/*******************************************************************************
 * hdr.cpp
 *
 * This module contains the code to read and write files in Radiance HDRI format
 * (sometimes known as 'RGBE' format).
 *
 * Author: Christopher Cason
 * Based on MegaPOV HDR code written by Mael and Christoph Hormann
 *
 * ---------------------------------------------------------------------------
 * Persistence of Vision Ray Tracer ('POV-Ray') version 3.7.
 * Copyright 1991-2013 Persistence of Vision Raytracer Pty. Ltd.
 *
 * POV-Ray is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as
 * published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 *
 * POV-Ray 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
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 * ---------------------------------------------------------------------------
 * POV-Ray is based on the popular DKB raytracer version 2.12.
 * DKBTrace was originally written by David K. Buck.
 * DKBTrace Ver 2.0-2.12 were written by David K. Buck & Aaron A. Collins.
 * ---------------------------------------------------------------------------
 * $File: //depot/public/povray/3.x/source/base/image/hdr.cpp $
 * $Revision: #1 $
 * $Change: 6069 $
 * $DateTime: 2013/11/06 11:59:40 $
 * $Author: chrisc $
 *******************************************************************************/

#include <boost/scoped_ptr.hpp>
#include <boost/scoped_array.hpp>

#include <string>

// configbase.h must always be the first POV file included within base *.cpp files
#include "base/configbase.h"
#include "base/image/image.h"
#include "base/fileinputoutput.h"
#include "base/image/hdr.h"
#include "base/types.h"

#include "metadata.h"

// this must be the last file included
#include "base/povdebug.h"

namespace pov_base
{

namespace HDR
{

/*****************************************************************************
* Local preprocessor defines
******************************************************************************/

#define  MINELEN        8       /* minimum scanline length for encoding */
#define  MAXELEN        0x7fff  /* maximum scanline length for encoding */
#define  MINRUN         4       /* minimum run length */

/*****************************************************************************
* Local typedefs
******************************************************************************/

struct Messages
{
	vector<string> warnings;
	string error;
};

typedef unsigned char RGBE[4]; // red, green, blue, exponent

void GetRGBE(RGBE rgbe, const Image *image, int col, int row, const GammaCurvePtr& gamma, DitherHandler* dither);
void SetRGBE(const unsigned char *scanline, Image *image, int row, int width, const GammaCurvePtr& gamma);
void ReadOldLine(unsigned char *scanline, int width, IStream *file);

/*****************************************************************************
* Code
******************************************************************************/
void GetRGBE(RGBE rgbe, const Image *image, int col, int row, const GammaCurvePtr& gamma, DitherHandler* dh)
{
	float r, g, b, d;
	int e;

	DitherHandler::OffsetInfo linOff, encOff;
	dh->getOffset(col,row,linOff,encOff);

	GetEncodedRGBValue(image, col, row, gamma, r, g, b);
	r += linOff.red;
	g += linOff.green;
	b += linOff.blue;

	if((d = max3(r, g, b)) <= 1.0e-32)
	{
		rgbe[0] = rgbe[1] = rgbe[2] = rgbe[3] = 0;
		return;
	}

	d = frexp(d, &e) * 256.0 / d;

	rgbe[0] = (unsigned char)(clip(r * d + encOff.red,   0.0f, 255.0f));
	rgbe[1] = (unsigned char)(clip(g * d + encOff.green, 0.0f, 255.0f));
	rgbe[2] = (unsigned char)(clip(b * d + encOff.blue,  0.0f, 255.0f));
	rgbe[3] = (unsigned char)(clip(e + 128.0f, 0.0f, 255.0f));

	linOff.red   = r - (double(rgbe[0]) + 0.5) / d;
	linOff.green = g - (double(rgbe[1]) + 0.5) / d;
	linOff.blue  = b - (double(rgbe[2]) + 0.5) / d;
	dh->setError(col,row,linOff);
}

void SetRGBE(const unsigned char *scanline, Image *image, int row, int width, const GammaCurvePtr& gamma)
{
	for(int i = 0; i < width; i++)
	{
		double v = ldexp(1.0, int(scanline[3]) - (128 + 8));
		float r = (double(scanline[0]) + 0.5) * v;
		float g = (double(scanline[1]) + 0.5) * v;
		float b = (double(scanline[2]) + 0.5) * v;

		SetEncodedRGBValue(image, i, row, gamma, r, g, b);
		scanline += 4;
	}
}

void ReadOldLine(unsigned char *scanline, int width, IStream *file)
{
	int rshift = 0;
	unsigned char b;

	while(width > 0)
	{
		scanline[0] = file->Read_Byte();
		scanline[1] = file->Read_Byte();
		scanline[2] = file->Read_Byte();

		// NB EOF won't be set at this point even if the last read obtained the
		// final byte in the file (we need to read another byte for that to happen).
		if(!*file)
			throw POV_EXCEPTION(kFileDataErr, "Invalid HDR file (unexpected EOF)");

		if(file->Read_Byte(b).eof())
			return;

		scanline[3] = b;

		if((scanline[0] == 1) && (scanline[1] == 1) && (scanline[2] == 1))
		{
			for(int i = scanline[3] << rshift; i > 0; i--)
			{
				memcpy(scanline, scanline - 4, 4);
				scanline += 4;
				width--;
			}
			rshift += 8;
		}
		else
		{
			scanline += 4;
			width--;
			rshift = 0;
		}
	}
}

