add support for old electrumx servers that do not support batching. Also call wallet.init() on creation

lib/pages/add_wallet_views/restore_wallet_view/restore_wallet_view.dart

@@ -292,6 +292,7 @@ class _RestoreWalletViewState extends ConsumerState<RestoreWalletView> {
             mnemonic: mnemonic,
           );
 
+          await wallet.init();
           await wallet.recover(isRescan: false);
 
           // check if state is still active before continuing

lib/pages/settings_views/global_settings_view/stack_backup_views/helpers/restore_create_backup.dart

@@ -414,6 +414,8 @@ abstract class SWB {
         privateKey: privateKey,
       );
 
+      await wallet.init();
+
       int restoreHeight = walletbackup['restoreHeight'] as int? ?? 0;
       if (restoreHeight <= 0) {
         restoreHeight = walletbackup['storedChainHeight'] as int? ?? 0;

lib/wallets/wallet/impl/bitcoincash_wallet.dart

@@ -354,7 +354,7 @@ class BitcoincashWallet extends Bip39HDWallet with ElectrumXMixin {
 
   // not all coins need to override this. BCH does due to cash addr string formatting
   @override
-  Future<({List<Address> addresses, int index})> checkGaps(
+  Future<({List<Address> addresses, int index})> checkGapsBatched(
     int txCountBatchSize,
     coinlib.HDPrivateKey root,
     DerivePathType type,

lib/wallets/wallet/impl/ecash_wallet.dart

@@ -352,9 +352,75 @@ class EcashWallet extends Bip39HDWallet with ElectrumXMixin {
     return vSize * (feeRatePerKB / 1000).ceil();
   }
 
+  @override
+  Future<({List<Address> addresses, int index})> checkGapsLinearly(
+    coinlib.HDPrivateKey root,
+    DerivePathType type,
+    int chain,
+  ) async {
+    List<Address> addressArray = [];
+    int gapCounter = 0;
+    int index = 0;
+    for (;
+        index < cryptoCurrency.maxNumberOfIndexesToCheck &&
+            gapCounter < cryptoCurrency.maxUnusedAddressGap;
+        index++) {
+      Logging.instance.log(
+          "index: $index, \t GapCounter chain=$chain ${type.name}: $gapCounter",
+          level: LogLevel.Info);
+
+      final derivePath = cryptoCurrency.constructDerivePath(
+        derivePathType: type,
+        chain: chain,
+        index: index,
+      );
+      final keys = root.derivePath(derivePath);
+      final addressData = cryptoCurrency.getAddressForPublicKey(
+        publicKey: keys.publicKey,
+        derivePathType: type,
+      );
+
+      // ecash specific
+      final addressString = bitbox.Address.toECashAddress(
+        addressData.address.toString(),
+      );
+
+      final address = Address(
+        walletId: walletId,
+        value: addressString,
+        publicKey: keys.publicKey.data,
+        type: addressData.addressType,
+        derivationIndex: index,
+        derivationPath: DerivationPath()..value = derivePath,
+        subType: chain == 0 ? AddressSubType.receiving : AddressSubType.change,
+      );
+
+      // get address tx count
+      final count = await fetchTxCount(
+        addressScriptHash: cryptoCurrency.addressToScriptHash(
+          address: address.value,
+        ),
+      );
+
+      // check and add appropriate addresses
+      if (count > 0) {
+        // add address to array
+        addressArray.add(address);
+        // reset counter
+        gapCounter = 0;
+        // add info to derivations
+      } else {
+        // increase counter when no tx history found
+        gapCounter++;
+      }
+    }
+
+    return (addresses: addressArray, index: index);
+  }
+
   // not all coins need to override this. ecash does due to cash addr string formatting
   @override
-  Future<({List<Address> addresses, int index})> checkGaps(
+  Future<({List<Address> addresses, int index})> checkGapsBatched(
     int txCountBatchSize,
     coinlib.HDPrivateKey root,
     DerivePathType type,

lib/wallets/wallet/mixins/electrumx_mixin.dart

@@ -25,6 +25,9 @@ mixin ElectrumXMixin on Bip39HDWallet {
   late ElectrumX electrumX;
   late CachedElectrumX electrumXCached;
 
+  double? _serverVersion;
+  bool get serverCanBatch => _serverVersion != null && _serverVersion! >= 1.6;
+
   List<({String address, Amount amount})> _helperRecipientsConvert(
       List<String> addrs, List<int> satValues) {
     final List<({String address, Amount amount})> results = [];
@@ -792,7 +795,7 @@ mixin ElectrumXMixin on Bip39HDWallet {
 
   //============================================================================
 
-  Future<({List<Address> addresses, int index})> checkGaps(
+  Future<({List<Address> addresses, int index})> checkGapsBatched(
     int txCountBatchSize,
     coinlib.HDPrivateKey root,
     DerivePathType type,
@@ -873,12 +876,75 @@ mixin ElectrumXMixin on Bip39HDWallet {
     return (index: highestIndexWithHistory, addresses: addressArray);
   }
 
