/*
Copyright 2015 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 podautoscaler

import (
	"encoding/json"
	"fmt"
	"io"
	"math"
	"sync"
	"testing"
	"time"

	"k8s.io/kubernetes/pkg/api"
	"k8s.io/kubernetes/pkg/api/resource"
	"k8s.io/kubernetes/pkg/api/unversioned"
	"k8s.io/kubernetes/pkg/api/v1"
	_ "k8s.io/kubernetes/pkg/apimachinery/registered"
	"k8s.io/kubernetes/pkg/apis/autoscaling"
	"k8s.io/kubernetes/pkg/apis/extensions"
	"k8s.io/kubernetes/pkg/client/clientset_generated/internalclientset/fake"
	unversionedcore "k8s.io/kubernetes/pkg/client/clientset_generated/internalclientset/typed/core/unversioned"
	"k8s.io/kubernetes/pkg/client/record"
	"k8s.io/kubernetes/pkg/client/restclient"
	"k8s.io/kubernetes/pkg/client/testing/core"
	"k8s.io/kubernetes/pkg/controller/podautoscaler/metrics"
	"k8s.io/kubernetes/pkg/runtime"
	"k8s.io/kubernetes/pkg/watch"

	heapster "k8s.io/heapster/metrics/api/v1/types"
	metrics_api "k8s.io/heapster/metrics/apis/metrics/v1alpha1"

	"github.com/stretchr/testify/assert"
)

func (w fakeResponseWrapper) DoRaw() ([]byte, error) {
	return w.raw, nil
}

func (w fakeResponseWrapper) Stream() (io.ReadCloser, error) {
	return nil, nil
}

func newFakeResponseWrapper(raw []byte) fakeResponseWrapper {
	return fakeResponseWrapper{raw: raw}
}

type fakeResponseWrapper struct {
	raw []byte
}

type fakeResource struct {
	name       string
	apiVersion string
	kind       string
}

type testCase struct {
	sync.Mutex
	minReplicas     int32
	maxReplicas     int32
	initialReplicas int32
	desiredReplicas int32

	// CPU target utilization as a percentage of the requested resources.
	CPUTarget           int32
	CPUCurrent          int32
	verifyCPUCurrent    bool
	reportedLevels      []uint64
	reportedCPURequests []resource.Quantity
	cmTarget            *extensions.CustomMetricTargetList
	scaleUpdated        bool
	statusUpdated       bool
	eventCreated        bool
	verifyEvents        bool
	useMetricsApi       bool
	// Channel with names of HPA objects which we have reconciled.
	processed chan string

	// Target resource information.
	resource *fakeResource
}

// Needs to be called under a lock.
func (tc *testCase) computeCPUCurrent() {
	if len(tc.reportedLevels) != len(tc.reportedCPURequests) || len(tc.reportedLevels) == 0 {
		return
	}
	reported := 0
	for _, r := range tc.reportedLevels {
		reported += int(r)
	}
	requested := 0
	for _, req := range tc.reportedCPURequests {
		requested += int(req.MilliValue())
	}
	tc.CPUCurrent = int32(100 * reported / requested)
}

func (tc *testCase) prepareTestClient(t *testing.T) *fake.Clientset {
	namespace := "test-namespace"
	hpaName := "test-hpa"
	podNamePrefix := "test-pod"
	selector := &unversioned.LabelSelector{
		MatchLabels: map[string]string{"name": podNamePrefix},
	}

	tc.Lock()

	tc.scaleUpdated = false
	tc.statusUpdated = false
	tc.eventCreated = false
	tc.processed = make(chan string, 100)
	tc.computeCPUCurrent()

