/*
Copyright 2018 The Volcano 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 helpers

import (
	"context"
	"fmt"
	"net"
	"net/http"
	"os"
	"os/signal"
	"reflect"
	"syscall"
	"time"

	v1 "k8s.io/api/core/v1"
	apierrors "k8s.io/apimachinery/pkg/api/errors"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	utilruntime "k8s.io/apimachinery/pkg/util/runtime"
	"k8s.io/apiserver/pkg/server/healthz"
	"k8s.io/apiserver/pkg/server/mux"
	"k8s.io/client-go/kubernetes"
	"k8s.io/klog"

	vcbatch "volcano.sh/volcano/pkg/apis/batch/v1alpha1"
	vcbus "volcano.sh/volcano/pkg/apis/bus/v1alpha1"
	schedulerv1beta1 "volcano.sh/volcano/pkg/apis/scheduling/v1beta1"
)

// JobKind  creates job GroupVersionKind
var JobKind = vcbatch.SchemeGroupVersion.WithKind("Job")

// CommandKind  creates command GroupVersionKind
var CommandKind = vcbus.SchemeGroupVersion.WithKind("Command")

// V1beta1QueueKind is queue kind with v1alpha2 version
var V1beta1QueueKind = schedulerv1beta1.SchemeGroupVersion.WithKind("Queue")

// CreateOrUpdateConfigMap :
// 1. creates config map resource if not present
// 2. updates config map is necessary
func CreateOrUpdateConfigMap(job *vcbatch.Job, kubeClients kubernetes.Interface, data map[string]string, cmName string) error {
	// If ConfigMap does not exist, create one for Job.
	cmOld, err := kubeClients.CoreV1().ConfigMaps(job.Namespace).Get(cmName, metav1.GetOptions{})
	if err != nil {
		if !apierrors.IsNotFound(err) {
			klog.V(3).Infof("Failed to get Configmap for Job <%s/%s>: %v",
				job.Namespace, job.Name, err)
			return err
		}

		cm := &v1.ConfigMap{
			ObjectMeta: metav1.ObjectMeta{
				Namespace: job.Namespace,
				Name:      cmName,
				OwnerReferences: []metav1.OwnerReference{
					*metav1.NewControllerRef(job, JobKind),
				},
			},
			Data: data,
		}

		if _, err := kubeClients.CoreV1().ConfigMaps(job.Namespace).Create(cm); err != nil {
			klog.V(3).Infof("Failed to create ConfigMap for Job <%s/%s>: %v",
				job.Namespace, job.Name, err)
			return err
		}
		return nil
	}

	// no changes
	if reflect.DeepEqual(cmOld.Data, data) {
		return nil
	}

	cmOld.Data = data
	if _, err := kubeClients.CoreV1().ConfigMaps(job.Namespace).Update(cmOld); err != nil {
		klog.V(3).Infof("Failed to update ConfigMap for Job <%s/%s>: %v",
			job.Namespace, job.Name, err)
		return err
	}

	return nil
}

// CreateSecret create secret
func CreateSecret(job *vcbatch.Job, kubeClients kubernetes.Interface, data map[string][]byte, secretName string) error {
	secret := &v1.Secret{
		ObjectMeta: metav1.ObjectMeta{
			Name:      secretName,
			Namespace: job.Namespace,
			OwnerReferences: []metav1.OwnerReference{
				*metav1.NewControllerRef(job, JobKind),
			},
		},
		Data: data,
	}

	_, err := kubeClients.CoreV1().Secrets(job.Namespace).Create(secret)
	if apierrors.IsAlreadyExists(err) {
		return nil
	}

	return err
}

// DeleteConfigmap  deletes the config map resource
func DeleteConfigmap(job *vcbatch.Job, kubeClients kubernetes.Interface, cmName string) error {
	if _, err := kubeClients.CoreV1().ConfigMaps(job.Namespace).Get(cmName, metav1.GetOptions{}); err != nil {
		if !apierrors.IsNotFound(err) {
			klog.V(3).Infof("Failed to get Configmap for Job <%s/%s>: %v",
				job.Namespace, job.Name, err)
			return err
		}
		return nil

	}

	if err := kubeClients.CoreV1().ConfigMaps(job.Namespace).Delete(cmName, nil); err != nil {
		if !apierrors.IsNotFound(err) {
			klog.Errorf("Failed to delete Configmap of Job %v/%v: %v",
				job.Namespace, job.Name, err)
			return err
		}
	}

	return nil
}

// DeleteSecret delete secret
func DeleteSecret(job *vcbatch.Job, kubeClients kubernetes.Interface, secretName string) error {
	err := kubeClients.CoreV1().Secrets(job.Namespace).Delete(secretName, nil)
	if err != nil && true == apierrors.IsNotFound(err) {
		return nil
	}

	return err
}

// GeneratePodgroupName  generate podgroup name of normal pod
func GeneratePodgroupName(pod *v1.Pod) string {
	pgName := vcbatch.PodgroupNamePrefix

	if len(pod.OwnerReferences) != 0 {
		for _, ownerReference := range pod.OwnerReferences {
			if ownerReference.Controller != nil && *ownerReference.Controller == true {
				pgName += string(ownerReference.UID)
				return pgName
			}
		}
	}

	pgName += string(pod.UID)

	return pgName
}

// StartHealthz register healthz interface
func StartHealthz(healthzBindAddress, name string) error {
	listener, err := net.Listen("tcp", healthzBindAddress)
	if err != nil {
		return fmt.Errorf("failed to create listener: %v", err)
	}

	pathRecorderMux := mux.NewPathRecorderMux(name)
	healthz.InstallHandler(pathRecorderMux)

	server := &http.Server{
		Addr:           listener.Addr().String(),
		Handler:        pathRecorderMux,
		MaxHeaderBytes: 1 << 20,
	}

	return runServer(server, listener)
}

func runServer(server *http.Server, ln net.Listener) error {
	if ln == nil || server == nil {
		return fmt.Errorf("listener and server must not be nil")
	}

	stopCh := make(chan os.Signal)
	signal.Notify(stopCh, syscall.SIGTERM, syscall.SIGINT)

	go func() {
		<-stopCh
		ctx, cancel := context.WithTimeout(context.Background(), 0)
		server.Shutdown(ctx)
		cancel()
	}()

	go func() {
		defer utilruntime.HandleCrash()

		var listener net.Listener
		listener = tcpKeepAliveListener{ln.(*net.TCPListener)}

		err := server.Serve(listener)
		msg := fmt.Sprintf("Stopped listening on %s", listener.Addr().String())
		select {
		case <-stopCh:
			klog.Info(msg)
		default:
			klog.Fatalf("%s due to error: %v", msg, err)
		}
	}()

	return nil
}

type tcpKeepAliveListener struct {
	*net.TCPListener
}

// Accept waits for and returns the next connection to the listener.
func (ln tcpKeepAliveListener) Accept() (net.Conn, error) {
	tc, err := ln.AcceptTCP()
	if err != nil {
		return nil, err
	}
	tc.SetKeepAlive(true)
	tc.SetKeepAlivePeriod(3 * time.Minute)
	return tc, nil
}