// Copyright (c) 2018 SAP SE or an SAP affiliate company. All rights reserved. This file is licensed under the Apache Software License, v. 2 except as noted otherwise in the LICENSE file
//
// Licensed 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 shoot

import (
	"context"
	"fmt"
	"sync"
	"time"

	gardencorev1beta1 "github.com/gardener/gardener/pkg/apis/core/v1beta1"
	gardencoreinformers "github.com/gardener/gardener/pkg/client/core/informers/externalversions"
	gardencorelisters "github.com/gardener/gardener/pkg/client/core/listers/core/v1beta1"
	"github.com/gardener/gardener/pkg/client/kubernetes"
	"github.com/gardener/gardener/pkg/controllerutils"
	"github.com/gardener/gardener/pkg/gardenlet"
	"github.com/gardener/gardener/pkg/gardenlet/apis/config"
	confighelper "github.com/gardener/gardener/pkg/gardenlet/apis/config/helper"
	"github.com/gardener/gardener/pkg/logger"
	"github.com/gardener/gardener/pkg/utils/imagevector"

	"github.com/prometheus/client_golang/prometheus"
	corev1 "k8s.io/api/core/v1"
	"k8s.io/apimachinery/pkg/labels"
	kubeinformers "k8s.io/client-go/informers"
	"k8s.io/client-go/tools/cache"
	"k8s.io/client-go/tools/record"
	"k8s.io/client-go/util/workqueue"
	"sigs.k8s.io/controller-runtime/pkg/reconcile"
)

// Controller controls Shoots.
type Controller struct {
	k8sGardenClient        kubernetes.Interface
	k8sGardenCoreInformers gardencoreinformers.SharedInformerFactory

	config                        *config.GardenletConfiguration
	identity                      *gardencorev1beta1.Gardener
	careControl                   CareControlInterface
	controllerInstallationControl ControllerInstallationControlInterface
	seedRegistrationControl       SeedRegistrationControlInterface
	recorder                      record.EventRecorder
	secrets                       map[string]*corev1.Secret
	imageVector                   imagevector.ImageVector

	controllerInstallationLister gardencorelisters.ControllerInstallationLister
	seedLister                   gardencorelisters.SeedLister
	shootLister                  gardencorelisters.ShootLister

	controllerInstallationQueue workqueue.RateLimitingInterface
	shootCareQueue              workqueue.RateLimitingInterface
	shootQueue                  workqueue.RateLimitingInterface
	shootSeedQueue              workqueue.RateLimitingInterface
	seedRegistrationQueue       workqueue.RateLimitingInterface

	controllerInstallationSynced cache.InformerSynced
	seedSynced                   cache.InformerSynced
	shootSynced                  cache.InformerSynced

	numberOfRunningWorkers int
	workerCh               chan int
}

// NewShootController takes a Kubernetes client for the Garden clusters <k8sGardenClient>, a struct
// holding information about the acting Gardener, a <shootInformer>, and a <recorder> for
// event recording. It creates a new Gardener controller.
func NewShootController(k8sGardenClient kubernetes.Interface, k8sGardenCoreInformers gardencoreinformers.SharedInformerFactory, kubeInformerFactory kubeinformers.SharedInformerFactory, config *config.GardenletConfiguration, identity *gardencorev1beta1.Gardener, secrets map[string]*corev1.Secret, imageVector imagevector.ImageVector, recorder record.EventRecorder) *Controller {
	var (
		gardenCoreV1beta1Informer = k8sGardenCoreInformers.Core().V1beta1()

		controllerInstallationInformer = gardenCoreV1beta1Informer.ControllerInstallations()
		controllerInstallationLister   = controllerInstallationInformer.Lister()

		seedInformer = gardenCoreV1beta1Informer.Seeds()
		seedLister   = seedInformer.Lister()

		shootInformer = gardenCoreV1beta1Informer.Shoots()
		shootLister   = shootInformer.Lister()
	)

	shootController := &Controller{
		k8sGardenClient:        k8sGardenClient,
		k8sGardenCoreInformers: k8sGardenCoreInformers,

