/*
Copyright 2019 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 windows

import (
	"context"
	"fmt"
	"strconv"
	"time"

	v1 "k8s.io/api/core/v1"
	"k8s.io/apimachinery/pkg/api/resource"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/apimachinery/pkg/labels"
	"k8s.io/apimachinery/pkg/util/uuid"
	"k8s.io/kubernetes/test/e2e/framework"
	e2ekubelet "k8s.io/kubernetes/test/e2e/framework/kubelet"
	e2eskipper "k8s.io/kubernetes/test/e2e/framework/skipper"
	imageutils "k8s.io/kubernetes/test/utils/image"

	"github.com/onsi/ginkgo"
	"github.com/onsi/gomega"
)

var _ = SIGDescribe("[Feature:Windows] Memory Limits [Serial] [Slow]", func() {

	f := framework.NewDefaultFramework("memory-limit-test-windows")

	ginkgo.BeforeEach(func() {
		// NOTE(vyta): these tests are Windows specific
		e2eskipper.SkipUnlessNodeOSDistroIs("windows")
	})

	ginkgo.Context("Allocatable node memory", func() {
		ginkgo.It("should be equal to a calculated allocatable memory value", func() {
			checkNodeAllocatableTest(f)
		})
	})

	ginkgo.Context("attempt to deploy past allocatable memory limits", func() {
		ginkgo.It("should fail deployments of pods once there isn't enough memory", func() {
			overrideAllocatableMemoryTest(f, 4)
		})
	})

})

type nodeMemory struct {
	// capacity
	capacity resource.Quantity
	// allocatable memory
	allocatable resource.Quantity
	// memory reserved for OS level processes
	systemReserve resource.Quantity
	// memory reserved for kubelet (not implemented)
	kubeReserve resource.Quantity
	// grace period memory limit (not implemented)
	softEviction resource.Quantity
	// no grace period memory limit
	hardEviction resource.Quantity
}

// runDensityBatchTest runs the density batch pod creation test
// checks that a calculated value for NodeAllocatable is equal to the reported value
func checkNodeAllocatableTest(f *framework.Framework) {

	nodeMem := getNodeMemory(f)
	framework.Logf("nodeMem says: %+v", nodeMem)

	// calculate the allocatable mem based on capacity - reserved amounts
	calculatedNodeAlloc := nodeMem.capacity.DeepCopy()
	calculatedNodeAlloc.Sub(nodeMem.systemReserve)
	calculatedNodeAlloc.Sub(nodeMem.kubeReserve)
	calculatedNodeAlloc.Sub(nodeMem.softEviction)
	calculatedNodeAlloc.Sub(nodeMem.hardEviction)

	ginkgo.By(fmt.Sprintf("Checking stated allocatable memory %v against calculated allocatable memory %v", &nodeMem.allocatable, calculatedNodeAlloc))

	// sanity check against stated allocatable
	framework.ExpectEqual(calculatedNodeAlloc.Cmp(nodeMem.allocatable), 0)
}

// Deploys `allocatablePods + 1` pods, each with a memory limit of `1/allocatablePods` of the total allocatable
// memory, then confirms that the last pod failed because of failedScheduling
func overrideAllocatableMemoryTest(f *framework.Framework, allocatablePods int) {
	const (
		podType = "memory_limit_test_pod"
	)

	totalAllocatable := getTotalAllocatableMemory(f)

	memValue := totalAllocatable.Value()
	memPerPod := memValue / int64(allocatablePods)
	ginkgo.By(fmt.Sprintf("Deploying %d pods with mem limit %v, then one additional pod", allocatablePods, memPerPod))

	// these should all work
	pods := newMemLimitTestPods(allocatablePods, imageutils.GetPauseImageName(), podType, strconv.FormatInt(memPerPod, 10))
	f.PodClient().CreateBatch(pods)

	failurePods := newMemLimitTestPods(1, imageutils.GetPauseImageName(), podType, strconv.FormatInt(memPerPod, 10))
	f.PodClient().Create(failurePods[0])

	gomega.Eventually(func() bool {
		eventList, err := f.ClientSet.CoreV1().Events(f.Namespace.Name).List(context.TODO(), metav1.ListOptions{})
		framework.ExpectNoError(err)
		for _, e := range eventList.Items {
			// Look for an event that shows FailedScheduling
			if e.Type == "Warning" && e.Reason == "FailedScheduling" && e.InvolvedObject.Name == failurePods[0].ObjectMeta.Name {
				framework.Logf("Found %+v event with message %+v", e.Reason, e.Message)
				return true
			}
		}
		return false
	}, 3*time.Minute, 10*time.Second).Should(gomega.Equal(true))
}

