const (
	ImageGarbageCollectedTotalReasonAge   = "age"
	ImageGarbageCollectedTotalReasonSpace = "space"
)

var (
	// ErrImagePullBackOff - Container image pull failed, kubelet is backing off image pull
	ErrImagePullBackOff = errors.New("ImagePullBackOff")

	// ErrImageInspect - Unable to inspect image
	ErrImageInspect = errors.New("ImageInspectError")

	// ErrImagePull - General image pull error
	ErrImagePull = errors.New("ErrImagePull")

	// ErrImageNeverPull - Required Image is absent on host and PullPolicy is NeverPullImage
	ErrImageNeverPull = errors.New("ErrImageNeverPull")

	// ErrInvalidImageName - Unable to parse the image name.
	ErrInvalidImageName = errors.New("InvalidImageName")
)

type ImageGCManager interface {
	// Applies the garbage collection policy. Errors include being unable to free
	// enough space as per the garbage collection policy.
	GarbageCollect(ctx context.Context, beganGC time.Time) error

	// Start async garbage collection of images.
	Start()

	GetImageList() ([]container.Image, error)

	// Delete all unused images.
	DeleteUnusedImages(ctx context.Context) error
}

type ImageGCPolicy struct {
	// Any usage above this threshold will always trigger garbage collection.
	// This is the highest usage we will allow.
	HighThresholdPercent int

	// Any usage below this threshold will never trigger garbage collection.
	// This is the lowest threshold we will try to garbage collect to.
	LowThresholdPercent int

	// Minimum age at which an image can be garbage collected.
	MinAge time.Duration

	// Maximum age after which an image can be garbage collected, regardless of disk usage.
	// Currently gated by MaximumImageGCAge feature gate and Kubelet configuration.
	// If 0, the feature is disabled.
	MaxAge time.Duration
}

type ImageManager interface {
	// EnsureImageExists ensures that image specified by `imgRef` exists.
	EnsureImageExists(ctx context.Context, objRef *v1.ObjectReference, pod *v1.Pod, imgRef string, pullSecrets []v1.Secret, podSandboxConfig *runtimeapi.PodSandboxConfig, podRuntimeHandler string, pullPolicy v1.PullPolicy) (string, string, error)
}

type ImagePodPullingTimeRecorder interface {
	RecordImageStartedPulling(podUID types.UID)
	RecordImageFinishedPulling(podUID types.UID)
}

type PostImageGCHook func(remainingImages []string, gcStart time.Time)

type StatsProvider interface {
	// ImageFsStats returns the stats of the image filesystem.
	ImageFsStats(ctx context.Context) (*statsapi.FsStats, *statsapi.FsStats, error)
}