/// Single particle in a particle filter cloud snapshot.
class Particle {
  const Particle({required this.x, required this.y, required this.weight});

  /// Normalised 0..1 coordinates (same space as [Position]).
  final double x;
  final double y;

  /// Unnormalised likelihood weight.
  final double weight;

  factory Particle.fromJson(Map<String, dynamic> json) => Particle(
        x: (json['x'] as num).toDouble(),
        y: (json['y'] as num).toDouble(),
        weight: (json['w'] as num).toDouble(),
      );
}

/// Position estimate from the particle filter (weighted mean).
class Estimate {
  const Estimate({required this.x, required this.y});

  final double x;
  final double y;

  factory Estimate.fromJson(Map<String, dynamic> json) => Estimate(
        x: (json['x'] as num).toDouble(),
        y: (json['y'] as num).toDouble(),
      );
}

/// A single `particles_updated` push from the server: estimate + raw cloud.
class ParticleSnapshot {
  const ParticleSnapshot({
    required this.tagId,
    required this.estimate,
    required this.particles,
  });

  final String tagId;
  final Estimate estimate;
  final List<Particle> particles;
}