/*
Copyright 2020 KubeSphere Authors

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 ippool

import (
	"fmt"
	"reflect"
	"time"

	cnet "github.com/projectcalico/libcalico-go/lib/net"
	v1 "k8s.io/api/core/v1"
	apierrors "k8s.io/apimachinery/pkg/api/errors"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/apimachinery/pkg/labels"
	utilruntime "k8s.io/apimachinery/pkg/util/runtime"
	"k8s.io/apimachinery/pkg/util/wait"
	clientset "k8s.io/client-go/kubernetes"
	"k8s.io/client-go/kubernetes/scheme"
	corev1 "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/workqueue"
	"k8s.io/klog"
	networkv1alpha1 "kubesphere.io/kubesphere/pkg/apis/network/v1alpha1"
	kubesphereclient "kubesphere.io/kubesphere/pkg/client/clientset/versioned"
	networkInformer "kubesphere.io/kubesphere/pkg/client/informers/externalversions/network/v1alpha1"
	"kubesphere.io/kubesphere/pkg/controller/network/utils"
	"kubesphere.io/kubesphere/pkg/simple/client/network/ippool"
	"sigs.k8s.io/controller-runtime/pkg/controller/controllerutil"
)

var (
	ErrCIDROverlap = fmt.Errorf("CIDR is overlap")
)

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

	provider ippool.Provider

	ippoolInformer networkInformer.IPPoolInformer
	ippoolSynced   cache.InformerSynced
	ippoolQueue    workqueue.RateLimitingInterface

	ipamblockInformer networkInformer.IPAMBlockInformer
	ipamblockSynced   cache.InformerSynced

	client           clientset.Interface
	kubesphereClient kubesphereclient.Interface

	options ippool.Options
}

func (c *IPPoolController) ippoolHandle(obj interface{}) {
	pool, ok := obj.(*networkv1alpha1.IPPool)
	if !ok {
		utilruntime.HandleError(fmt.Errorf("IPPool informer returned non-ippool object: %#v", obj))
		return
	}
	key, err := cache.MetaNamespaceKeyFunc(pool)
	if err != nil {
		utilruntime.HandleError(fmt.Errorf("couldn't get key for ippool %#v: %v", pool, err))
		return
	}

	if utils.NeedToAddFinalizer(pool, networkv1alpha1.IPPoolFinalizer) || utils.IsDeletionCandidate(pool, networkv1alpha1.IPPoolFinalizer) {
		c.ippoolQueue.Add(key)
	}
}

func (c *IPPoolController) addFinalizer(pool *networkv1alpha1.IPPool) error {
	clone := pool.DeepCopy()
	controllerutil.AddFinalizer(clone, networkv1alpha1.IPPoolFinalizer)
	clone.Labels = map[string]string{
		networkv1alpha1.IPPoolNameLabel: clone.Name,
		networkv1alpha1.IPPoolTypeLabel: clone.Spec.Type,
		networkv1alpha1.IPPoolIDLabel:   fmt.Sprintf("%d", clone.ID()),
	}
	pool, err := c.kubesphereClient.NetworkV1alpha1().IPPools().Update(clone)
	if err != nil {
		klog.V(3).Infof("Error adding  finalizer to pool %s: %v", pool.Name, err)
		return err
	}
	klog.V(3).Infof("Added finalizer to pool %s", pool.Name)
	return nil
}

func (c *IPPoolController) removeFinalizer(pool *networkv1alpha1.IPPool) error {
	clone := pool.DeepCopy()
	controllerutil.RemoveFinalizer(clone, networkv1alpha1.IPPoolFinalizer)
	pool, err := c.kubesphereClient.NetworkV1alpha1().IPPools().Update(clone)
	if err != nil {
		klog.V(3).Infof("Error removing  finalizer from pool %s: %v", pool.Name, err)
		return err
	}
	klog.V(3).Infof("Removed protection finalizer from pool %s", pool.Name)
	return nil
}

// check cidr overlap
func (c *IPPoolController) checkIPPool(pool *networkv1alpha1.IPPool) (bool, error) {
	_, poolCIDR, err := cnet.ParseCIDR(pool.Spec.CIDR)
	if err != nil {
		return false, err
	}

	pools, err := c.kubesphereClient.NetworkV1alpha1().IPPools().List(metav1.ListOptions{
		LabelSelector: labels.SelectorFromSet(labels.Set{
			networkv1alpha1.IPPoolIDLabel: fmt.Sprintf("%d", pool.ID()),
		}).String(),
	})

	if err != nil {
		return false, err
	}

	for _, p := range pools.Items {
		_, cidr, err := cnet.ParseCIDR(p.Spec.CIDR)
		if err != nil {
			return false, err
		}

		if cidr.IsNetOverlap(poolCIDR.IPNet) {
			return false, ErrCIDROverlap
		}
	}

	return true, nil
}

func (c *IPPoolController) disableIPPool(old *networkv1alpha1.IPPool) error {
	if old.Spec.Disabled {
		return nil
	}

	clone := old.DeepCopy()
	clone.Spec.Disabled = true

	old, err := c.kubesphereClient.NetworkV1alpha1().IPPools().Update(clone)

	return err
}

func (c *IPPoolController) updateIPPoolStatus(old *networkv1alpha1.IPPool) error {
	new, err := c.provider.GetIPPoolStats(old)
	if err != nil {
		return err
	}

	if reflect.DeepEqual(old.Status, new.Status) {
		return nil
	}

	clone := old.DeepCopy()
	clone.Status = new.Status
	old, err = c.kubesphereClient.NetworkV1alpha1().IPPools().Update(clone)

	return err
}

func (c *IPPoolController) processIPPool(name string) (*time.Duration, error) {
	klog.V(4).Infof("Processing IPPool %s", name)
	startTime := time.Now()
	defer func() {
		klog.V(4).Infof("Finished processing IPPool %s (%v)", name, time.Since(startTime))
	}()

	pool, err := c.ippoolInformer.Lister().Get(name)
	if apierrors.IsNotFound(err) {
		return nil, nil
	} else if err != nil {
		return nil, err
	}

	if utils.IsDeletionCandidate(pool, networkv1alpha1.IPPoolFinalizer) {
		err = c.disableIPPool(pool)
		if err != nil {
			return nil, err
		}

