/*

 Copyright 2020 The 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 auditing

import (
	"fmt"
	utilruntime "k8s.io/apimachinery/pkg/util/runtime"
	"k8s.io/apimachinery/pkg/util/wait"
	"k8s.io/client-go/kubernetes/scheme"
	"k8s.io/client-go/tools/cache"
	"k8s.io/client-go/util/workqueue"
	"k8s.io/klog"
	kubespherescheme "kubesphere.io/kubesphere/pkg/client/clientset/versioned/scheme"
	auditinginformer "kubesphere.io/kubesphere/pkg/client/informers/externalversions/auditing/v1alpha1"
	auditinglister "kubesphere.io/kubesphere/pkg/client/listers/auditing/v1alpha1"
	"time"
)

type Controller struct {
	auditingLister auditinglister.WebhookLister
	auditingSynced cache.InformerSynced
	workQueue      workqueue.RateLimitingInterface
}

func NewController(informer auditinginformer.WebhookInformer) *Controller {
	// Create auditing webhook informer

	utilruntime.Must(kubespherescheme.AddToScheme(scheme.Scheme))

	return &Controller{
		auditingLister: informer.Lister(),
		auditingSynced: informer.Informer().HasSynced,
		workQueue:      workqueue.NewNamedRateLimitingQueue(workqueue.DefaultControllerRateLimiter(), "auditing"),
	}
}

func (c *Controller) Run(threadiness int, stopCh <-chan struct{}) error {
	defer utilruntime.HandleCrash()
	defer c.workQueue.ShutDown()

	//init client

	// Start the informer factories to begin populating the informer caches
	klog.Info("Starting User controller")

	// Wait for the caches to be synced before starting workers
	klog.Info("Waiting for informer caches to sync")
	if ok := cache.WaitForCacheSync(stopCh, c.auditingSynced); !ok {
		return fmt.Errorf("failed to wait for caches to sync")
	}

	klog.Info("Starting workers")
	// Launch two workers to process Foo resources
	for i := 0; i < threadiness; i++ {
		go wait.Until(c.runWorker, time.Second, stopCh)
	}

	klog.Info("Started workers")
	<-stopCh
	klog.Info("Shutting down workers")
	return nil
}

func (c *Controller) enqueueUser(obj interface{}) {
	var key string
	var err error
	if key, err = cache.MetaNamespaceKeyFunc(obj); err != nil {
		utilruntime.HandleError(err)
		return
	}
	c.workQueue.Add(key)
}

func (c *Controller) runWorker() {
	for c.processNextWorkItem() {
	}
}

func (c *Controller) processNextWorkItem() bool {
	obj, shutdown := c.workQueue.Get()

	if shutdown {
		return false
	}

	// We wrap this block in a func so we can defer c.workqueue.Done.
	err := func(obj interface{}) error {
		// We call Done here so the workqueue knows we have finished
		// processing this item. We also must remember to call Forget if we
		// do not want this work item being re-queued. For example, we do
		// not call Forget if a transient error occurs, instead the item is
		// put back on the workqueue and attempted again after a back-off
		// period.
		defer c.workQueue.Done(obj)
		var key string
		var ok bool
		// We expect strings to come off the workqueue. These are of the
		// form namespace/name. We do this as the delayed nature of the
		// workqueue means the items in the informer cache may actually be
		// more up to date that when the item was initially put onto the
		// workqueue.
		if key, ok = obj.(string); !ok {
			// As the item in the workqueue is actually invalid, we call
			// Forget here else we'd go into a loop of attempting to
			// process a work item that is invalid.
			c.workQueue.Forget(obj)
			utilruntime.HandleError(fmt.Errorf("expected string in workqueue but got %#v", obj))
			return nil
		}

		// Finally, if no error occurs we Forget this item so it does not
		// get queued again until another change happens.
		c.workQueue.Forget(obj)
		klog.Infof("Successfully synced %s:%s", "key", key)
		return nil
	}(obj)

	if err != nil {
		utilruntime.HandleError(err)
		return true
	}

	return true
}

func (c *Controller) Start(stopCh <-chan struct{}) error {
	return c.Run(4, stopCh)
}