	// TODO(madhusudancs): HPA only supports resources in extensions/v1beta1 right now. Add
	// tests for "v1" replicationcontrollers when HPA adds support for cross-group scale.
	if tc.resource == nil {
		tc.resource = &fakeResource{
			name:       "test-rc",
			apiVersion: "extensions/v1beta1",
			kind:       "replicationcontrollers",
		}
	}
	tc.Unlock()

	fakeClient := &fake.Clientset{}
	fakeClient.AddReactor("list", "horizontalpodautoscalers", func(action core.Action) (handled bool, ret runtime.Object, err error) {
		tc.Lock()
		defer tc.Unlock()

		obj := &autoscaling.HorizontalPodAutoscalerList{
			Items: []autoscaling.HorizontalPodAutoscaler{
				{
					ObjectMeta: api.ObjectMeta{
						Name:      hpaName,
						Namespace: namespace,
						SelfLink:  "experimental/v1/namespaces/" + namespace + "/horizontalpodautoscalers/" + hpaName,
					},
					Spec: autoscaling.HorizontalPodAutoscalerSpec{
						ScaleTargetRef: autoscaling.CrossVersionObjectReference{
							Kind:       tc.resource.kind,
							Name:       tc.resource.name,
							APIVersion: tc.resource.apiVersion,
						},
						MinReplicas: &tc.minReplicas,
						MaxReplicas: tc.maxReplicas,
					},
					Status: autoscaling.HorizontalPodAutoscalerStatus{
						CurrentReplicas: tc.initialReplicas,
						DesiredReplicas: tc.initialReplicas,
					},
				},
			},
		}

		if tc.CPUTarget > 0.0 {
			obj.Items[0].Spec.TargetCPUUtilizationPercentage = &tc.CPUTarget
		}
		if tc.cmTarget != nil {
			b, err := json.Marshal(tc.cmTarget)
			if err != nil {
				t.Fatalf("Failed to marshal cm: %v", err)
			}
			obj.Items[0].Annotations = make(map[string]string)
			obj.Items[0].Annotations[HpaCustomMetricsTargetAnnotationName] = string(b)
		}
		return true, obj, nil
	})

	fakeClient.AddReactor("get", "replicationcontrollers", func(action core.Action) (handled bool, ret runtime.Object, err error) {
		tc.Lock()
		defer tc.Unlock()

		obj := &extensions.Scale{
			ObjectMeta: api.ObjectMeta{
				Name:      tc.resource.name,
				Namespace: namespace,
			},
			Spec: extensions.ScaleSpec{
				Replicas: tc.initialReplicas,
			},
			Status: extensions.ScaleStatus{
				Replicas: tc.initialReplicas,
				Selector: selector,
			},
		}
		return true, obj, nil
	})

	fakeClient.AddReactor("get", "deployments", func(action core.Action) (handled bool, ret runtime.Object, err error) {
		tc.Lock()
		defer tc.Unlock()

		obj := &extensions.Scale{
			ObjectMeta: api.ObjectMeta{
				Name:      tc.resource.name,
				Namespace: namespace,
			},
			Spec: extensions.ScaleSpec{
				Replicas: tc.initialReplicas,
			},
			Status: extensions.ScaleStatus{
				Replicas: tc.initialReplicas,
				Selector: selector,
			},
		}
		return true, obj, nil
	})

	fakeClient.AddReactor("get", "replicasets", func(action core.Action) (handled bool, ret runtime.Object, err error) {
		tc.Lock()
		defer tc.Unlock()

		obj := &extensions.Scale{
			ObjectMeta: api.ObjectMeta{
				Name:      tc.resource.name,
				Namespace: namespace,
			},
			Spec: extensions.ScaleSpec{
				Replicas: tc.initialReplicas,
			},
			Status: extensions.ScaleStatus{
				Replicas: tc.initialReplicas,
				Selector: selector,
			},
		}
		return true, obj, nil
	})

	fakeClient.AddReactor("list", "pods", func(action core.Action) (handled bool, ret runtime.Object, err error) {
		tc.Lock()
		defer tc.Unlock()

