/*
Copyright 2014 The Kubernetes Authors.
Copyright 2020 Authors of Arktos - file modified.

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 config

import (
	"fmt"
	"time"

	"k8s.io/api/core/v1"
	utilruntime "k8s.io/apimachinery/pkg/util/runtime"
	coreinformers "k8s.io/client-go/informers/core/v1"
	"k8s.io/client-go/tools/cache"
	"k8s.io/klog"
	"k8s.io/kubernetes/pkg/controller"
)

// ServiceHandler is an abstract interface of objects which receive
// notifications about service object changes.
type ServiceHandler interface {
	// OnServiceAdd is called whenever creation of new service object
	// is observed.
	OnServiceAdd(service *v1.Service, tenantParitionId int)
	// OnServiceUpdate is called whenever modification of an existing
	// service object is observed.
	OnServiceUpdate(oldService, service *v1.Service, tenantParitionId int)
	// OnServiceDelete is called whenever deletion of an existing service
	// object is observed.
	OnServiceDelete(service *v1.Service, tenantParitionId int)
	// OnServiceSynced is called once all the initial even handlers were
	// called and the state is fully propagated to local cache.
	OnServiceSynced(tenantParitionId int)
}

// EndpointsHandler is an abstract interface of objects which receive
// notifications about endpoints object changes.
type EndpointsHandler interface {
	// OnEndpointsAdd is called whenever creation of new endpoints object
	// is observed.
	OnEndpointsAdd(endpoints *v1.Endpoints, tenantPartitionId int)
	// OnEndpointsUpdate is called whenever modification of an existing
	// endpoints object is observed.
	OnEndpointsUpdate(oldEndpoints, endpoints *v1.Endpoints, tenantPartitionId int)
	// OnEndpointsDelete is called whever deletion of an existing endpoints
	// object is observed.
	OnEndpointsDelete(endpoints *v1.Endpoints, tenantPartitionId int)
	// OnEndpointsSynced is called once all the initial event handlers were
	// called and the state is fully propagated to local cache.
	OnEndpointsSynced(tenantPartitionId int)
}

// EndpointsConfig tracks a set of endpoints configurations.
type EndpointsConfig struct {
	listerSynced      cache.InformerSynced
	eventHandlers     []EndpointsHandler
	tenantPartitionId int
}

// NewEndpointsConfig creates a new EndpointsConfig.
func NewEndpointsConfig(endpointsInformer coreinformers.EndpointsInformer, resyncPeriod time.Duration, tenantParitionId int) *EndpointsConfig {
	result := &EndpointsConfig{
		listerSynced:      endpointsInformer.Informer().HasSynced,
		tenantPartitionId: tenantParitionId,
	}

	endpointsInformer.Informer().AddEventHandlerWithResyncPeriod(
		cache.ResourceEventHandlerFuncs{
			AddFunc:    result.handleAddEndpoints,
			UpdateFunc: result.handleUpdateEndpoints,
			DeleteFunc: result.handleDeleteEndpoints,
		},
		resyncPeriod,
	)

	return result
}

// RegisterEventHandler registers a handler which is called on every endpoints change.
func (c *EndpointsConfig) RegisterEventHandler(handler EndpointsHandler) {
	c.eventHandlers = append(c.eventHandlers, handler)
}

// Run waits for cache synced and invokes handlers after syncing.
func (c *EndpointsConfig) Run(stopCh <-chan struct{}) {
	klog.Info("Starting endpoints config controller")

	if !controller.WaitForCacheSync("endpoints config", stopCh, c.listerSynced) {
		return
	}

	for i := range c.eventHandlers {
		klog.V(3).Infof("Calling handler.OnEndpointsSynced()")
		c.eventHandlers[i].OnEndpointsSynced(c.tenantPartitionId)
	}
}

func (c *EndpointsConfig) handleAddEndpoints(obj interface{}) {
	endpoints, ok := obj.(*v1.Endpoints)
	if !ok {
		utilruntime.HandleError(fmt.Errorf("unexpected object type: %v", obj))
		return
	}
	for i := range c.eventHandlers {
		klog.V(4).Infof("Calling handler.OnEndpointsAdd")
		c.eventHandlers[i].OnEndpointsAdd(endpoints, c.tenantPartitionId)
	}
}

