Update coin configs at runtime

lib/app_config/coin_converter.dart

@@ -1,14 +1,13 @@
 import 'dart:convert';
 
 import 'package:flutter/services.dart';
+import 'package:komodo_dex/app_config/coins_updater.dart';
 
 import '../model/coin_type.dart';
 import '../utils/utils.dart';
 
 Future<List<dynamic>> convertCoinsConfigToAppConfig() async {
-  final String coins =
-      await rootBundle.loadString('assets/coins_config.json', cache: false);
-  // 561 coins
+  final String coins = await CoinUpdater().getConfig();
   Map coinsResponse = jsonDecode(coins);
   List allCoinsList = [];
 

lib/app_config/coins_updater.dart

@@ -0,0 +1,147 @@
+import 'dart:async';
+import 'dart:io';
+import 'dart:isolate';
+import 'package:flutter/services.dart';
+import 'package:http/http.dart' as http;
+import 'package:komodo_dex/utils/log.dart';
+import 'package:path_provider/path_provider.dart';
+
+/// Provides methods for fetching coin data either from local assets or a remote Git repository.
+///
+/// `CoinUpdater` uses a singleton pattern to ensure a single instance throughout the app's lifecycle.
+/// It checks first if there is a cached version of the data. If not, it uses the bundled asset.
+/// In the background, it tries to fetch the most recent data and cache it for future launches.
+///
+/// Usage:
+/// ```dart
+/// final coinUpdater = CoinUpdater();
+/// final config = await coinUpdater.getConfig();
+/// final coins = await coinUpdater.getCoins();
+/// ```
+///
+/// NB! [coinsRepoBranch] and [coinsRepoUrl] only take effect for the next
+/// launch of the app. So 2x restart is needed to switch to a different branch.
+///
+/// TODO: Implement coin icon fetching.
+class CoinUpdater {
+  factory CoinUpdater() => _instance;
+
+  CoinUpdater._internal();
+
+  static final CoinUpdater _instance = CoinUpdater._internal();
+
+  /// The branch of the coins repository to use.
+  //! QA: change branch name here and then restart twice after logging in.
+  static const coinsRepoBranch = 'master';
+
+  static const coinsRepoUrl =
+      'https://raw.githubusercontent.com/KomodoPlatform/coins';
+
+  static const isUpdateEnabled = true;
+
+  final String localAssetPathConfig = 'assets/coins_config.json';
+  final String localAssetPathCoins = 'assets/coins.json';
+
+  String get remotePathConfig =>
+      '$coinsRepoUrl/$coinsRepoBranch/utils/coins_config.json';
+  String get remotePathCoins => '$coinsRepoUrl/$coinsRepoBranch/coins';
+
+  String _cachedConfig;
+  String _cachedCoins;
+
+  Future<String> _fetchAsset(String path) async {
+    return await rootBundle.loadString(path);
+  }
+
+  Future<File> _getLocalFile(String filename) async {
+    final directory = await getApplicationDocumentsDirectory();
+    return File('${directory.path}/$filename');
+  }
+
+  Future<String> _fetchOrCache(
+    String localPath,
+    String remoteUrl,
+    String cacheName,
+    String cacheProperty,
+  ) async {
+    try {
+      if (cacheProperty != null) {
+        return cacheProperty;
+      }
+
+      File cacheFile = await _getLocalFile(cacheName);
+
+      if (await cacheFile.exists()) {
+        cacheProperty = await cacheFile.readAsString();
+        return cacheProperty;
+      } else {
+        String localData = await _fetchAsset(localPath);
+        if (isUpdateEnabled) {
+          scheduleMicrotask(
+            () => _updateCacheInBackground(remoteUrl, cacheFile),
+          );
+        }
+        cacheProperty = localData;
+        return localData;
+      }
+    } catch (e) {
+      // If there's an error, first try to return the cached value,
+      // if that's null too, then fall back to the local asset.
+      if (cacheProperty != null) {
+        return cacheProperty;
+      } else {
+        return await _fetchAsset(localPath);
+      }
+    }
+  }
+
+  void _updateCacheInBackground(String remoteUrl, File cacheFile) async {
+    final ReceivePort receivePort = ReceivePort();
+    await Isolate.spawn(
+      _isolateEntry,
+      [remoteUrl, cacheFile.path],
+      onExit: receivePort.sendPort,
+    );
+    receivePort.listen((data) {
+      // Close the receive port when the isolate is done
+      receivePort.close();
+
+      Log(
+        'CoinUpdater',
+        'Coin updater updated coins to latest commit on branch '
+            '$coinsRepoBranch from $coinsRepoUrl. \n $remoteUrl',
+      );
+    });
+  }
+
+  static void _isolateEntry(List<String> data) async {
+    final String remoteUrl = data[0];
+    final String filePath = data[1];
+
+    final response = await http.get(Uri.parse(remoteUrl));
+    if (response.statusCode == 200) {
+      final file = File(filePath);
+      file.writeAsString(response.body);
+    }
+  }
+
+  Future<String> getConfig() async {
+    _cachedConfig = await _fetchOrCache(
+      localAssetPathConfig,
+      remotePathConfig,
+      'coins_config_cache.json',
+      _cachedConfig,
+    );
+    return _cachedConfig;
+  }
+
+  Future<String> getCoins() async {
+    _cachedCoins = await _fetchOrCache(
+      localAssetPathCoins,
+      remotePathCoins,
+      'coins_cache.json',
+      _cachedCoins,
+    );
+    return _cachedCoins;
+  }
+}

lib/model/coin.dart

@@ -2,6 +2,7 @@ import 'dart:collection';
 import 'dart:convert';
 
 import 'package:flutter/services.dart';
+import 'package:komodo_dex/app_config/coins_updater.dart';
 
 import '../app_config/app_config.dart';
 import '../app_config/coin_converter.dart';
@@ -33,8 +34,7 @@ Future<LinkedHashMap<String, Coin>> get coins async {
   _coinsInvoked = true;
 
   Log('coin:29', 'Loading coins.json…');
-  const ci = 'assets/coins.json';
-  final cis = await rootBundle.loadString(ci, cache: false);
+  final String cis = await CoinUpdater().getCoins();
   final List<dynamic> cil = json.decode(cis);
   final Map<String, Map<String, dynamic>> cim = {};
   for (dynamic js in cil) cim[js['coin']] = Map<String, dynamic>.from(js);
@@ -195,8 +195,7 @@ class Coin {
         if (lightWalletDServers != null)
           'light_wallet_d_servers':
               List<dynamic>.from(lightWalletDServers.map<String>((x) => x)),
-
-  };
+      };
 
   String getTxFeeSatoshi() {
     int txFeeRes = 0;

lib/services/mm_service.dart

@@ -8,6 +8,7 @@ import 'package:flutter/services.dart'
     show EventChannel, MethodChannel, rootBundle, SystemChannels;
 import 'package:http/http.dart' as http;
 import 'package:http/http.dart';
+import 'package:komodo_dex/app_config/coins_updater.dart';
 import 'package:package_info_plus/package_info_plus.dart';
 
 import '../app_config/app_config.dart';
@@ -457,7 +458,7 @@ class MMService {
 
   Future<List<dynamic>> readJsonCoinInit() async {
     try {
-      return jsonDecode(await rootBundle.loadString('assets/coins.json'));
+      return jsonDecode(await CoinUpdater().getCoins());
     } catch (e) {
       if (kDebugMode) {
         Log('mm_service', 'readJsonCoinInit] $e');