/*
Copyright 2016 The Kubernetes Authors All rights reserved.

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 store

import (
	"context"

	autoscaling "k8s.io/api/autoscaling/v2"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/apimachinery/pkg/runtime"
	"k8s.io/apimachinery/pkg/watch"
	clientset "k8s.io/client-go/kubernetes"
	"k8s.io/client-go/tools/cache"
	basemetrics "k8s.io/component-base/metrics"

	"k8s.io/kube-state-metrics/v2/pkg/metric"
	generator "k8s.io/kube-state-metrics/v2/pkg/metric_generator"
)

type metricTargetType int

const (
	value metricTargetType = iota
	utilization
	average
)

func (m metricTargetType) String() string {
	return [...]string{"value", "utilization", "average"}[m]
}

var (
	descHorizontalPodAutoscalerAnnotationsName     = "kube_horizontalpodautoscaler_annotations"
	descHorizontalPodAutoscalerAnnotationsHelp     = "Kubernetes annotations converted to Prometheus labels."
	descHorizontalPodAutoscalerLabelsName          = "kube_horizontalpodautoscaler_labels"
	descHorizontalPodAutoscalerLabelsHelp          = "Kubernetes labels converted to Prometheus labels."
	descHorizontalPodAutoscalerLabelsDefaultLabels = []string{"namespace", "horizontalpodautoscaler"}

	targetMetricLabels = []string{"metric_name", "metric_target_type"}
)

func hpaMetricFamilies(allowAnnotationsList, allowLabelsList []string) []generator.FamilyGenerator {
	return []generator.FamilyGenerator{
		*generator.NewFamilyGeneratorWithStability(
			"kube_horizontalpodautoscaler_info",
			"Information about this autoscaler.",
			metric.Gauge,
			basemetrics.ALPHA,
			"",
			wrapHPAFunc(func(a *autoscaling.HorizontalPodAutoscaler) *metric.Family {
				labelKeys := []string{"scaletargetref_kind", "scaletargetref_name"}
				labelValues := []string{a.Spec.ScaleTargetRef.Kind, a.Spec.ScaleTargetRef.Name}
				if a.Spec.ScaleTargetRef.APIVersion != "" {
					labelKeys = append([]string{"scaletargetref_api_version"}, labelKeys...)
					labelValues = append([]string{a.Spec.ScaleTargetRef.APIVersion}, labelValues...)
				}
				return &metric.Family{
					Metrics: []*metric.Metric{
						{
							LabelKeys:   labelKeys,
							LabelValues: labelValues,
							Value:       1,
						},
					},
				}
			}),
		),
		*generator.NewFamilyGeneratorWithStability(
			"kube_horizontalpodautoscaler_metadata_generation",
			"The generation observed by the HorizontalPodAutoscaler controller.",
			metric.Gauge,
			basemetrics.STABLE,
			"",
			wrapHPAFunc(func(a *autoscaling.HorizontalPodAutoscaler) *metric.Family {
				return &metric.Family{
					Metrics: []*metric.Metric{
						{
							Value: float64(a.ObjectMeta.Generation),
						},
					},
				}
			}),
		),
		*generator.NewFamilyGeneratorWithStability(
			"kube_horizontalpodautoscaler_spec_max_replicas",
			"Upper limit for the number of pods that can be set by the autoscaler; cannot be smaller than MinReplicas.",
			metric.Gauge,
			basemetrics.STABLE,
			"",
			wrapHPAFunc(func(a *autoscaling.HorizontalPodAutoscaler) *metric.Family {
				return &metric.Family{
					Metrics: []*metric.Metric{
						{
							Value: float64(a.Spec.MaxReplicas),
						},
					},
				}
			}),
		),
		*generator.NewFamilyGeneratorWithStability(
			"kube_horizontalpodautoscaler_spec_min_replicas",
			"Lower limit for the number of pods that can be set by the autoscaler, default 1.",
			metric.Gauge,
			basemetrics.STABLE,
			"",
			wrapHPAFunc(func(a *autoscaling.HorizontalPodAutoscaler) *metric.Family {
				return &metric.Family{
					Metrics: []*metric.Metric{
						{
							Value: float64(*a.Spec.MinReplicas),
						},
					},
				}
			}),
		),
		*generator.NewFamilyGeneratorWithStability(
			"kube_horizontalpodautoscaler_spec_target_metric",
			"The metric specifications used by this autoscaler when calculating the desired replica count.",
			metric.Gauge,
			basemetrics.ALPHA,
			"",
			wrapHPAFunc(func(a *autoscaling.HorizontalPodAutoscaler) *metric.Family {
				ms := make([]*metric.Metric, 0, len(a.Spec.Metrics))
				for _, m := range a.Spec.Metrics {
					var metricName string
					var metricTarget autoscaling.MetricTarget
					// The variable maps the type of metric to the corresponding value
					metricMap := make(map[metricTargetType]float64)