		// Pool should be deleted. Check if it's used and remove finalizer if
		// it's not.
		canDelete, err := c.provider.DeleteIPPool(pool)
		if err != nil {
			return nil, err
		}
		if canDelete {
			return nil, c.removeFinalizer(pool)
		}

		//The  ippool is being used, update status and try again later.
		delay := time.Second * 3
		return &delay, c.updateIPPoolStatus(pool)
	}

	if utils.NeedToAddFinalizer(pool, networkv1alpha1.IPPoolFinalizer) {
		valid, err := c.checkIPPool(pool)
		if err != nil {
			return nil, err
		}
		if !valid {
			return nil, nil
		}

		err = c.addFinalizer(pool)
		if err != nil {
			return nil, err
		}

		err = c.provider.CreateIPPool(pool)
		if err != nil {
			klog.V(4).Infof("Provider failed to create IPPool %s, err=%v", pool.Name, err)
			return nil, err
		}

		return nil, c.updateIPPoolStatus(pool)
	}

	err = c.provider.UpdateIPPool(pool)
	if err != nil {
		klog.V(4).Infof("Provider failed to update IPPool %s, err=%v", pool.Name, err)
		return nil, err
	}

	return nil, c.updateIPPoolStatus(pool)
}

func (c *IPPoolController) Start(stopCh <-chan struct{}) error {
	go c.provider.SyncStatus(stopCh, c.ippoolQueue)
	return c.Run(5, stopCh)
}

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

	klog.Info("starting ippool controller")
	defer klog.Info("shutting down ippool controller")

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

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

	<-stopCh
	return nil
}

func (c *IPPoolController) runWorker() {
	for c.processIPPoolItem() {
	}
}

func (c *IPPoolController) processIPPoolItem() bool {
	key, quit := c.ippoolQueue.Get()
	if quit {
		return false
	}
	defer c.ippoolQueue.Done(key)

	_, name, err := cache.SplitMetaNamespaceKey(key.(string))
	if err != nil {
		utilruntime.HandleError(fmt.Errorf("error parsing ippool key %q: %v", key, err))
		return true
	}

	delay, err := c.processIPPool(name)
	if err == nil {
		c.ippoolQueue.Forget(key)
		return true
	} else if delay != nil {
		c.ippoolQueue.AddAfter(key, *delay)
	}

	utilruntime.HandleError(fmt.Errorf("error processing ippool %v (will retry): %v", key, err))
	c.ippoolQueue.AddRateLimited(key)
	return true
}

func (c *IPPoolController) ipamblockHandle(obj interface{}) {
	block, ok := obj.(*networkv1alpha1.IPAMBlock)
	if !ok {
		return
	}

	poolName := block.Labels[networkv1alpha1.IPPoolNameLabel]
	c.ippoolQueue.Add(poolName)
}

func NewIPPoolController(
	ippoolInformer networkInformer.IPPoolInformer,
	ipamblockInformer networkInformer.IPAMBlockInformer,
	client clientset.Interface,
	kubesphereClient kubesphereclient.Interface,
	options ippool.Options,
	provider ippool.Provider) *IPPoolController {

	broadcaster := record.NewBroadcaster()
	broadcaster.StartLogging(func(format string, args ...interface{}) {
		klog.Info(fmt.Sprintf(format, args))
	})
	broadcaster.StartRecordingToSink(&corev1.EventSinkImpl{Interface: client.CoreV1().Events("")})
	recorder := broadcaster.NewRecorder(scheme.Scheme, v1.EventSource{Component: "cluster-controller"})

	c := &IPPoolController{
		eventBroadcaster:  broadcaster,
		eventRecorder:     recorder,
		ippoolInformer:    ippoolInformer,
		ippoolSynced:      ippoolInformer.Informer().HasSynced,
		ippoolQueue:       workqueue.NewNamedRateLimitingQueue(workqueue.DefaultControllerRateLimiter(), "ippool"),
		ipamblockInformer: ipamblockInformer,
		ipamblockSynced:   ipamblockInformer.Informer().HasSynced,
		client:            client,
		kubesphereClient:  kubesphereClient,
		options:           options,
		provider:          provider,
	}

	ippoolInformer.Informer().AddEventHandler(cache.ResourceEventHandlerFuncs{
		AddFunc: c.ippoolHandle,
		UpdateFunc: func(old, new interface{}) {
			c.ippoolHandle(new)
		},
	})

	//just for update ippool status
	ipamblockInformer.Informer().AddEventHandler(cache.ResourceEventHandlerFuncs{
		AddFunc: c.ipamblockHandle,
		UpdateFunc: func(old, new interface{}) {
			c.ipamblockHandle(new)
		},
		DeleteFunc: c.ipamblockHandle,
	})

	return c
}