/*
Copyright 2018 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.
*/

// +k8s:openapi-gen=true

package v2beta2

import (
	v1 "k8s.io/api/core/v1"
	"k8s.io/apimachinery/pkg/api/resource"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
)

// +genclient
// +k8s:deepcopy-gen:interfaces=k8s.io/apimachinery/pkg/runtime.Object

// HorizontalPodAutoscaler is the configuration for a horizontal pod
// autoscaler, which automatically manages the replica count of any resource
// implementing the scale subresource based on the metrics specified.
type HorizontalPodAutoscaler struct {
	metav1.TypeMeta `json:",inline"`
	// metadata is the standard object metadata.
	// More info: https://git.k8s.io/community/contributors/devel/sig-architecture/api-conventions.md#metadata
	// +optional
	metav1.ObjectMeta `json:"metadata,omitempty" protobuf:"bytes,1,opt,name=metadata"`

	// spec is the specification for the behaviour of the autoscaler.
	// More info: https://git.k8s.io/community/contributors/devel/sig-architecture/api-conventions.md#spec-and-status.
	// +optional
	Spec HorizontalPodAutoscalerSpec `json:"spec,omitempty" protobuf:"bytes,2,opt,name=spec"`

	// status is the current information about the autoscaler.
	// +optional
	Status HorizontalPodAutoscalerStatus `json:"status,omitempty" protobuf:"bytes,3,opt,name=status"`
}

// HorizontalPodAutoscalerSpec describes the desired functionality of the HorizontalPodAutoscaler.
type HorizontalPodAutoscalerSpec struct {
	// scaleTargetRef points to the target resource to scale, and is used to the pods for which metrics
	// should be collected, as well as to actually change the replica count.
	ScaleTargetRef CrossVersionObjectReference `json:"scaleTargetRef" protobuf:"bytes,1,opt,name=scaleTargetRef"`
	// minReplicas is the lower limit for the number of replicas to which the autoscaler
	// can scale down.  It defaults to 1 pod.  minReplicas is allowed to be 0 if the
	// alpha feature gate HPAScaleToZero is enabled and at least one Object or External
	// metric is configured.  Scaling is active as long as at least one metric value is
	// available.
	// +optional
	MinReplicas *int32 `json:"minReplicas,omitempty" protobuf:"varint,2,opt,name=minReplicas"`
	// maxReplicas is the upper limit for the number of replicas to which the autoscaler can scale up.
	// It cannot be less that minReplicas.
	MaxReplicas int32 `json:"maxReplicas" protobuf:"varint,3,opt,name=maxReplicas"`
	// metrics contains the specifications for which to use to calculate the
	// desired replica count (the maximum replica count across all metrics will
	// be used).  The desired replica count is calculated multiplying the
	// ratio between the target value and the current value by the current
	// number of pods.  Ergo, metrics used must decrease as the pod count is
	// increased, and vice-versa.  See the individual metric source types for
	// more information about how each type of metric must respond.
	// If not set, the default metric will be set to 80% average CPU utilization.
	// +optional
	Metrics []MetricSpec `json:"metrics,omitempty" protobuf:"bytes,4,rep,name=metrics"`
}

// CrossVersionObjectReference contains enough information to let you identify the referred resource.
type CrossVersionObjectReference struct {
	// Kind of the referent; More info: https://git.k8s.io/community/contributors/devel/sig-architecture/api-conventions.md#types-kinds"
	Kind string `json:"kind" protobuf:"bytes,1,opt,name=kind"`
	// Name of the referent; More info: http://kubernetes.io/docs/user-guide/identifiers#names
	Name string `json:"name" protobuf:"bytes,2,opt,name=name"`
	// API version of the referent
	// +optional
	APIVersion string `json:"apiVersion,omitempty" protobuf:"bytes,3,opt,name=apiVersion"`
}

