update

2026-06-10 10:25:28 +03:00 · 2026-03-20 10:32:36 +03:00
parent 99d985ca45
commit 047d5bdf36
17 changed files with 982 additions and 246 deletions
@@ -0,0 +1,111 @@
+import 'dart:convert';
+import 'package:http/http.dart' as http;
+import 'package:shared_preferences/shared_preferences.dart';
+
+class ExchangeRateService {
+  static const String _primaryUrl = 'https://open.er-api.com/v6/latest/USD';
+  static const String _fallbackUrl =
+      'https://cdn.jsdelivr.net/npm/@fawazahmed0/currency-api@latest/v1/currencies/usd.json';
+  static const String _cacheKey = 'exchange_rates';
+
+  static const Map<String, double> _fallbackRates = {
+    'USD': 1.0,
+    'EUR': 0.92,
+    'BYN': 3.25,
+    'RUB': 90.0,
+  };
+
+  final SharedPreferences _prefs;
+  Map<String, double> _rates = {};
+
+  ExchangeRateService(this._prefs) {
+    _loadCachedRates();
+  }
+
+  Map<String, double> get currentRates => _rates.isEmpty ? _fallbackRates : _rates;
+
+  void _loadCachedRates() {
+    final cached = _prefs.getString(_cacheKey);
+    if (cached != null) {
+      try {
+        final decoded = jsonDecode(cached) as Map<String, dynamic>;
+        _rates = decoded.map((k, v) => MapEntry(k, (v as num).toDouble()));
+      } catch (e) {
+        _rates = Map.from(_fallbackRates);
+      }
+    } else {
+      _rates = Map.from(_fallbackRates);
+    }
+  }
+
+  Future<void> fetchRates() async {
+    try {
+      // Try primary URL
+      final response = await http
+          .get(Uri.parse(_primaryUrl))
+          .timeout(const Duration(seconds: 10));
+
+      if (response.statusCode == 200) {
+        final data = jsonDecode(response.body);
+        if (data['rates'] != null) {
+          final rates = data['rates'] as Map<String, dynamic>;
+          _rates = {
+            'USD': 1.0,
+            'EUR': (rates['EUR'] as num?)?.toDouble() ?? _fallbackRates['EUR']!,
+            'BYN': (rates['BYN'] as num?)?.toDouble() ?? _fallbackRates['BYN']!,
+            'RUB': (rates['RUB'] as num?)?.toDouble() ?? _fallbackRates['RUB']!,
+          };
+          await _cacheRates();
+          return;
+        }
+      }
+    } catch (e) {
+      // Primary failed, try fallback
+    }
+
+    try {
+      // Try fallback URL
+      final response = await http
+          .get(Uri.parse(_fallbackUrl))
+          .timeout(const Duration(seconds: 10));
+
+      if (response.statusCode == 200) {
+        final data = jsonDecode(response.body);
+        if (data['usd'] != null) {
+          final rates = data['usd'] as Map<String, dynamic>;
+          _rates = {
+            'USD': 1.0,
+            'EUR': (rates['eur'] as num?)?.toDouble() ?? _fallbackRates['EUR']!,
+            'BYN': (rates['byn'] as num?)?.toDouble() ?? _fallbackRates['BYN']!,
+            'RUB': (rates['rub'] as num?)?.toDouble() ?? _fallbackRates['RUB']!,
+          };
+          await _cacheRates();
+          return;
+        }
+      }
+    } catch (e) {
+      // Both failed, use cached or fallback
+    }
+
+    // If both failed and no cache, use fallback
+    if (_rates.isEmpty) {
+      _rates = Map.from(_fallbackRates);
+    }
+  }
+
+  Future<void> _cacheRates() async {
+    final encoded = jsonEncode(_rates);
+    await _prefs.setString(_cacheKey, encoded);
+  }
+
+  double convert(double amount, String from, String to) {
+    if (from == to) return amount;
+
+    final fromRate = currentRates[from] ?? 1.0;
+    final toRate = currentRates[to] ?? 1.0;
+
+    // Convert to USD first, then to target currency
+    final amountInUsd = amount / fromRate;
+    return amountInUsd * toRate;
+  }
+}