#include <memory></memory>

#include "tropcm.h"

// TnzCore includes

#include "traster.h"

// STD includes

#include <limits></limits>

//#define UNIT_TEST                                             // Enables unit testing at program startup

//************************************************************************

//    Rationale

//************************************************************************

/*!

  \file                   tdistancetransform.cpp

  \brief    This file implements an O(rows * cols) 2-dimensional distance

            transform algorithm with customizable action on squared pixel

            distance from the closest pixel.

*/

//************************************************************************

//    Local namespace  stuff

//************************************************************************

namespace

{

/*!

  \brief    Given 2 parabolas with (minimal) height at centers \p a and \p b

            and centers separated by distance \p d, returns the min between

            \p d and the value \p x satisfying <tt>a + x^2 == b + (x - d)^2</tt>.

*/

unsigned int takeoverDist(unsigned int a, unsigned int b, unsigned int d)

{

	// The actual formula is: x = (h^2 + b - a) / 2h. It simplifies as follows

	// using integers only.

	// NOTE: It can be proven that with integer division, x/ab == (x/a)/b.

	return (b < a) ? d : std::max((d + (b - a) / d + 1) / 2, d); // Note the +1 to get the ceil

}

//--------------------------------------------------------------

template <typename isinsidefunc="" pix,="" typename=""></typename>

void initializeDT(const TRasterPT<pix> &ras, const TRasterPT<unsigned int=""> &dtRas,</unsigned></pix>

				  IsInsideFunc isInside)

{

	assert(ras->getLx() == dtRas->getLx() && ras->getLy() == dtRas->getLy());

	static const unsigned int uiMax =					// Due to the above takeoverDist, for

		(std::numeric_limits<unsigned int="">::max)() - 2; // d == 1</unsigned>

	int lx = ras->getLx(), ly = ras->getLy();

	for (int y = 0; y != ly; ++y) {

		Pix *pix = ras->pixels(y), *rowEnd = pix + lx;

		unsigned int *dt = dtRas->pixels(y);

		for (; pix != rowEnd; ++pix, ++dt) {

			assert(*dt == 0u);

			if (!isInside(*pix))

				*dt = uiMax;

		}

	}

}

//--------------------------------------------------------------

template <typename outfunc="" pix,="" typename=""></typename>

void expand(int lineLength, int linesCount,

			Pix *buf, int incrPix,

			int incrLine,

			unsigned int *dtBuf, int dtIncrPix,

			int dtIncrLine,

			OutFunc outFunc)

{

	struct locals {

		static void copyLine(unsigned int *dst, unsigned int *src, unsigned int *srcEnd,

							 int srcStride)

		{

			for (; src != srcEnd; src += srcStride, ++dst)

				*dst = *src;

		}

		static void buildRange(unsigned int *dtRef, unsigned int *dtLineEnd,

							   unsigned int *&dtEnd, unsigned int *&dtNewRef)

		{

			unsigned int d = 1, dNew = 0,						   // dNew at 0 to provide a consistent dtNewRef

				dMax = (std::numeric_limits<unsigned int="">::max)(); // at the end - should not matter though</unsigned>

			unsigned int *dt = dtRef + 1;

			for (; d <= dMax && dt != dtLineEnd; ++d, ++dt) // Pick larger intervals if possible

			{

				unsigned int newDMax = ::takeoverDist(*dtRef, *dt, d); //

				if (newDMax <= dMax) {

					dNew = d;

					dMax = newDMax;

				}

			}

			dtEnd = dtRef + std::min(d, dMax); // Could end the line before (dMax < d)

			dtNewRef = dtRef + dNew;

		}

	}; // locals

	// Allocate a buffer equivalent to a dt line. It will store the original

	// dt values. Final dt values will be written directly on the dt raster.

	// This is necessary since read and write intervals overlap.

	std::unique_ptr<unsigned[]> dtOriginalLine(new unsigned[lineLength]);</unsigned[]>

	unsigned int *odtLineStart = dtOriginalLine.get(),

				 *odtLineEnd = odtLineStart + lineLength;

	// Process each line

	for (int l = 0; l != linesCount; ++l) {

		unsigned int *dtLineStart = dtBuf + dtIncrLine * l,	// Using dtBuf to track colors from now on,

			*dtLineEnd = dtLineStart + dtIncrPix * lineLength, // it already embeds colorFunc's output due

				*dt = dtLineStart,							   // to the way it was initialized.

					*odtRef = odtLineStart;

		Pix *lineStart = buf + incrLine * l,

			*pix = lineStart;

		// Make a copy of the original dt values

		locals::copyLine(dtOriginalLine.get(), dtLineStart, dtLineEnd, dtIncrPix);

		// Expand a colored pixel along the line

		while (dt != dtLineEnd) {

			// The line is subdivided in consecutive ranges associated to the same

			// half-parabola - process one

			// Build a half-parabola range

			unsigned int *dtEnd, *odtNewRef;

			locals::buildRange(odtRef, odtLineEnd, dtEnd, odtNewRef);

			assert(odtLineStart <= odtNewRef && odtNewRef <= odtLineEnd);

			assert(odtLineStart <= dtEnd && dtEnd <= odtLineEnd);

			dtEnd = dtLineStart + dtIncrPix * (dtEnd - odtLineStart); // Convert dtEnd to the dt raster buffer

			// Process the range

			Pix *ref = lineStart + incrPix * (odtRef - odtLineStart);

			unsigned int d = (pix - ref) / incrPix;

			for (; dt != dtEnd; ++d, dt += dtIncrPix, pix += incrPix)

				outFunc(*pix, *ref, *dt = *odtRef + sq(d));

			odtRef = odtNewRef;

		}

	}

}

//--------------------------------------------------------------

/*!

