import 'dart:math' as math;

/// A robust, immutable 2D coordinate.
class Coordinate2D implements Comparable<Coordinate2D> {
  final double x;
  final double y;

  const Coordinate2D(this.x, this.y);

  /// Factory for a (0,0) coordinate.
  static const Coordinate2D zero = Coordinate2D(0.0, 0.0);

  // --- Core Logic ---

  /// Returns the Euclidean distance between this and [other].
  /// Uses the formula: $$d = \sqrt{(x_2 - x_1)^2 + (y_2 - y_1)^2}$$
  double distanceTo(Coordinate2D other) {
    final dx = x - other.x;
    final dy = y - other.y;
    return math.sqrt(dx * dx + dy * dy);
  }

  /// True if both ordinates are finite (not NaN or Infinity).
  bool get isValid => x.isFinite && y.isFinite;

  Coordinate2D operator +(Coordinate2D other) =>
      Coordinate2D(x + other.x, y + other.y);
  Coordinate2D operator -(Coordinate2D other) =>
      Coordinate2D(x - other.x, y - other.y);
  Coordinate2D operator *(double factor) =>
      Coordinate2D(x * factor, y * factor);
  Coordinate2D operator /(double divisor) =>
      Coordinate2D(x / divisor, y / divisor);

  @override
  bool operator ==(Object other) =>
      identical(this, other) ||
      other is Coordinate2D &&
          runtimeType == other.runtimeType &&
          x == other.x &&
          y == other.y;

  @override
  int get hashCode => Object.hash(x, y);

  @override
  int compareTo(Coordinate2D other) {
    if (x != other.x) return x.compareTo(other.x);
    return y.compareTo(other.y);
  }

  @override
  String toString() => 'Coordinate($x, $y)';
}