					switch m.Type {
					case autoscaling.ObjectMetricSourceType:
						metricName = m.Object.Metric.Name
						metricTarget = m.Object.Target
					case autoscaling.PodsMetricSourceType:
						metricName = m.Pods.Metric.Name
						metricTarget = m.Pods.Target
					case autoscaling.ResourceMetricSourceType:
						metricName = string(m.Resource.Name)
						metricTarget = m.Resource.Target
					case autoscaling.ContainerResourceMetricSourceType:
						metricName = string(m.ContainerResource.Name)
						metricTarget = m.ContainerResource.Target
					case autoscaling.ExternalMetricSourceType:
						metricName = m.External.Metric.Name
						metricTarget = m.External.Target
					default:
						// Skip unsupported metric type
						continue
					}

					if metricTarget.Value != nil {
						metricMap[value] = float64(metricTarget.Value.MilliValue()) / 1000
					}
					if metricTarget.AverageValue != nil {
						metricMap[average] = float64(metricTarget.AverageValue.MilliValue()) / 1000
					}
					if metricTarget.AverageUtilization != nil {
						metricMap[utilization] = float64(*metricTarget.AverageUtilization)
					}

					for metricTypeIndex, metricValue := range metricMap {
						ms = append(ms, &metric.Metric{
							LabelKeys:   targetMetricLabels,
							LabelValues: []string{metricName, metricTypeIndex.String()},
							Value:       metricValue,
						})
					}
				}
				return &metric.Family{Metrics: ms}
			}),
		),
		*generator.NewFamilyGeneratorWithStability(
			"kube_horizontalpodautoscaler_status_target_metric",
			"The current metric status used by this autoscaler when calculating the desired replica count.",
			metric.Gauge,
			basemetrics.ALPHA,
			"",
			wrapHPAFunc(func(a *autoscaling.HorizontalPodAutoscaler) *metric.Family {
				ms := make([]*metric.Metric, 0, len(a.Status.CurrentMetrics))
				for _, m := range a.Status.CurrentMetrics {
					var metricName string
					var currentMetric autoscaling.MetricValueStatus
					// The variable maps the type of metric to the corresponding value
					metricMap := make(map[metricTargetType]float64)

					switch m.Type {
					case autoscaling.ObjectMetricSourceType:
						metricName = m.Object.Metric.Name
						currentMetric = m.Object.Current
					case autoscaling.PodsMetricSourceType:
						metricName = m.Pods.Metric.Name
						currentMetric = m.Pods.Current
					case autoscaling.ResourceMetricSourceType:
						metricName = string(m.Resource.Name)
						currentMetric = m.Resource.Current
					case autoscaling.ContainerResourceMetricSourceType:
						metricName = string(m.ContainerResource.Name)
						currentMetric = m.ContainerResource.Current
					case autoscaling.ExternalMetricSourceType:
						metricName = m.External.Metric.Name
						currentMetric = m.External.Current
					default:
						// Skip unsupported metric type
						continue
					}

					if currentMetric.Value != nil {
						metricMap[value] = float64(currentMetric.Value.MilliValue()) / 1000
					}
					if currentMetric.AverageValue != nil {
						metricMap[average] = float64(currentMetric.AverageValue.MilliValue()) / 1000
					}
					if currentMetric.AverageUtilization != nil {
						metricMap[utilization] = float64(*currentMetric.AverageUtilization)
					}