// MetricSpec specifies how to scale based on a single metric
// (only `type` and one other matching field should be set at once).
type MetricSpec struct {
	// type is the type of metric source.  It should be one of "Object",
	// "Pods" or "Resource", each mapping to a matching field in the object.
	Type MetricSourceType `json:"type" protobuf:"bytes,1,name=type"`

	// object refers to a metric describing a single kubernetes object
	// (for example, hits-per-second on an Ingress object).
	// +optional
	Object *ObjectMetricSource `json:"object,omitempty" protobuf:"bytes,2,opt,name=object"`
	// pods refers to a metric describing each pod in the current scale target
	// (for example, transactions-processed-per-second).  The values will be
	// averaged together before being compared to the target value.
	// +optional
	Pods *PodsMetricSource `json:"pods,omitempty" protobuf:"bytes,3,opt,name=pods"`
	// resource refers to a resource metric (such as those specified in
	// requests and limits) known to Kubernetes describing each pod in the
	// current scale target (e.g. CPU or memory). Such metrics are built in to
	// Kubernetes, and have special scaling options on top of those available
	// to normal per-pod metrics using the "pods" source.
	// +optional
	Resource *ResourceMetricSource `json:"resource,omitempty" protobuf:"bytes,4,opt,name=resource"`
	// external refers to a global metric that is not associated
	// with any Kubernetes object. It allows autoscaling based on information
	// coming from components running outside of cluster
	// (for example length of queue in cloud messaging service, or
	// QPS from loadbalancer running outside of cluster).
	// +optional
	External *ExternalMetricSource `json:"external,omitempty" protobuf:"bytes,5,opt,name=external"`
}

// MetricSourceType indicates the type of metric.
type MetricSourceType string

const (
	// ObjectMetricSourceType is a metric describing a kubernetes object
	// (for example, hits-per-second on an Ingress object).
	ObjectMetricSourceType MetricSourceType = "Object"
	// PodsMetricSourceType is a metric describing each pod in the current scale
	// target (for example, transactions-processed-per-second).  The values
	// will be averaged together before being compared to the target value.
	PodsMetricSourceType MetricSourceType = "Pods"
	// ResourceMetricSourceType is a resource metric known to Kubernetes, as
	// specified in requests and limits, describing each pod in the current
	// scale target (e.g. CPU or memory).  Such metrics are built in to
	// Kubernetes, and have special scaling options on top of those available
	// to normal per-pod metrics (the "pods" source).
	ResourceMetricSourceType MetricSourceType = "Resource"
	// ExternalMetricSourceType is a global metric that is not associated
	// with any Kubernetes object. It allows autoscaling based on information
	// coming from components running outside of cluster
	// (for example length of queue in cloud messaging service, or
	// QPS from loadbalancer running outside of cluster).
	ExternalMetricSourceType MetricSourceType = "External"
)

// ObjectMetricSource indicates how to scale on a metric describing a
// kubernetes object (for example, hits-per-second on an Ingress object).
type ObjectMetricSource struct {
	DescribedObject CrossVersionObjectReference `json:"describedObject" protobuf:"bytes,1,name=describedObject"`
	// target specifies the target value for the given metric
	Target MetricTarget `json:"target" protobuf:"bytes,2,name=target"`
	// metric identifies the target metric by name and selector
	Metric MetricIdentifier `json:"metric" protobuf:"bytes,3,name=metric"`
}

// PodsMetricSource indicates how to scale on a metric describing each pod in
// the current scale target (for example, transactions-processed-per-second).
// The values will be averaged together before being compared to the target
// value.
type PodsMetricSource struct {
	// metric identifies the target metric by name and selector
	Metric MetricIdentifier `json:"metric" protobuf:"bytes,1,name=metric"`
	// target specifies the target value for the given metric
	Target MetricTarget `json:"target" protobuf:"bytes,2,name=target"`
}

