const (
	TriggerReasonPodResized  = "pod_resized"
	TriggerReasonPodUpdated  = "pod_updated"
	TriggerReasonPodsAdded   = "pods_added"
	TriggerReasonPodsRemoved = "pods_removed"
)

type Manager interface {
	// GetContainerResourceAllocation returns the AllocatedResources value for the container
	GetContainerResourceAllocation(podUID types.UID, containerName string) (v1.ResourceRequirements, bool)

	// UpdatePodFromAllocation overwrites the pod spec with the allocation.
	// This function does a deep copy only if updates are needed.
	// Returns the updated (or original) pod, and whether there was an allocation stored.
	UpdatePodFromAllocation(pod *v1.Pod) (*v1.Pod, bool)

	// SetAllocatedResources checkpoints the resources allocated to a pod's containers.
	SetAllocatedResources(allocatedPod *v1.Pod) error

	// SetActuatedResources records the actuated resources of the given container (or the entire
	// pod, if actuatedContainer is nil).
	SetActuatedResources(allocatedPod *v1.Pod, actuatedContainer *v1.Container) error

	// GetActuatedResources returns the stored actuated resources for the container, and whether they exist.
	GetActuatedResources(podUID types.UID, containerName string) (v1.ResourceRequirements, bool)

	// AddPodAdmitHandlers adds the admit handlers to the allocation manager.
	// TODO: See if we can remove this and just add them in the allocation manager constructor.
	AddPodAdmitHandlers(handlers lifecycle.PodAdmitHandlers)

	// SetContainerRuntime sets the allocation manager's container runtime.
	// TODO: See if we can remove this and just add it in the allocation manager constructor.
	SetContainerRuntime(runtime kubecontainer.Runtime)

	// AddPod checks if a pod can be admitted. If so, it admits the pod and updates the allocation.
	// The function returns a boolean value indicating whether the pod
	// can be admitted, a brief single-word reason and a message explaining why
	// the pod cannot be admitted.
	// allocatedPods should represent the pods that have already been admitted, along with their
	// admitted (allocated) resources.
	AddPod(activePods []*v1.Pod, pod *v1.Pod) (ok bool, reason, message string)

	// RemovePod removes any stored state for the given pod UID.
	RemovePod(uid types.UID)

	// RemoveOrphanedPods removes the stored state for any pods not included in the set of remaining pods.
	RemoveOrphanedPods(remainingPods sets.Set[types.UID])

	// Run starts the allocation manager. This is currently only used to handle periodic retry of
	// pending resizes.
	Run(ctx context.Context)

	// PushPendingResize queues a pod with a pending resize request for later reevaluation.
	PushPendingResize(uid types.UID)

	// HasPendingResizes returns whether there are currently any pending resizes.
	HasPendingResizes() bool

	// RetryPendingResizes retries all pending resizes.
	RetryPendingResizes(trigger string)

	// CheckPodResizeInProgress checks whether the actuated resizable resources differ from the allocated resources
	// for any running containers.
	CheckPodResizeInProgress(allocatedPod *v1.Pod, podStatus *kubecontainer.PodStatus)
}