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 * OpenSpace                                                                             *
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#include <glm/gtx/euler_angles.hpp>

#include <modules/base/rotation/staticrotation.h>

#include <openspace/documentation/documentation.h>
#include <openspace/documentation/verifier.h>

namespace {
    constexpr openspace::properties::Property::PropertyInfo RotationInfo = {
        "Rotation",
        "Rotation",
        "This value is the used as a 3x3 rotation matrix that is applied to the scene "
        "graph node that this transformation is attached to relative to its parent.",
        openspace::properties::Property::Visibility::AdvancedUser
    };

    constexpr openspace::properties::Property::PropertyInfo EulerSequenceInfo = {
        "EulerSequence",
        "Euler Sequence",
        "This value specifies in which order the rotations should be applied to "
        "compose the final rotation matrix.",
        openspace::properties::Property::Visibility::AdvancedUser
    };

    // Conversion from rotation matrix to euler angles, given that the rotation is a pure
    // rotation matrix.
    // Inspired by: https://www.learnopencv.com/rotation-matrix-to-euler-angles/
    glm::dvec3 rotationMatrixToEulerAngles(glm::dmat4 mat) {
        const double sy = glm::sqrt(mat[0][0] * mat[0][0] + mat[0][1] * mat[0][1]);
        const bool singular = (sy < 1e-6);

        glm::dvec3 res;
        if (singular) {
            res.x = glm::atan(-mat[2][1], mat[1][1]);
            res.y = glm::atan(-mat[0][2], sy);
            res.z = 0;
        }
        else {
            res.x = glm::atan(mat[1][2], mat[2][2]);
            res.y = glm::atan(-mat[0][2], sy);
            res.z = glm::atan(mat[0][1], mat[0][0]);
        }
        return res;
    }

    // A StaticRotation is using a fixed and constant rotation factor that does not change
    // over time. The rotation value is provided as a property that can be changed at
    // runtime, but it will not change automatically over time.
    struct [[codegen::Dictionary(StaticRotation)]] Parameters {
        // Stores the static rotation as a vector containing Euler angles, a quaternion
        // representation, or a rotation matrix.
        //
        // For the Euler angles, the values have to be provided in radians. To convert
        // degres to radians, you can use the `math.rad` function.
        //
        // For the Quaternion representation, the values have to be provided in the order
        // (w, x, y, z).
        //
        // For the matrix form, the provided matrix will be converted into Euler angles,
        // an operation which might fail if the matrix is not a true rotation matrix. The
        // values are assumed to be in row-major order.
        std::variant<glm::dvec3, glm::dvec4, glm::dmat3x3> rotation;

        enum class EulerSequence {
            XYZ,
            XZY,
            YXZ,
            YZX,
            ZXY,
            ZYX,
            Default
        };

        std::optional<EulerSequence> eulerSequence;
    };
#include "staticrotation_codegen.cpp"
} // namespace

namespace openspace {

documentation::Documentation StaticRotation::Documentation() {
    return codegen::doc<Parameters>("base_transform_rotation_static");
}

StaticRotation::StaticRotation()
    : _eulerRotation(
        RotationInfo,
        glm::vec3(0.f),
        glm::vec3(-glm::pi<float>()),
        glm::vec3(glm::pi<float>())
    ),
    _eulerSequence(
        EulerSequenceInfo,
        properties::OptionProperty::DisplayType::Dropdown
    )
{
    addProperty(_eulerRotation);
    _eulerRotation.onChange([this]() {
        _matrixIsDirty = true;
        requireUpdate();
    });

    _eulerSequence.addOptions(
        {
            { static_cast<int>(Parameters::EulerSequence::XYZ), "XYZ" },
            { static_cast<int>(Parameters::EulerSequence::XZY), "XZY" },
            { static_cast<int>(Parameters::EulerSequence::YXZ), "YXZ" },
            { static_cast<int>(Parameters::EulerSequence::YZX), "YZX" },
            { static_cast<int>(Parameters::EulerSequence::ZXY), "ZXY" },
            { static_cast<int>(Parameters::EulerSequence::ZYX), "ZYX" },
            { static_cast<int>(Parameters::EulerSequence::Default), "Default" },
        }
    );

    addProperty(_eulerSequence);
    _eulerSequence.onChange([this]() {
        _matrixIsDirty = true;
        requireUpdate();
    });