		obj := &api.PodList{}
		for i := 0; i < len(tc.reportedCPURequests); i++ {
			podName := fmt.Sprintf("%s-%d", podNamePrefix, i)
			pod := api.Pod{
				Status: api.PodStatus{
					Phase: api.PodRunning,
				},
				ObjectMeta: api.ObjectMeta{
					Name:      podName,
					Namespace: namespace,
					Labels: map[string]string{
						"name": podNamePrefix,
					},
				},
				Spec: api.PodSpec{
					Containers: []api.Container{
						{
							Resources: api.ResourceRequirements{
								Requests: api.ResourceList{
									api.ResourceCPU: tc.reportedCPURequests[i],
								},
							},
						},
					},
				},
			}
			obj.Items = append(obj.Items, pod)
		}
		return true, obj, nil
	})

	fakeClient.AddProxyReactor("services", func(action core.Action) (handled bool, ret restclient.ResponseWrapper, err error) {
		tc.Lock()
		defer tc.Unlock()

		var heapsterRawMemResponse []byte

		if tc.useMetricsApi {
			metrics := metrics_api.PodMetricsList{}
			for i, cpu := range tc.reportedLevels {
				podMetric := metrics_api.PodMetrics{
					ObjectMeta: v1.ObjectMeta{
						Name:      fmt.Sprintf("%s-%d", podNamePrefix, i),
						Namespace: namespace,
					},
					Timestamp: unversioned.Time{Time: time.Now()},
					Containers: []metrics_api.ContainerMetrics{
						{
							Name: "container",
							Usage: v1.ResourceList{
								v1.ResourceCPU: *resource.NewMilliQuantity(
									int64(cpu),
									resource.DecimalSI),
								v1.ResourceMemory: *resource.NewQuantity(
									int64(1024*1024),
									resource.BinarySI),
							},
						},
					},
				}
				metrics.Items = append(metrics.Items, podMetric)
			}
			heapsterRawMemResponse, _ = json.Marshal(&metrics)
		} else {
			timestamp := time.Now()
			metrics := heapster.MetricResultList{}
			for _, level := range tc.reportedLevels {
				metric := heapster.MetricResult{
					Metrics:         []heapster.MetricPoint{{Timestamp: timestamp, Value: level, FloatValue: nil}},
					LatestTimestamp: timestamp,
				}
				metrics.Items = append(metrics.Items, metric)
			}
			heapsterRawMemResponse, _ = json.Marshal(&metrics)
		}

		return true, newFakeResponseWrapper(heapsterRawMemResponse), nil
	})

	fakeClient.AddReactor("update", "replicationcontrollers", func(action core.Action) (handled bool, ret runtime.Object, err error) {
		tc.Lock()
		defer tc.Unlock()

		obj := action.(core.UpdateAction).GetObject().(*extensions.Scale)
		replicas := action.(core.UpdateAction).GetObject().(*extensions.Scale).Spec.Replicas
		assert.Equal(t, tc.desiredReplicas, replicas)
		tc.scaleUpdated = true
		return true, obj, nil
	})

	fakeClient.AddReactor("update", "deployments", func(action core.Action) (handled bool, ret runtime.Object, err error) {
		tc.Lock()
		defer tc.Unlock()

		obj := action.(core.UpdateAction).GetObject().(*extensions.Scale)
		replicas := action.(core.UpdateAction).GetObject().(*extensions.Scale).Spec.Replicas
		assert.Equal(t, tc.desiredReplicas, replicas)
		tc.scaleUpdated = true
		return true, obj, nil
	})

	fakeClient.AddReactor("update", "replicasets", func(action core.Action) (handled bool, ret runtime.Object, err error) {
		tc.Lock()
		defer tc.Unlock()

		obj := action.(core.UpdateAction).GetObject().(*extensions.Scale)
		replicas := action.(core.UpdateAction).GetObject().(*extensions.Scale).Spec.Replicas
		assert.Equal(t, tc.desiredReplicas, replicas)
		tc.scaleUpdated = true
		return true, obj, nil
	})

	fakeClient.AddReactor("update", "horizontalpodautoscalers", func(action core.Action) (handled bool, ret runtime.Object, err error) {
		tc.Lock()
		defer tc.Unlock()

