/* +------------------------------------------------------------------------+
   |                     Mobile Robot Programming Toolkit (MRPT)            |
   |                          https://www.mrpt.org/                         |
   |                                                                        |
   | Copyright (c) 2005-2023, Individual contributors, see AUTHORS file     |
   | See: https://www.mrpt.org/Authors - All rights reserved.               |
   | Released under BSD License. See: https://www.mrpt.org/License          |
   +------------------------------------------------------------------------+ */
#pragma once

#include <mrpt/math/CMatrixD.h>
#include <mrpt/poses/CPose3DPDF.h>
#include <mrpt/poses/CPose3DQuatPDF.h>
#include <mrpt/poses/CPosePDF.h>

namespace mrpt
{
namespace poses
{
class CPosePDFGaussian;
class CPose3DPDFGaussian;

/** Declares a class that represents a Probability Density function (PDF) of a
 * 3D pose using a quaternion \f$ p(\mathbf{x}) = [x ~ y ~ z ~ qr ~ qx ~ qy ~
 * qz]^\top \f$.
 *
 *   This class implements that PDF using a mono-modal Gaussian distribution.
 * See mrpt::poses::CPose3DQuatPDF for more details, or
 *    mrpt::poses::CPose3DPDF for classes based on Euler angles instead.
 *
 *  Uncertainty of pose composition operations (\f$ y = x \oplus u \f$) is
 * implemented in the methods "CPose3DQuatPDFGaussian::operator+=" and
 * "CPose3DQuatPDF::jacobiansPoseComposition".
 *
 * \note Read also: "A tutorial on SE(3) transformation parameterizations and
 * on-manifold optimization", in \cite blanco_se3_tutorial
 *
 * \sa CPose3DQuat, CPose3DQuatPDF, CPose3DPDF, CPose3DQuatPDFGaussianInf
 * \ingroup poses_pdf_grp
 */
class CPose3DQuatPDFGaussian : public CPose3DQuatPDF
{
	DEFINE_SERIALIZABLE(CPose3DQuatPDFGaussian, mrpt::poses)

   protected:
	/** Assures the symmetry of the covariance matrix (eventually certain
	 * operations in the math-coprocessor lead to non-symmetric matrixes!)
	 */
	void enforceCovSymmetry();

   public:
	/** Default constructor - set all values to zero. */
	CPose3DQuatPDFGaussian();

	/** Constructor which left all the member uninitialized, for using when
	 * speed is critical - as argument, use UNINITIALIZED_QUATERNION. */
	CPose3DQuatPDFGaussian(
		mrpt::math::TConstructorFlags_Quaternions constructor_dummy_param);

	/** Constructor from a default mean value, covariance equals to zero. */
	explicit CPose3DQuatPDFGaussian(const CPose3DQuat& init_Mean);

	/** Constructor with mean and covariance. */
	CPose3DQuatPDFGaussian(
		const CPose3DQuat& init_Mean,
		const mrpt::math::CMatrixDouble77& init_Cov);

	/** Constructor from a Gaussian 2D pose PDF (sets to 0 the missing
	 * variables). */
	explicit CPose3DQuatPDFGaussian(const CPosePDFGaussian& o);

	/** Constructor from an equivalent Gaussian in Euler angles representation.
	 */
	explicit CPose3DQuatPDFGaussian(const CPose3DPDFGaussian& o);

	/** The mean value */
	CPose3DQuat mean;
	/** The 7x7 covariance matrix */
	mrpt::math::CMatrixDouble77 cov;

	inline const CPose3DQuat& getPoseMean() const { return mean; }
	inline CPose3DQuat& getPoseMean() { return mean; }

	void getMean(CPose3DQuat& mean_pose) const override;

	std::tuple<cov_mat_t, type_value> getCovarianceAndMean() const override
	{
		return {cov, mean};
	}

	/** Copy operator, translating if necesary (for example, between particles
	 * and gaussian representations) */
	void copyFrom(const CPose3DQuatPDF& o) override;
	/** Copy operator, translating if necesary (for example, between particles
	 * and gaussian representations) */
	void copyFrom(const CPosePDF& o);
	/** Copy operator, translating if necesary (for example, between particles
	 * and gaussian representations) */
	void copyFrom(const CPose3DPDFGaussian& o);
	/** Save the PDF to a text file, containing the 3D pose in the first line (x
	 * y z qr qx qy qz), then the covariance matrix in the next 7 lines. */
	bool saveToTextFile(const std::string& file) const override;

	/** this = p (+) this. This can be used to convert a PDF from local
	 * coordinates to global, providing the point (newReferenceBase) from which
	 *   "to project" the current pdf. Result PDF substituted the currently
	 * stored one in the object. */
	void changeCoordinatesReference(const CPose3DQuat& newReferenceBase);