  \brief    Performs an O(rows * cols) distance transform on the specified

            raster image.

  \details  The algorithm relies on the separability of the 2D DT into 2

            passes (by rows and columns) of 1-dimensional DTs.

            The 1D DT sums a pre-existing (from the previous DT step if any)

            DT result with the one currently calculated.

  \warning  Templace parameter OutFunc is supposed to satisfy \a transitivity

            upon comparison of its output - so, if \p b is the output of \p a,

            and \p c is the output of \p b, then \p c is the same as the output

            of \p a.

  \todo     Accept a different output raster - but preserve the case where

            (srcRas == dstRas).

*/

template <typename isinsidefunc,="" outfunc="" pix,="" typename=""></typename>

void distanceTransform(const TRasterPT<pix> &ras, IsInsideFunc isInside, OutFunc outFunc)</pix>

{

	int lx = ras->getLx(), ly = ras->getLy();

	// Allocate a suitable temporary raster holding the (squared) distance transform

	// built from the specified color function

	TRasterPT<unsigned int=""> dtRas(lx, ly); // Summed squared distances will be limited to</unsigned>

										   // 2 billions. This is generally suitable.

	::initializeDT(ras, dtRas, isInside);  // The raster is binarized directly into the

										   // auxiliary dtRas. Pixels in the set to expand

										   // will have value 0, the others a suitable high value.

	expand(lx, ly, ras->pixels(0), 1, ras->getWrap(),

		   dtRas->pixels(0), 1, dtRas->getWrap(), outFunc);

	expand(lx, ly, ras->pixels(0) + lx - 1, -1, ras->getWrap(),

		   dtRas->pixels(0) + lx - 1, -1, dtRas->getWrap(), outFunc);

	expand(ly, lx, ras->pixels(0), ras->getWrap(), 1,

		   dtRas->pixels(0), dtRas->getWrap(), 1, outFunc);

	expand(ly, lx, ras->pixels(ly - 1), -ras->getWrap(), 1,

		   dtRas->pixels(ly - 1), -dtRas->getWrap(), 1, outFunc);

}

}

//************************************************************************

//    Local Functors

//************************************************************************

/*

  Using functors here just to be absolutely sure that calls are not

  callbacks.

*/

namespace

{

struct SomePaint {

	inline bool operator()(const TPixelCM32 &pix) const

	{

		return (pix.getTone() != 0) || (pix.getPaint() != 0);

	}

};

struct CopyPaint {

	inline void operator()(TPixelCM32 &out, const TPixelCM32 &in, unsigned int) const

	{

		out.setPaint(in.getPaint());

	}

};

}

//************************************************************************

//    API functions

//************************************************************************

void TRop::expandPaint(const TRasterCM32P &rasCM)

{

	distanceTransform(rasCM, SomePaint(), CopyPaint());

}

//************************************************************************

//    Unit testing

//************************************************************************

#if defined UNIT_TEST && !defined NDEBUG

namespace

{

void assertEqualBufs(const TRasterT<unsigned int=""> &a, const TRasterT<unsigned int=""> &b)</unsigned></unsigned>

{

	for (int y = 0; y != a.getLy(); ++y) {

		for (int x = 0; x != a.getLx(); ++x)

			assert(a.pixels(y)[x] == b.pixels(y)[x]);

	}

}

struct Selector {

	inline bool operator()(unsigned int val) const

	{

		return val;

	}

};

struct OutputDT {

	inline void operator()(unsigned int &out, const unsigned int &in, unsigned int d2) const

	{

		out = d2;

	}

};

struct DTTest {

	DTTest()

	{

		unsigned int imgBuf[] = {

			0, 0, 1, 0, 0, 0,

			0, 0, 1, 0, 0, 0,

			0, 1, 1, 1, 1, 0,

			0, 1, 0, 0, 0, 0,

			0, 0, 0, 0, 0, 0,

		};

		unsigned int dtBuf[] = {

			4, 1, 0, 1, 4, 5,

			2, 1, 0, 1, 1, 2,

			1, 0, 0, 0, 0, 1,

			1, 0, 1, 1, 1, 2,

			2, 1, 2, 4, 4, 5,

		};

		TRasterPT<unsigned int=""> imgRas(6, 5, 6, imgBuf, false),</unsigned>

			dtRas(6, 5, 6, dtBuf, false);

		distanceTransform(imgRas, Selector(), OutputDT());

		assertEqualBufs(*imgRas, *dtRas);

	}

} dtTest;

} // namespace

#endif // UNIT_TEST && !NDEBUG