// /*
// Copyright 2025 The Grove 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 v1alpha1

import (
	autoscalingv2 "k8s.io/api/autoscaling/v2"
	corev1 "k8s.io/api/core/v1"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
)

// +genclient
// +k8s:deepcopy-gen:interfaces=k8s.io/apimachinery/pkg/runtime.Object
// +kubebuilder:object:root=true
// +kubebuilder:subresource:status
// +kubebuilder:subresource:scale:specpath=.spec.replicas,statuspath=.status.replicas,selectorpath=.status.hpaPodSelector
// +kubebuilder:resource:shortName={pclq}

// PodClique is a set of pods running the same image.
type PodClique struct {
	metav1.TypeMeta   `json:",inline"`
	metav1.ObjectMeta `json:"metadata,omitempty"`
	// Spec defines the specification of a PodClique.
	Spec PodCliqueSpec `json:"spec"`
	// Status defines the status of a PodClique.
	Status PodCliqueStatus `json:"status,omitempty"`
}

// +kubebuilder:object:root=true
// +k8s:deepcopy-gen:interfaces=k8s.io/apimachinery/pkg/runtime.Object

// PodCliqueList is a list of PodClique's.
type PodCliqueList struct {
	metav1.TypeMeta `json:",inline"`
	metav1.ListMeta `json:"metadata,omitempty"`
	// Items is a slice of PodClique.
	Items []PodClique `json:"items"`
}

// PodCliqueSpec defines the specification of a PodClique.
type PodCliqueSpec struct {
	// RoleName is the name of the role that this PodClique will assume.
	RoleName string `json:"roleName"`
	// Spec is the spec of the pods in the clique.
	PodSpec corev1.PodSpec `json:"podSpec"`
	// Replicas is the number of replicas of the pods in the clique. It cannot be less than 1.
	Replicas int32 `json:"replicas"`
	// MinAvailable serves two purposes:
	// 1. It defines the minimum number of pods that are guaranteed to be gang scheduled.
	// 2. It defines the minimum requirement of available pods in a PodClique. Violation of this threshold will result
	// in termination of the PodGang that it belongs to. If MinAvailable is not set, then it will default to the template
	// Replicas.
	// +optional
	MinAvailable *int32 `json:"minAvailable,omitempty"`
	// StartsAfter provides you a way to explicitly define the startup dependencies amongst cliques.
	// If CliqueStartupType in PodGang has been set to 'CliqueStartupTypeExplicit', then to create an ordered start
	// amongst PodClique's StartsAfter can be used. A forest of DAG's can be defined to model any start order dependencies.
	// If there are more than one PodClique's defined and StartsAfter is not set for any of them, then their startup order
	// is random at best and must not be relied upon.
	// Validations:
	// 1. If a StartsAfter has been defined and one or more cycles are detected in DAG's then it will be flagged as validation error.
	// 2. If StartsAfter is defined and does not identify any PodClique then it will be flagged as a validation error.
	// +optional
	StartsAfter []string `json:"startsAfter,omitempty"`
	// ScaleConfig is the horizontal pod autoscaler configuration for a PodClique.
	// +optional
	ScaleConfig *AutoScalingConfig `json:"autoScalingConfig,omitempty"`
}

// AutoScalingConfig defines the configuration for the horizontal pod autoscaler.
type AutoScalingConfig struct {
	// MinReplicas is the lower limit for the number of replicas for the target resource.
	// It will be used by the horizontal pod autoscaler to determine the minimum number of replicas to scale-in to.
	// +optional
	MinReplicas *int32 `json:"minReplicas,omitempty"`
	// 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"`
	// 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.
	// +listType=atomic
	// +optional
	Metrics []autoscalingv2.MetricSpec `json:"metrics,omitempty" protobuf:"bytes,4,rep,name=metrics"`
}