		obj := action.(core.UpdateAction).GetObject().(*autoscaling.HorizontalPodAutoscaler)
		assert.Equal(t, namespace, obj.Namespace)
		assert.Equal(t, hpaName, obj.Name)
		assert.Equal(t, tc.desiredReplicas, obj.Status.DesiredReplicas)
		if tc.verifyCPUCurrent {
			assert.NotNil(t, obj.Status.CurrentCPUUtilizationPercentage)
			assert.Equal(t, tc.CPUCurrent, *obj.Status.CurrentCPUUtilizationPercentage)
		}
		tc.statusUpdated = true
		// Every time we reconcile HPA object we are updating status.
		tc.processed <- obj.Name
		return true, obj, nil
	})

	fakeClient.AddReactor("*", "events", func(action core.Action) (handled bool, ret runtime.Object, err error) {
		tc.Lock()
		defer tc.Unlock()

		obj := action.(core.CreateAction).GetObject().(*api.Event)
		if tc.verifyEvents {
			assert.Equal(t, "SuccessfulRescale", obj.Reason)
			assert.Equal(t, fmt.Sprintf("New size: %d; reason: CPU utilization above target", tc.desiredReplicas), obj.Message)
		}
		tc.eventCreated = true
		return true, obj, nil
	})

	fakeWatch := watch.NewFake()
	fakeClient.AddWatchReactor("*", core.DefaultWatchReactor(fakeWatch, nil))

	return fakeClient
}

func (tc *testCase) verifyResults(t *testing.T) {
	tc.Lock()
	defer tc.Unlock()

	assert.Equal(t, tc.initialReplicas != tc.desiredReplicas, tc.scaleUpdated)
	assert.True(t, tc.statusUpdated)
	if tc.verifyEvents {
		assert.Equal(t, tc.initialReplicas != tc.desiredReplicas, tc.eventCreated)
	}
}

func (tc *testCase) runTest(t *testing.T) {
	testClient := tc.prepareTestClient(t)
	metricsClient := metrics.NewHeapsterMetricsClient(testClient, metrics.DefaultHeapsterNamespace, metrics.DefaultHeapsterScheme, metrics.DefaultHeapsterService, metrics.DefaultHeapsterPort)

	broadcaster := record.NewBroadcasterForTests(0)
	broadcaster.StartRecordingToSink(&unversionedcore.EventSinkImpl{Interface: testClient.Core().Events("")})
	recorder := broadcaster.NewRecorder(api.EventSource{Component: "horizontal-pod-autoscaler"})

	hpaController := &HorizontalController{
		metricsClient:   metricsClient,
		eventRecorder:   recorder,
		scaleNamespacer: testClient.Extensions(),
		hpaNamespacer:   testClient.Autoscaling(),
	}

	store, frameworkController := newInformer(hpaController, time.Minute)
	hpaController.store = store
	hpaController.controller = frameworkController

	stop := make(chan struct{})
	defer close(stop)
	go hpaController.Run(stop)

	tc.Lock()
	if tc.verifyEvents {
		tc.Unlock()
		// We need to wait for events to be broadcasted (sleep for longer than record.sleepDuration).
		time.Sleep(2 * time.Second)
	} else {
		tc.Unlock()
	}
	// Wait for HPA to be processed.
	<-tc.processed
	tc.verifyResults(t)
}

func TestDefaultScaleUpRC(t *testing.T) {
	tc := testCase{
		minReplicas:         2,
		maxReplicas:         6,
		initialReplicas:     4,
		desiredReplicas:     5,
		verifyCPUCurrent:    true,
		reportedLevels:      []uint64{900, 950, 950, 1000},
		reportedCPURequests: []resource.Quantity{resource.MustParse("1.0"), resource.MustParse("1.0"), resource.MustParse("1.0"), resource.MustParse("1.0")},
		useMetricsApi:       true,
	}
	tc.runTest(t)
}

