Update API references from OpenExchange to ForexRateAPI in code and documentation

Signed-off-by: Hans Kokx <hans.d.kokx@gmail.com>

lib/screens/settings_screen.dart

@@ -112,7 +112,7 @@ class _SettingsScreenState extends State<SettingsScreen> {
               ),
               const SizedBox(height: 16),
               const Text(
-                'OpenExchange API key is configured in code constant openExchangeApiKey.',
+                'ForexRateAPI key is configured in code constant forexRateApiKey.',
               ),
             ],
           ),

lib/services/open_exchange_service.dart

@@ -3,30 +3,42 @@ import 'dart:convert';
 import 'package:http/http.dart' as http;
 import 'package:intl/intl.dart';
 
-class OpenExchangeService {
-  OpenExchangeService({required this.httpClient, required this.apiKey});
+class ForexConversionResult {
+  ForexConversionResult({required this.quote, required this.result});
+
+  final double quote;
+  final double result;
+}
+
+class ForexRateApiService {
+  ForexRateApiService({required this.httpClient, required this.apiKey});
 
   final http.Client httpClient;
   final String apiKey;
 
   Future<double> fetchUsdToSekRate({required DateTime estDate}) async {
-    if (apiKey == 'REPLACE_WITH_YOUR_OPENEXCHANGE_API_KEY') {
-      throw StateError('OpenExchange API key is not configured.');
+    if (apiKey == 'REPLACE_WITH_YOUR_FOREXRATE_API_KEY') {
+      throw StateError('ForexRateAPI key is not configured.');
     }
 
     final date = DateFormat('yyyy-MM-dd').format(estDate);
-    final uri = Uri.https(
-      'openexchangerates.org',
-      '/api/historical/$date.json',
-      <String, String>{'app_id': apiKey, 'symbols': 'SEK'},
-    );
+    final uri = Uri.https('api.forexrateapi.com', '/v1/$date', <String, String>{
+      'api_key': apiKey,
+      'base': 'USD',
+      'currencies': 'SEK',
+    });
 
     final response = await httpClient.get(uri);
     if (response.statusCode != 200) {
-      throw StateError('OpenExchange request failed (${response.statusCode}).');
+      throw StateError('ForexRateAPI request failed (${response.statusCode}).');
     }
 
     final json = jsonDecode(response.body) as Map<String, dynamic>;
+    final success = json['success'] as bool? ?? false;
+    if (!success) {
+      throw StateError('ForexRateAPI returned success=false.');
+    }
+
     final rates = json['rates'] as Map<String, dynamic>?;
     final sek = rates?['SEK'];
     if (sek == null) {
@@ -35,4 +47,48 @@ class OpenExchangeService {
 
     return (sek as num).toDouble();
   }
+
+  Future<ForexConversionResult> convertUsdToSek({
+    required DateTime estDate,
+    required double amount,
+  }) async {
+    if (apiKey == 'REPLACE_WITH_YOUR_FOREXRATE_API_KEY') {
+      throw StateError('ForexRateAPI key is not configured.');
+    }
+
+    final date = DateFormat('yyyy-MM-dd').format(estDate);
+    final uri =
+        Uri.https('api.forexrateapi.com', '/v1/convert', <String, String>{
+          'api_key': apiKey,
+          'from': 'USD',
+          'to': 'SEK',
+          'amount': amount.toStringAsFixed(2),
+          'date': date,
+        });
+
+    final response = await httpClient.get(uri);
+    if (response.statusCode != 200) {
+      throw StateError('ForexRateAPI convert failed (${response.statusCode}).');
+    }
+
+    final json = jsonDecode(response.body) as Map<String, dynamic>;
+    final success = json['success'] as bool? ?? false;
+    if (!success) {
+      throw StateError('ForexRateAPI convert returned success=false.');
+    }
+
+    final info = json['info'] as Map<String, dynamic>?;
+    final quote = info?['quote'];
+    final result = json['result'];
+    if (quote == null || result == null) {
+      throw StateError(
+        'ForexRateAPI convert response was missing quote/result.',
+      );
+    }
+
+    return ForexConversionResult(
+      quote: (quote as num).toDouble(),
+      result: (result as num).toDouble(),
+    );
+  }
 }

lib/state/rent_controller.dart

@@ -13,7 +13,7 @@ import 'package:rental_income_tracker/services/storage_service.dart';
 import 'package:rental_income_tracker/services/time_service.dart';
 import 'package:timezone/timezone.dart' as tz;
 
