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package main

import (
	"fmt"
	"time"

	"github.com/golang/glog"
	corev1 "k8s.io/api/core/v1"
	"k8s.io/apimachinery/pkg/api/errors"
	"k8s.io/apimachinery/pkg/util/runtime"
	utilruntime "k8s.io/apimachinery/pkg/util/runtime"
	"k8s.io/apimachinery/pkg/util/wait"
	"k8s.io/client-go/kubernetes"
	"k8s.io/client-go/kubernetes/scheme"
	typedcorev1 "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"

	bolingcavalryv1 "github.com/zq2599/k8s-controller-custom-resource/pkg/apis/bolingcavalry/v1"
	clientset "github.com/zq2599/k8s-controller-custom-resource/pkg/client/clientset/versioned"
	studentscheme "github.com/zq2599/k8s-controller-custom-resource/pkg/client/clientset/versioned/scheme"
	informers "github.com/zq2599/k8s-controller-custom-resource/pkg/client/informers/externalversions/bolingcavalry/v1"
	listers "github.com/zq2599/k8s-controller-custom-resource/pkg/client/listers/bolingcavalry/v1"
)

const controllerAgentName = "student-controller"

const (
	SuccessSynced = "Synced"

	MessageResourceSynced = "Student synced successfully"
)

// Controller is the controller implementation for Student resources
type Controller struct {
	// kubeclientset is a standard kubernetes clientset
	kubeclientset kubernetes.Interface
	// studentclientset is a clientset for our own API group
	studentclientset clientset.Interface

	studentsLister listers.StudentLister
	studentsSynced cache.InformerSynced

	workqueue workqueue.RateLimitingInterface

	recorder record.EventRecorder
}

// NewController returns a new student controller
func NewController(
	kubeclientset kubernetes.Interface,
	studentclientset clientset.Interface,
	studentInformer informers.StudentInformer) *Controller {

	utilruntime.Must(studentscheme.AddToScheme(scheme.Scheme))
	glog.V(4).Info("Creating event broadcaster")
	eventBroadcaster := record.NewBroadcaster()
	eventBroadcaster.StartLogging(glog.Infof)
	eventBroadcaster.StartRecordingToSink(&typedcorev1.EventSinkImpl{Interface: kubeclientset.CoreV1().Events("")})
	recorder := eventBroadcaster.NewRecorder(scheme.Scheme, corev1.EventSource{Component: controllerAgentName})

	controller := &Controller{
		kubeclientset:    kubeclientset,
		studentclientset: studentclientset,
		studentsLister:   studentInformer.Lister(),
		studentsSynced:   studentInformer.Informer().HasSynced,
		workqueue:        workqueue.NewNamedRateLimitingQueue(workqueue.DefaultControllerRateLimiter(), "Students"),
		recorder:         recorder,
	}

	glog.Info("Setting up event handlers")
	// Set up an event handler for when Student resources change
	studentInformer.Informer().AddEventHandler(cache.ResourceEventHandlerFuncs{
		AddFunc: controller.enqueueStudent,
		UpdateFunc: func(old, new interface{}) {
			oldStudent := old.(*bolingcavalryv1.Student)
			newStudent := new.(*bolingcavalryv1.Student)
			if oldStudent.ResourceVersion == newStudent.ResourceVersion {
                //版本一致，就表示没有实际更新的操作，立即返回
				return
			}
			controller.enqueueStudent(new)
		},
		DeleteFunc: controller.enqueueStudentForDelete,
	})

	return controller
}

//在此处开始controller的业务
func (c *Controller) Run(threadiness int, stopCh <-chan struct{}) error {
	defer runtime.HandleCrash()
	defer c.workqueue.ShutDown()

	glog.Info("开始controller业务，开始一次缓存数据同步")
	if ok := cache.WaitForCacheSync(stopCh, c.studentsSynced); !ok {
		return fmt.Errorf("failed to wait for caches to sync")
	}

	glog.Info("worker启动")
	for i := 0; i < threadiness; i++ {
		go wait.Until(c.runWorker, time.Second, stopCh)
	}

	glog.Info("worker已经启动")
	<-stopCh
	glog.Info("worker已经结束")

	return nil
}

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

// 取数据处理
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 {
		defer c.workqueue.Done(obj)
		var key string
		var ok bool

		if key, ok = obj.(string); !ok {

			c.workqueue.Forget(obj)
			runtime.HandleError(fmt.Errorf("expected string in workqueue but got %#v", obj))
			return nil
		}
		// 在syncHandler中处理业务
		if err := c.syncHandler(key); err != nil {
			return fmt.Errorf("error syncing '%s': %s", key, err.Error())
		}

		c.workqueue.Forget(obj)
		glog.Infof("Successfully synced '%s'", key)
		return nil
	}(obj)

