package e2e

import (
	"context"
	"fmt"

	"github.com/onsi/ginkgo/v2"
	"github.com/onsi/gomega"
	appsv1 "k8s.io/api/apps/v1"
	corev1 "k8s.io/api/core/v1"
	apierrors "k8s.io/apimachinery/pkg/api/errors"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/apimachinery/pkg/util/rand"
	"k8s.io/apimachinery/pkg/util/wait"
	"k8s.io/klog/v2"
	"sigs.k8s.io/controller-runtime/pkg/client"

	clusterv1alpha1 "github.com/karmada-io/karmada/pkg/apis/cluster/v1alpha1"
	policyv1alpha1 "github.com/karmada-io/karmada/pkg/apis/policy/v1alpha1"
	controllercluster "github.com/karmada-io/karmada/pkg/controllers/cluster"
	"github.com/karmada-io/karmada/pkg/util"
	"github.com/karmada-io/karmada/pkg/util/helper"
	"github.com/karmada-io/karmada/test/e2e/framework"
	testhelper "github.com/karmada-io/karmada/test/helper"
)

// failover testing is used to test the rescheduling situation when some initially scheduled clusters fail
var _ = framework.SerialDescribe("failover testing", func() {
	ginkgo.Context("Deployment propagation testing", func() {
		var policyNamespace, policyName string
		var deploymentNamespace, deploymentName string
		var deployment *appsv1.Deployment
		var maxGroups, minGroups, numOfFailedClusters int
		var policy *policyv1alpha1.PropagationPolicy

		ginkgo.BeforeEach(func() {
			policyNamespace = testNamespace
			policyName = deploymentNamePrefix + rand.String(RandomStrLength)
			deploymentNamespace = testNamespace
			deploymentName = policyName
			deployment = testhelper.NewDeployment(deploymentNamespace, deploymentName)
			maxGroups = 1
			minGroups = 1
			numOfFailedClusters = 1

			// set MaxGroups=MinGroups=1, label is location=CHN.
			policy = testhelper.NewPropagationPolicy(policyNamespace, policyName, []policyv1alpha1.ResourceSelector{
				{
					APIVersion: deployment.APIVersion,
					Kind:       deployment.Kind,
					Name:       deployment.Name,
				},
			}, policyv1alpha1.Placement{
				ClusterAffinity: &policyv1alpha1.ClusterAffinity{
					LabelSelector: &metav1.LabelSelector{
						// only test push mode clusters
						// because pull mode clusters cannot be disabled by changing APIEndpoint
						MatchLabels: pushModeClusterLabels,
					},
				},
				ClusterTolerations: []corev1.Toleration{
					*helper.NewNotReadyToleration(2),
					*helper.NewUnreachableToleration(2),
				},
				SpreadConstraints: []policyv1alpha1.SpreadConstraint{
					{
						SpreadByField: policyv1alpha1.SpreadByFieldCluster,
						MaxGroups:     maxGroups,
						MinGroups:     minGroups,
					},
				},
			})
		})

		ginkgo.BeforeEach(func() {
			framework.CreatePropagationPolicy(karmadaClient, policy)
			framework.CreateDeployment(kubeClient, deployment)
			ginkgo.DeferCleanup(func() {
				framework.RemoveDeployment(kubeClient, deployment.Namespace, deployment.Name)
				framework.RemovePropagationPolicy(karmadaClient, policy.Namespace, policy.Name)
			})
		})

		ginkgo.It("deployment failover testing", func() {
			var disabledClusters []string
			targetClusterNames := framework.ExtractTargetClustersFrom(controlPlaneClient, deployment)

			ginkgo.By("set one cluster condition status to false", func() {
				temp := numOfFailedClusters
				for _, targetClusterName := range targetClusterNames {
					if temp > 0 {
						klog.Infof("Set cluster %s to disable.", targetClusterName)
						err := disableCluster(controlPlaneClient, targetClusterName)
						gomega.Expect(err).ShouldNot(gomega.HaveOccurred())

