package financial

// PaybackCalculatorImpl implements PaybackCalculator interface
type PaybackCalculatorImpl struct{}

// NewPaybackCalculator creates a new payback period calculator
func NewPaybackCalculator() PaybackCalculator {
	return &PaybackCalculatorImpl{}
}

// CalculatePaybackPeriod calculates simple payback period
// payback = CAPEX / annual_cash_flow
func (pb *PaybackCalculatorImpl) CalculatePaybackPeriod(capex, annualCashFlow float64) float64 {
	if annualCashFlow <= 0 {
		return 999.0 // Never pays back
	}

	return capex / annualCashFlow
}