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

	return true
}

// 处理
func (c *Controller) syncHandler(key string) error {
	// Convert the namespace/name string into a distinct namespace and name
	namespace, name, err := cache.SplitMetaNamespaceKey(key)
	if err != nil {
		runtime.HandleError(fmt.Errorf("invalid resource key: %s", key))
		return nil
	}

	// 从缓存中取对象
	student, err := c.studentsLister.Students(namespace).Get(name)
	if err != nil {
		// 如果Student对象被删除了，就会走到这里，所以应该在这里加入执行
		if errors.IsNotFound(err) {
			glog.Infof("Student对象被删除，请在这里执行实际的删除业务: %s/%s ...", namespace, name)

			return nil
		}

		runtime.HandleError(fmt.Errorf("failed to list student by: %s/%s", namespace, name))

		return err
	}

	glog.Infof("这里是student对象的期望状态: %#v ...", student)
	glog.Infof("实际状态是从业务层面得到的，此处应该去的实际状态，与期望状态做对比，并根据差异做出响应(新增或者删除)")

	c.recorder.Event(student, corev1.EventTypeNormal, SuccessSynced, MessageResourceSynced)
	return nil
}

// 数据先放入缓存，再入队列
func (c *Controller) enqueueStudent(obj interface{}) {
	var key string
	var err error
	// 将对象放入缓存
	if key, err = cache.MetaNamespaceKeyFunc(obj); err != nil {
		runtime.HandleError(err)
		return
	}

	// 将key放入队列
	c.workqueue.AddRateLimited(key)
}

// 删除操作
func (c *Controller) enqueueStudentForDelete(obj interface{}) {
	var key string
	var err error
	// 从缓存中删除指定对象
	key, err = cache.DeletionHandlingMetaNamespaceKeyFunc(obj)
	if err != nil {
		runtime.HandleError(err)
		return
	}
	//再将key放入队列
	c.workqueue.AddRateLimited(key)
}

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// +build !windows

package signals

import (
	"os"
	"syscall"
)

var shutdownSignals = []os.Signal{os.Interrupt, syscall.SIGTERM}

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package signals

import (
	"os"
)

var shutdownSignals = []os.Signal{os.Interrupt}

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package signals

import (
        "os"
        "os/signal"
)

var onlyOneSignalHandler = make(chan struct{})

func SetupSignalHandler() (stopCh <-chan struct{}) {
        close(onlyOneSignalHandler) // panics when called twice

        stop := make(chan struct{})
        c := make(chan os.Signal, 2)
        signal.Notify(c, shutdownSignals...)
        go func() {
                <-c
                close(stop)
                <-c
                os.Exit(1) // second signal. Exit directly.
        }()

        return stop
}

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package main

import (
	"flag"
	"time"

	"github.com/golang/glog"
	"k8s.io/client-go/kubernetes"
	"k8s.io/client-go/tools/clientcmd"
	// Uncomment the following line to load the gcp plugin (only required to authenticate against GKE clusters).
	// _ "k8s.io/client-go/plugin/pkg/client/auth/gcp"

	clientset "k8s_customize_controller/pkg/client/clientset/versioned"
	informers "k8s_customize_controller/pkg/client/informers/externalversions"
	"k8s_customize_controller/pkg/signals"
)

var (
	masterURL  string
	kubeconfig string
)

func main() {
	flag.Parse()

	// 处理信号量
	stopCh := signals.SetupSignalHandler()

    // 处理入参
	cfg, err := clientcmd.BuildConfigFromFlags(masterURL, kubeconfig)
	if err != nil {
		glog.Fatalf("Error building kubeconfig: %s", err.Error())
	}

	kubeClient, err := kubernetes.NewForConfig(cfg)
	if err != nil {
		glog.Fatalf("Error building kubernetes clientset: %s", err.Error())
	}

	studentClient, err := clientset.NewForConfig(cfg)
	if err != nil {
		glog.Fatalf("Error building example clientset: %s", err.Error())
	}

	studentInformerFactory := informers.NewSharedInformerFactory(studentClient, time.Second*30)

    //得到controller
	controller := NewController(kubeClient, studentClient,
		studentInformerFactory.Bolingcavalry().V1().Students())

    //启动informer
	go studentInformerFactory.Start(stopCh)

    //controller开始处理消息
	if err = controller.Run(2, stopCh); err != nil {
		glog.Fatalf("Error running controller: %s", err.Error())
	}
}

func init() {
	flag.StringVar(&kubeconfig, "kubeconfig", "", "Path to a kubeconfig. Only required if out-of-cluster.")
	flag.StringVar(&masterURL, "master", "", "The address of the Kubernetes API server. Overrides any value in kubeconfig. Only required if out-of-cluster.")
}