+  Future<({List<Address> addresses, int index})> checkGapsLinearly(
+    coinlib.HDPrivateKey root,
+    DerivePathType type,
+    int chain,
+  ) async {
+    List<Address> addressArray = [];
+    int gapCounter = 0;
+    int index = 0;
+    for (;
+        index < cryptoCurrency.maxNumberOfIndexesToCheck &&
+            gapCounter < cryptoCurrency.maxUnusedAddressGap;
+        index++) {
+      Logging.instance.log(
+          "index: $index, \t GapCounter chain=$chain ${type.name}: $gapCounter",
+          level: LogLevel.Info);
+
+      final derivePath = cryptoCurrency.constructDerivePath(
+        derivePathType: type,
+        chain: chain,
+        index: index,
+      );
+      final keys = root.derivePath(derivePath);
+      final addressData = cryptoCurrency.getAddressForPublicKey(
+        publicKey: keys.publicKey,
+        derivePathType: type,
+      );
+
+      final addressString = addressData.address.toString();
+
+      final address = Address(
+        walletId: walletId,
+        value: addressString,
+        publicKey: keys.publicKey.data,
+        type: addressData.addressType,
+        derivationIndex: index,
+        derivationPath: DerivationPath()..value = derivePath,
+        subType: chain == 0 ? AddressSubType.receiving : AddressSubType.change,
+      );
+
+      // get address tx count
+      final count = await fetchTxCount(
+        addressScriptHash: cryptoCurrency.addressToScriptHash(
+          address: address.value,
+        ),
+      );
+
+      // check and add appropriate addresses
+      if (count > 0) {
+        // add address to array
+        addressArray.add(address);
+        // reset counter
+        gapCounter = 0;
+        // add info to derivations
+      } else {
+        // increase counter when no tx history found
+        gapCounter++;
+      }
+    }
+
+    return (addresses: addressArray, index: index);
+  }
+
   Future<List<Map<String, dynamic>>> fetchHistory(
     Iterable<String> allAddresses,
   ) async {
     try {
       List<Map<String, dynamic>> allTxHashes = [];
 
+      if (serverCanBatch) {
         final Map<int, Map<String, List<dynamic>>> batches = {};
         final Map<String, String> requestIdToAddressMap = {};
         const batchSizeMax = 100;
@@ -911,6 +977,24 @@ mixin ElectrumXMixin on Bip39HDWallet {
             }
           }
         }
+      } else {
+        for (int i = 0; i < allAddresses.length; i++) {
+          final scriptHash = cryptoCurrency.addressToScriptHash(
+            address: allAddresses.elementAt(1),
+          );
+
+          final response = await electrumX.getHistory(
+            scripthash: scriptHash,
+          );
+
+          for (int j = 0; j < response.length; j++) {
+            response[j]["address"] = allAddresses.elementAt(1);
+            if (!allTxHashes.contains(response[j])) {
+              allTxHashes.add(response[j]);
+            }
+          }
+        }
+      }
 
       return allTxHashes;
     } catch (e, s) {
@@ -1446,11 +1530,17 @@ mixin ElectrumXMixin on Bip39HDWallet {
 
         for (final type in cryptoCurrency.supportedDerivationPathTypes) {
           receiveFutures.add(
-            checkGaps(
+            serverCanBatch
+                ? checkGapsBatched(
                     txCountBatchSize,
                     root,
                     type,
                     receiveChain,
+                  )
+                : checkGapsLinearly(
+                    root,
+                    type,
+                    receiveChain,
                   ),
           );
         }
@@ -1462,11 +1552,17 @@ mixin ElectrumXMixin on Bip39HDWallet {
         );
         for (final type in cryptoCurrency.supportedDerivationPathTypes) {
           changeFutures.add(
-            checkGaps(
+            serverCanBatch
+                ? checkGapsBatched(
                     txCountBatchSize,
                     root,
                     type,
                     changeChain,
+                  )
+                : checkGapsLinearly(
+                    root,
+                    type,
+                    changeChain,
                   ),
           );
         }
@@ -1539,6 +1635,7 @@ mixin ElectrumXMixin on Bip39HDWallet {
     try {
       final fetchedUtxoList = <List<Map<String, dynamic>>>[];
 
+      if (serverCanBatch) {
         final Map<int, Map<String, List<dynamic>>> batches = {};
         const batchSizeMax = 10;
         int batchNumber = 0;
@@ -1566,6 +1663,18 @@ mixin ElectrumXMixin on Bip39HDWallet {
             }
           }
         }
+      } else {
+        for (int i = 0; i < allAddresses.length; i++) {
+          final scriptHash = cryptoCurrency.addressToScriptHash(
+            address: allAddresses[i].value,
+          );
+
+          final utxos = await electrumX.getUTXOs(scripthash: scriptHash);
+          if (utxos.isNotEmpty) {
+            fetchedUtxoList.add(utxos);
+          }
+        }
+      }
 
       final List<UTXO> outputArray = [];
 
@@ -1707,6 +1816,28 @@ mixin ElectrumXMixin on Bip39HDWallet {
     }
   }
 
+  @override
+  Future<void> init() async {
+    try {
+      final features = await electrumX
+          .getServerFeatures()
+          .timeout(const Duration(seconds: 3));
+
+      Logging.instance.log("features: $features", level: LogLevel.Info);
+
+      _serverVersion =
+          _parseServerVersion(features["server_version"] as String);
+
+      if (cryptoCurrency.genesisHash != features['genesis_hash']) {
+        throw Exception("genesis hash does not match!");
+      }
+    } catch (e, s) {
+      Logging.instance.log("$e/n$s", level: LogLevel.Info);
+    }
+
+    await super.init();
+  }
+
   // ===========================================================================
   // ========== Interface functions ============================================
 
@@ -1755,5 +1886,25 @@ mixin ElectrumXMixin on Bip39HDWallet {
         estimatedFee;
   }
 
+  // stupid + fragile
+  double? _parseServerVersion(String version) {
+    double? result;
+    try {
+      final list = version.split(" ");
+      if (list.isNotEmpty) {
+        final numberStrings = list.last.split(".");
+        final major = numberStrings.removeAt(0);
+
+        result = double.tryParse("$major.${numberStrings.join("")}");
+      }
+    } catch (_) {}
+
+    Logging.instance.log(
+      "${info.name} _parseServerVersion($version) => $result",
+      level: LogLevel.Info,
+    );
+    return result;
+  }
+
   // ===========================================================================
 }