package health

// TaskMetricsObserver accepts only the low-cardinality dimensions emitted by
// Checker task processing. Implementations must not add task, proxy, checker,
// endpoint, target URL, or credential values as metric labels.
type TaskMetricsObserver interface {
	ObserveTaskDispatch(Level, int)
	ObserveObservation(Level, ObservationMetricResult)
}

// DrainReason is intentionally finite so Controller metrics cannot expose
// upstream, proxy, Worker, session or endpoint identity as labels.
type DrainReason string

const (
	DrainReasonUnhealthy        DrainReason = "unhealthy"
	DrainReasonUpstreamDisabled DrainReason = "upstream_disabled"
)

// DrainMetricsObserver records bounded Controller-side Drain attempts after a
// complete sweep. Candidate and started counts are separate because a fenced
// candidate may legitimately become stale before the ownership transition.
type DrainMetricsObserver interface {
	ObserveDrain(reason DrainReason, candidates, started int)
}

type ObservationMetricResult string

const (
	ObservationMetricAccepted ObservationMetricResult = "accepted"
	ObservationMetricRejected ObservationMetricResult = "rejected"
)