Release v0.3.0

vendor/github.com/muun/libwallet/fees/fees.go

@@ -0,0 +1,113 @@
+package fees
+
+import "github.com/btcsuite/btcutil"
+
+const dustThreshold = 546
+
+type BestRouteFees struct {
+	MaxCapacity              btcutil.Amount
+	FeeProportionalMillionth uint64
+	FeeBase                  btcutil.Amount
+}
+
+type FundingOutputPolicies struct {
+	MaximumDebt       btcutil.Amount
+	PotentialCollect  btcutil.Amount
+	MaxAmountFor0Conf btcutil.Amount
+}
+
+type DebtType string
+
+const (
+	DebtTypeNone    DebtType = "NONE"
+	DebtTypeCollect          = "COLLECT"
+	DebtTypeLend             = "LEND"
+)
+
+type SwapFees struct {
+	RoutingFee          btcutil.Amount
+	SweepFee            btcutil.Amount
+	DebtType            DebtType
+	DebtAmount          btcutil.Amount
+	ConfirmationsNeeded uint32
+}
+
+func (p *FundingOutputPolicies) FundingConfirmations(paymentAmount, lightningFee btcutil.Amount) uint32 {
+	totalAmount := paymentAmount + lightningFee
+	if totalAmount <= p.MaxAmountFor0Conf {
+		return 0
+	}
+	return 1
+}
+
+func (p *FundingOutputPolicies) DebtType(paymentAmount, lightningFee btcutil.Amount) DebtType {
+	numConfirmations := p.FundingConfirmations(paymentAmount, lightningFee)
+	totalAmount := paymentAmount + lightningFee
+	if numConfirmations == 0 && totalAmount <= p.MaximumDebt {
+		return DebtTypeLend
+	}
+	if p.PotentialCollect > 0 {
+		return DebtTypeCollect
+	}
+	return DebtTypeNone
+}
+
+func (p *FundingOutputPolicies) DebtAmount(paymentAmount, lightningFee btcutil.Amount) btcutil.Amount {
+	switch p.DebtType(paymentAmount, lightningFee) {
+	case DebtTypeLend:
+		return paymentAmount + lightningFee
+	case DebtTypeCollect:
+		return p.PotentialCollect
+	case DebtTypeNone:
+		return 0
+	default:
+		return 0
+	}
+}
+
+func (p *FundingOutputPolicies) MinFundingAmount(paymentAmount, lightningFee btcutil.Amount) btcutil.Amount {
+	inputAmount := paymentAmount + lightningFee
+	if p.DebtType(paymentAmount, lightningFee) == DebtTypeCollect {
+		inputAmount += p.DebtAmount(paymentAmount, lightningFee)
+	}
+	return inputAmount
+}
+
+func (p *FundingOutputPolicies) FundingOutputAmount(paymentAmount, lightningFee btcutil.Amount) btcutil.Amount {
+	minAmount := p.MinFundingAmount(paymentAmount, lightningFee)
+	if minAmount < dustThreshold {
+		return dustThreshold
+	}
+	return minAmount
+}
+
+func (p *FundingOutputPolicies) FundingOutputPadding(paymentAmount, lightningFee btcutil.Amount) btcutil.Amount {
+	minAmount := p.MinFundingAmount(paymentAmount, lightningFee)
+	outputAmount := p.FundingOutputAmount(paymentAmount, lightningFee)
+	return outputAmount - minAmount
+}
+
+func ComputeSwapFees(amount btcutil.Amount, bestRouteFees []BestRouteFees, policies *FundingOutputPolicies) *SwapFees {
+	lightningFee := computeLightningFee(amount, bestRouteFees)
+	return &SwapFees{
+		RoutingFee:          lightningFee,
+		SweepFee:            policies.FundingOutputPadding(amount, lightningFee),
+		DebtType:            policies.DebtType(amount, lightningFee),
+		DebtAmount:          policies.DebtAmount(amount, lightningFee),
+		ConfirmationsNeeded: policies.FundingConfirmations(amount, lightningFee),
+	}
+}
+
+func computeLightningFee(amount btcutil.Amount, bestRouteFees []BestRouteFees) btcutil.Amount {
+	for _, fee := range bestRouteFees {
+		if amount <= fee.MaxCapacity {
+			return fee.ForAmount(amount)
+		}
+	}
+	lastRouteFee := bestRouteFees[len(bestRouteFees)-1]
+	return lastRouteFee.ForAmount(amount)
+}
+
+func (f *BestRouteFees) ForAmount(amount btcutil.Amount) btcutil.Amount {
+	return (btcutil.Amount(f.FeeProportionalMillionth)*amount)/1000000 + f.FeeBase
+}