Fix legacy type issues

Author: ben-kaufman

Bitkit/Services/LightningService.swift

@@ -749,6 +749,49 @@ extension LightningService {
         }
     }
 
+    /// Get the total balance that can be used for channel funding (excludes Legacy/P2PKH UTXOs)
+    /// LDK channel funding requires witness-compatible UTXOs (NativeSegwit, NestedSegwit, Taproot)
+    /// - Returns: Total spendable sats from witness-compatible address types
+    func getChannelFundableBalance() async throws -> UInt64 {
+        guard let node else {
+            throw AppError(serviceError: .nodeNotSetup)
+        }
+
+        // Get monitored address types from UserDefaults
+        let storedTypes = UserDefaults.standard.string(forKey: "addressTypesToMonitor") ?? "nativeSegwit"
+        let typeStrings = storedTypes.split(separator: ",").map { String($0).trimmingCharacters(in: .whitespaces) }
+        let monitoredTypes: [LDKNode.AddressType] = typeStrings.compactMap { str in
+            switch str {
+            case "legacy": return .legacy
+            case "nestedSegwit": return .nestedSegwit
+            case "nativeSegwit": return .nativeSegwit
+            case "taproot": return .taproot
+            default: return nil
+            }
+        }
+
+        var totalFundable: UInt64 = 0
+
+        for addressType in monitoredTypes {
+            // Skip Legacy (P2PKH) as it cannot be used for channel funding
+            if addressType == .legacy {
+                continue
+            }
+
+            do {
+                let balance = try await ServiceQueue.background(.ldk) {
+                    try node.getBalanceForAddressType(addressType: addressType)
+                }
+                totalFundable += balance.spendableSats
+            } catch {
+                // If we can't get balance for this type, log and continue
+                Logger.warn("Failed to get balance for \(addressType) when calculating channel fundable balance: \(error)")
+            }
+        }
+
+        return totalFundable
+    }
+
     /// Returns LSP (Blocktank) peer node IDs
     func getLspPeerNodeIds() -> [String] {
         return Env.trustedLnPeers.map(\.nodeId)

Bitkit/ViewModels/SettingsViewModel.swift

@@ -333,6 +333,16 @@ class SettingsViewModel: NSObject, ObservableObject {
             let balance = await getBalanceForAddressType(addressType)
             if balance > 0 { return false }
 
+            // If primary is Legacy, ensure at least one SegWit-compatible wallet remains enabled
+            // (Legacy UTXOs cannot be used for Lightning channel funding)
+            if selectedAddressType == .legacy {
+                let segwitTypes: [AddressScriptType] = [.nestedSegwit, .nativeSegwit, .taproot]
+                let remainingSegwit = current.filter { $0 != addressType && segwitTypes.contains($0) }
+                if remainingSegwit.isEmpty {
+                    return false
+                }
+            }
+
             current.removeAll { $0 == addressType }
             addressTypesToMonitor = current
         }
@@ -364,6 +374,22 @@ class SettingsViewModel: NSObject, ObservableObject {
         addressTypesToMonitor = Self.allAddressTypes
     }
 
+    /// Check if disabling an address type would leave no SegWit wallets when Legacy is primary
+    /// - Parameter addressType: The address type to check
+    /// - Returns: True if this is the last SegWit wallet and Legacy is primary
+    func isLastRequiredSegwitWallet(_ addressType: AddressScriptType) -> Bool {
+        // Only applies when Legacy is the primary wallet
+        guard selectedAddressType == .legacy else { return false }
+
+        // Only applies to SegWit-compatible types
+        let segwitTypes: [AddressScriptType] = [.nestedSegwit, .nativeSegwit, .taproot]
+        guard segwitTypes.contains(addressType) else { return false }
+
+        // Check if disabling this would leave no SegWit wallets
+        let remainingSegwit = addressTypesToMonitor.filter { $0 != addressType && segwitTypes.contains($0) }
+        return remainingSegwit.isEmpty
+    }
+
     var selectedAddressType: AddressScriptType {
         get {
             // Parse the stored string value

