/* +------------------------------------------------------------------------+
   |                     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          |
   +------------------------------------------------------------------------+ */

#include "math-precomp.h"  // Precompiled headers
//
#include <mrpt/math/CAtan2LookUpTable.h>

#include <cmath>
#include <vector>

using namespace mrpt::math;

CAtan2LookUpTable::CAtan2LookUpTable() noexcept
{
	this->resize(-1.0, 1.0, -1.0, 1.0, 0.5);
}
CAtan2LookUpTable::CAtan2LookUpTable(
	double xmin, double xmax, double ymin, double ymax,
	double resolution) noexcept
{
	this->resize(xmin, xmax, ymin, ymax, resolution);
}

void CAtan2LookUpTable::resize(
	double xmin, double xmax, double ymin, double ymax,
	double resolution) noexcept
{
	const double def = .0;
	if (m_grid.getResolution() == resolution)
		m_grid.resize(xmin, xmax, ymin, ymax, def, .0);
	else
		m_grid.setSize(xmin, xmax, ymin, ymax, resolution, &def);

	const size_t nx = m_grid.getSizeX(), ny = m_grid.getSizeY();

	std::vector<double> idx2x(nx), idx2y(ny);

	for (size_t ix = 0; ix < nx; ix++)
		idx2x[ix] = m_grid.idx2x(ix);
	for (size_t iy = 0; iy < ny; iy++)
		idx2y[iy] = m_grid.idx2y(iy);

	for (size_t ix = 0; ix < nx; ix++)
	{
		const double x = idx2x[ix];
		for (size_t iy = 0; iy < ny; iy++)
		{
			const double y = idx2y[iy];
			double* cp = m_grid.cellByIndex(ix, iy);
			if (cp) *cp = ::atan2(y, x);
		}
	}
}

CAtan2LookUpTableMultiRes::CAtan2LookUpTableMultiRes(
	const std::map<double, double>& lst_resolutions2extensions) noexcept
{
	resize(lst_resolutions2extensions);
}
void CAtan2LookUpTableMultiRes::resize(
	const std::map<double, double>& lst_resolutions2extensions) noexcept
{
	m_grids.clear();

	for (const auto& it : lst_resolutions2extensions)
	{
		const double res = it.first;
		const double exten = it.second;

		mrpt::containers::CDynamicGrid<double>& dg = m_grids[exten] =
			mrpt::containers::CDynamicGrid<double>(
				-exten, exten, -exten, exten, res);

		const size_t nx = dg.getSizeX(), ny = dg.getSizeY();
		std::vector<double> idx2x(nx), idx2y(ny);

		for (size_t ix = 0; ix < nx; ix++)
			idx2x[ix] = dg.idx2x(ix);
		for (size_t iy = 0; iy < ny; iy++)
			idx2y[iy] = dg.idx2y(iy);

		for (size_t ix = 0; ix < nx; ix++)
		{
			const double x = idx2x[ix];
			for (size_t iy = 0; iy < ny; iy++)
			{
				const double y = idx2y[iy];
				double* cp = dg.cellByIndex(ix, iy);
				if (cp) *cp = ::atan2(y, x);
			}
		}
	}
}

bool CAtan2LookUpTableMultiRes::atan2(
	double y, double x, double& out_atan2) const noexcept
{
	for (const auto& it : m_grids)
	{
		const double exten = it.first;
		const mrpt::containers::CDynamicGrid<double>& dg = it.second;

		if (std::abs(x) > exten || std::abs(y) > exten) continue;

		const double* cp = dg.cellByPos(x, y);
		if (!cp) continue;
		out_atan2 = *cp;
		return true;
	}
	return false;
}
