypes.ListerInformer{
		ApisixFactory: apisixFactory,
		KubeFactory:   kubeFactory,

		EpLister:          epLister,
		EpInformer:        epInformer,
		SvcLister:         svcLister,
		SvcInformer:       svcInformer,
		SecretLister:      secretLister,
		SecretInformer:    secretInformer,
		PodLister:         podLister,
		PodInformer:       podInformer,
		ConfigMapInformer: configmapInformer,
		ConfigMapLister:   configmapLister,
		IngressInformer:   ingressInformer,
		IngressLister:     ingressLister,

		ApisixUpstreamLister:      apisixUpstreamLister,
		ApisixRouteLister:         apisixRouteLister,
		ApisixConsumerLister:      apisixConsumerLister,
		ApisixTlsLister:           apisixTlsLister,
		ApisixPluginConfigLister:  apisixPluginConfigLister,
		ApisixClusterConfigLister: apisixClusterConfigLister,

		ApisixUpstreamInformer:      apisixUpstreamInformer,
		ApisixPluginConfigInformer:  apisixPluginConfigInformer,
		ApisixRouteInformer:         apisixRouteInformer,
		ApisixClusterConfigInformer: apisixClusterConfigInformer,
		ApisixConsumerInformer:      apisixConsumerInformer,
		ApisixTlsInformer:           apisixTlsInformer,
	}

	return listerInformer
}

func (c *Controller) run(ctx context.Context) {
	log.Infow("controller tries to leading ...",
		zap.String("namespace", c.namespace),
		zap.String("pod", c.name),
	)

	var cancelFunc context.CancelFunc
	ctx, cancelFunc = context.WithCancel(ctx)
	defer cancelFunc()

	// give up leader
	defer c.leaderContextCancelFunc()

	clusterOpts := &apisix.ClusterOptions{
		AdminAPIVersion:  c.cfg.APISIX.AdminAPIVersion,
		Name:             c.cfg.APISIX.DefaultClusterName,
		AdminKey:         c.cfg.APISIX.DefaultClusterAdminKey,
		BaseURL:          c.cfg.APISIX.DefaultClusterBaseURL,
		MetricsCollector: c.MetricsCollector,
	}
	err := c.apisix.AddCluster(ctx, clusterOpts)
	if err != nil && err != apisix.ErrDuplicatedCluster {
		// TODO give up the leader role
		log.Errorf("failed to add default cluster: %s", err)
		return
	}

	if err := c.apisix.Cluster(c.cfg.APISIX.DefaultClusterName).HasSynced(ctx); err != nil {
		// TODO give up the leader role
		log.Errorf("failed to wait the default cluster to be ready: %s", err)

		// re-create apisix cluster, used in next c.run
		if err = c.apisix.UpdateCluster(ctx, clusterOpts); err != nil {
			log.Errorf("failed to update default cluster: %s", err)
			return
		}
		return
	}

	// Creation Phase

	c.informers = c.initSharedInformers()
	common := &providertypes.Common{
		ControllerNamespace: c.namespace,
		ListerInformer:      c.informers,
		Config:              c.cfg,
		APISIX:              c.apisix,
		KubeClient:          c.kubeClient,
		MetricsCollector:    c.MetricsCollector,
		Recorder:            c.recorder,
	}

	c.namespaceProvider, err = namespace.NewWatchingNamespaceProvider(ctx, c.kubeClient, c.cfg)
	if err != nil {
		ctx.Done()
		return
	}

	c.podProvider, err = pod.NewProvider(common, c.namespaceProvider)
	if err != nil {
		ctx.Done()
		return
	}

	c.translator = translation.NewTranslator(&translation.TranslatorOptions{
		APIVersion:           c.cfg.Kubernetes.APIVersion,
		EndpointLister:       c.informers.EpLister,
		ServiceLister:        c.informers.SvcLister,
		SecretLister:         c.informers.SecretLister,
		PodLister:            c.informers.PodLister,
		ApisixUpstreamLister: c.informers.ApisixUpstreamLister,
		PodProvider:          c.podProvider,
	})

	c.apisixProvider, c.apisixTranslator, err = apisixprovider.NewProvider(common, c.namespaceProvider, c.translator)
	if err != nil {
		ctx.Done()
		return
	}

