Can backfill the previous year, although some API rate limiting but it works

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

lib/services/open_exchange_service.dart

@@ -1,5 +1,5 @@
-import 'dart:convert';
 import 'dart:async';
+import 'dart:convert';
 
 import 'package:flutter/foundation.dart';
 import 'package:http/http.dart' as http;
@@ -143,4 +143,75 @@ class ForexRateApiService {
 
     return ForexConversionResult(quote: quote, result: result);
   }
+
+  /// Fetches USD->SEK cross-rates for every day of [year] in a single timeseries
+  /// API call. Returns a map of 'yyyy-MM-dd' -> rate, or null if the timeseries
+  /// endpoint is not available on the current subscription plan.
+  Future<Map<String, double>?> tryFetchYearRates(int year) async {
+    if (apiKey == 'REPLACE_WITH_YOUR_EXCHANGE_RATE_API_KEY') {
+      throw StateError('ExchangeratesAPI key is not configured.');
+    }
+
+    final uri =
+        Uri.https('api.exchangeratesapi.io', '/v1/timeseries', <String, String>{
+          'access_key': apiKey,
+          'start_date': '$year-01-01',
+          'end_date': '$year-12-31',
+          'symbols': 'USD,SEK',
+        });
+
+    _log('Timeseries request: ${_redactedUri(uri)}');
+
+    final response = await _getWithRateLimitRetry(uri, operation: 'Timeseries');
+
+    if (response.statusCode == 403) {
+      _log(
+        'Timeseries endpoint not available on current plan; falling back to daily requests.',
+      );
+      return null;
+    }
+
+    if (response.statusCode != 200) {
+      throw StateError(
+        'ExchangeratesAPI timeseries failed (${response.statusCode}).',
+      );
+    }
+
+    final json = jsonDecode(response.body) as Map<String, dynamic>;
+    final success = json['success'] as bool? ?? false;
+    if (!success) {
+      final error = json['error'] as Map<String, dynamic>?;
+      final code = error?['code']?.toString() ?? '';
+      if (code == 'function_access_restricted' ||
+          code == 'subscription_plan_not_support_endpoint') {
+        _log(
+          'Timeseries endpoint not available on current plan; falling back to daily requests.',
+        );
+        return null;
+      }
+      _log('Timeseries success=false. error=$error');
+      throw StateError(
+        'ExchangeratesAPI timeseries returned success=false. error=$error',
+      );
+    }
+
+    final rates = json['rates'] as Map<String, dynamic>?;
+    if (rates == null) {
+      throw StateError('Timeseries response missing rates object.');
+    }
+
+    final result = <String, double>{};
+    for (final entry in rates.entries) {
+      final date = entry.key;
+      final dayRates = entry.value as Map<String, dynamic>?;
+      final usdPerEur = (dayRates?['USD'] as num?)?.toDouble();
+      final sekPerEur = (dayRates?['SEK'] as num?)?.toDouble();
+      if (usdPerEur != null && sekPerEur != null && usdPerEur != 0) {
+        result[date] = sekPerEur / usdPerEur;
+      }
+    }
+
+    _log('Timeseries parsed ${result.length} rate entries for year $year');
+    return result;
+  }
 }

lib/state/rent_controller.dart

@@ -241,8 +241,20 @@ class RentController extends ChangeNotifier {
       }
 
       final year = DateTime.now().year - 1;
+
+      // Attempt a single timeseries call covering the whole year.
+      final batchRates = await _exchangeService.tryFetchYearRates(year);
+      if (kDebugMode) {
+        debugPrint(
+          batchRates != null
+              ? '[RentController] backfill using batch timeseries (${batchRates.length} dates)'
+              : '[RentController] backfill falling back to individual daily requests',
+        );
+      }
+
       var savedMonths = 0;
       var pausedByRateLimit = false;
+      var isFirstIndividualFetch = true;
 
       for (var month = 1; month <= 12; month++) {
         final key = TimeService.monthKey(year, month);
@@ -256,10 +268,29 @@ class RentController extends ChangeNotifier {
         try {
           final usd = _settings.rentUsd;
           final estDate = DateTime(year, month, 1);
-          final conversion = await _exchangeService.convertUsdToSek(
+
+          final ForexConversionResult conversion;
+          if (batchRates != null) {
+            final dateStr = DateFormat('yyyy-MM-dd').format(estDate);
+            final quote = batchRates[dateStr];
+            if (quote == null) {
+              throw StateError('Batch rates missing entry for $dateStr.');
+            }
+            conversion = ForexConversionResult(
+              quote: quote,
+              result: quote * usd,
+            );
+          } else {
+            // Pace individual requests to avoid triggering the rate limit.
+            if (!isFirstIndividualFetch) {
+              await Future.delayed(const Duration(milliseconds: 700));
+            }
+            isFirstIndividualFetch = false;
+            conversion = await _exchangeService.convertUsdToSek(
               estDate: estDate,
               amount: usd,
             );
+          }
 
           if (kDebugMode) {
             debugPrint(