/********************************************************************************
 *                                                                              *
 * This file is part of IfcOpenShell.                                           *
 *                                                                              *
 * IfcOpenShell is free software: you can redistribute it and/or modify         *
 * it under the terms of the Lesser GNU General Public License as published by  *
 * the Free Software Foundation, either version 3.0 of the License, or          *
 * (at your option) any later version.                                          *
 *                                                                              *
 * IfcOpenShell is distributed in the hope that it will be useful,              *
 * but WITHOUT ANY WARRANTY; without even the implied warranty of               *
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the                 *
 * Lesser GNU General Public License for more details.                          *
 *                                                                              *
 * You should have received a copy of the Lesser GNU General Public License     *
 * along with this program. If not, see <http://www.gnu.org/licenses/>.         *
 *                                                                              *
 ********************************************************************************/

#include "mapping.h"
#define mapping POSTFIX_SCHEMA(mapping)
using namespace ifcopenshell::geometry;

#ifdef SCHEMA_HAS_IfcFixedReferenceSweptAreaSolid

taxonomy::ptr mapping::map_impl(const IfcSchema::IfcFixedReferenceSweptAreaSolid* inst) {
	auto dir = map(inst->Directrix());
	auto ref = taxonomy::cast<taxonomy::direction3>(map(inst->FixedReference()));
	auto profile = taxonomy::cast<taxonomy::face>(map(inst->SweptArea()));

	auto loft = taxonomy::make<taxonomy::loft>();
	// @todo intialize as default
	loft->axis = nullptr;

	// @todo currently only the case is handled where directrix returns a piecewise_function
	if (auto pwf = taxonomy::dcast<taxonomy::piecewise_function>(dir)) {
		double start = 0;
		double end = pwf->length();
#ifdef SCHEMA_HAS_IfcDirectrixCurveSweptAreaSolid
		// IfcDirectrixCurveSweptAreaSolid introduced in 4.3 changed attribute type
		// from optional IfcParamValue to optional IfcCurveMeasureSelect.
		// Invocation of mapping on pre-4.3 models can never result in a piecewise_function.
		if (inst->StartParam() && inst->StartParam()->as<IfcSchema::IfcLengthMeasure>()) {
			double s = *inst->StartParam()->as<IfcSchema::IfcLengthMeasure>();
			if (s > start) {
				start = s;
			}
		}
		if (inst->EndParam() && inst->EndParam()->as<IfcSchema::IfcLengthMeasure>()) {
			double e = *inst->EndParam()->as<IfcSchema::IfcLengthMeasure>();
			if (e < end) {
				end = e;
			}
		}
#endif
		auto curve_length = end - start;
		auto param_type = settings_.get<ifcopenshell::geometry::settings::PiecewiseStepType>().get();
		auto param = settings_.get<ifcopenshell::geometry::settings::PiecewiseStepParam>().get();
		size_t num_steps = 0;
		if (param_type == ifcopenshell::geometry::settings::PiecewiseStepMethod::MAXSTEPSIZE) {
			// parameter is max step size
			num_steps = (size_t) std::ceil(curve_length / param);
		} else {
			// parameter is minimum number of steps
			num_steps = (size_t) std::ceil(param);
		}
		for (size_t i = 0; i <= num_steps; ++i) {
			auto distalong = start + curve_length / num_steps * i;
			auto m4 = pwf->evaluate(distalong);
			
			/*
			std::stringstream ss;
			ss << m4;
			auto s = ss.str();
			std::wcout << s.c_str() << std::endl;
            std::wcout << "determinant: " << m4.determinant() << std::endl;
			*/

			Eigen::Matrix4d m4b = Eigen::Matrix4d::Identity();
			bool is_directrix_derived = false;
			
#ifdef SCHEMA_HAS_IfcDirectrixDerivedReferenceSweptAreaSolid
			if (inst->as<IfcSchema::IfcDirectrixDerivedReferenceSweptAreaSolid>()) {
				is_directrix_derived = true;
			}
#endif
			auto pos = m4.col(3).head<3>();

			if (is_directrix_derived) {
				m4b.col(0).head<3>() = m4.col(1).head<3>();
				m4b.col(1).head<3>() = m4.col(0).head<3>().cross(m4.col(1).head<3>());
				m4b.col(2).head<3>() = m4.col(0).head<3>();
				m4b.col(3).head<3>() = pos;
			} else {
				Eigen::Vector3d tangent = m4.col(0).head<3>().normalized();
				Eigen::Vector3d proj = (ref->components() - tangent * tangent.dot(ref->components()));
				proj.normalize();
				auto ref = proj.cross(tangent);

				m4b.col(0).head<3>() = proj;
				m4b.col(1).head<3>() = ref;
				m4b.col(2).head<3>() = tangent;
				m4b.col(3).head<3>() = pos;

				/*
				Eigen::JacobiSVD<decltype(m4b)> svd(m4b);
				auto condition_number = svd.singularValues()(0)
					/ svd.singularValues()(svd.singularValues().size() - 1);
				if (condition_number > 1.e10) {
					Logger::Error("Non-invertible matrix at " + std::to_string(distalong) + " conversion will likely fail.");
				}
				*/
			}

			// @todo taxonomy::clone() does not actually clone. That's really confusing.
			// loft->children.push_back(taxonomy::clone(profile));
			loft->children.push_back(taxonomy::face::ptr(profile->clone_()));
			loft->children.back()->matrix = taxonomy::make<taxonomy::matrix4>();
			
			if (profile->matrix) {
				loft->children.back()->matrix->components() = (m4b * profile->matrix->ccomponents()).eval();
			} else {
				loft->children.back()->matrix->components() = m4b;
			}
		}
	}

	return loft;
}

#endif