						// wait for the current cluster status changing to false
						framework.WaitClusterFitWith(controlPlaneClient, targetClusterName, func(cluster *clusterv1alpha1.Cluster) bool {
							return helper.TaintExists(cluster.Spec.Taints, controllercluster.NotReadyTaintTemplate)
						})
						disabledClusters = append(disabledClusters, targetClusterName)
						temp--
					}
				}
			})

			ginkgo.By("check whether deployment of failed cluster is rescheduled to other available cluster", func() {
				gomega.Eventually(func() int {
					targetClusterNames = framework.ExtractTargetClustersFrom(controlPlaneClient, deployment)
					for _, targetClusterName := range targetClusterNames {
						// the target cluster should be overwritten to another available cluster
						if !testhelper.IsExclude(targetClusterName, disabledClusters) {
							return 0
						}
					}

					return len(targetClusterNames)
				}, pollTimeout, pollInterval).Should(gomega.Equal(minGroups))
			})

			ginkgo.By("recover not ready cluster", func() {
				for _, disabledCluster := range disabledClusters {
					fmt.Printf("cluster %s is waiting for recovering\n", disabledCluster)
					originalAPIEndpoint := getClusterAPIEndpoint(disabledCluster)

					err := recoverCluster(controlPlaneClient, disabledCluster, originalAPIEndpoint)
					gomega.Expect(err).ShouldNot(gomega.HaveOccurred())
					// wait for the disabled cluster recovered
					err = wait.PollImmediate(pollInterval, pollTimeout, func() (done bool, err error) {
						currentCluster, err := util.GetCluster(controlPlaneClient, disabledCluster)
						if err != nil {
							return false, err
						}
						if !helper.TaintExists(currentCluster.Spec.Taints, controllercluster.NotReadyTaintTemplate) {
							fmt.Printf("cluster %s recovered\n", disabledCluster)
							return true, nil
						}
						return false, nil
					})
					gomega.Expect(err).ShouldNot(gomega.HaveOccurred())
				}
			})
		})
	})
})

// disableCluster will set wrong API endpoint of current cluster
func disableCluster(c client.Client, clusterName string) error {
	err := wait.PollImmediate(pollInterval, pollTimeout, func() (done bool, err error) {
		clusterObj := &clusterv1alpha1.Cluster{}
		if err := c.Get(context.TODO(), client.ObjectKey{Name: clusterName}, clusterObj); err != nil {
			if apierrors.IsConflict(err) {
				return false, nil
			}
			return false, err
		}
		// set the APIEndpoint of matched cluster to a wrong value
		unavailableAPIEndpoint := "https://172.19.1.3:6443"
		clusterObj.Spec.APIEndpoint = unavailableAPIEndpoint
		if err := c.Update(context.TODO(), clusterObj); err != nil {
			if apierrors.IsConflict(err) {
				return false, nil
			}
			return false, err
		}
		return true, nil
	})
	return err
}

// recoverCluster will recover API endpoint of the disable cluster
func recoverCluster(c client.Client, clusterName string, originalAPIEndpoint string) error {
	err := wait.PollImmediate(pollInterval, pollTimeout, func() (done bool, err error) {
		clusterObj := &clusterv1alpha1.Cluster{}
		if err := c.Get(context.TODO(), client.ObjectKey{Name: clusterName}, clusterObj); err != nil {
			return false, err
		}
		clusterObj.Spec.APIEndpoint = originalAPIEndpoint
		if err := c.Update(context.TODO(), clusterObj); err != nil {
			if apierrors.IsConflict(err) {
				return false, nil
			}
			return false, err
		}
		fmt.Printf("recovered API endpoint is %s\n", clusterObj.Spec.APIEndpoint)
		return true, nil
	})
	return err
}

// get the API endpoint of a specific cluster
func getClusterAPIEndpoint(clusterName string) (apiEndpoint string) {
	for _, cluster := range framework.Clusters() {
		if cluster.Name == clusterName {
			apiEndpoint = cluster.Spec.APIEndpoint
			fmt.Printf("original API endpoint of the cluster %s is %s\n", clusterName, apiEndpoint)
		}
	}
	return apiEndpoint
}