// ResourceMetricSource indicates how to scale on a resource metric known to
// Kubernetes, as specified in requests and limits, describing each pod in the
// current scale target (e.g. CPU or memory).  The values will be averaged
// together before being compared to the target.  Such metrics are built in to
// Kubernetes, and have special scaling options on top of those available to
// normal per-pod metrics using the "pods" source.  Only one "target" type
// should be set.
type ResourceMetricSource struct {
	// name is the name of the resource in question.
	Name v1.ResourceName `json:"name" protobuf:"bytes,1,name=name"`
	// target specifies the target value for the given metric
	Target MetricTarget `json:"target" protobuf:"bytes,2,name=target"`
}

// ExternalMetricSource indicates how to scale on a metric not associated with
// any Kubernetes object (for example length of queue in cloud
// messaging service, or QPS from loadbalancer running outside of cluster).
type ExternalMetricSource struct {
	// metric identifies the target metric by name and selector
	Metric MetricIdentifier `json:"metric" protobuf:"bytes,1,name=metric"`
	// target specifies the target value for the given metric
	Target MetricTarget `json:"target" protobuf:"bytes,2,name=target"`
}

// MetricIdentifier defines the name and optionally selector for a metric
type MetricIdentifier struct {
	// name is the name of the given metric
	Name string `json:"name" protobuf:"bytes,1,name=name"`
	// selector is the string-encoded form of a standard kubernetes label selector for the given metric
	// When set, it is passed as an additional parameter to the metrics server for more specific metrics scoping.
	// When unset, just the metricName will be used to gather metrics.
	// +optional
	Selector *metav1.LabelSelector `json:"selector,omitempty" protobuf:"bytes,2,name=selector"`
}

// MetricTarget defines the target value, average value, or average utilization of a specific metric
type MetricTarget struct {
	// type represents whether the metric type is Utilization, Value, or AverageValue
	Type MetricTargetType `json:"type" protobuf:"bytes,1,name=type"`
	// value is the target value of the metric (as a quantity).
	// +optional
	Value *resource.Quantity `json:"value,omitempty" protobuf:"bytes,2,opt,name=value"`
	// averageValue is the target value of the average of the
	// metric across all relevant pods (as a quantity)
	// +optional
	AverageValue *resource.Quantity `json:"averageValue,omitempty" protobuf:"bytes,3,opt,name=averageValue"`
	// averageUtilization is the target value of the average of the
	// resource metric across all relevant pods, represented as a percentage of
	// the requested value of the resource for the pods.
	// Currently only valid for Resource metric source type
	// +optional
	AverageUtilization *int32 `json:"averageUtilization,omitempty" protobuf:"bytes,4,opt,name=averageUtilization"`
}

// MetricTargetType specifies the type of metric being targeted, and should be either
// "Value", "AverageValue", or "Utilization"
type MetricTargetType string

const (
	// UtilizationMetricType declares a MetricTarget is an AverageUtilization value
	UtilizationMetricType MetricTargetType = "Utilization"
	// ValueMetricType declares a MetricTarget is a raw value
	ValueMetricType MetricTargetType = "Value"
	// AverageValueMetricType declares a MetricTarget is an
	AverageValueMetricType MetricTargetType = "AverageValue"
)

// HorizontalPodAutoscalerStatus describes the current status of a horizontal pod autoscaler.
type HorizontalPodAutoscalerStatus struct {
	// observedGeneration is the most recent generation observed by this autoscaler.
	// +optional
	ObservedGeneration *int64 `json:"observedGeneration,omitempty" protobuf:"varint,1,opt,name=observedGeneration"`

	// lastScaleTime is the last time the HorizontalPodAutoscaler scaled the number of pods,
	// used by the autoscaler to control how often the number of pods is changed.
	// +optional
	LastScaleTime *metav1.Time `json:"lastScaleTime,omitempty" protobuf:"bytes,2,opt,name=lastScaleTime"`

