/*****************************************************************************************
 *                                                                                       *
 * OpenSpace                                                                             *
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 * Copyright (c) 2014-2023                                                               *
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#ifndef __OPENSPACE_MODULE_TOUCH___DIRECTINPUT_SOLVER___H__
#define __OPENSPACE_MODULE_TOUCH___DIRECTINPUT_SOLVER___H__

#include <openspace/util/touch.h>
#include <modules/touch/ext/levmarq.h>
#include <vector>


namespace openspace {

class Camera;
class SceneGraphNode;

/**
 * The DirectInputSolver is used to minimize the L2 error of touch input
 * to 3D camera position. It uses the levmarq algorithm in order to do this.
 * */
class DirectInputSolver {
public:
    // Stores the selected node, the cursor ID as well as the surface coordinates the
    // cursor touched
    struct SelectedBody {
        size_t id = 0;
        SceneGraphNode* node = nullptr;
        glm::dvec3 coordinates = glm::dvec3(0.0);
    };

    DirectInputSolver();

    /**
     * Returns true if the error could be minimized within certain bounds.
     * If the error is found to be outside the bounds after a certain amount of
     * iterations, this function fails.
     * */
    bool solve(const std::vector<TouchInputHolder>& list,
        const std::vector<SelectedBody>& selectedBodies,
        std::vector<double>* calculatedValues, const Camera& camera);

    int nDof() const;

    const LMstat& levMarqStat();

    void setLevMarqVerbosity(bool verbose);

private:
    int _nDof = 0;
    LMstat _lmstat;
};

} // openspace namespace

#endif // __OPENSPACE_MODULE_TOUCH___DIRECTINPUT_SOLVER___H__