const (
	// DefaultExtenderTimeout defines the default extender timeout in second.
	DefaultExtenderTimeout = 5 * time.Second
)

const (
	// NoNodeAvailableMsg is used to format message when no nodes available.
	NoNodeAvailableMsg = "0/%v nodes are available"
)

var ErrNoNodesAvailable = fmt.Errorf("no nodes available to schedule pods")

type FitError struct {
	Pod                   *v1.Pod
	NumAllNodes           int
	FilteredNodesStatuses framework.NodeToStatusMap
}

type HTTPExtender struct {
	// contains filtered or unexported fields
}

type ScheduleAlgorithm interface {
	Schedule(context.Context, *profile.Profile, *framework.CycleState, *v1.Pod) (scheduleResult ScheduleResult, err error)
	// Preempt receives scheduling errors for a pod and tries to create room for
	// the pod by preempting lower priority pods if possible.
	// It returns the node where preemption happened, a list of preempted pods, a
	// list of pods whose nominated node name should be removed, and error if any.
	Preempt(context.Context, *profile.Profile, *framework.CycleState, *v1.Pod, error) (selectedNode *v1.Node, preemptedPods []*v1.Pod, cleanupNominatedPods []*v1.Pod, err error)
	// Prioritizers returns a slice of priority config. This is exposed for
	// testing.
	Extenders() []SchedulerExtender
}

type ScheduleResult struct {
	// Name of the scheduler suggest host
	SuggestedHost string
	// Number of nodes scheduler evaluated on one pod scheduled
	EvaluatedNodes int
	// Number of feasible nodes on one pod scheduled
	FeasibleNodes int
}

type SchedulerExtender interface {
	// Name returns a unique name that identifies the extender.
	Name() string

	// Filter based on extender-implemented predicate functions. The filtered list is
	// expected to be a subset of the supplied list. failedNodesMap optionally contains
	// the list of failed nodes and failure reasons.
	Filter(pod *v1.Pod, nodes []*v1.Node) (filteredNodes []*v1.Node, failedNodesMap extenderv1.FailedNodesMap, err error)

	// Prioritize based on extender-implemented priority functions. The returned scores & weight
	// are used to compute the weighted score for an extender. The weighted scores are added to
	// the scores computed by Kubernetes scheduler. The total scores are used to do the host selection.
	Prioritize(pod *v1.Pod, nodes []*v1.Node) (hostPriorities *extenderv1.HostPriorityList, weight int64, err error)

	// Bind delegates the action of binding a pod to a node to the extender.
	Bind(binding *v1.Binding) error

	// IsBinder returns whether this extender is configured for the Bind method.
	IsBinder() bool

	// IsInterested returns true if at least one extended resource requested by
	// this pod is managed by this extender.
	IsInterested(pod *v1.Pod) bool

	// ProcessPreemption returns nodes with their victim pods processed by extender based on
	// given:
	//   1. Pod to schedule
	//   2. Candidate nodes and victim pods (nodeToVictims) generated by previous scheduling process.
	//   3. nodeNameToInfo to restore v1.Node from node name if extender cache is enabled.
	// The possible changes made by extender may include:
	//   1. Subset of given candidate nodes after preemption phase of extender.
	//   2. A different set of victim pod for every given candidate node after preemption phase of extender.
	ProcessPreemption(
		pod *v1.Pod,
		nodeToVictims map[*v1.Node]*extenderv1.Victims,
		nodeInfos listers.NodeInfoLister) (map[*v1.Node]*extenderv1.Victims, error)

	// SupportsPreemption returns if the scheduler extender support preemption or not.
	SupportsPreemption() bool

	// IsIgnorable returns true indicates scheduling should not fail when this extender
	// is unavailable. This gives scheduler ability to fail fast and tolerate non-critical extenders as well.
	IsIgnorable() bool
}