From 341e06196da34df29891fb3ec28b47ca94fee3a5 Mon Sep 17 00:00:00 2001
From: Adegoke David <64401859+Blazebrain@users.noreply.github.com>
Date: Sun, 21 Jul 2024 00:26:05 +0100
Subject: [PATCH] CW-674: Improve Exchange Flow With Timeout For Rates (#1536)

* fix: Improve exchange flow by adding a timeout to the call to fetch rate from providers

* fix: Adjust time limit for fetching rate to 7 seconds and add timelimit to fetching limits

* Improve loadlimits function [skip ci]

---------

Co-authored-by: OmarHatem <omarh.ismail1@gmail.com>
---
 .../provider/sideshift_exchange_provider.dart | 16 ++++-
 .../exchange/exchange_view_model.dart         | 58 ++++++++++++-------
 2 files changed, 52 insertions(+), 22 deletions(-)

diff --git a/lib/exchange/provider/sideshift_exchange_provider.dart b/lib/exchange/provider/sideshift_exchange_provider.dart
index 1be4f8045..127421bbd 100644
--- a/lib/exchange/provider/sideshift_exchange_provider.dart
+++ b/lib/exchange/provider/sideshift_exchange_provider.dart
@@ -1,4 +1,5 @@
 import 'dart:convert';
+import 'dart:developer';
 
 import 'package:cake_wallet/.secrets.g.dart' as secrets;
 import 'package:cake_wallet/exchange/provider/exchange_provider.dart';
@@ -29,6 +30,7 @@ class SideShiftExchangeProvider extends ExchangeProvider {
     CryptoCurrency.bttc,
     CryptoCurrency.usdt,
     CryptoCurrency.eos,
+    CryptoCurrency.xmr,
   ];
 
   static const affiliateId = secrets.sideShiftAffiliateId;
@@ -137,8 +139,20 @@ class SideShiftExchangeProvider extends ExchangeProvider {
       final response = await get(uri);
       final responseJSON = json.decode(response.body) as Map<String, dynamic>;
 
+      if (response.statusCode == 500) {
+        final responseJSON = json.decode(response.body) as Map<String, dynamic>;
+        final error = responseJSON['error']['message'] as String;
+
+        throw Exception('SideShift Internal Server Error: $error');
+      }
+
+      if (response.statusCode != 200) {
+        throw Exception('Unexpected http status: ${response.statusCode}');
+      }
+
       return double.parse(responseJSON['rate'] as String);
-    } catch (_) {
+    } catch (e) {
+      log('Error fetching rate in SideShift Provider: ${e.toString()}');
       return 0.00;
     }
   }
diff --git a/lib/view_model/exchange/exchange_view_model.dart b/lib/view_model/exchange/exchange_view_model.dart
index 404fa0f25..a97b3dc05 100644
--- a/lib/view_model/exchange/exchange_view_model.dart
+++ b/lib/view_model/exchange/exchange_view_model.dart
@@ -405,13 +405,22 @@ abstract class ExchangeViewModelBase extends WalletChangeListenerViewModel with
         .where((element) => !isFixedRateMode || element.supportsFixedRate)
         .toList();
 
-    final result = await Future.wait<double>(_providers.map((element) => element.fetchRate(
-        from: depositCurrency,
-        to: receiveCurrency,
-        amount: amount,
-        isFixedRateMode: isFixedRateMode,
-        isReceiveAmount: isFixedRateMode)));
-
+    final result = await Future.wait<double>(
+      _providers.map(
+        (element) => element
+            .fetchRate(
+              from: depositCurrency,
+              to: receiveCurrency,
+              amount: amount,
+              isFixedRateMode: isFixedRateMode,
+              isReceiveAmount: isFixedRateMode,
+            )
+            .timeout(
+              Duration(seconds: 7),
+              onTimeout: () => 0.0,
+            ),
+      ),
+    );
     _sortedAvailableProviders.clear();
 
     for (int i = 0; i < result.length; i++) {
@@ -441,22 +450,29 @@ abstract class ExchangeViewModelBase extends WalletChangeListenerViewModel with
     double? highestMax = 0.0;
 
     try {
-      for (var provider in selectedProviders) {
-        /// if this provider is not valid for the current pair, skip it
-        if (!providersForCurrentPair().contains(provider)) continue;
+      final result = await Future.wait(selectedProviders
+          .where((element) => providersForCurrentPair().contains(provider))
+          .map((provider) => provider
+              .fetchLimits(
+                from: from,
+                to: to,
+                isFixedRateMode: isFixedRateMode,
+              )
+              .onError((error, stackTrace) => Limits(max: 0.0, min: double.maxFinite))
+              .timeout(
+                Duration(seconds: 7),
+                onTimeout: () => Limits(max: 0.0, min: double.maxFinite),
+              )));
 
-        try {
-          final tempLimits =
-              await provider.fetchLimits(from: from, to: to, isFixedRateMode: isFixedRateMode);
-
-          if (lowestMin != null && (tempLimits.min ?? -1) < lowestMin) lowestMin = tempLimits.min;
-
-          if (highestMax != null && (tempLimits.max ?? double.maxFinite) > highestMax)
-            highestMax = tempLimits.max;
-        } catch (e) {
-          continue;
+      result.forEach((tempLimits) {
+        if (lowestMin != null && (tempLimits.min ?? -1) < lowestMin!) {
+          lowestMin = tempLimits.min;
         }
-      }
+
+        if (highestMax != null && (tempLimits.max ?? double.maxFinite) > highestMax!) {
+          highestMax = tempLimits.max;
+        }
+      });
     } on ConcurrentModificationError {
       /// if user changed the selected providers while fetching limits
       /// then delay the fetching limits a bit and try again