CAKE-278 | applied fixed-rate flow to changenow_exchange_provider.dart, exchange_view_model.dart and exchange_page.dart; added isFixedRateMode to fetchLimits(), createTrade() and calculateAmount() methods in the exchange_provider.dart

lib/exchange/changenow/changenow_exchange_provider.dart

@@ -29,6 +29,8 @@ class ChangeNowExchangeProvider extends ExchangeProvider {
   static const _exchangeAmountUriSufix = '/exchange-amount/';
   static const _transactionsUriSufix = '/transactions/';
   static const _minAmountUriSufix = '/min-amount/';
+  static const _marketInfoUriSufix = '/market-info/';
+  static const _fixedRateUriSufix = 'fixed-rate/';
 
   @override
   String get title => 'ChangeNOW';
@@ -44,19 +46,43 @@ class ChangeNowExchangeProvider extends ExchangeProvider {
   Future<bool> checkIsAvailable() async => true;
 
   @override
-  Future<Limits> fetchLimits({CryptoCurrency from, CryptoCurrency to}) async {
+  Future<Limits> fetchLimits({CryptoCurrency from, CryptoCurrency to,
+    bool isFixedRateMode}) async {
     final symbol = from.toString() + '_' + to.toString();
-    final url = apiUri + _minAmountUriSufix + symbol;
+    final url = isFixedRateMode
+        ? apiUri + _marketInfoUriSufix + _fixedRateUriSufix + apiKey
+        : apiUri + _minAmountUriSufix + symbol;
     final response = await get(url);
-    final responseJSON = json.decode(response.body) as Map<String, dynamic>;
-    final min = responseJSON['minAmount'] as double;
 
-    return Limits(min: min, max: null);
+    if (isFixedRateMode) {
+      final responseJSON = json.decode(response.body) as List<dynamic>;
+
+      for (var elem in responseJSON) {
+        final elemFrom = elem["from"] as String;
+        final elemTo = elem["to"] as String;
+
+        if ((elemFrom == from.toString().toLowerCase()) &&
+            (elemTo == to.toString().toLowerCase())) {
+          final min = elem["min"] as double;
+          final max = elem["max"] as double;
+
+          return Limits(min: min, max: max);
+        }
+      }
+      return Limits(min: 0, max: 0);
+    } else {
+      final responseJSON = json.decode(response.body) as Map<String, dynamic>;
+      final min = responseJSON['minAmount'] as double;
+
+      return Limits(min: min, max: null);
+    }
   }
 
   @override
-  Future<Trade> createTrade({TradeRequest request}) async {
-    const url = apiUri + _transactionsUriSufix + apiKey;
+  Future<Trade> createTrade({TradeRequest request, bool isFixedRateMode}) async {
+    final url = isFixedRateMode
+    ? apiUri + _transactionsUriSufix + _fixedRateUriSufix + apiKey
+    : apiUri + _transactionsUriSufix + apiKey;
     final _request = request as ChangeNowRequest;
     final body = {
       'from': _request.from.toString(),
@@ -145,14 +171,25 @@ class ChangeNowExchangeProvider extends ExchangeProvider {
       {CryptoCurrency from,
       CryptoCurrency to,
       double amount,
+      bool isFixedRateMode,
       bool isReceiveAmount}) async {
-    final url = apiUri +
-        _exchangeAmountUriSufix +
-        amount.toString() +
-        '/' +
-        from.toString() +
-        '_' +
-        to.toString();
+    final url = isFixedRateMode
+        ? apiUri +
+          _exchangeAmountUriSufix +
+          _fixedRateUriSufix +
+          amount.toString() +
+          '/' +
+          from.toString() +
+          '_' +
+          to.toString() +
+          '?api_key=' + apiKey
+        : apiUri +
+          _exchangeAmountUriSufix +
+          amount.toString() +
+          '/' +
+          from.toString() +
+          '_' +
+          to.toString();
     final response = await get(url);
     final responseJSON = json.decode(response.body) as Map<String, dynamic>;
     final estimatedAmount = responseJSON['estimatedAmount'] as double;

lib/exchange/exchange_provider.dart

@@ -17,10 +17,11 @@ abstract class ExchangeProvider {
   @override
   String toString() => title;
 
-  Future<Limits> fetchLimits({CryptoCurrency from, CryptoCurrency to});
-  Future<Trade> createTrade({TradeRequest request});
+  Future<Limits> fetchLimits(
+      {CryptoCurrency from, CryptoCurrency to, bool isFixedRateMode});
+  Future<Trade> createTrade({TradeRequest request, bool isFixedRateMode});
   Future<Trade> findTradeById({@required String id});
-  Future<double> calculateAmount(
-    {CryptoCurrency from, CryptoCurrency to, double amount, bool isReceiveAmount});
+  Future<double> calculateAmount({CryptoCurrency from, CryptoCurrency to,
+    double amount, bool isFixedRateMode, bool isReceiveAmount});
   Future<bool> checkIsAvailable();
 }

lib/exchange/morphtoken/morphtoken_exchange_provider.dart

@@ -71,7 +71,7 @@ class MorphTokenExchangeProvider extends ExchangeProvider {
   Future<bool> checkIsAvailable() async => true;
 
   @override
-  Future<Limits> fetchLimits({CryptoCurrency from, CryptoCurrency to}) async {
+  Future<Limits> fetchLimits({CryptoCurrency from, CryptoCurrency to, bool isFixedRateMode}) async {
     final url = apiUri + _limitsURISuffix;
     final headers = {'Content-type': 'application/json'};
     final body = json.encode({
@@ -100,7 +100,7 @@ class MorphTokenExchangeProvider extends ExchangeProvider {
   }
 