	c.ingressProvider, err = ingressprovider.NewProvider(common, c.namespaceProvider, c.translator, c.apisixTranslator)
	if err != nil {
		ctx.Done()
		return
	}

	c.kubeProvider, err = k8s.NewProvider(common, c.translator, c.namespaceProvider, c.apisixProvider, c.ingressProvider)
	if err != nil {
		ctx.Done()
		return
	}

	if c.cfg.Kubernetes.EnableGatewayAPI {
		c.gatewayProvider, err = gateway.NewGatewayProvider(&gateway.ProviderOptions{
			Cfg:               c.cfg,
			APISIX:            c.apisix,
			APISIXClusterName: c.cfg.APISIX.DefaultClusterName,
			KubeTranslator:    c.translator,
			RestConfig:        nil,
			KubeClient:        c.kubeClient.Client,
			MetricsCollector:  c.MetricsCollector,
			NamespaceProvider: c.namespaceProvider,
		})
		if err != nil {
			ctx.Done()
			return
		}
	}

	// Init Phase

	if err = c.namespaceProvider.Init(ctx); err != nil {
		ctx.Done()
		return
	}

	// Wait Resouce sync
	if ok := c.informers.StartAndWaitForCacheSync(ctx); !ok {
		ctx.Done()
		return
	}

	// Compare resource
	if err = c.apisixProvider.Init(ctx); err != nil {
		ctx.Done()
		return
	}

	// Run Phase

	e := utils.ParallelExecutor{}

	e.Add(func() {
		c.checkClusterHealth(ctx, cancelFunc)
	})

	e.Add(func() {
		c.namespaceProvider.Run(ctx)
	})

	e.Add(func() {
		c.kubeProvider.Run(ctx)
	})

	e.Add(func() {
		c.apisixProvider.Run(ctx)
	})

	e.Add(func() {
		c.ingressProvider.Run(ctx)
	})

	if c.cfg.Kubernetes.EnableGatewayAPI {
		e.Add(func() {
			c.gatewayProvider.Run(ctx)
		})
	}

	e.Add(func() {
		c.resourceSyncLoop(ctx, c.cfg.ApisixResourceSyncInterval.Duration)
	})
	c.MetricsCollector.ResetLeader(true)

	log.Infow("controller now is running as leader",
		zap.String("namespace", c.namespace),
		zap.String("pod", c.name),
	)

	<-ctx.Done()
	e.Wait()

	for _, execErr := range e.Errors() {
		log.Error(execErr.Error())
	}
	if len(e.Errors()) > 0 {
		log.Error("Start failed, abort...")
		cancelFunc()
	}
}

func (c *Controller) checkClusterHealth(ctx context.Context, cancelFunc context.CancelFunc) {
	defer cancelFunc()
	t := time.NewTicker(5 * time.Second)
	defer t.Stop()
	for {
		select {
		case <-ctx.Done():
			return
		case <-t.C:
		}

		err := c.apisix.Cluster(c.cfg.APISIX.DefaultClusterName).HealthCheck(ctx)
		if err != nil {
			// Finally failed health check, then give up leader.
			log.Warnf("failed to check health for default cluster: %s, give up leader", err)
			c.apiServer.HealthState.Lock()
			defer c.apiServer.HealthState.Unlock()

			c.apiServer.HealthState.Err = err
			return
		}
		log.Debugf("success check health for default cluster")
		c.MetricsCollector.IncrCheckClusterHealth(c.name)
	}
}

func (c *Controller) syncAllResources() {
	e := utils.ParallelExecutor{}

	e.Add(c.ingressProvider.ResourceSync)
	e.Add(c.apisixProvider.ResourceSync)

	e.Wait()
}

func (c *Controller) resourceSyncLoop(ctx context.Context, interval time.Duration) {
	// The interval shall not be less than 60 seconds.
	if interval < _mininumApisixResourceSyncInterval {
		log.Warnw("The apisix-resource-sync-interval shall not be less than 60 seconds.",
			zap.String("apisix-resource-sync-interval", interval.String()),
		)
		interval = _mininumApisixResourceSyncInterval
	}
	ticker := time.NewTicker(interval)
	defer ticker.Stop()
	for {
		select {
		case <-ticker.C:
			c.syncAllResources()
			continue
		case <-ctx.Done():
			return
		}
	}
}