import 'dart:convert';

import 'package:http/http.dart' as http;
import 'package:intl/intl.dart';

class OpenExchangeService {
  OpenExchangeService({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.');
    }

    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 response = await httpClient.get(uri);
    if (response.statusCode != 200) {
      throw StateError('OpenExchange request failed (${response.statusCode}).');
    }

    final json = jsonDecode(response.body) as Map<String, dynamic>;
    final rates = json['rates'] as Map<String, dynamic>?;
    final sek = rates?['SEK'];
    if (sek == null) {
      throw StateError('SEK rate was missing in API response.');
    }

    return (sek as num).toDouble();
  }
}