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#ifndef DART_COLLISION_DISTANCE_RESULT_HPP_
#define DART_COLLISION_DISTANCE_RESULT_HPP_

#include <Eigen/Dense>

namespace dart {

namespace dynamics {
class ShapeFrame;
} // namespace dynamics

namespace collision {

struct DistanceResult
{
  /// Minimum \b singed distance between the checked Shape pairs.
  ///
  /// If no shape pair was checked (the collision group was empty or all pairs
  /// were excluded by the filter) then this value will be remained the default
  /// value 0.0. You can check if a valid distance was found using
  /// DistanceResult::found() that returns true when it's found.
  ///
  /// The result minimum distance is clamped by
  /// DistanceOption::distanceLowerBound
  /// (min. distance >= distance lower bound). You can still get the unclamped
  /// distance from DistanceResult::unclampedMinDistance.
  ///
  /// If the minimum distance is negative value, that means the distance is
  /// the negative penetration depth measured from the shapes that are in
  /// collision.
  double minDistance;

  /// Unclamped minimum distance that is the first distance equal to or less
  /// than DistanceOption::distanceLowerBound.
  ///
  /// \warning This value is implementation defined, which means the value could
  /// be different depending on various factors (e.g., the collision detector
  /// and even the version of the collision detector), and we don't intend this
  /// value to be (reasonably) indentical over thoes factors. This valude is for
  /// debugging purpose or advanced use.
  double unclampedMinDistance;

  /// First ShapeFrame of the minDistance
  ///
  /// If no shape pair was checked then shapeFrame1 will be nullptr.
  const dynamics::ShapeFrame* shapeFrame1;

  /// Second ShapeFrame of the minDistance
  ///
  /// If no shape pair was checked then shapeFrame2 will be nullptr.
  const dynamics::ShapeFrame* shapeFrame2;

  /// The nearest point on DistanceResult::shapeFrame1 expressed in the world
  /// coordinates.
  ///
  /// The point is calculated only when DistanceOption::enableNearestPoints is
  /// true.
  ///
  /// The distance between the two nearest points is equal to
  /// unclampedMinDistance rather than minDistance.
  Eigen::Vector3d nearestPoint1;

  /// The nearest point on DistanceResult::shapeFrame2 expressed the world
  /// coordinates.
  ///
  /// The point is calculated only when DistanceOption::enableNearestPoints is
  /// true.
  ///
  /// The distance between the two nearest points is equal to
  /// unclampedMinDistance rather than minDistance.
  Eigen::Vector3d nearestPoint2;

  /// Constructor
  DistanceResult();

  /// Clear the result
  void clear();

  /// Get true if the result is valid (at least one shape pair was checked
  /// and the result values are good to use).
  bool found() const;

  /// Get true if the minimum distance was not clamped
  /// (minDistance == unclampedMinDistance).
  bool isMinDistanceClamped() const;
};

} // namespace collision
} // namespace dart

#endif // DART_COLLISION_DISTANCE_RESULT_HPP_
