package oracle

import "git.mleku.dev/mleku/dendrite/pkg/ewma"

// StabilityMonitor wraps the EWMA oscillation detector for oracle triggering.
// When the bond rate of the current learning source oscillates (the organism
// is no longer absorbing new structure), the monitor fires and the oracle
// should cast a new reading.
type StabilityMonitor struct {
	// Detector is the EWMA oscillation detector.
	Detector *ewma.OscillationDetector

	// LastSignalGen records when the most recent stability signal fired.
	LastSignalGen uint32
}

// NewStabilityMonitor creates a monitor. ewmaWindow is the smoothing window
// size for the EWMA (typical: 5-10). threshold is the reversal count needed
// to declare oscillation (typical: 3 = ~1.5 full cycles).
func NewStabilityMonitor(ewmaWindow, threshold int) *StabilityMonitor {
	return &StabilityMonitor{
		Detector: ewma.NewDetector(ewmaWindow, 0, threshold),
	}
}

// Observe feeds a (fetched, bonded) pair from the current data source
// into the EWMA. Returns true if the current reading has been absorbed
// (the bond rate is oscillating = no more new structure being absorbed).
//
// After returning true, the caller should mark the oracle's current reading
// as absorbed and cast a new one. The detector is reset automatically.
func (sm *StabilityMonitor) Observe(fetched, bonded int64, gen uint32) bool {
	oscillating := sm.Detector.Observe(fetched, bonded)
	if oscillating {
		sm.LastSignalGen = gen
		sm.Detector.Reset()
		return true
	}
	return false
}