import 'dart:convert';

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

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_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/$date', <String, String>{
      'api_key': apiKey,
      'base': 'USD',
      'currencies': 'SEK',
    });

    final response = await httpClient.get(uri);
    if (response.statusCode != 200) {
      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) {
      throw StateError('SEK rate was missing in API response.');
    }

    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(),
    );
  }
}