func TestDefaultScaleUpDeployment(t *testing.T) {
	tc := testCase{
		minReplicas:         2,
		maxReplicas:         6,
		initialReplicas:     4,
		desiredReplicas:     5,
		verifyCPUCurrent:    true,
		reportedLevels:      []uint64{900, 950, 950, 1000},
		reportedCPURequests: []resource.Quantity{resource.MustParse("1.0"), resource.MustParse("1.0"), resource.MustParse("1.0"), resource.MustParse("1.0")},
		useMetricsApi:       true,
		resource: &fakeResource{
			name:       "test-dep",
			apiVersion: "extensions/v1beta1",
			kind:       "deployments",
		},
	}
	tc.runTest(t)
}

func TestDefaultScaleUpReplicaSet(t *testing.T) {
	tc := testCase{
		minReplicas:         2,
		maxReplicas:         6,
		initialReplicas:     4,
		desiredReplicas:     5,
		verifyCPUCurrent:    true,
		reportedLevels:      []uint64{900, 950, 950, 1000},
		reportedCPURequests: []resource.Quantity{resource.MustParse("1.0"), resource.MustParse("1.0"), resource.MustParse("1.0"), resource.MustParse("1.0")},
		useMetricsApi:       true,
		resource: &fakeResource{
			name:       "test-replicaset",
			apiVersion: "extensions/v1beta1",
			kind:       "replicasets",
		},
	}
	tc.runTest(t)
}

func TestScaleUp(t *testing.T) {
	tc := testCase{
		minReplicas:         2,
		maxReplicas:         6,
		initialReplicas:     3,
		desiredReplicas:     5,
		CPUTarget:           30,
		verifyCPUCurrent:    true,
		reportedLevels:      []uint64{300, 500, 700},
		reportedCPURequests: []resource.Quantity{resource.MustParse("1.0"), resource.MustParse("1.0"), resource.MustParse("1.0")},
		useMetricsApi:       true,
	}
	tc.runTest(t)
}

func TestScaleUpDeployment(t *testing.T) {
	tc := testCase{
		minReplicas:         2,
		maxReplicas:         6,
		initialReplicas:     3,
		desiredReplicas:     5,
		CPUTarget:           30,
		verifyCPUCurrent:    true,
		reportedLevels:      []uint64{300, 500, 700},
		reportedCPURequests: []resource.Quantity{resource.MustParse("1.0"), resource.MustParse("1.0"), resource.MustParse("1.0")},
		useMetricsApi:       true,
		resource: &fakeResource{
			name:       "test-dep",
			apiVersion: "extensions/v1beta1",
			kind:       "deployments",
		},
	}
	tc.runTest(t)
}

func TestScaleUpReplicaSet(t *testing.T) {
	tc := testCase{
		minReplicas:         2,
		maxReplicas:         6,
		initialReplicas:     3,
		desiredReplicas:     5,
		CPUTarget:           30,
		verifyCPUCurrent:    true,
		reportedLevels:      []uint64{300, 500, 700},
		reportedCPURequests: []resource.Quantity{resource.MustParse("1.0"), resource.MustParse("1.0"), resource.MustParse("1.0")},
		useMetricsApi:       true,
		resource: &fakeResource{
			name:       "test-replicaset",
			apiVersion: "extensions/v1beta1",
			kind:       "replicasets",
		},
	}
	tc.runTest(t)
}

func TestScaleUpCM(t *testing.T) {
	tc := testCase{
		minReplicas:     2,
		maxReplicas:     6,
		initialReplicas: 3,
		desiredReplicas: 4,
		CPUTarget:       0,
		cmTarget: &extensions.CustomMetricTargetList{
			Items: []extensions.CustomMetricTarget{{
				Name:        "qps",
				TargetValue: resource.MustParse("15.0"),
			}},
		},
		reportedLevels:      []uint64{20, 10, 30},
		reportedCPURequests: []resource.Quantity{resource.MustParse("1.0"), resource.MustParse("1.0"), resource.MustParse("1.0")},
	}
	tc.runTest(t)
}