// newMemLimitTestPods creates a list of pods (specification) for test.
func newMemLimitTestPods(numPods int, imageName, podType string, memoryLimit string) []*v1.Pod {
	var pods []*v1.Pod

	memLimitQuantity, err := resource.ParseQuantity(memoryLimit)
	framework.ExpectNoError(err)

	for i := 0; i < numPods; i++ {

		podName := "test-" + string(uuid.NewUUID())
		pod := v1.Pod{
			ObjectMeta: metav1.ObjectMeta{
				Name: podName,
				Labels: map[string]string{
					"type": podType,
					"name": podName,
				},
			},
			Spec: v1.PodSpec{
				// Restart policy is always (default).
				Containers: []v1.Container{
					{
						Image: imageName,
						Name:  podName,
						Resources: v1.ResourceRequirements{
							Limits: v1.ResourceList{
								v1.ResourceMemory: memLimitQuantity,
							},
						},
					},
				},
				NodeSelector: map[string]string{
					"kubernetes.io/os": "windows",
				},
			},
		}

		pods = append(pods, &pod)
	}

	return pods
}

// getNodeMemory populates a nodeMemory struct with information from the first
func getNodeMemory(f *framework.Framework) nodeMemory {
	selector := labels.Set{"kubernetes.io/os": "windows"}.AsSelector()
	nodeList, err := f.ClientSet.CoreV1().Nodes().List(context.TODO(), metav1.ListOptions{
		LabelSelector: selector.String(),
	})
	framework.ExpectNoError(err)

	// Assuming that agent nodes have the same config
	// Make sure there is >0 agent nodes, then use the first one for info
	framework.ExpectNotEqual(nodeList.Size(), 0)

	ginkgo.By("Getting memory details from node status and kubelet config")

	status := nodeList.Items[0].Status

	nodeName := nodeList.Items[0].ObjectMeta.Name

	kubeletConfig, err := e2ekubelet.GetCurrentKubeletConfig(nodeName, f.Namespace.Name, true)
	framework.ExpectNoError(err)

	systemReserve, err := resource.ParseQuantity(kubeletConfig.SystemReserved["memory"])
	if err != nil {
		systemReserve = *resource.NewQuantity(0, resource.BinarySI)
	}
	kubeReserve, err := resource.ParseQuantity(kubeletConfig.KubeReserved["memory"])
	if err != nil {
		kubeReserve = *resource.NewQuantity(0, resource.BinarySI)
	}
	hardEviction, err := resource.ParseQuantity(kubeletConfig.EvictionHard["memory.available"])
	if err != nil {
		hardEviction = *resource.NewQuantity(0, resource.BinarySI)
	}
	softEviction, err := resource.ParseQuantity(kubeletConfig.EvictionSoft["memory.available"])
	if err != nil {
		softEviction = *resource.NewQuantity(0, resource.BinarySI)
	}

	nodeMem := nodeMemory{
		capacity:      status.Capacity[v1.ResourceMemory],
		allocatable:   status.Allocatable[v1.ResourceMemory],
		systemReserve: systemReserve,
		hardEviction:  hardEviction,
		// these are not implemented and are here for future use - will always be 0 at the moment
		kubeReserve:  kubeReserve,
		softEviction: softEviction,
	}

	return nodeMem
}

// getTotalAllocatableMemory gets the sum of all agent node's allocatable memory
func getTotalAllocatableMemory(f *framework.Framework) *resource.Quantity {
	selector := labels.Set{"kubernetes.io/os": "windows"}.AsSelector()
	nodeList, err := f.ClientSet.CoreV1().Nodes().List(context.TODO(), metav1.ListOptions{
		LabelSelector: selector.String(),
	})
	framework.ExpectNoError(err)

	ginkgo.By("Summing allocatable memory across all agent nodes")

	totalAllocatable := resource.NewQuantity(0, resource.BinarySI)

	for _, node := range nodeList.Items {
		status := node.Status

		totalAllocatable.Add(status.Allocatable[v1.ResourceMemory])
	}

	return totalAllocatable
}