	// currentReplicas is current number of replicas of pods managed by this autoscaler,
	// as last seen by the autoscaler.
	CurrentReplicas int32 `json:"currentReplicas" protobuf:"varint,3,opt,name=currentReplicas"`

	// desiredReplicas is the desired number of replicas of pods managed by this autoscaler,
	// as last calculated by the autoscaler.
	DesiredReplicas int32 `json:"desiredReplicas" protobuf:"varint,4,opt,name=desiredReplicas"`

	// currentMetrics is the last read state of the metrics used by this autoscaler.
	// +optional
	CurrentMetrics []MetricStatus `json:"currentMetrics" protobuf:"bytes,5,rep,name=currentMetrics"`

	// conditions is the set of conditions required for this autoscaler to scale its target,
	// and indicates whether or not those conditions are met.
	Conditions []HorizontalPodAutoscalerCondition `json:"conditions" protobuf:"bytes,6,rep,name=conditions"`
}

// HorizontalPodAutoscalerConditionType are the valid conditions of
// a HorizontalPodAutoscaler.
type HorizontalPodAutoscalerConditionType string

const (
	// ScalingActive indicates that the HPA controller is able to scale if necessary:
	// it's correctly configured, can fetch the desired metrics, and isn't disabled.
	ScalingActive HorizontalPodAutoscalerConditionType = "ScalingActive"
	// AbleToScale indicates a lack of transient issues which prevent scaling from occurring,
	// such as being in a backoff window, or being unable to access/update the target scale.
	AbleToScale HorizontalPodAutoscalerConditionType = "AbleToScale"
	// ScalingLimited indicates that the calculated scale based on metrics would be above or
	// below the range for the HPA, and has thus been capped.
	ScalingLimited HorizontalPodAutoscalerConditionType = "ScalingLimited"
)

// HorizontalPodAutoscalerCondition describes the state of
// a HorizontalPodAutoscaler at a certain point.
type HorizontalPodAutoscalerCondition struct {
	// type describes the current condition
	Type HorizontalPodAutoscalerConditionType `json:"type" protobuf:"bytes,1,name=type"`
	// status is the status of the condition (True, False, Unknown)
	Status v1.ConditionStatus `json:"status" protobuf:"bytes,2,name=status"`
	// lastTransitionTime is the last time the condition transitioned from
	// one status to another
	// +optional
	LastTransitionTime metav1.Time `json:"lastTransitionTime,omitempty" protobuf:"bytes,3,opt,name=lastTransitionTime"`
	// reason is the reason for the condition's last transition.
	// +optional
	Reason string `json:"reason,omitempty" protobuf:"bytes,4,opt,name=reason"`
	// message is a human-readable explanation containing details about
	// the transition
	// +optional
	Message string `json:"message,omitempty" protobuf:"bytes,5,opt,name=message"`
}

// MetricStatus describes the last-read state of a single metric.
type MetricStatus struct {
	// type is the type of metric source.  It will be one of "Object",
	// "Pods" or "Resource", each corresponds to a matching field in the object.
	Type MetricSourceType `json:"type" protobuf:"bytes,1,name=type"`

	// object refers to a metric describing a single kubernetes object
	// (for example, hits-per-second on an Ingress object).
	// +optional
	Object *ObjectMetricStatus `json:"object,omitempty" protobuf:"bytes,2,opt,name=object"`
	// pods refers to a metric describing each pod in the current scale target
	// (for example, transactions-processed-per-second).  The values will be
	// averaged together before being compared to the target value.
	// +optional
	Pods *PodsMetricStatus `json:"pods,omitempty" protobuf:"bytes,3,opt,name=pods"`
	// resource refers to a resource metric (such as those specified in
	// requests and limits) known to Kubernetes describing each pod in the
	// current scale target (e.g. CPU or memory). Such metrics are built in to
	// Kubernetes, and have special scaling options on top of those available
	// to normal per-pod metrics using the "pods" source.
	// +optional
	Resource *ResourceMetricStatus `json:"resource,omitempty" protobuf:"bytes,4,opt,name=resource"`
	// external refers to a global metric that is not associated
	// with any Kubernetes object. It allows autoscaling based on information
	// coming from components running outside of cluster
	// (for example length of queue in cloud messaging service, or
	// QPS from loadbalancer running outside of cluster).
	// +optional
	External *ExternalMetricStatus `json:"external,omitempty" protobuf:"bytes,5,opt,name=external"`
}