func TestDefaultScaleDown(t *testing.T) {
	tc := testCase{
		minReplicas:         2,
		maxReplicas:         6,
		initialReplicas:     5,
		desiredReplicas:     4,
		verifyCPUCurrent:    true,
		reportedLevels:      []uint64{400, 500, 600, 700, 800},
		reportedCPURequests: []resource.Quantity{resource.MustParse("1.0"), resource.MustParse("1.0"), resource.MustParse("1.0"), resource.MustParse("1.0"), resource.MustParse("1.0")},
		useMetricsApi:       true,
	}
	tc.runTest(t)
}

func TestScaleDown(t *testing.T) {
	tc := testCase{
		minReplicas:         2,
		maxReplicas:         6,
		initialReplicas:     5,
		desiredReplicas:     3,
		CPUTarget:           50,
		verifyCPUCurrent:    true,
		reportedLevels:      []uint64{100, 300, 500, 250, 250},
		reportedCPURequests: []resource.Quantity{resource.MustParse("1.0"), resource.MustParse("1.0"), resource.MustParse("1.0"), resource.MustParse("1.0"), resource.MustParse("1.0")},
		useMetricsApi:       true,
	}
	tc.runTest(t)
}

func TestScaleDownCM(t *testing.T) {
	tc := testCase{
		minReplicas:     2,
		maxReplicas:     6,
		initialReplicas: 5,
		desiredReplicas: 3,
		CPUTarget:       0,
		cmTarget: &extensions.CustomMetricTargetList{
			Items: []extensions.CustomMetricTarget{{
				Name:        "qps",
				TargetValue: resource.MustParse("20"),
			}}},
		reportedLevels:      []uint64{12, 12, 12, 12, 12},
		reportedCPURequests: []resource.Quantity{resource.MustParse("1.0"), resource.MustParse("1.0"), resource.MustParse("1.0"), resource.MustParse("1.0"), resource.MustParse("1.0")},
	}
	tc.runTest(t)
}

func TestTolerance(t *testing.T) {
	tc := testCase{
		minReplicas:         1,
		maxReplicas:         5,
		initialReplicas:     3,
		desiredReplicas:     3,
		CPUTarget:           100,
		reportedLevels:      []uint64{1010, 1030, 1020},
		reportedCPURequests: []resource.Quantity{resource.MustParse("0.9"), resource.MustParse("1.0"), resource.MustParse("1.1")},
		useMetricsApi:       true,
	}
	tc.runTest(t)
}

func TestToleranceCM(t *testing.T) {
	tc := testCase{
		minReplicas:     1,
		maxReplicas:     5,
		initialReplicas: 3,
		desiredReplicas: 3,
		cmTarget: &extensions.CustomMetricTargetList{
			Items: []extensions.CustomMetricTarget{{
				Name:        "qps",
				TargetValue: resource.MustParse("20"),
			}}},
		reportedLevels:      []uint64{20, 21, 21},
		reportedCPURequests: []resource.Quantity{resource.MustParse("0.9"), resource.MustParse("1.0"), resource.MustParse("1.1")},
	}
	tc.runTest(t)
}

func TestMinReplicas(t *testing.T) {
	tc := testCase{
		minReplicas:         2,
		maxReplicas:         5,
		initialReplicas:     3,
		desiredReplicas:     2,
		CPUTarget:           90,
		reportedLevels:      []uint64{10, 95, 10},
		reportedCPURequests: []resource.Quantity{resource.MustParse("0.9"), resource.MustParse("1.0"), resource.MustParse("1.1")},
		useMetricsApi:       true,
	}
	tc.runTest(t)
}

func TestZeroReplicas(t *testing.T) {
	tc := testCase{
		minReplicas:         3,
		maxReplicas:         5,
		initialReplicas:     0,
		desiredReplicas:     0,
		CPUTarget:           90,
		reportedLevels:      []uint64{},
		reportedCPURequests: []resource.Quantity{},
		useMetricsApi:       true,
	}
	tc.runTest(t)
}

