import 'dart:convert';
import 'package:flutter/services.dart' show rootBundle;
import 'package:http/http.dart' as http;
import 'package:latlong2/latlong.dart';
import '../hoogerheide_streets.dart';

class GeocodingService {
  static final GeocodingService _instance = GeocodingService._internal();
  factory GeocodingService() => _instance;
  GeocodingService._internal();

  static const _nominatimBaseUrl = 'https://nominatim.openstreetmap.org';
  static const _userAgent = 'DeliveryApp/1.0 (delivery-app-openclaw@users.noreply.github.com)';

  Map<String, dynamic>? _addressCache;

  String _normalize(String name) =>
      name.replaceAll(RegExp(r'[–—]'), ' ').replaceAll(RegExp(r'\s+'), ' ').trim().toLowerCase();

  Future<Map<String, dynamic>> _loadAddressCache() async {
    if (_addressCache != null) return _addressCache!;
    try {
      final jsonStr = await rootBundle.loadString('assets/hoogerheide_addresses.json');
      _addressCache = jsonDecode(jsonStr);
      return _addressCache!;
    } catch (_) {
      return {'addresses': []};
    }
  }

  /// Geocode a street + house number to LatLng.
  /// Priority: local JSON cache → Nominatim → hoogerheide_streets.dart → default
  Future<LatLng> geocode(String street, String houseNum) async {
    final ns = _normalize(street);
    final hn = houseNum.trim();

    // 1. Local address cache (fast, no rate limits)
    try {
      final cache = await _loadAddressCache();
      final addresses = cache['addresses'] as List? ?? [];
      for (final addr in addresses) {
        final addrStreet = (addr['street'] as String).toLowerCase();
        final addrNum = addr['housenumber'] as String;
        if (addrStreet == ns && addrNum == hn) {
          return LatLng(addr['lat'] as double, addr['lon'] as double);
        }
      }
    } catch (_) {}

    // 2. Nominatim API
    try {
      final query = Uri.encodeComponent('$street $houseNum, Hoogerheide, Netherlands');
      final url = '$_nominatimBaseUrl/search?format=jsonv2&q=$query&limit=1';
      final resp = await http.get(
        Uri.parse(url),
        headers: {'User-Agent': _userAgent},
      ).timeout(const Duration(seconds: 5));

      if (resp.statusCode == 200) {
        final data = jsonDecode(resp.body);
        if (data is List && data.isNotEmpty) {
          return LatLng(
            double.parse(data[0]['lat']),
            double.parse(data[0]['lon']),
          );
        }
      }
    } catch (_) {}

    // 3. hoogerheide_streets.dart lookup (exact then partial match)
    final streetResult = _lookupInStreets(street);
    if (streetResult != null) {
      // Offset by house number to spread markers along the street
      final hnInt = int.tryParse(houseNum.replaceAll(RegExp(r'[A-Za-z]'), '')) ?? 1;
      return LatLng(
        streetResult.latitude + (hnInt - 1) * 0.00015,
        streetResult.longitude + ((hnInt / 25).floor() % 2 == 0 ? 0 : 0.0002),
      );
    }

    // 4. Default to Hoogerheide center
    return const LatLng(51.4243390, 4.3238380);
  }

  LatLng? _lookupInStreets(String street) {
    final ns = _normalize(street);

    // Exact match
    for (final entry in HoogerheideStreets.streetCoords.entries) {
      if (_normalize(entry.key) == ns) {
        return LatLng(entry.value[0], entry.value[1]);
      }
    }

    // Partial match
    for (final entry in HoogerheideStreets.streetCoords.entries) {
      final ek = _normalize(entry.key);
      if (ns.contains(ek) || ek.contains(ns)) {
        return LatLng(entry.value[0], entry.value[1]);
      }
    }
    return null;
  }

  /// Batch-geocode a list of stops, updating coords only when they changed.
  Future<List<LatLng?>> geocodeStops(List<(String street, String houseNum)> addresses) async {
    final results = <LatLng?>[];
    for (final (street, houseNum) in addresses) {
      try {
        results.add(await geocode(street, houseNum));
      } catch (_) {
        results.add(null);
      }
    }
    return results;
  }
}