func (c *EndpointsConfig) handleUpdateEndpoints(oldObj, newObj interface{}) {
	oldEndpoints, ok := oldObj.(*v1.Endpoints)
	if !ok {
		utilruntime.HandleError(fmt.Errorf("unexpected object type: %v", oldObj))
		return
	}
	endpoints, ok := newObj.(*v1.Endpoints)
	if !ok {
		utilruntime.HandleError(fmt.Errorf("unexpected object type: %v", newObj))
		return
	}
	for i := range c.eventHandlers {
		klog.V(4).Infof("Calling handler.OnEndpointsUpdate")
		c.eventHandlers[i].OnEndpointsUpdate(oldEndpoints, endpoints, c.tenantPartitionId)
	}
}

func (c *EndpointsConfig) handleDeleteEndpoints(obj interface{}) {
	endpoints, ok := obj.(*v1.Endpoints)
	if !ok {
		tombstone, ok := obj.(cache.DeletedFinalStateUnknown)
		if !ok {
			utilruntime.HandleError(fmt.Errorf("unexpected object type: %v", obj))
			return
		}
		if endpoints, ok = tombstone.Obj.(*v1.Endpoints); !ok {
			utilruntime.HandleError(fmt.Errorf("unexpected object type: %v", obj))
			return
		}
	}
	for i := range c.eventHandlers {
		klog.V(4).Infof("Calling handler.OnEndpointsDelete")
		c.eventHandlers[i].OnEndpointsDelete(endpoints, c.tenantPartitionId)
	}
}

// ServiceConfig tracks a set of service configurations.
type ServiceConfig struct {
	listerSynced      cache.InformerSynced
	eventHandlers     []ServiceHandler
	tenantPartitionId int
}

// NewServiceConfig creates a new ServiceConfig.
func NewServiceConfig(serviceInformer coreinformers.ServiceInformer, resyncPeriod time.Duration, tenantPartitionId int) *ServiceConfig {
	result := &ServiceConfig{
		listerSynced:      serviceInformer.Informer().HasSynced,
		tenantPartitionId: tenantPartitionId,
	}

	serviceInformer.Informer().AddEventHandlerWithResyncPeriod(
		cache.ResourceEventHandlerFuncs{
			AddFunc:    result.handleAddService,
			UpdateFunc: result.handleUpdateService,
			DeleteFunc: result.handleDeleteService,
		},
		resyncPeriod,
	)

	return result
}

// RegisterEventHandler registers a handler which is called on every service change.
func (c *ServiceConfig) RegisterEventHandler(handler ServiceHandler) {
	c.eventHandlers = append(c.eventHandlers, handler)
}

// Run waits for cache synced and invokes handlers after syncing.
func (c *ServiceConfig) Run(stopCh <-chan struct{}) {
	klog.Info("Starting service config controller")

	if !controller.WaitForCacheSync("service config", stopCh, c.listerSynced) {
		return
	}

	for i := range c.eventHandlers {
		klog.V(3).Info("Calling handler.OnServiceSynced()")
		c.eventHandlers[i].OnServiceSynced(c.tenantPartitionId)
	}
}

func (c *ServiceConfig) handleAddService(obj interface{}) {
	service, ok := obj.(*v1.Service)
	if !ok {
		utilruntime.HandleError(fmt.Errorf("unexpected object type: %v", obj))
		return
	}
	for i := range c.eventHandlers {
		klog.V(4).Info("Calling handler.OnServiceAdd")
		c.eventHandlers[i].OnServiceAdd(service, c.tenantPartitionId)
	}
}

func (c *ServiceConfig) handleUpdateService(oldObj, newObj interface{}) {
	oldService, ok := oldObj.(*v1.Service)
	if !ok {
		utilruntime.HandleError(fmt.Errorf("unexpected object type: %v", oldObj))
		return
	}
	service, ok := newObj.(*v1.Service)
	if !ok {
		utilruntime.HandleError(fmt.Errorf("unexpected object type: %v", newObj))
		return
	}
	for i := range c.eventHandlers {
		klog.V(4).Info("Calling handler.OnServiceUpdate")
		c.eventHandlers[i].OnServiceUpdate(oldService, service, c.tenantPartitionId)
	}
}

func (c *ServiceConfig) handleDeleteService(obj interface{}) {
	service, ok := obj.(*v1.Service)
	if !ok {
		tombstone, ok := obj.(cache.DeletedFinalStateUnknown)
		if !ok {
			utilruntime.HandleError(fmt.Errorf("unexpected object type: %v", obj))
			return
		}
		if service, ok = tombstone.Obj.(*v1.Service); !ok {
			utilruntime.HandleError(fmt.Errorf("unexpected object type: %v", obj))
			return
		}
	}
	for i := range c.eventHandlers {
		klog.V(4).Info("Calling handler.OnServiceDelete")
		c.eventHandlers[i].OnServiceDelete(service, c.tenantPartitionId)
	}
}