func TestTooFewReplicas(t *testing.T) {
	tc := testCase{
		minReplicas:         3,
		maxReplicas:         5,
		initialReplicas:     2,
		desiredReplicas:     3,
		CPUTarget:           90,
		reportedLevels:      []uint64{},
		reportedCPURequests: []resource.Quantity{},
		useMetricsApi:       true,
	}
	tc.runTest(t)
}

func TestTooManyReplicas(t *testing.T) {
	tc := testCase{
		minReplicas:         3,
		maxReplicas:         5,
		initialReplicas:     10,
		desiredReplicas:     5,
		CPUTarget:           90,
		reportedLevels:      []uint64{},
		reportedCPURequests: []resource.Quantity{},
		useMetricsApi:       true,
	}
	tc.runTest(t)
}

func TestMaxReplicas(t *testing.T) {
	tc := testCase{
		minReplicas:         2,
		maxReplicas:         5,
		initialReplicas:     3,
		desiredReplicas:     5,
		CPUTarget:           90,
		reportedLevels:      []uint64{8000, 9500, 1000},
		reportedCPURequests: []resource.Quantity{resource.MustParse("0.9"), resource.MustParse("1.0"), resource.MustParse("1.1")},
		useMetricsApi:       true,
	}
	tc.runTest(t)
}

func TestSuperfluousMetrics(t *testing.T) {
	tc := testCase{
		minReplicas:         2,
		maxReplicas:         6,
		initialReplicas:     4,
		desiredReplicas:     4,
		CPUTarget:           100,
		reportedLevels:      []uint64{4000, 9500, 3000, 7000, 3200, 2000},
		reportedCPURequests: []resource.Quantity{resource.MustParse("1.0"), resource.MustParse("1.0"), resource.MustParse("1.0"), resource.MustParse("1.0")},
		useMetricsApi:       true,
	}
	tc.runTest(t)
}

func TestMissingMetrics(t *testing.T) {
	tc := testCase{
		minReplicas:         2,
		maxReplicas:         6,
		initialReplicas:     4,
		desiredReplicas:     4,
		CPUTarget:           100,
		reportedLevels:      []uint64{400, 95},
		reportedCPURequests: []resource.Quantity{resource.MustParse("1.0"), resource.MustParse("1.0"), resource.MustParse("1.0"), resource.MustParse("1.0")},
		useMetricsApi:       true,
	}
	tc.runTest(t)
}

func TestEmptyMetrics(t *testing.T) {
	tc := testCase{
		minReplicas:         2,
		maxReplicas:         6,
		initialReplicas:     4,
		desiredReplicas:     4,
		CPUTarget:           100,
		reportedLevels:      []uint64{},
		reportedCPURequests: []resource.Quantity{resource.MustParse("1.0"), resource.MustParse("1.0"), resource.MustParse("1.0"), resource.MustParse("1.0")},
		useMetricsApi:       true,
	}
	tc.runTest(t)
}

func TestEmptyCPURequest(t *testing.T) {
	tc := testCase{
		minReplicas:     1,
		maxReplicas:     5,
		initialReplicas: 1,
		desiredReplicas: 1,
		CPUTarget:       100,
		reportedLevels:  []uint64{200},
		useMetricsApi:   true,
	}
	tc.runTest(t)
}

func TestEventCreated(t *testing.T) {
	tc := testCase{
		minReplicas:         1,
		maxReplicas:         5,
		initialReplicas:     1,
		desiredReplicas:     2,
		CPUTarget:           50,
		reportedLevels:      []uint64{200},
		reportedCPURequests: []resource.Quantity{resource.MustParse("0.2")},
		verifyEvents:        true,
		useMetricsApi:       true,
	}
	tc.runTest(t)
}

func TestEventNotCreated(t *testing.T) {
	tc := testCase{
		minReplicas:         1,
		maxReplicas:         5,
		initialReplicas:     2,
		desiredReplicas:     2,
		CPUTarget:           50,
		reportedLevels:      []uint64{200, 200},
		reportedCPURequests: []resource.Quantity{resource.MustParse("0.4"), resource.MustParse("0.4")},
		verifyEvents:        true,
		useMetricsApi:       true,
	}
	tc.runTest(t)
}