	/** this = p (+) this. This can be used to convert a PDF from local
	 * coordinates to global, providing the point (newReferenceBase) from which
	 *   "to project" the current pdf. Result PDF substituted the currently
	 * stored one in the object.
	 */
	void changeCoordinatesReference(const CPose3D& newReferenceBase) override;

	/** Draws a single sample from the distribution */
	void drawSingleSample(CPose3DQuat& outPart) const override;
	/** Draws a number of samples from the distribution, and saves as a list of
	 * 1x7 vectors, where each row contains a (x,y,z,qr,qx,qy,qz) datum. */
	void drawManySamples(
		size_t N,
		std::vector<mrpt::math::CVectorDouble>& outSamples) const override;
	/** Compute the inverse Jacobian */
	mrpt::math::CMatrixDouble77 inverseJacobian() const;
	/** Returns a new PDF such as: NEW_PDF = (0,0,0) - THIS_PDF */
	void inverse(CPose3DQuatPDF& o) const override;
	/** Returns the displacement from the current pose (pose_from) to pose_to:
	 * displacement = - pose_from + pose_to
	 * It assumes that both poses are correlated via
	 * the direct generative model:
	 * pose_to = pose_from + displacement
	 * For a deeper explanation, check https://github.com/MRPT/mrpt/pull/1243
	 * */
	mrpt::poses::CPose3DQuatPDFGaussian inverseCompositionCrossCorrelation(
		const mrpt::poses::CPose3DQuatPDFGaussian& pose_to) const;

	/** Unary - operator, returns the PDF of the inverse pose.  */
	inline CPose3DQuatPDFGaussian operator-() const
	{
		CPose3DQuatPDFGaussian p(mrpt::math::UNINITIALIZED_QUATERNION);
		this->inverse(p);
		return p;
	}

	/** Makes: thisPDF = thisPDF + Ap, where "+" is pose composition (both the
	 * mean, and the covariance matrix are updated). */
	void operator+=(const CPose3DQuat& Ap);
	/** Makes: thisPDF = thisPDF + Ap, where "+" is pose composition (both the
	 * mean, and the covariance matrix are updated) (see formulas in
	 * jacobiansPoseComposition ). */
	void operator+=(const CPose3DQuatPDFGaussian& Ap);
	/** Makes: thisPDF = thisPDF - Ap, where "-" is pose inverse composition
	 * (both the mean, and the covariance matrix are updated).
	 * This operation assumes statistical independence between the two
	 * variables. If you want to take into account the cross-correlation between
	 * pose_1 and pose_2, use:
	 * displacement = pose_1.inverseCompositionCrossCorrelation(pose_2)
	 * Note: Both poses are correlated if the direct generative model is
	 * pose_2 = pose_1 + displacement
	 * \sa inverseCompositionCrossCorrelation
	 * */
	void operator-=(const CPose3DQuatPDFGaussian& Ap);

	/** Evaluates the PDF at a given point. */
	double evaluatePDF(const CPose3DQuat& x) const;

	/** Evaluates the ratio PDF(x) / PDF(MEAN), that is, the normalized PDF in
	 * the range [0,1]. */
	double evaluateNormalizedPDF(const CPose3DQuat& x) const;

	/** Computes the Mahalanobis distance between the centers of two Gaussians.
	 *  The variables with a variance exactly equal to 0 are not taken into
	 * account in the process, but
	 *   "infinity" is returned if the corresponding elements are not exactly
	 * equal. */
	double mahalanobisDistanceTo(const CPose3DQuatPDFGaussian& theOther);

};	// End of class def.

bool operator==(
	const CPose3DQuatPDFGaussian& p1, const CPose3DQuatPDFGaussian& p2);
/** Pose composition for two 3D pose Gaussians  \sa
 * CPose3DQuatPDFGaussian::operator += */
CPose3DQuatPDFGaussian operator+(
	const CPose3DQuatPDFGaussian& x, const CPose3DQuatPDFGaussian& u);
/** Inverse pose composition for two 3D pose Gaussians  \sa
 * CPose3DQuatPDFGaussian::operator -= */
CPose3DQuatPDFGaussian operator-(
	const CPose3DQuatPDFGaussian& x, const CPose3DQuatPDFGaussian& u);

/** Dumps the mean and covariance matrix to a text stream. */
std::ostream& operator<<(std::ostream& out, const CPose3DQuatPDFGaussian& obj);

}  // namespace poses

namespace global_settings
{
/** If set to true (default), a Scaled Unscented Transform is used instead of a
 *linear approximation with Jacobians.
 * Affects to:
 *		- CPose3DQuatPDFGaussian::copyFrom(const CPose3DPDFGaussian &o)
 *		- CPose3DQuatPDFGaussianInf::copyFrom(const CPose3DPDFGaussianInf &o)
 */
void USE_SUT_EULER2QUAT_CONVERSION(bool value);
bool USE_SUT_EULER2QUAT_CONVERSION();
}  // namespace global_settings

}  // namespace mrpt