		config:                        config,
		identity:                      identity,
		careControl:                   NewDefaultCareControl(k8sGardenClient, gardenCoreV1beta1Informer, secrets, imageVector, identity, config),
		controllerInstallationControl: NewDefaultControllerInstallationControl(k8sGardenClient, gardenCoreV1beta1Informer, recorder),
		seedRegistrationControl:       NewDefaultSeedRegistrationControl(k8sGardenClient, gardenCoreV1beta1Informer, imageVector, config, recorder),
		recorder:                      recorder,
		secrets:                       secrets,
		imageVector:                   imageVector,

		seedLister:                   seedLister,
		shootLister:                  shootLister,
		controllerInstallationLister: controllerInstallationLister,

		controllerInstallationQueue: workqueue.NewNamedRateLimitingQueue(workqueue.DefaultControllerRateLimiter(), "shoot-controllerinstallation"),
		shootCareQueue:              workqueue.NewNamedRateLimitingQueue(workqueue.DefaultControllerRateLimiter(), "shoot-care"),
		shootQueue:                  workqueue.NewNamedRateLimitingQueue(workqueue.DefaultControllerRateLimiter(), "shoot"),
		shootSeedQueue:              workqueue.NewNamedRateLimitingQueue(workqueue.DefaultControllerRateLimiter(), "shoot-seeds"),
		seedRegistrationQueue:       workqueue.NewNamedRateLimitingQueue(workqueue.DefaultControllerRateLimiter(), "shooted-seed-registration"),

		workerCh: make(chan int),
	}

	shootInformer.Informer().AddEventHandler(cache.FilteringResourceEventHandler{
		FilterFunc: controllerutils.ShootFilterFunc(confighelper.SeedNameFromSeedConfig(config.SeedConfig), seedLister, config.SeedSelector),
		Handler: cache.ResourceEventHandlerFuncs{
			AddFunc:    shootController.shootAdd,
			UpdateFunc: shootController.shootUpdate,
			DeleteFunc: shootController.shootDelete,
		},
	})

	shootInformer.Informer().AddEventHandler(cache.FilteringResourceEventHandler{
		FilterFunc: controllerutils.ShootFilterFunc(confighelper.SeedNameFromSeedConfig(config.SeedConfig), seedLister, config.SeedSelector),
		Handler: cache.ResourceEventHandlerFuncs{
			AddFunc: shootController.shootCareAdd,
		},
	})

	controllerInstallationInformer.Informer().AddEventHandler(cache.FilteringResourceEventHandler{
		FilterFunc: controllerutils.ControllerInstallationFilterFunc(confighelper.SeedNameFromSeedConfig(config.SeedConfig), seedLister, config.SeedSelector),
		Handler: cache.ResourceEventHandlerFuncs{
			AddFunc:    shootController.controllerInstallationAdd,
			UpdateFunc: shootController.controllerInstallationUpdate,
		},
	})

	shootInformer.Informer().AddEventHandler(cache.FilteringResourceEventHandler{
		FilterFunc: controllerutils.ShootFilterFunc(confighelper.SeedNameFromSeedConfig(config.SeedConfig), seedLister, config.SeedSelector),
		Handler: cache.ResourceEventHandlerFuncs{
			AddFunc:    shootController.seedRegistrationAdd,
			UpdateFunc: shootController.seedRegistrationUpdate,
		},
	})

	shootController.controllerInstallationSynced = controllerInstallationInformer.Informer().HasSynced
	shootController.seedSynced = seedInformer.Informer().HasSynced
	shootController.shootSynced = shootInformer.Informer().HasSynced

	return shootController
}

// Run runs the Controller until the given stop channel can be read from.
func (c *Controller) Run(ctx context.Context, shootWorkers, shootCareWorkers int) {
	var waitGroup sync.WaitGroup

	if !cache.WaitForCacheSync(ctx.Done(), c.controllerInstallationSynced, c.seedSynced, c.shootSynced) {
		logger.Logger.Error("Timed out waiting for caches to sync")
		return
	}

	// Count number of running workers.
	go func() {
		for res := range c.workerCh {
			c.numberOfRunningWorkers += res
			logger.Logger.Debugf("Current number of running Shoot workers is %d", c.numberOfRunningWorkers)
		}
	}()

	// Update Shoots before starting the workers.
	shootFilterFunc := controllerutils.ShootFilterFunc(confighelper.SeedNameFromSeedConfig(c.config.SeedConfig), c.seedLister, c.config.SeedSelector)
	shoots, err := c.shootLister.List(labels.Everything())
	if err != nil {
		logger.Logger.Errorf("Failed to fetch shoots resources: %v", err.Error())
		return
	}
	for _, shoot := range shoots {
		if !shootFilterFunc(shoot) {
			continue
		}