					for metricTypeIndex, metricValue := range metricMap {
						ms = append(ms, &metric.Metric{
							LabelKeys:   targetMetricLabels,
							LabelValues: []string{metricName, metricTypeIndex.String()},
							Value:       metricValue,
						})
					}
				}
				return &metric.Family{Metrics: ms}
			}),
		),
		*generator.NewFamilyGeneratorWithStability(
			"kube_horizontalpodautoscaler_status_current_replicas",
			"Current number of replicas of pods managed by this autoscaler.",
			metric.Gauge,
			basemetrics.STABLE,
			"",
			wrapHPAFunc(func(a *autoscaling.HorizontalPodAutoscaler) *metric.Family {
				return &metric.Family{
					Metrics: []*metric.Metric{
						{
							Value: float64(a.Status.CurrentReplicas),
						},
					},
				}
			}),
		),
		*generator.NewFamilyGeneratorWithStability(
			"kube_horizontalpodautoscaler_status_desired_replicas",
			"Desired number of replicas of pods managed by this autoscaler.",
			metric.Gauge,
			basemetrics.STABLE,
			"",
			wrapHPAFunc(func(a *autoscaling.HorizontalPodAutoscaler) *metric.Family {
				return &metric.Family{
					Metrics: []*metric.Metric{
						{
							Value: float64(a.Status.DesiredReplicas),
						},
					},
				}
			}),
		),
		*generator.NewFamilyGeneratorWithStability(
			descHorizontalPodAutoscalerAnnotationsName,
			descHorizontalPodAutoscalerAnnotationsHelp,
			metric.Gauge,
			basemetrics.ALPHA,
			"",
			wrapHPAFunc(func(a *autoscaling.HorizontalPodAutoscaler) *metric.Family {
				annotationKeys, annotationValues := createPrometheusLabelKeysValues("annotation", a.Annotations, allowAnnotationsList)
				return &metric.Family{
					Metrics: []*metric.Metric{
						{
							LabelKeys:   annotationKeys,
							LabelValues: annotationValues,
							Value:       1,
						},
					},
				}
			}),
		),
		*generator.NewFamilyGeneratorWithStability(
			descHorizontalPodAutoscalerLabelsName,
			descHorizontalPodAutoscalerLabelsHelp,
			metric.Gauge,
			basemetrics.STABLE,
			"",
			wrapHPAFunc(func(a *autoscaling.HorizontalPodAutoscaler) *metric.Family {
				labelKeys, labelValues := createPrometheusLabelKeysValues("label", a.Labels, allowLabelsList)
				return &metric.Family{
					Metrics: []*metric.Metric{
						{
							LabelKeys:   labelKeys,
							LabelValues: labelValues,
							Value:       1,
						},
					},
				}
			}),
		),
		*generator.NewFamilyGeneratorWithStability(
			"kube_horizontalpodautoscaler_status_condition",
			"The condition of this autoscaler.",
			metric.Gauge,
			basemetrics.STABLE,
			"",
			wrapHPAFunc(func(a *autoscaling.HorizontalPodAutoscaler) *metric.Family {
				ms := make([]*metric.Metric, 0, len(a.Status.Conditions)*len(conditionStatuses))

				for _, c := range a.Status.Conditions {
					metrics := addConditionMetrics(c.Status)

					for _, m := range metrics {
						metric := m
						metric.LabelKeys = []string{"condition", "status"}
						metric.LabelValues = append([]string{string(c.Type)}, metric.LabelValues...)
						ms = append(ms, metric)
					}
				}

				return &metric.Family{
					Metrics: ms,
				}
			}),
		),
	}
}

func wrapHPAFunc(f func(*autoscaling.HorizontalPodAutoscaler) *metric.Family) func(interface{}) *metric.Family {
	return func(obj interface{}) *metric.Family {
		hpa := obj.(*autoscaling.HorizontalPodAutoscaler)

		metricFamily := f(hpa)

		for _, m := range metricFamily.Metrics {
			m.LabelKeys, m.LabelValues = mergeKeyValues(descHorizontalPodAutoscalerLabelsDefaultLabels, []string{hpa.Namespace, hpa.Name}, m.LabelKeys, m.LabelValues)
		}

		return metricFamily
	}
}

func createHPAListWatch(kubeClient clientset.Interface, ns string, fieldSelector string) cache.ListerWatcher {
	return &cache.ListWatch{
		ListFunc: func(opts metav1.ListOptions) (runtime.Object, error) {
			opts.FieldSelector = fieldSelector
			return kubeClient.AutoscalingV2().HorizontalPodAutoscalers(ns).List(context.TODO(), opts)
		},
		WatchFunc: func(opts metav1.ListOptions) (watch.Interface, error) {
			opts.FieldSelector = fieldSelector
			return kubeClient.AutoscalingV2().HorizontalPodAutoscalers(ns).Watch(context.TODO(), opts)
		},
	}
}