import 'dart:convert';

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

/// Ergebnis einer Ortssuche: Koordinaten plus ein kompakter Anzeigename,
/// der auch als Missionsname dient (siehe MapSearchControls).
class GeocodingResult {
  const GeocodingResult({
    required this.label,
    required this.lat,
    required this.lon,
  });

  final String label;
  final double lat;
  final double lon;
}

/// Geocoding ueber Nominatim (OpenStreetMap) - analog doSearch() im HTML-
/// Demonstrator. Injectable http.Client analog WindService, damit dies in
/// Tests ohne echten Netzwerkzugriff ueberschrieben werden kann.
class NominatimService {
  NominatimService({http.Client? client}) : _client = client ?? http.Client();

  final http.Client _client;

  Future<GeocodingResult?> search(String query) async {
    final uri = Uri.https('nominatim.openstreetmap.org', '/search', {
      'format': 'json',
      'addressdetails': '1',
      'accept-language': 'en',
      'limit': '1',
      'q': query,
    });
    final response = await _client
        .get(uri, headers: {'User-Agent': 'dmc_app (Drone Mission Control)'});
    if (response.statusCode != 200) return null;

    final results = jsonDecode(response.body) as List;
    if (results.isEmpty) return null;

    final first = results.first as Map<String, dynamic>;
    return GeocodingResult(
      label: _extractPlaceLabel(first),
      lat: double.parse(first['lat'] as String),
      lon: double.parse(first['lon'] as String),
    );
  }

  /// Analog extractPlaceLabel() im HTML-Demonstrator: bevorzugt einen
  /// kompakten Ortsnamen aus den Nominatim-Adressbestandteilen, faellt sonst
  /// auf den ersten Abschnitt von display_name zurueck.
  String _extractPlaceLabel(Map<String, dynamic> result) {
    final address = result['address'] as Map<String, dynamic>?;
    final label = address?['city'] ??
        address?['town'] ??
        address?['village'] ??
        address?['municipality'] ??
        address?['suburb'] ??
        address?['county'];
    if (label is String && label.isNotEmpty) return label;
    final displayName = result['display_name'] as String?;
    if (displayName != null && displayName.isNotEmpty) {
      return displayName.split(',').first;
    }
    return 'Unknown location';
  }
}