/*
Copyright 2022 The Kubernetes 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 apimachinery

import (
	"context"
	"crypto/sha256"
	"encoding/base32"
	"errors"
	"fmt"
	"net"
	"strings"
	"time"

	"github.com/onsi/gomega"
	"golang.org/x/crypto/cryptobyte"

	v1 "k8s.io/api/core/v1"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/apimachinery/pkg/util/wait"
	"k8s.io/kubernetes/test/e2e/feature"
	"k8s.io/kubernetes/test/e2e/framework"
	e2enode "k8s.io/kubernetes/test/e2e/framework/node"
	e2eskipper "k8s.io/kubernetes/test/e2e/framework/skipper"
	e2essh "k8s.io/kubernetes/test/e2e/framework/ssh"
	admissionapi "k8s.io/pod-security-admission/api"
)

func getControlPlaneHostname(ctx context.Context, node *v1.Node) (string, error) {
	nodeAddresses := e2enode.GetAddresses(node, v1.NodeExternalIP)
	if len(nodeAddresses) == 0 {
		return "", errors.New("no valid addresses to use for SSH")
	}

	controlPlaneAddress := nodeAddresses[0]

	host := controlPlaneAddress + ":" + e2essh.SSHPort
	result, err := e2essh.SSH(ctx, "hostname", host, framework.TestContext.Provider)
	if err != nil {
		return "", err
	}

	if result.Code != 0 {
		return "", fmt.Errorf("encountered non-zero exit code when running hostname command: %d", result.Code)
	}

	return strings.TrimSpace(result.Stdout), nil
}

// restartAPIServer attempts to restart the kube-apiserver on a node
func restartAPIServer(ctx context.Context, node *v1.Node) error {
	nodeAddresses := e2enode.GetAddresses(node, v1.NodeExternalIP)
	if len(nodeAddresses) == 0 {
		return errors.New("no valid addresses to use for SSH")
	}

	controlPlaneAddress := nodeAddresses[0]
	cmd := "pidof kube-apiserver | xargs sudo kill"
	framework.Logf("Restarting kube-apiserver via ssh, running: %v", cmd)
	result, err := e2essh.SSH(ctx, cmd, net.JoinHostPort(controlPlaneAddress, e2essh.SSHPort), framework.TestContext.Provider)
	if err != nil || result.Code != 0 {
		e2essh.LogResult(result)
		return fmt.Errorf("couldn't restart kube-apiserver: %w", err)
	}
	return nil
}

// This test requires that --feature-gates=APIServerIdentity=true be set on the apiserver
var _ = SIGDescribe("kube-apiserver identity", feature.APIServerIdentity, func() {
	f := framework.NewDefaultFramework("kube-apiserver-identity")
	f.NamespacePodSecurityLevel = admissionapi.LevelPrivileged

	f.It("kube-apiserver identity should persist after restart", f.WithDisruptive(), func(ctx context.Context) {
		e2eskipper.SkipUnlessProviderIs("gce")

		client := f.ClientSet

		var controlPlaneNodes []v1.Node
		nodes, err := client.CoreV1().Nodes().List(context.TODO(), metav1.ListOptions{})
		framework.ExpectNoError(err)

		for _, node := range nodes.Items {
			if _, ok := node.Labels["node-role.kubernetes.io/control-plane"]; ok {
				controlPlaneNodes = append(controlPlaneNodes, node)
				continue
			}

			if _, ok := node.Labels["node-role.kubernetes.io/master"]; ok {
				controlPlaneNodes = append(controlPlaneNodes, node)
				continue
			}

			for _, taint := range node.Spec.Taints {
				if taint.Key == "node-role.kubernetes.io/master" {
					controlPlaneNodes = append(controlPlaneNodes, node)
					break
				}

				if taint.Key == "node-role.kubernetes.io/control-plane" {
					controlPlaneNodes = append(controlPlaneNodes, node)
					break
				}
			}
		}

		leases, err := client.CoordinationV1().Leases(metav1.NamespaceSystem).List(context.TODO(), metav1.ListOptions{
			LabelSelector: "apiserver.kubernetes.io/identity=kube-apiserver",
		})
		framework.ExpectNoError(err)
		gomega.Expect(leases.Items).To(gomega.HaveLen(len(controlPlaneNodes)), "unexpected number of leases")

		for _, node := range controlPlaneNodes {
			hostname, err := getControlPlaneHostname(ctx, &node)
			framework.ExpectNoError(err)

			b := cryptobyte.NewBuilder(nil)
			b.AddUint16LengthPrefixed(func(b *cryptobyte.Builder) {
				b.AddBytes([]byte(hostname))
			})
			b.AddUint16LengthPrefixed(func(b *cryptobyte.Builder) {
				b.AddBytes([]byte("kube-apiserver"))
			})

			hashData, err := b.Bytes()
			framework.ExpectNoError(err)
			hash := sha256.Sum256(hashData)
			leaseName := "apiserver-" + strings.ToLower(base32.StdEncoding.WithPadding(base32.NoPadding).EncodeToString(hash[:16]))

			lease, err := client.CoordinationV1().Leases(metav1.NamespaceSystem).Get(context.TODO(), leaseName, metav1.GetOptions{})
			framework.ExpectNoError(err)
			oldHolderIdentity := lease.Spec.HolderIdentity
			lastRenewedTime := lease.Spec.RenewTime

			err = restartAPIServer(ctx, &node)
			framework.ExpectNoError(err)

			err = wait.PollImmediate(time.Second, wait.ForeverTestTimeout, func() (bool, error) {
				lease, err = client.CoordinationV1().Leases(metav1.NamespaceSystem).Get(context.TODO(), leaseName, metav1.GetOptions{})
				if err != nil {
					return false, nil
				}

				// expect only the holder identity to change after a restart
				newHolderIdentity := lease.Spec.HolderIdentity
				if newHolderIdentity == oldHolderIdentity {
					return false, nil
				}

				// wait for at least one lease heart beat after the holder identity changes
				if !lease.Spec.RenewTime.After(lastRenewedTime.Time) {
					return false, nil
				}

				return true, nil

			})
			framework.ExpectNoError(err, "holder identity did not change after a restart")
		}

		// As long as the hostname of kube-apiserver is unchanged, a restart should not result in new Lease objects.
		// Check that the number of lease objects remains the same after restarting kube-apiserver.
		leases, err = client.CoordinationV1().Leases(metav1.NamespaceSystem).List(context.TODO(), metav1.ListOptions{
			LabelSelector: "apiserver.kubernetes.io/identity=kube-apiserver",
		})
		framework.ExpectNoError(err)
		gomega.Expect(leases.Items).To(gomega.HaveLen(len(controlPlaneNodes)), "unexpected number of leases")
	})
})