deflock-app/lib/services/camera_cache.dart

import 'package:latlong2/latlong.dart';
import '../models/osm_camera_node.dart';
import 'package:flutter_map/flutter_map.dart' show LatLngBounds;

class CameraCache {
  // Singleton instance
  static final CameraCache instance = CameraCache._internal();
  factory CameraCache() => instance;
  CameraCache._internal();

  final Map<int, OsmCameraNode> _nodes = {};

  /// Add or update a batch of camera nodes in the cache.
  void addOrUpdate(List<OsmCameraNode> nodes) {
    for (var node in nodes) {
      final existing = _nodes[node.id];
      if (existing != null) {
        // Preserve any tags starting with underscore when updating existing nodes
        final mergedTags = Map<String, String>.from(node.tags);
        for (final entry in existing.tags.entries) {
          if (entry.key.startsWith('_')) {
            mergedTags[entry.key] = entry.value;
          }
        }
        _nodes[node.id] = OsmCameraNode(
          id: node.id,
          coord: node.coord,
          tags: mergedTags,
        );
      } else {
        _nodes[node.id] = node;
      }
    }
  }

  /// Query for all cached cameras currently within the given LatLngBounds.
  List<OsmCameraNode> queryByBounds(LatLngBounds bounds) {
    return _nodes.values
        .where((node) => _inBounds(node.coord, bounds))
        .toList();
  }

  /// Retrieve all cached cameras.
  List<OsmCameraNode> getAll() => _nodes.values.toList();

  /// Optionally clear the cache (rarely needed)
  void clear() => _nodes.clear();

  /// Utility: point-in-bounds for coordinates
  bool _inBounds(LatLng coord, LatLngBounds bounds) {
    return coord.latitude >= bounds.southWest.latitude &&
        coord.latitude <= bounds.northEast.latitude &&
        coord.longitude >= bounds.southWest.longitude &&
        coord.longitude <= bounds.northEast.longitude;
  }
}