		// Check if the status indicates that an operation is processing and mark it as "aborted".
		if shoot.Status.LastOperation != nil && shoot.Status.LastOperation.State == gardencorev1beta1.LastOperationStateProcessing {
			newShoot := shoot.DeepCopy()
			newShoot.Status.LastOperation.State = gardencorev1beta1.LastOperationStateAborted
			if _, err := c.k8sGardenClient.GardenCore().CoreV1beta1().Shoots(newShoot.Namespace).UpdateStatus(newShoot); err != nil {
				panic(fmt.Sprintf("Failed to update shoot status [%v]: %v ", newShoot.Name, err.Error()))
			}
		}
	}

	logger.Logger.Info("Shoot controller initialized.")

	for i := 0; i < shootWorkers; i++ {
		controllerutils.CreateWorker(ctx, c.shootQueue, "Shoot", reconcile.Func(c.reconcileShootRequest), &waitGroup, c.workerCh)
	}
	for i := 0; i < shootCareWorkers; i++ {
		controllerutils.DeprecatedCreateWorker(ctx, c.shootCareQueue, "Shoot Care", c.reconcileShootCareKey, &waitGroup, c.workerCh)
	}
	for i := 0; i < shootWorkers/2+1; i++ {
		controllerutils.CreateWorker(ctx, c.shootSeedQueue, "Shooted Seeds Reconciliation", reconcile.Func(c.reconcileShootRequest), &waitGroup, c.workerCh)
		controllerutils.CreateWorker(ctx, c.seedRegistrationQueue, "Shooted Seeds Registration", reconcile.Func(c.reconcileShootedSeedRegistrationKey), &waitGroup, c.workerCh)
		controllerutils.DeprecatedCreateWorker(ctx, c.controllerInstallationQueue, "ControllerInstallation Queue", c.reconcileControllerInstallationKey, &waitGroup, c.workerCh)
	}

	// Shutdown handling
	<-ctx.Done()
	c.controllerInstallationQueue.ShutDown()
	c.seedRegistrationQueue.ShutDown()
	c.shootCareQueue.ShutDown()
	c.shootQueue.ShutDown()
	c.shootSeedQueue.ShutDown()

	for {
		var (
			controllerInstallationQueueLength = c.controllerInstallationQueue.Len()
			seedRegistrationQueueLength       = c.seedRegistrationQueue.Len()
			shootQueueLength                  = c.shootQueue.Len()
			shootCareQueueLength              = c.shootCareQueue.Len()
			shootSeedQueueLength              = c.shootSeedQueue.Len()
			queueLengths                      = shootQueueLength + shootCareQueueLength + shootSeedQueueLength + seedRegistrationQueueLength + controllerInstallationQueueLength
		)
		if queueLengths == 0 && c.numberOfRunningWorkers == 0 {
			logger.Logger.Debug("No running Shoot worker and no items left in the queues. Terminated Shoot controller...")
			break
		}
		logger.Logger.Debugf("Waiting for %d Shoot worker(s) to finish (%d item(s) left in the queues)...", c.numberOfRunningWorkers, queueLengths)
		time.Sleep(5 * time.Second)
	}

	waitGroup.Wait()
}

// RunningWorkers returns the number of running workers.
func (c *Controller) RunningWorkers() int {
	return c.numberOfRunningWorkers
}

// CollectMetrics implements gardenmetrics.ControllerMetricsCollector interface
func (c *Controller) CollectMetrics(ch chan<- prometheus.Metric) {
	metric, err := prometheus.NewConstMetric(gardenlet.ControllerWorkerSum, prometheus.GaugeValue, float64(c.RunningWorkers()), "shoot")
	if err != nil {
		gardenlet.ScrapeFailures.With(prometheus.Labels{"kind": "shoot-controller"}).Inc()
		return
	}
	ch <- metric
}

func (c *Controller) getShootQueue(obj interface{}) workqueue.RateLimitingInterface {
	if shoot, ok := obj.(*gardencorev1beta1.Shoot); ok && shootIsSeed(shoot) {
		return c.shootSeedQueue
	}
	return c.shootQueue
}