mirror of
https://github.com/koloideal/Casha.git
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105 lines
3.0 KiB
Dart
105 lines
3.0 KiB
Dart
import 'dart:convert';
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import 'package:http/http.dart' as http;
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import 'package:shared_preferences/shared_preferences.dart';
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class ExchangeRateService {
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static const String _primaryUrl = 'https://open.er-api.com/v6/latest/USD';
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static const String _fallbackUrl = 'https://cdn.jsdelivr.net/npm/@fawazahmed0/currency-api@latest/v1/currencies/usd.json';
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static const String _cacheKey = 'exchange_rates';
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static const Map<String, double> _fallbackRates = {
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'USD': 1.0,
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'EUR': 0.92,
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'BYN': 3.25,
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'RUB': 90.0,
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};
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final SharedPreferences _prefs;
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Map<String, double> _rates = {};
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ExchangeRateService(this._prefs) {
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_loadCachedRates();
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}
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Map<String, double> get currentRates => _rates.isEmpty ? _fallbackRates : _rates;
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void _loadCachedRates() {
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final cached = _prefs.getString(_cacheKey);
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if (cached != null) {
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try {
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final decoded = jsonDecode(cached) as Map<String, dynamic>;
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_rates = decoded.map((k, v) => MapEntry(k, (v as num).toDouble()));
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} catch (e) {
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_rates = Map.from(_fallbackRates);
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}
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} else {
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_rates = Map.from(_fallbackRates);
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}
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}
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Future<void> fetchRates() async {
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try {
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final response = await http
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.get(Uri.parse(_primaryUrl))
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.timeout(const Duration(seconds: 10));
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if (response.statusCode == 200) {
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final data = jsonDecode(response.body);
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if (data['rates'] != null) {
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final rates = data['rates'] as Map<String, dynamic>;
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_rates = {
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'USD': 1.0,
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'EUR': (rates['EUR'] as num?)?.toDouble() ?? _fallbackRates['EUR']!,
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'BYN': (rates['BYN'] as num?)?.toDouble() ?? _fallbackRates['BYN']!,
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'RUB': (rates['RUB'] as num?)?.toDouble() ?? _fallbackRates['RUB']!,
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};
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await _cacheRates();
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return;
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}
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}
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} catch (e) {
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}
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try {
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final response = await http
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.get(Uri.parse(_fallbackUrl))
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.timeout(const Duration(seconds: 10));
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if (response.statusCode == 200) {
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final data = jsonDecode(response.body);
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if (data['usd'] != null) {
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final rates = data['usd'] as Map<String, dynamic>;
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_rates = {
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'USD': 1.0,
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'EUR': (rates['eur'] as num?)?.toDouble() ?? _fallbackRates['EUR']!,
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'BYN': (rates['byn'] as num?)?.toDouble() ?? _fallbackRates['BYN']!,
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'RUB': (rates['rub'] as num?)?.toDouble() ?? _fallbackRates['RUB']!,
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};
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await _cacheRates();
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return;
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}
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}
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} catch (e) {
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}
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if (_rates.isEmpty) {
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_rates = Map.from(_fallbackRates);
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}
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}
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Future<void> _cacheRates() async {
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final encoded = jsonEncode(_rates);
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await _prefs.setString(_cacheKey, encoded);
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}
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double convert(double amount, String from, String to) {
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if (from == to) return amount;
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final fromRate = currentRates[from] ?? 1.0;
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final toRate = currentRates[to] ?? 1.0;
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final amountInUsd = amount / fromRate;
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return amountInUsd * toRate;
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}
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}
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