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refactor: move LSP balance calculations to BitkitCore #265

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Merged
pwltr merged 2 commits into from
Dec 5, 2025
+123 −169
Merged

refactor: move LSP balance calculations to BitkitCore #265

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b2d2009
refactor: move LSP balance calculations to BitkitCore and improve tra…
ben-kaufman Dec 5, 2025
754e124
Fix comments
ben-kaufman Dec 5, 2025
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2 changes: 1 addition & 1 deletion Bitkit.xcodeproj/project.xcworkspace/xcshareddata/swiftpm/Package.resolved
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33 changes: 8 additions & 25 deletions Bitkit/ViewModels/BlocktankViewModel.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -209,44 +209,27 @@ class BlocktankViewModel: ObservableObject {
)
}

/// Calculates default LSP balance for CJIT channels using bitkit-core
private func getDefaultLspBalance(clientBalance: UInt64) async throws -> UInt64 {
if info == nil {
try await refreshInfo()
}
let maxLspBalance = info?.options.maxChannelSizeSat ?? 0

// Get current rates
guard let rates = currencyService.loadCachedRates(),
let eurRate = currencyService.getCurrentRate(for: "EUR", from: rates)
else {
Logger.error("Failed to get EUR rate for lspBalance calculation")
throw CustomServiceError.currencyRateUnavailable
}

// Calculate thresholds in sats
let threshold1 = currencyService.convertFiatToSats(fiatValue: 225, rate: eurRate)
let threshold2 = currencyService.convertFiatToSats(fiatValue: 495, rate: eurRate)
let defaultLspBalance = currencyService.convertFiatToSats(fiatValue: 450, rate: eurRate)

Logger.debug("getDefaultLspBalance - clientBalance: \(clientBalance)")
Logger.debug("getDefaultLspBalance - maxLspBalance: \(maxLspBalance)")
Logger.debug("getDefaultLspBalance - defaultLspBalance: \(defaultLspBalance)")

// Safely calculate lspBalance to avoid arithmetic overflow
var lspBalance: UInt64 = 0
if defaultLspBalance > clientBalance {
lspBalance = defaultLspBalance - clientBalance
}

if clientBalance > threshold1 {
lspBalance = clientBalance
}

if clientBalance > threshold2 {
lspBalance = maxLspBalance
}
let satsPerEur = currencyService.convertFiatToSats(fiatValue: 1, rate: eurRate)
let params = DefaultLspBalanceParams(
clientBalanceSat: clientBalance,
maxChannelSizeSat: info?.options.maxChannelSizeSat ?? 0,
satsPerEur: satsPerEur
)

return min(lspBalance, maxLspBalance)
return BitkitCore.getDefaultLspBalance(params: params)
}

func refreshMinCjitSats() async throws {
Expand Down
95 changes: 28 additions & 67 deletions Bitkit/ViewModels/TransferViewModel.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -294,91 +294,52 @@ class TransferViewModel: ObservableObject {
selectedChannelIds = []
}

// MARK: - Balance Calculation Functions
// MARK: - Balance Calculation

/// Calculates channel liquidity options using bitkit-core
func calculateTransferValues(clientBalanceSat: UInt64, blocktankInfo: IBtInfo?) -> TransferValues {
guard let blocktankInfo else {
return TransferValues()
}

func getDefaultLspBalance(clientBalanceSat: UInt64, maxLspBalance: UInt64) -> UInt64 {
// Get current rates
guard let rates = currencyService.loadCachedRates(),
let eurRate = currencyService.getCurrentRate(for: "EUR", from: rates)
else {
Logger.error("Failed to get rates for getDefaultLspBalance", context: "TransferViewModel")
return 0
Logger.error("Failed to get rates for calculateTransferValues", context: "TransferViewModel")
return TransferValues()
}