// ObjectMetricStatus indicates the current value of a metric describing a
// kubernetes object (for example, hits-per-second on an Ingress object).
type ObjectMetricStatus struct {
	// metric identifies the target metric by name and selector
	Metric MetricIdentifier `json:"metric" protobuf:"bytes,1,name=metric"`
	// current contains the current value for the given metric
	Current MetricValueStatus `json:"current" protobuf:"bytes,2,name=current"`

	DescribedObject CrossVersionObjectReference `json:"describedObject" protobuf:"bytes,3,name=describedObject"`
}

// PodsMetricStatus indicates the current value of a metric describing each pod in
// the current scale target (for example, transactions-processed-per-second).
type PodsMetricStatus struct {
	// metric identifies the target metric by name and selector
	Metric MetricIdentifier `json:"metric" protobuf:"bytes,1,name=metric"`
	// current contains the current value for the given metric
	Current MetricValueStatus `json:"current" protobuf:"bytes,2,name=current"`
}

// ResourceMetricStatus indicates the current value of a resource metric known to
// Kubernetes, as specified in requests and limits, describing each pod in the
// current scale target (e.g. CPU or memory).  Such metrics are built in to
// Kubernetes, and have special scaling options on top of those available to
// normal per-pod metrics using the "pods" source.
type ResourceMetricStatus struct {
	// Name is the name of the resource in question.
	Name v1.ResourceName `json:"name" protobuf:"bytes,1,name=name"`
	// current contains the current value for the given metric
	Current MetricValueStatus `json:"current" protobuf:"bytes,2,name=current"`
}

// ExternalMetricStatus indicates the current value of a global metric
// not associated with any Kubernetes object.
type ExternalMetricStatus struct {
	// metric identifies the target metric by name and selector
	Metric MetricIdentifier `json:"metric" protobuf:"bytes,1,name=metric"`
	// current contains the current value for the given metric
	Current MetricValueStatus `json:"current" protobuf:"bytes,2,name=current"`
}

// MetricValueStatus holds the current value for a metric
type MetricValueStatus struct {
	// value is the current value of the metric (as a quantity).
	// +optional
	Value *resource.Quantity `json:"value,omitempty" protobuf:"bytes,1,opt,name=value"`
	// averageValue is the current value of the average of the
	// metric across all relevant pods (as a quantity)
	// +optional
	AverageValue *resource.Quantity `json:"averageValue,omitempty" protobuf:"bytes,2,opt,name=averageValue"`
	// currentAverageUtilization is the current value of the average of the
	// resource metric across all relevant pods, represented as a percentage of
	// the requested value of the resource for the pods.
	// +optional
	AverageUtilization *int32 `json:"averageUtilization,omitempty" protobuf:"bytes,3,opt,name=averageUtilization"`
}

// +k8s:deepcopy-gen:interfaces=k8s.io/apimachinery/pkg/runtime.Object

// HorizontalPodAutoscalerList is a list of horizontal pod autoscaler objects.
type HorizontalPodAutoscalerList struct {
	metav1.TypeMeta `json:",inline"`
	// metadata is the standard list metadata.
	// +optional
	metav1.ListMeta `json:"metadata,omitempty" protobuf:"bytes,1,opt,name=metadata"`

	// items is the list of horizontal pod autoscaler objects.
	Items []HorizontalPodAutoscaler `json:"items" protobuf:"bytes,2,rep,name=items"`
}