Bitkit/ViewModels/WalletViewModel.swift

@@ -11,6 +11,7 @@ class WalletViewModel: ObservableObject {
     @AppStorage("totalLightningSats") var totalLightningSats: Int = 0 // Combined LN
     @AppStorage("spendableOnchainBalanceSats") var spendableOnchainBalanceSats: Int = 0 // The spendable balance of our on-chain wallet
     @AppStorage("maxSendLightningSats") var maxSendLightningSats: Int = 0 // Maximum amount that can be sent via lightning (outbound capacity)
+    @AppStorage("channelFundableBalanceSats") var channelFundableBalanceSats: Int = 0 // Balance usable for channel funding (excludes Legacy UTXOs)
 
     // Receive flow
     @AppStorage("onchainAddress") var onchainAddress = ""
@@ -587,6 +588,11 @@ class WalletViewModel: ObservableObject {
             totalBalanceSats = Int(state.totalBalanceSats)
             maxSendLightningSats = Int(state.maxSendLightningSats)
 
+            // Update channel fundable balance (excludes Legacy UTXOs which can't be used for channels)
+            if let fundableBalance = try? await lightningService.getChannelFundableBalance() {
+                channelFundableBalanceSats = Int(fundableBalance)
+            }
+
             // Get force close timelock from active transfers
             let activeTransfers = try? transferService.getActiveTransfers()
             let forceCloseTransfer = activeTransfers?.first {

Bitkit/Views/Settings/Advanced/AddressTypePreferenceView.swift

@@ -265,11 +265,20 @@ struct AddressTypePreferenceView: View {
                                                     description: "Address monitoring settings applied."
                                                 )
                                             } else if !enabled {
-                                                app.toast(
-                                                    type: .error,
-                                                    title: "Cannot Disable",
-                                                    description: "\(addressType.localizedTitle) addresses have balance."
-                                                )
+                                                // Determine reason for failure
+                                                if settingsViewModel.isLastRequiredSegwitWallet(addressType) {
+                                                    app.toast(
+                                                        type: .error,
+                                                        title: "Cannot Disable",
+                                                        description: "At least one SegWit wallet is required for Lightning when using Legacy as primary."
+                                                    )
+                                                } else {
+                                                    app.toast(
+                                                        type: .error,
+                                                        title: "Cannot Disable",
+                                                        description: "\(addressType.localizedTitle) addresses have balance."
+                                                    )
+                                                }
                                             }
                                         }
                                     }

Bitkit/Views/Transfer/FundManualAmountView.swift

@@ -32,9 +32,10 @@ struct FundManualAmountView: View {
                 Spacer()
 
                 HStack(alignment: .bottom) {
-                    AvailableAmount(label: t("wallet__send_available"), amount: wallet.totalOnchainSats)
+                    // Show channel fundable balance (excludes Legacy UTXOs which can't be used for channel funding)
+                    AvailableAmount(label: t("wallet__send_available"), amount: wallet.channelFundableBalanceSats)
                         .onTapGesture {
-                            amountViewModel.updateFromSats(UInt64(wallet.totalOnchainSats), currency: currency)
+                            amountViewModel.updateFromSats(UInt64(wallet.channelFundableBalanceSats), currency: currency)
                         }
 
                     Spacer()
@@ -80,11 +81,11 @@ struct FundManualAmountView: View {
             }
 
             NumberPadActionButton(text: t("lightning__spending_amount__quarter")) {
-                amountViewModel.updateFromSats(UInt64(wallet.totalOnchainSats) / 4, currency: currency)
+                amountViewModel.updateFromSats(UInt64(wallet.channelFundableBalanceSats) / 4, currency: currency)
             }
 
             NumberPadActionButton(text: t("common__max")) {
-                amountViewModel.updateFromSats(UInt64(wallet.totalOnchainSats), currency: currency)
+                amountViewModel.updateFromSats(UInt64(wallet.channelFundableBalanceSats), currency: currency)
             }
         }
     }