-const String openExchangeApiKey = 'REPLACE_WITH_YOUR_OPENEXCHANGE_API_KEY';
+const String forexRateApiKey = 'REPLACE_WITH_YOUR_FOREXRATE_API_KEY';
 
 class RentTableRow {
   RentTableRow({
@@ -40,19 +40,19 @@ class RentTableRow {
 class RentController extends ChangeNotifier {
   RentController({
     StorageService? storageService,
-    OpenExchangeService? exchangeService,
+    ForexRateApiService? exchangeService,
   }) : _storageService = storageService ?? StorageService(),
        _exchangeService =
            exchangeService ??
-           OpenExchangeService(
+           ForexRateApiService(
              httpClient: http.Client(),
-             apiKey: openExchangeApiKey,
+             apiKey: forexRateApiKey,
            ) {
     _notificationService = NotificationService(_onNotificationAction);
   }
 
   final StorageService _storageService;
-  final OpenExchangeService _exchangeService;
+  final ForexRateApiService _exchangeService;
   late NotificationService _notificationService;
 
   AppSettings _settings = AppSettings.defaults();
@@ -146,12 +146,21 @@ class RentController extends ChangeNotifier {
         throw StateError('Set rent amount in Settings before marking paid.');
       }
 
+      final key = TimeService.monthKey(year, month);
+      if (_records.containsKey(key)) {
+        await _notificationService.cancelForMonth(year, month);
+        await _syncNotificationScheduleForCurrentMonth();
+        return;
+      }
+
       final paidAt = DateTime.now().toUtc();
+      final usd = _settings.rentUsd;
       final estPaidAt = tz.TZDateTime.from(paidAt, TimeService.est);
       final estDate = DateTime(estPaidAt.year, estPaidAt.month, estPaidAt.day);
-      final rate = await _exchangeService.fetchUsdToSekRate(estDate: estDate);
-      final usd = _settings.rentUsd;
-      final sek = usd * rate;
+      final conversion = await _exchangeService.convertUsdToSek(
+        estDate: estDate,
+        amount: usd,
+      );
       final onTime =
           assumeOnTime || TimeService.isOnTimeByDeadline(paidAt, year, month);
 
@@ -159,8 +168,8 @@ class RentController extends ChangeNotifier {
         year: year,
         month: month,
         usdAmount: usd,
-        sekAmount: sek,
-        usdToSekRate: rate,
+        sekAmount: conversion.result,
+        usdToSekRate: conversion.quote,
         paidAtUtc: paidAt,
         onTime: onTime,
         source: source,
@@ -194,9 +203,12 @@ class RentController extends ChangeNotifier {
           continue;
         }
 
-        final estDate = DateTime(year, month, 1);
-        final rate = await _exchangeService.fetchUsdToSekRate(estDate: estDate);
         final usd = _settings.rentUsd;
+        final estDate = DateTime(year, month, 1);
+        final conversion = await _exchangeService.convertUsdToSek(
+          estDate: estDate,
+          amount: usd,
+        );
 
         final paidAtUtc = tz.TZDateTime(
           TimeService.est,
@@ -210,8 +222,8 @@ class RentController extends ChangeNotifier {
           year: year,
           month: month,
           usdAmount: usd,
-          sekAmount: usd * rate,
-          usdToSekRate: rate,
+          sekAmount: conversion.result,
+          usdToSekRate: conversion.quote,
           paidAtUtc: paidAtUtc,
           onTime: true,
           source: 'backfill',