// TestComputedToleranceAlgImplementation is a regression test which
// back-calculates a minimal percentage for downscaling based on a small percentage
// increase in pod utilization which is calibrated against the tolerance value.
func TestComputedToleranceAlgImplementation(t *testing.T) {

	startPods := int32(10)
	// 150 mCPU per pod.
	totalUsedCPUOfAllPods := uint64(startPods * 150)
	// Each pod starts out asking for 2X what is really needed.
	// This means we will have a 50% ratio of used/requested
	totalRequestedCPUOfAllPods := int32(2 * totalUsedCPUOfAllPods)
	requestedToUsed := float64(totalRequestedCPUOfAllPods / int32(totalUsedCPUOfAllPods))
	// Spread the amount we ask over 10 pods.  We can add some jitter later in reportedLevels.
	perPodRequested := totalRequestedCPUOfAllPods / startPods

	// Force a minimal scaling event by satisfying  (tolerance < 1 - resourcesUsedRatio).
	target := math.Abs(1/(requestedToUsed*(1-tolerance))) + .01
	finalCpuPercentTarget := int32(target * 100)
	resourcesUsedRatio := float64(totalUsedCPUOfAllPods) / float64(float64(totalRequestedCPUOfAllPods)*target)

	// i.e. .60 * 20 -> scaled down expectation.
	finalPods := int32(math.Ceil(resourcesUsedRatio * float64(startPods)))

	// To breach tolerance we will create a utilization ratio difference of tolerance to usageRatioToleranceValue)
	tc := testCase{
		minReplicas:     0,
		maxReplicas:     1000,
		initialReplicas: startPods,
		desiredReplicas: finalPods,
		CPUTarget:       finalCpuPercentTarget,
		reportedLevels: []uint64{
			totalUsedCPUOfAllPods / 10,
			totalUsedCPUOfAllPods / 10,
			totalUsedCPUOfAllPods / 10,
			totalUsedCPUOfAllPods / 10,
			totalUsedCPUOfAllPods / 10,
			totalUsedCPUOfAllPods / 10,
			totalUsedCPUOfAllPods / 10,
			totalUsedCPUOfAllPods / 10,
			totalUsedCPUOfAllPods / 10,
			totalUsedCPUOfAllPods / 10,
		},
		reportedCPURequests: []resource.Quantity{
			resource.MustParse(fmt.Sprint(perPodRequested+100) + "m"),
			resource.MustParse(fmt.Sprint(perPodRequested-100) + "m"),
			resource.MustParse(fmt.Sprint(perPodRequested+10) + "m"),
			resource.MustParse(fmt.Sprint(perPodRequested-10) + "m"),
			resource.MustParse(fmt.Sprint(perPodRequested+2) + "m"),
			resource.MustParse(fmt.Sprint(perPodRequested-2) + "m"),
			resource.MustParse(fmt.Sprint(perPodRequested+1) + "m"),
			resource.MustParse(fmt.Sprint(perPodRequested-1) + "m"),
			resource.MustParse(fmt.Sprint(perPodRequested) + "m"),
			resource.MustParse(fmt.Sprint(perPodRequested) + "m"),
		},
		useMetricsApi: true,
	}

	tc.runTest(t)

	// Reuse the data structure above, now testing "unscaling".
	// Now, we test that no scaling happens if we are in a very close margin to the tolerance
	target = math.Abs(1/(requestedToUsed*(1-tolerance))) + .004
	finalCpuPercentTarget = int32(target * 100)
	tc.CPUTarget = finalCpuPercentTarget
	tc.initialReplicas = startPods
	tc.desiredReplicas = startPods
	tc.runTest(t)
}

// TODO: add more tests