package stats

// StubFallbackCPUPercent is returned after the first sample on platforms without
// OS CPU counters (cpu_stub.go). Kept below the default idle threshold (20%).
const StubFallbackCPUPercent = 5.0

// stubSystemCPUPercent implements idle-mining-safe defaults when real counters
// are unavailable: first sample returns 0 (no delta yet), then a low busy %.
func (r *Reporter) stubSystemCPUPercent() float64 {
	r.mu.Lock()
	defer r.mu.Unlock()
	if !r.hasSample {
		r.hasSample = true
		return 0
	}
	return StubFallbackCPUPercent
}

func cpuBusyPercentFromDeltas(idleDelta, totalDelta float64) float64 {
	if totalDelta <= 0 {
		return 0
	}
	busyPct := (1.0 - idleDelta/totalDelta) * 100
	if busyPct < 0 {
		return 0
	}
	if busyPct > 100 {
		return 100
	}
	return busyPct
}