Fee calculation and presentation

lib/bloc/fee_options/fee_options_bloc.dart

@@ -33,16 +33,15 @@ class FeeOptionsBloc extends Cubit<FeeOptionsState> {
   }
 
   /// Fetches the current recommended fees
-  Future<List<FeeOption>> fetchFeeOptions() async {
+  Future<List<FeeOption>> fetchFeeOptions(String address) async {
     RecommendedFees recommendedFees;
     try {
       recommendedFees = await _breezLib.recommendedFees();
       _log.fine(
         "fetchFeeOptions recommendedFees:\nfastestFee: ${recommendedFees.fastestFee},"
         "\nhalfHourFee: ${recommendedFees.halfHourFee},\nhourFee: ${recommendedFees.hourFee}.",
       );
-      final utxos = await _retrieveUTXOS();
-      return _constructFeeOptionList(utxos, recommendedFees);
+      return await _constructFeeOptionList(address, recommendedFees);
     } catch (e) {
       _log.severe("fetchFeeOptions error", e);
       emit(FeeOptionsState(error: extractExceptionMessage(e, getSystemAppLocalizations())));
@@ -61,34 +60,39 @@ class FeeOptionsBloc extends Cubit<FeeOptionsState> {
     return utxos;
   }
 
-  List<FeeOption> _constructFeeOptionList(int utxos, RecommendedFees recommendedFees) {
+  Future<List<FeeOption>> _constructFeeOptionList(
+    String address,
+    RecommendedFees recommendedFees,
+  ) async {
     final List<FeeOption> feeOptions = [
       FeeOption(
         processingSpeed: ProcessingSpeed.economy,
         waitingTime: const Duration(minutes: 60),
-        fee: _calculateTransactionFee(utxos, recommendedFees.hourFee),
+        fee: await _calculateTransactionFee(address, recommendedFees.hourFee),
         feeVByte: recommendedFees.hourFee,
       ),
       FeeOption(
         processingSpeed: ProcessingSpeed.regular,
         waitingTime: const Duration(minutes: 30),
-        fee: _calculateTransactionFee(utxos, recommendedFees.halfHourFee),
+        fee: await _calculateTransactionFee(address, recommendedFees.halfHourFee),
         feeVByte: recommendedFees.halfHourFee,
       ),
       FeeOption(
         processingSpeed: ProcessingSpeed.priority,
         waitingTime: const Duration(minutes: 10),
-        fee: _calculateTransactionFee(utxos, recommendedFees.fastestFee),
+        fee: await _calculateTransactionFee(address, recommendedFees.fastestFee),
         feeVByte: recommendedFees.fastestFee,
       ),
     ];
     emit(state.copyWith(feeOptions: feeOptions));
     return feeOptions;
   }
 
-  int _calculateTransactionFee(int inputs, int feeRateSatsPerVbyte) {
-    // based on https://bitcoin.stackexchange.com/a/3011
-    final transactionSize = (inputs * 148) + (2 * 34) + 10;
-    return transactionSize * feeRateSatsPerVbyte;
+  Future<int> _calculateTransactionFee(String address, int satsPerVbyte) async {
+    final response = await _breezLib.prepareSweep(
+      address: address,
+      satsPerVbyte: satsPerVbyte,
+    );
+    return response.sweepTxFeeSat;
   }
 }

lib/routes/withdraw/reverse_swap/confirmation_page/reverse_swap_confirmation_page.dart

@@ -34,7 +34,9 @@ class _ReverseSwapConfirmationPageState extends State<ReverseSwapConfirmationPag
   @override
   void initState() {
     super.initState();
-    _fetchFeeOptionsFuture = context.read<FeeOptionsBloc>().fetchFeeOptions();
+    _fetchFeeOptionsFuture = context.read<FeeOptionsBloc>().fetchFeeOptions(
+      widget.onchainRecipientAddress,
+    );
     _fetchFeeOptionsFuture.then((feeOptions) {
       setState(() {
         affordableFees = feeOptions.where((f) => f.isAffordable(widget.amountSat)).toList();

lib/routes/withdraw/sweep/confirmation_page/sweep_confirmation_page.dart

@@ -30,7 +30,7 @@ class _SweepConfirmationPageState extends State<SweepConfirmationPage> {
   @override
   void initState() {
     super.initState();
-    _fetchFeeOptionsFuture = context.read<FeeOptionsBloc>().fetchFeeOptions();
+    _fetchFeeOptionsFuture = context.read<FeeOptionsBloc>().fetchFeeOptions(widget.toAddress);
     _fetchFeeOptionsFuture.then((feeOptions) {
       setState(() {
         affordableFees = feeOptions.where((f) => f.isAffordable(widget.amountSat)).toList();
@@ -56,7 +56,11 @@ class _SweepConfirmationPageState extends State<SweepConfirmationPage> {
             );
           }
           if (snapshot.connectionState != ConnectionState.done) {
-            return const Center(child: Loader());
+            return const Center(
+              child: Loader(
+                color: Colors.white,
+              ),
+            );
           }
 
           if (affordableFees.isNotEmpty) {

pubspec.lock

@@ -401,14 +401,6 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "0.9.3+1"
-  fimber:
-    dependency: transitive
-    description:
-      name: fimber
-      sha256: "42fcfa33acd43556c1e7ebfc12c2b03893418bc04a07931368c3573e228af2f0"
-      url: "https://pub.dev"
-    source: hosted
-    version: "0.7.0"
   firebase_core:
     dependency: "direct main"
     description: