feat: implement metadata extraction and display in transaction flow

Author: Tommytrg

lib/util/metadata_utils.dart

@@ -0,0 +1,75 @@
+import 'dart:convert';
+
+import 'package:witnet/schema.dart';
+
+String? metadataFromOutputs(
+  List<ValueTransferOutput> outputs, {
+  List<String> trueOutputAddresses = const [],
+  List<String> changeOutputAddresses = const [],
+}) {
+  if (outputs.isEmpty) {
+    return null;
+  }
+
+  Iterable<ValueTransferOutput> candidates =
+      outputs.where((output) => output.value.toInt() == 1);
+
+  if (trueOutputAddresses.isNotEmpty || changeOutputAddresses.isNotEmpty) {
+    final excluded = <String>{
+      ...trueOutputAddresses,
+      ...changeOutputAddresses,
+    };
+    final filtered = candidates
+        .where((output) => !excluded.contains(output.pkh.address))
+        .toList();
+    if (filtered.isNotEmpty) {
+      candidates = filtered;
+    }
+  }
+
+  if (candidates.isEmpty) {
+    return null;
+  }
+
+  return _decodeMetadataOutput(candidates.first);
+}
+
+String? _decodeMetadataOutput(ValueTransferOutput output) {
+  final bytes = List<int>.from(output.pkh.hash);
+  int end = bytes.length;
+  while (end > 0 && bytes[end - 1] == 0) {
+    end--;
+  }
+  if (end == 0) {
+    return null;
+  }
+
+  final trimmed = bytes.sublist(0, end);
+  String decoded;
+  try {
+    decoded = utf8.decode(trimmed, allowMalformed: true);
+  } catch (_) {
+    return '0x${output.pkh.hex}';
+  }
+
+  if (_isPrintable(decoded)) {
+    return decoded;
+  }
+
+  return '0x${output.pkh.hex}';
+}
+
+bool _isPrintable(String value) {
+  if (value.contains('\uFFFD')) {
+    return false;
+  }
+  for (final rune in value.runes) {
+    if (rune == 0x09 || rune == 0x0A || rune == 0x0D) {
+      continue;
+    }
+    if (rune < 0x20 || rune == 0x7F) {
+      return false;
+    }
+  }
+  return true;
+}

lib/util/transactions_list/transaction_utils.dart

@@ -5,6 +5,7 @@ import 'package:my_wit_wallet/shared/locator.dart';
 import 'package:my_wit_wallet/theme/colors.dart';
 import 'package:my_wit_wallet/theme/extended_theme.dart';
 import 'package:my_wit_wallet/util/get_localization.dart';
+import 'package:my_wit_wallet/util/metadata_utils.dart';
 import 'package:my_wit_wallet/util/storage/database/account.dart';
 import 'package:my_wit_wallet/util/storage/database/adapters/transaction_adapter.dart';
 import 'package:my_wit_wallet/util/storage/database/wallet.dart';
@@ -308,6 +309,14 @@ class TransactionUtils {
     }
   }
 
+  String? metadata() {
+    if (vti.type != TransactionType.value_transfer || vti.vtt == null) {
+      return null;
+    }
+
+    return metadataFromOutputs(vti.vtt!.outputs);
+  }
+
   Widget buildTransactionValue(label, context) {
     final theme = Theme.of(context);
     final extendedTheme = theme.extension<ExtendedTheme>()!;

lib/widgets/transaction_details.dart

@@ -237,6 +237,7 @@ class TransactionDetails extends StatelessWidget {
     TransactionUtils transactionUtils = TransactionUtils(vti: transaction);
     String label = transactionUtils.getLabel();
     String? timelock = transactionUtils.timelock();
+    String? metadata = transactionUtils.metadata();
 
     return ClosableView(
         closeSetting: goToList,
@@ -302,7 +303,14 @@ class TransactionDetails extends StatelessWidget {
                       label: localization.total,
                       text: transactionUtils.getTransactionValue().amount,
                       isContentImportant: true,
-                      isLastItem: timelock == null),
+                      isLastItem: timelock == null && metadata == null),
+                  if (metadata != null)
+                    InfoCopy(
+                        label: localization.metadata,
+                        text: metadata.cropMiddle(18),
+                        infoToCopy: metadata,
+                        isContentImportant: true,
+                        isLastItem: timelock == null),
                   timelock != null
                       ? InfoElement(
                           label: localization.timelock,

lib/widgets/witnet/transactions/value_transfer/create_dialog_box/vtt_builder/01_recipient_step.dart

@@ -7,6 +7,8 @@ import 'package:flutter_bloc/flutter_bloc.dart';
 import 'package:font_awesome_flutter/font_awesome_flutter.dart';
 import 'package:my_wit_wallet/util/min_amount_unstake.dart';
 import 'package:my_wit_wallet/util/showTxConnectionError.dart';
+import 'package:my_wit_wallet/util/metadata_utils.dart';
+import 'package:my_wit_wallet/util/storage/database/adapters/transaction_adapter.dart';
 import 'package:my_wit_wallet/util/storage/database/wallet_storage.dart';
 import 'package:my_wit_wallet/util/storage/scanned_content.dart';
 import 'package:my_wit_wallet/widgets/buttons/icon_btn.dart';
@@ -257,6 +259,9 @@ class RecipientStepState extends State<RecipientStep>
           transactionBloc.state.transaction.get(widget.transactionType) != null
               ? transactionBloc.authorizationString
               : null;
+      String? savedMetadata = isVttTransaction
+          ? _getSavedMetadata(transactionBloc.state.transaction)
+          : null;
 
       if (savedAddress != null) {
         _addressController.text = savedAddress;
@@ -273,6 +278,12 @@ class RecipientStepState extends State<RecipientStep>
         setAuthorization(savedAuthorization);
       }
 
+      if (savedMetadata != null) {
+        _metadataController.text = savedMetadata;
+        setMetadata(savedMetadata, validate: false);
+        showAdvancedSettings = true;
+      }
+
       transactionBloc.add(ResetTransactionEvent());
     }
 
@@ -294,12 +305,21 @@ class RecipientStepState extends State<RecipientStep>
 
   setMetadata(String value, {bool? validate}) {
     _metadata = MetadataInput.dirty(
-      value: _metadata.value,
+      value: value,
       allowValidation:
           validate ?? validationUtils.isFormUnFocus(_formFocusElements()),
     );
   }
 
+  String? _getSavedMetadata(BuildTransaction transaction) {
+    final vtTransaction = transaction.vtTransaction;
+    if (vtTransaction == null) {
+      return null;
+    }
+
+    return metadataFromOutputs(vtTransaction.body.outputs);
+  }
+
   void nextAction() {
     final theme = Theme.of(context);
     if (_connectionError) {

lib/widgets/witnet/transactions/value_transfer/create_dialog_box/vtt_builder/03_review_step.dart

@@ -3,6 +3,7 @@ import 'package:flutter_bloc/flutter_bloc.dart';
 import 'package:intl/intl.dart';
 import 'package:my_wit_wallet/util/allow_biometrics.dart';
 import 'package:my_wit_wallet/util/extensions/string_extensions.dart';
+import 'package:my_wit_wallet/util/metadata_utils.dart';
 import 'package:my_wit_wallet/util/storage/database/adapters/transaction_adapter.dart';
 import 'package:my_wit_wallet/widgets/layouts/send_transaction_layout.dart';
 import 'package:my_wit_wallet/widgets/witnet/transactions/value_transfer/modals/general_error_tx_modal.dart';
@@ -102,6 +103,18 @@ class ReviewStepState extends State<ReviewStep>
     return '${state.transaction.getAmount(state.transactionType)} ${WIT_UNIT[WitUnit.Wit]}';
   }
 
+  String? _getMetadata(TransactionState state) {
+    if (!isVttTransaction) {
+      return null;
+    }
+    final vtTransaction = state.transaction.vtTransaction;
+    if (vtTransaction == null) {
+      return null;
+    }
+
+    return metadataFromOutputs(vtTransaction.body.outputs);
+  }
+
   @override
   Widget build(BuildContext context) {
     final theme = Theme.of(context);
@@ -163,6 +176,7 @@ class ReviewStepState extends State<ReviewStep>
                 state.transaction.hasTimelock(state.transactionType);
             String address =
                 state.transaction.getRecipient(state.transactionType);
+            String? metadata = _getMetadata(state);
             return Padding(
                 padding: EdgeInsets.only(left: 8, right: 8),
                 child: Column(
@@ -188,22 +202,32 @@ class ReviewStepState extends State<ReviewStep>
                         SizedBox(
                           height: 16,
                         ),
-                      if (showFeeInfo) ..._buildTransactionFeeInfo(context),
+                      if (showFeeInfo)
+                        ..._buildTransactionFeeInfo(context,
+                            addBottomSpacing: metadata == null),
+                      if (metadata != null)
+                        InfoCopy(
+                            infoToCopy: metadata,
+                            label: localization.metadata,
+                            text: metadata.cropMiddle(18),
+                            isLastItem: true),
+                      if (metadata != null) SizedBox(height: 16),
                     ]));
           },
         ));
   }
 }
 
-List<Widget> _buildTransactionFeeInfo(BuildContext context) {
+List<Widget> _buildTransactionFeeInfo(BuildContext context,
+    {bool addBottomSpacing = true}) {
   int fee = BlocProvider.of<TransactionBloc>(context).getFee();
   return [
     InfoElement(
         label: localization.fee,
-        isLastItem: true,
+        isLastItem: addBottomSpacing,
         text:
             '${fee.standardizeWitUnits().formatWithCommaSeparator()} ${WIT_UNIT[WitUnit.Wit]}'),
-    SizedBox(height: 16),
+    if (addBottomSpacing) SizedBox(height: 16),
   ];
 }