// Calculate thresholds in sats
let threshold1 = currencyService.convertFiatToSats(fiatValue: 225, rate: eurRate)
let threshold2 = currencyService.convertFiatToSats(fiatValue: 495, rate: eurRate)
let defaultLspBalanceSats = currencyService.convertFiatToSats(fiatValue: 450, rate: eurRate)

var lspBalance = Int64(defaultLspBalanceSats) - Int64(clientBalanceSat)

// Ensure non-negative result
if lspBalance < 0 {
lspBalance = 0
}
let satsPerEur = currencyService.convertFiatToSats(fiatValue: 1, rate: eurRate)
let existingChannelsTotalSat = totalBtChannelsValueSats(blocktankInfo: blocktankInfo)

if clientBalanceSat > threshold1 {
lspBalance = Int64(clientBalanceSat)
}
let params = ChannelLiquidityParams(
clientBalanceSat: clientBalanceSat,
existingChannelsTotalSat: existingChannelsTotalSat,
minChannelSizeSat: blocktankInfo.options.minChannelSizeSat,
maxChannelSizeSat: blocktankInfo.options.maxChannelSizeSat,
satsPerEur: satsPerEur
)

if clientBalanceSat > threshold2 {
lspBalance = Int64(maxLspBalance)
}
let options = BitkitCore.calculateChannelLiquidityOptions(params: params)

return min(UInt64(lspBalance), maxLspBalance)
return TransferValues(
defaultLspBalance: options.defaultLspBalanceSat,
minLspBalance: options.minLspBalanceSat,
maxLspBalance: options.maxLspBalanceSat,
maxClientBalance: options.maxClientBalanceSat
)
}

func getMinLspBalance(clientBalance: UInt64, minChannelSize: UInt64) -> UInt64 {
// LSP balance must be at least 2.5% of the channel size for LDK to accept (reserve balance)
let ldkMinimum = UInt64(Double(clientBalance) * 0.025)
// Channel size must be at least minChannelSize
let lspMinimum = clientBalance < minChannelSize ? minChannelSize - clientBalance : 0

return max(ldkMinimum, lspMinimum)
func updateTransferValues(clientBalanceSat: UInt64, blocktankInfo: IBtInfo?) {
transferValues = calculateTransferValues(clientBalanceSat: clientBalanceSat, blocktankInfo: blocktankInfo)
}

/// Calculates max client balance accounting for LDK reserve requirement
func getMaxClientBalance(maxChannelSize: UInt64) -> UInt64 {
// Remote balance must be at least 2.5% of the channel size for LDK to accept (reserve balance)
let minRemoteBalance = UInt64(Double(maxChannelSize) * 0.025)
return maxChannelSize - minRemoteBalance
}

func updateTransferValues(clientBalanceSat: UInt64, blocktankInfo: IBtInfo?) {
transferValues = calculateTransferValues(clientBalanceSat: clientBalanceSat, blocktankInfo: blocktankInfo)
}

func calculateTransferValues(clientBalanceSat: UInt64, blocktankInfo: IBtInfo?) -> TransferValues {
guard let blocktankInfo else {
return TransferValues()
}

// Calculate the total value of existing Blocktank channels
let channelsSize = totalBtChannelsValueSats(blocktankInfo: blocktankInfo)

let minChannelSizeSat = UInt64(blocktankInfo.options.minChannelSizeSat)
let maxChannelSizeSat = UInt64(blocktankInfo.options.maxChannelSizeSat)

// Because LSP limits constantly change depending on network fees
// Add a 2% buffer to avoid fluctuations while making the order
let maxChannelSize1 = UInt64(Double(maxChannelSizeSat) * 0.98)

// The maximum channel size the user can open including existing channels
let maxChannelSize2 = maxChannelSize1 > channelsSize ? maxChannelSize1 - channelsSize : 0
let maxChannelSize = min(maxChannelSize1, maxChannelSize2)

let minLspBalance = getMinLspBalance(clientBalance: clientBalanceSat, minChannelSize: minChannelSizeSat)
let maxLspBalance = maxChannelSize > clientBalanceSat ? maxChannelSize - clientBalanceSat : 0
let defaultLspBalance = getDefaultLspBalance(clientBalanceSat: clientBalanceSat, maxLspBalance: maxLspBalance)
let maxClientBalance = getMaxClientBalance(maxChannelSize: maxChannelSize)

return TransferValues(
defaultLspBalance: defaultLspBalance,
minLspBalance: minLspBalance,
maxLspBalance: maxLspBalance,
maxClientBalance: maxClientBalance
)
}

// MARK: - Manual Channel Opening

/// Opens a manual channel and tracks the transfer
Expand Down
39 changes: 25 additions & 14 deletions Bitkit/Views/Transfer/SpendingAdvancedView.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -8,20 +8,21 @@ struct SpendingAdvancedView: View {
@EnvironmentObject var blocktank: BlocktankViewModel
@EnvironmentObject var currency: CurrencyViewModel
@EnvironmentObject var transfer: TransferViewModel
@EnvironmentObject var wallet: WalletViewModel
@Environment(\.dismiss) var dismiss

@StateObject private var amountViewModel = AmountInputViewModel()
@State private var feeEstimate: UInt64?
@State private var isLoading = false
@State private var feeEstimateTask: Task<Void, Never>?

var lspBalance: UInt64 {
amountViewModel.amountSats
}

private var isValid: Bool {
let isAboveMin = lspBalance >= transfer.transferValues.minLspBalance
let isBelowMax = lspBalance <= transfer.transferValues.maxLspBalance
return isAboveMin && isBelowMax
let values = transfer.transferValues
guard lspBalance > 0, values.maxLspBalance > 0 else { return false }
return lspBalance >= values.minLspBalance && lspBalance <= values.maxLspBalance
}

var body: some View {
Expand Down Expand Up @@ -73,15 +74,17 @@ struct SpendingAdvancedView: View {

CustomButton(
title: t("common__continue"),
isDisabled: !isValid
isDisabled: !isValid,
isLoading: isLoading
) {
isLoading = true
defer { isLoading = false }

do {
// Create a new order with the specified receiving capacity
let newOrder = try await blocktank.createOrder(
clientBalance: order.clientBalanceSat,
lspBalance: lspBalance
)

transfer.onAdvancedOrderCreated(order: newOrder)
dismiss()
} catch {
Expand All @@ -102,7 +105,11 @@ struct SpendingAdvancedView: View {
updateFeeEstimate()
}
.onChange(of: lspBalance) { _ in
updateFeeEstimate()
if isValid {
updateFeeEstimate()
} else {
feeEstimate = nil
}
}
}

Expand All @@ -129,17 +136,22 @@ struct SpendingAdvancedView: View {
private func updateFeeEstimate() {
guard lspBalance > 0 else { return }

Task {
feeEstimateTask?.cancel()
feeEstimate = nil

feeEstimateTask = Task {
do {
feeEstimate = nil
let estimate = try await blocktank.estimateOrderFee(
clientBalance: order.clientBalanceSat,
lspBalance: lspBalance
)
feeEstimate = estimate.feeSat
guard !Task.isCancelled else { return }
await MainActor.run {
feeEstimate = estimate.feeSat
}
} catch {
feeEstimate = nil
Logger.error("Failed to estimate fee: \(error.localizedDescription)")
guard !Task.isCancelled else { return }
Logger.debug("Fee estimation failed: \(error.localizedDescription)")
}
}
}
Expand All @@ -150,7 +162,6 @@ struct SpendingAdvancedView: View {
SpendingAdvancedView(
order: IBtOrder.mock(lspBalanceSat: 100_000, clientBalanceSat: 50000)
)
.environmentObject(WalletViewModel())
.environmentObject(AppViewModel())
.environmentObject(CurrencyViewModel())
.environmentObject(BlocktankViewModel())
Expand Down
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