// PodCliqueStatus defines the status of a PodClique.
type PodCliqueStatus struct {
	// ObservedGeneration is the most recent generation observed by the controller.
	ObservedGeneration *int64 `json:"observedGeneration,omitempty"`
	// LastErrors captures the last errors observed by the controller when reconciling the PodClique.
	LastErrors []LastError `json:"lastErrors,omitempty"`
	// Replicas is the total number of non-terminated Pods targeted by this PodClique.
	Replicas int32 `json:"replicas,omitempty"`
	// ReadyReplicas is the number of ready Pods targeted by this PodClique.
	// +kubebuilder:default=0
	ReadyReplicas int32 `json:"readyReplicas"`
	// UpdatedReplicas is the number of Pods that have been updated and are at the desired revision of the PodClique.
	// +kubebuilder:default=0
	UpdatedReplicas int32 `json:"updatedReplicas"`
	// ScheduleGatedReplicas is the number of Pods that have been created with one or more scheduling gate(s) set.
	// Sum of ReadyReplicas and ScheduleGatedReplicas will always be <= Replicas.
	// +kubebuilder:default=0
	ScheduleGatedReplicas int32 `json:"scheduleGatedReplicas"`
	// ScheduledReplicas is the number of Pods that have been scheduled by the backend scheduler.
	// +kubebuilder:default=0
	ScheduledReplicas int32 `json:"scheduledReplicas"`
	// Selector is the label selector that determines which pods are part of the PodClique.
	// PodClique is a unit of scale and this selector is used by HPA to scale the PodClique based on metrics captured
	// for the pods that match this selector.
	Selector *string `json:"hpaPodSelector,omitempty"`
	// Conditions represents the latest available observations of the clique by its controller.
	Conditions []metav1.Condition `json:"conditions,omitempty"`
	// CurrentPodCliqueSetGenerationHash establishes a correlation to PodCliqueSet generation hash indicating
	// that the spec of the PodCliqueSet at this generation is fully realized in the PodClique.
	CurrentPodCliqueSetGenerationHash *string `json:"currentPodCliqueSetGenerationHash,omitempty"`
	// CurrentPodTemplateHash establishes a correlation to PodClique template hash indicating
	// that the spec of the PodClique at this template hash is fully realized in the PodClique.
	CurrentPodTemplateHash *string `json:"currentPodTemplateHash,omitempty"`
	// UpdateProgress provides details about the ongoing update of the PodClique.
	UpdateProgress *PodCliqueUpdateProgress `json:"updateProgress,omitempty"`
}

// PodCliqueUpdateProgress provides details about the ongoing update of the PodClique.
type PodCliqueUpdateProgress struct {
	// UpdateStartedAt is the time at which the update started.
	UpdateStartedAt metav1.Time `json:"updateStartedAt,omitempty"`
	// UpdateEndedAt is the time at which Grove does not have any work pending to manifest the update according to the
	// configured update strategy. For auto update strategies where Grove handles the orchestration, while the update is
	// still in progress it will be nil, and will be set once the update finishes where all Pods are replaced by Grove with
	// the latest specification. For the OnDelete strategy, it is set to the same time as UpdateStartedAt, which implies
	// that there is no work pending on Grove. As can be observed with the OnDelete strategy, UpdateEndedAt being set does
	// not necessarily mean that all Pods are running with the latest specifications.
	UpdateEndedAt *metav1.Time `json:"updateEndedAt,omitempty"`
	// PodCliqueSetGenerationHash is the generation hash corresponding to the latest PodCliqueSet spec that this
	// PodClique should converge to. PodCliqueStatus.CurrentPodCliqueSetGenerationHash is set to this hash once
	// UpdateEndedAt is set, which marks the end of the update.
	PodCliqueSetGenerationHash string `json:"podCliqueSetGenerationHash"`
	// PodTemplateHash is the template hash of the PodClique that the Pods of this PodClique should converge to.
	// This hash is used to segregate Pods which are up to date with the specification, and ones which are outdated for
	// preferential deletions in auto update strategies, and in all strategies for scale-ins.
	// PodCliqueStatus.PodTemplateHash is set to this hash once UpdateEndedAt is set, which marks the end of the update.
	PodTemplateHash string `json:"podTemplateHash"`
	// ReadyPodsSelectedToUpdate captures the pod names of ready Pods that are either currently being updated or have
	// been previously updated. This field is only set for auto update strategies where Grove orchestrates Pod deletions.
	// For the OnDelete strategy this field is not set, because Pod replacement is initiated by user-driven Pod deletions.
	ReadyPodsSelectedToUpdate *PodsSelectedToUpdate `json:"readyPodsSelectedToUpdate,omitempty"`
}

// PodsSelectedToUpdate captures the current and previous set of pod names that have been selected for update in a
// rolling recreate. It is not set in an OnDelete update.
type PodsSelectedToUpdate struct {
	// Current captures the current pod name that is a target for update.
	Current string `json:"current"`
	// Completed captures the pod names that have already been updated.
	Completed []string `json:"completed,omitempty"`
}

// SetLastErrors sets the last errors observed by the controller when reconciling the PodClique.
func (pclq *PodClique) SetLastErrors(lastErrs ...LastError) {
	pclq.Status.LastErrors = lastErrs
}