   @override
-  Future<Trade> createTrade({TradeRequest request}) async {
+  Future<Trade> createTrade({TradeRequest request, bool isFixedRateMode}) async {
     const url = apiUri + _morphURISuffix;
     final _request = request as MorphTokenRequest;
     final body = {
@@ -191,7 +191,7 @@ class MorphTokenExchangeProvider extends ExchangeProvider {
 
   @override
   Future<double> calculateAmount(
-      {CryptoCurrency from, CryptoCurrency to, double amount,
+      {CryptoCurrency from, CryptoCurrency to, double amount, bool isFixedRateMode,
         bool isReceiveAmount}) async {
     final url = apiUri + _ratesURISuffix;
     final response = await get(url);

lib/exchange/xmrto/xmrto_exchange_provider.dart

@@ -58,7 +58,7 @@ class XMRTOExchangeProvider extends ExchangeProvider {
   }
 
   @override
-  Future<Limits> fetchLimits({CryptoCurrency from, CryptoCurrency to}) async {
+  Future<Limits> fetchLimits({CryptoCurrency from, CryptoCurrency to, bool isFixedRateMode}) async {
     final url = originalApiUri + _orderParameterUriSuffix;
     final response = await get(url);
     final correction = 0.001;
@@ -91,7 +91,7 @@ class XMRTOExchangeProvider extends ExchangeProvider {
   }
 
   @override
-  Future<Trade> createTrade({TradeRequest request}) async {
+  Future<Trade> createTrade({TradeRequest request, bool isFixedRateMode}) async {
     final _request = request as XMRTOTradeRequest;
     final url = originalApiUri + _orderCreateUriSuffix;
     final _amount =
@@ -188,6 +188,7 @@ class XMRTOExchangeProvider extends ExchangeProvider {
       {CryptoCurrency from,
       CryptoCurrency to,
       double amount,
+      bool isFixedRateMode,
       bool isReceiveAmount}) async {
     if (from != CryptoCurrency.xmr && to != CryptoCurrency.btc) {
       return 0;

lib/src/screens/exchange/exchange_page.dart

@@ -693,7 +693,14 @@ class ExchangePage extends BasePage {
            exchangeViewModel.isReceiveAmountEntered) && !isFixedRateMode) {
         FocusScope.of(context).unfocus();
         receiveAmountController.text = '';
+      } else {
+        exchangeViewModel.changeDepositAmount(
+            amount: depositAmountController.text);
       }
+
+      checkBoxKey.currentState
+          .changeValue(exchangeViewModel.isFixedRateMode);
+      exchangeViewModel.loadLimits();
     });
 
     _isReactionsSet = true;

lib/view_model/exchange/exchange_view_model.dart

@@ -137,12 +137,14 @@ abstract class ExchangeViewModelBase with Store {
     depositAmount = '';
     receiveAmount = '';
     isReceiveAmountEditable = provider is ChangeNowExchangeProvider;
+    isFixedRateMode = false;
     loadLimits();
   }
 
   @action
   void changeDepositCurrency({CryptoCurrency currency}) {
     depositCurrency = currency;
+    isFixedRateMode = false;
     _onPairChange();
     isDepositAddressEnabled = !(depositCurrency == wallet.currency);
     isReceiveAddressEnabled = !(receiveCurrency == wallet.currency);
@@ -151,6 +153,7 @@ abstract class ExchangeViewModelBase with Store {
   @action
   void changeReceiveCurrency({CryptoCurrency currency}) {
     receiveCurrency = currency;
+    isFixedRateMode = false;
     _onPairChange();
     isDepositAddressEnabled = !(depositCurrency == wallet.currency);
     isReceiveAddressEnabled = !(receiveCurrency == wallet.currency);
@@ -173,6 +176,7 @@ abstract class ExchangeViewModelBase with Store {
             from: receiveCurrency,
             to: depositCurrency,
             amount: _amount,
+            isFixedRateMode: isFixedRateMode,
             isReceiveAmount: true)
         .then((amount) => _cryptoNumberFormat
             .format(amount)
@@ -197,6 +201,7 @@ abstract class ExchangeViewModelBase with Store {
             from: depositCurrency,
             to: receiveCurrency,
             amount: _amount,
+            isFixedRateMode: isFixedRateMode,
             isReceiveAmount: false)
         .then((amount) => _cryptoNumberFormat
             .format(amount)
@@ -210,8 +215,8 @@ abstract class ExchangeViewModelBase with Store {
     limitsState = LimitsIsLoading();
 
     try {
-      limits = await provider.fetchLimits(
-          from: depositCurrency, to: receiveCurrency);
+      limits = await provider.fetchLimits(from: depositCurrency,
+          to: receiveCurrency, isFixedRateMode: isFixedRateMode);
       limitsState = LimitsLoadedSuccessfully(limits: limits);
     } catch (e) {
       limitsState = LimitsLoadedFailure(error: e.toString());
@@ -275,7 +280,8 @@ abstract class ExchangeViewModelBase with Store {
       } else {
         try {
           tradeState = TradeIsCreating();
-          final trade = await provider.createTrade(request: request);
+          final trade = await provider.createTrade(request: request,
+              isFixedRateMode: isFixedRateMode);
           trade.walletId = wallet.id;
           tradesStore.setTrade(trade);
           await trades.add(trade);
@@ -304,6 +310,7 @@ abstract class ExchangeViewModelBase with Store {
     receiveAddress = receiveCurrency == wallet.currency ? wallet.address : '';
     isDepositAddressEnabled = !(depositCurrency == wallet.currency);
     isReceiveAddressEnabled = !(receiveCurrency == wallet.currency);
+    isFixedRateMode = false;
     _onPairChange();
   }