import 'dart:async';
import 'dart:convert';

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

import 'location_plugin_platform_interface.dart';

class LocationPlugin {
  LocationPlugin({http.Client? httpClient}) : _httpClient = httpClient;

  final http.Client? _httpClient;

  static const _reverseGeocodeHost = 'siteapi.cloud.huawei.com';
  static const _reverseGeocodePath = '/mapApi/v1/siteService/reverseGeocode';
  static const _defaultReverseGeocodeKey =
      'DAEDAPlmscfMOlRxiAN/hCblSsGarZMJbjdbhzVnIE97zUnPB0U9x/ZN438CzDKINlrHcVDcUPPXryRsr1LJbfsKzv7Q8PXsFNypNA==';

  Future<String?> getPlatformVersion() {
    return LocationPluginPlatform.instance.getPlatformVersion();
  }

  Future<Map<String, double>?> getCurrentLocation() {
    return LocationPluginPlatform.instance.getCurrentLocation();
  }

  /// 通过经纬度访问华为逆地理编码接口，返回城市编号与名称信息。
  Future<CityInfo?> getCityInfo({
    required double latitude,
    required double longitude,
    String? apiKey,
    Duration timeout = const Duration(seconds: 10),
  }) async {
    final client = _httpClient ?? http.Client();
    final shouldCloseClient = _httpClient == null;
    try {
      final uri = Uri.https(_reverseGeocodeHost, _reverseGeocodePath, {
        'key': apiKey ?? _defaultReverseGeocodeKey,
      });
      print(uri);
      print(jsonEncode({'lat': latitude, 'lng': longitude}));
      final response = await client
          .post(
            uri,
            headers: const {'Content-Type': 'application/json'},
            body: jsonEncode({"location":{'lat': latitude, 'lng': longitude}}),
          )
          .timeout(timeout);

      if (response.statusCode != 200) {
        throw CityInfoLookupException(
          code: 'HTTP_${response.statusCode}',
          message:
              'Reverse geocode request failed with status ${response.statusCode}.',
        );
      }

      final payload = jsonDecode(response.body);
      if (payload is! Map<String, dynamic>) {
        throw CityInfoLookupException(
          code: 'BAD_RESPONSE',
          message: 'Unexpected reverse geocode response format.',
        );
      }

      final returnCode = payload['returnCode']?.toString();
      if (returnCode != '0') {
        throw CityInfoLookupException(
          code: 'API_$returnCode',
          message:
              payload['returnDesc']?.toString() ?? 'Reverse geocode API error.',
        );
      }

      final sites = payload['sites'];
      if (sites is! List || sites.isEmpty) {
        return null;
      }

      final firstSite = sites.first;
      if (firstSite is! Map) {
        return null;
      }
      final address = firstSite['address'];
      if (address is! Map) {
        return null;
      }

      return CityInfo.fromAddress(Map<String, dynamic>.from(address));
    } on TimeoutException catch (_) {
      throw CityInfoLookupException(
        code: 'TIMEOUT',
        message: 'Reverse geocode request timed out.',
      );
    } on FormatException catch (error) {
      throw CityInfoLookupException(
        code: 'BAD_RESPONSE',
        message: 'Unable to parse reverse geocode response: ${error.message}',
      );
    } finally {
      if (shouldCloseClient) {
        client.close();
      }
    }
  }
}

class CityInfo {
  const CityInfo({
    required this.code,
    required this.region,
    required this.cityName,
    this.rawAddress,
  });

  final int? code;
  final List<String> region;
  final String? cityName;
  final Map<String, dynamic>? rawAddress;

  factory CityInfo.fromAddress(Map<String, dynamic> address) {
    final adminCode = address['adminCode']?.toString();
    final code = (adminCode != null && adminCode.length >= 6)
        ? int.tryParse(adminCode.substring(0, 6))
        : null;
    final region = [
      address['adminArea'],
      address['subAdminArea'],
      address['tertiaryAdminArea'],
    ].whereType<String>().toList();
    final cityName =
        address['locality']?.toString() ??
        address['subAdminArea']?.toString() ??
        address['adminArea']?.toString();
    return CityInfo(
      code: code,
      region: region,
      cityName: cityName,
      rawAddress: address,
    );
  }
}

class CityInfoLookupException implements Exception {
  CityInfoLookupException({required this.code, required this.message});

  final String code;
  final String message;

  @override
  String toString() => 'CityInfoLookupException($code, $message)';
}