    _type = "StaticRotation";
}

StaticRotation::StaticRotation(const ghoul::Dictionary& dictionary) : StaticRotation() {
    const Parameters p = codegen::bake<Parameters>(dictionary);

    if (std::holds_alternative<glm::dvec3>(p.rotation)) {
        _eulerRotation = std::get<glm::dvec3>(p.rotation);
    }
    else if (std::holds_alternative<glm::dvec4>(p.rotation)) {
        const glm::dvec4 data = std::get<glm::dvec4>(p.rotation);
        _eulerRotation = rotationMatrixToEulerAngles(
            glm::mat3_cast(glm::dquat(data.w, data.x, data.y, data.z))
        );
    }
    else if (std::holds_alternative<glm::dmat3>(p.rotation)) {
        _eulerRotation = rotationMatrixToEulerAngles(std::get<glm::dmat3>(p.rotation));
    }

    if (p.eulerSequence.has_value()) {
        _eulerSequence = static_cast<int>(p.eulerSequence.value());
    }
    else {
        _eulerSequence = static_cast<int>(Parameters::EulerSequence::Default);
    }

    _matrixIsDirty = true;
    _type = "StaticRotation";
}

glm::dmat3 StaticRotation::matrix(const UpdateData&) const {
    if (_matrixIsDirty) {
        // Correct for pauls @ XZY
        /*switch (_eulerSequence.value()) {
        case static_cast<int>(Parameters::EulerSequence::XYZ):
            _cachedMatrix = glm::mat3(
                glm::eulerAngleX(_eulerRotation.value().x) *
                glm::eulerAngleY(_eulerRotation.value().y) *
                glm::eulerAngleZ(_eulerRotation.value().z)
            );
            break;
        case static_cast<int>(Parameters::EulerSequence::XZY):
            _cachedMatrix = glm::mat3(
                glm::eulerAngleX(_eulerRotation.value().x) *
                glm::eulerAngleZ(_eulerRotation.value().y) *
                glm::eulerAngleY(_eulerRotation.value().z)
            );
            break;
        case static_cast<int>(Parameters::EulerSequence::YXZ):
            _cachedMatrix = glm::mat3(
                glm::eulerAngleY(_eulerRotation.value().x) *
                glm::eulerAngleX(_eulerRotation.value().y) *
                glm::eulerAngleZ(_eulerRotation.value().z)
            );
            break;
        case static_cast<int>(Parameters::EulerSequence::YZX):
            _cachedMatrix = glm::mat3(
                glm::eulerAngleY(_eulerRotation.value().x) *
                glm::eulerAngleZ(_eulerRotation.value().y) *
                glm::eulerAngleX(_eulerRotation.value().z)
            );
            break;
        case static_cast<int>(Parameters::EulerSequence::ZXY):
            _cachedMatrix = glm::mat3(
                glm::eulerAngleZ(_eulerRotation.value().x) *
                glm::eulerAngleX(_eulerRotation.value().y) *
                glm::eulerAngleY(_eulerRotation.value().z)
            );
            break;
        case static_cast<int>(Parameters::EulerSequence::ZYX):
            _cachedMatrix = glm::mat3(
                glm::eulerAngleZ(_eulerRotation.value().x) *
                glm::eulerAngleY(_eulerRotation.value().y) *
                glm::eulerAngleX(_eulerRotation.value().z)
            );
            break;
        }
        //_cachedMatrix = glm::mat3_cast(glm::quat(_eulerRotation.value()));
        _matrixIsDirty = false;
        */
        auto x = glm::eulerAngleX(_eulerRotation.value().x);
        auto y = glm::eulerAngleY(_eulerRotation.value().y);
        auto z = glm::eulerAngleZ(_eulerRotation.value().z);
        switch (_eulerSequence.value()) {
        case static_cast<int>(Parameters::EulerSequence::XYZ):
            _cachedMatrix = glm::mat3(
                x * y * z
            );
            break;
        case static_cast<int>(Parameters::EulerSequence::XZY):
            _cachedMatrix = glm::mat3(
                x * z * y
            );
            break;
        case static_cast<int>(Parameters::EulerSequence::YXZ):
            _cachedMatrix = glm::mat3(
                y * x * z
            );
            break;
        case static_cast<int>(Parameters::EulerSequence::YZX):
            _cachedMatrix = glm::mat3(
                y * z * x
            );
            break;
        case static_cast<int>(Parameters::EulerSequence::ZXY):
            _cachedMatrix = glm::mat3(
                z * x * y
            );
            break;
        case static_cast<int>(Parameters::EulerSequence::ZYX):
            _cachedMatrix = glm::mat3(
                z * y * x
            );
            break;
        case static_cast<int>(Parameters::EulerSequence::Default):
            _cachedMatrix = glm::mat3_cast(glm::quat(_eulerRotation.value()));
            break;
        }

        _matrixIsDirty = false;
    }
    return _cachedMatrix;
}

} // namespace openspace