Fixes for electrum

lib/bitcoin/electrum.dart

@@ -318,11 +318,15 @@ class ElectrumClient {
       {@required String id,
       @required String method,
       List<Object> params = const []}) {
-    final subscription = BehaviorSubject<T>();
-    _regisrySubscription(id, subscription);
-    socket.write(jsonrpc(method: method, id: _id, params: params));
+    try {
+      final subscription = BehaviorSubject<T>();
+      _regisrySubscription(id, subscription);
+      socket.write(jsonrpc(method: method, id: _id, params: params));
 
-    return subscription;
+      return subscription;
+    } catch(e) {
+      print(e.toString());
+    }
   }
 
   Future<dynamic> call({String method, List<Object> params = const []}) async {
@@ -339,18 +343,22 @@ class ElectrumClient {
       {String method,
       List<Object> params = const [],
       int timeout = 2000}) async {
-    final completer = Completer<dynamic>();
-    _id += 1;
-    final id = _id;
-    _registryTask(id, completer);
-    socket.write(jsonrpc(method: method, id: id, params: params));
-    Timer(Duration(milliseconds: timeout), () {
-      if (!completer.isCompleted) {
-        completer.completeError(RequestFailedTimeoutException(method, id));
-      }
-    });
+    try {
+      final completer = Completer<dynamic>();
+      _id += 1;
+      final id = _id;
+      _registryTask(id, completer);
+      socket.write(jsonrpc(method: method, id: id, params: params));
+      Timer(Duration(milliseconds: timeout), () {
+        if (!completer.isCompleted) {
+          completer.completeError(RequestFailedTimeoutException(method, id));
+        }
+      });
 
-    return completer.future;
+      return completer.future;
+    } catch(e) {
+      print(e.toString());
+    }
   }
 
   Future<void> close() async {

lib/bitcoin/electrum_wallet.dart

@@ -90,6 +90,11 @@ abstract class ElectrumWalletBase extends WalletBase<ElectrumBalance,
       .map((addr) => scriptHash(addr.address, networkType: networkType))
       .toList();
 
+  List<String> get publicScriptHashes => walletAddresses.addresses
+    .where((addr) => !addr.isHidden)
+    .map((addr) => scriptHash(addr.address, networkType: networkType))
+    .toList();
+
   String get xpub => hd.base58;
 
   @override
@@ -476,7 +481,7 @@ abstract class ElectrumWalletBase extends WalletBase<ElectrumBalance,
   @override
   Future<Map<String, ElectrumTransactionInfo>> fetchTransactions() async {
     final histories =
-        scriptHashes.map((scriptHash) => electrumClient.getHistory(scriptHash));
+        publicScriptHashes.map((scriptHash) => electrumClient.getHistory(scriptHash));
     final _historiesWithDetails = await Future.wait(histories)
         .then((histories) => histories.expand((i) => i).toList())
         .then((histories) => histories.map((tx) => fetchTransactionInfo(

lib/bitcoin/electrum_wallet_addresses.dart

@@ -100,7 +100,6 @@ abstract class ElectrumWalletAddressesBase extends WalletAddresses with Store {
     for (var i = startIndex; i < count + startIndex; i++) {
       final address = BitcoinAddressRecord(getAddress(index: i, hd: hd),
           index: i, isHidden: isHidden);
-      print(address.address);
       list.add(address);
     }
 

lib/buy/moonpay/moonpay_buy_provider.dart

@@ -10,6 +10,42 @@ import 'package:cake_wallet/core/wallet_base.dart';
 import 'package:cake_wallet/entities/wallet_type.dart';
 import 'package:cake_wallet/exchange/trade_state.dart';
 import 'package:cake_wallet/.secrets.g.dart' as secrets;
+import 'package:cake_wallet/entities/crypto_currency.dart';
+
+class MoonPaySellProvider {
+  MoonPaySellProvider({this.isTest = false})
+    : baseUrl = isTest ? _baseTestUrl : _baseProductUrl;
+
+  static const _baseTestUrl = 'sell-staging.moonpay.com';
+  static const _baseProductUrl = 'sell.moonpay.com';
+  static String get _apiKey =>  secrets.moonPayApiKey;
+  static String get _secretKey =>  secrets.moonPaySecretKey;
+  final bool isTest;
+  final String baseUrl;
+
+  Future<String> requestUrl({CryptoCurrency currency, String refundWalletAddress}) async {
+    final originalUri = Uri.https(
+      baseUrl, '', <String, dynamic>{
+        'apiKey': _apiKey,
+        'defaultBaseCurrencyCode': currency.toString().toLowerCase(),
+        'refundWalletAddress': refundWalletAddress
+    });
+    final messageBytes = utf8.encode('?${originalUri.query}');
+    final key = utf8.encode(_secretKey);
+    final hmac = Hmac(sha256, key);
+    final digest = hmac.convert(messageBytes);
+    final signature = base64.encode(digest.bytes);
+
+    if (isTest) {
+      return originalUri.toString();
+    }
+
+    final query = Map<String, dynamic>.from(originalUri.queryParameters);
+    query['signature'] = signature;
+    final signedUri = originalUri.replace(queryParameters: query);
+    return signedUri.toString();
+  }
+}
 
 class MoonPayBuyProvider extends BuyProvider {
   MoonPayBuyProvider({WalletBase wallet, bool isTestEnvironment = false})

lib/src/screens/dashboard/dashboard_page.dart

@@ -24,6 +24,8 @@ import 'package:smooth_page_indicator/smooth_page_indicator.dart';
 import 'package:flutter_spinkit/flutter_spinkit.dart';
 import 'package:cake_wallet/main.dart';
 import 'package:cake_wallet/router.dart';
+import 'package:cake_wallet/buy/moonpay/moonpay_buy_provider.dart';
+import 'package:url_launcher/url_launcher.dart';
 
 class DashboardPage extends BasePage {
   DashboardPage({
@@ -261,10 +263,11 @@ class DashboardPage extends BasePage {
 
     switch (walletType) {
       case WalletType.bitcoin:
-        Navigator.of(context).pushNamed(Routes.preOrder);
-        break;
-      case WalletType.litecoin:
-        Navigator.of(context).pushNamed(Routes.preOrder);
+        final moonPaySellProvider = MoonPaySellProvider();
+        final uri = await moonPaySellProvider.requestUrl(
+          currency: walletViewModel.wallet.currency,
+          refundWalletAddress: walletViewModel.wallet.walletAddresses.address);
+        await launch(uri);
         break;
       default:
         await showPopUp<void>(