Image *Read(IStream *file, const Image::ReadOptions& options)
{
	char line[2048];
	char *s;
	char s1[3];
	char s2[3];
	unsigned char b;
	unsigned char val;
	float e;
	float exposure = 1.0;
	unsigned int width;
	unsigned int height;
	Image *image = NULL;
	Image::ImageDataType imagetype = options.itype;

	// Radiance HDR files store linear color values by default, so never convert unless the user overrides
	// (e.g. to handle a non-compliant file).
	GammaCurvePtr gamma;
	if (options.gammacorrect)
	{
		if (options.gammaOverride)
			gamma = TranscodingGammaCurve::Get(options.workingGamma, options.defaultGamma);
		else
			gamma = TranscodingGammaCurve::Get(options.workingGamma, NeutralGammaCurve::Get());
	}

	while(*file)
	{
		if(!file->getline(line, sizeof(line)) || (line[0] == '-') || (line[0] == '+'))
			break;

		// TODO: what do we do with exposure?
		if(strncmp(line, "EXPOSURE", 8) == 0)
		{
			if((s = strchr(line, '=')) != NULL)
			{
				if(sscanf(s + 1, "%f", &e) == 1)
					exposure *= e;
			}
		}
	}

	if(sscanf(line, "%2[+-XY] %u %2[+-XY] %u\n", s1, &height, s2, &width) != 4)
		throw POV_EXCEPTION(kFileDataErr, "Bad HDR file header");

	if(imagetype == Image::Undefined)
		imagetype = Image::RGBFT_Float;

	image = Image::Create(width, height, imagetype);
	// NB: HDR files don't use alpha, so premultiplied vs. non-premultiplied is not an issue

	boost::scoped_array<unsigned char> scanline(new unsigned char[4 * width]);
	for(int row = 0; row < height; row++)
	{
		// determine scanline type
		if((width < MINELEN) | (width > MAXELEN))
		{
			ReadOldLine(scanline.get(), width, file);
			SetRGBE(scanline.get(), image, row, width, gamma);
			continue;
		}

		if(!file->Read_Byte(b))
			throw POV_EXCEPTION(kFileDataErr, "Incomplete HDR file");

		if(b != 2)
		{
			file->UnRead_Byte(b);

			ReadOldLine(scanline.get(), width, file);
			SetRGBE(scanline.get(), image, row, width, gamma);
			continue;
		}

		scanline[1] = file->Read_Byte();
		scanline[2] = file->Read_Byte();

		if(!file->Read_Byte(b))
			throw POV_EXCEPTION(kFileDataErr, "Incomplete or invalid HDR file");

		if((scanline[1] != 2) || ((scanline[2] & 128) != 0))
		{
			scanline[0] = 2;
			scanline[3] = b;

			ReadOldLine(scanline.get() + 4, width - 1, file);
			SetRGBE(scanline.get(), image, row, width, gamma);
			continue;
		}

		if((((int) scanline[2] << 8) | b) != width)
			throw POV_EXCEPTION(kFileDataErr, "Invalid HDR file (length mismatch)");

		for(int i = 0; i < 4; i++)
		{
			for(int j = 0; j < width; )
			{
				if(!file->Read_Byte(b))
					throw POV_EXCEPTION(kFileDataErr, "Invalid HDR file (unexpected EOF)");

				if(b > 128)
				{
					// run
					b &= 127;

					if(!file->Read_Byte(val))
						throw POV_EXCEPTION(kFileDataErr, "Invalid HDR file (unexpected EOF)");

					while(b--)
						scanline[j++ * 4 + i] = (unsigned char) val;
				}
				else
				{
					while(b--)
					{
						if(!file->Read_Byte(val))
							throw POV_EXCEPTION(kFileDataErr, "Invalid HDR file (unexpected EOF)");

						scanline[j++ * 4 + i] = (unsigned char) val;
					}
				}
			}
		}

		SetRGBE(scanline.get(), image, row, width, gamma);
	}

	return image;
}

void Write(OStream *file, const Image *image, const Image::WriteOptions& options)
{
	int width = image->GetWidth();
	int height = image->GetHeight();
	int cnt = 1;
	int c2;
	RGBE rgbe;
	GammaCurvePtr gamma = TranscodingGammaCurve::Get(options.workingGamma, NeutralGammaCurve::Get());
	DitherHandler* dither = options.dither.get();

	Metadata meta;
	file->printf("#?RADIANCE\n");
	file->printf("SOFTWARE=%s\n", meta.getSoftware().c_str());
	file->printf("CREATION_TIME=%s\n" ,meta.getDateTime().c_str());
	if (!meta.getComment1().empty())
		file->printf("COMMENT=%s\n", meta.getComment1().c_str());
	if (!meta.getComment2().empty())
		file->printf("COMMENT=%s\n", meta.getComment2().c_str());
	if (!meta.getComment3().empty())
		file->printf("COMMENT=%s\n", meta.getComment3().c_str());
	if (!meta.getComment4().empty())
		file->printf("COMMENT=%s\n", meta.getComment4().c_str());

	file->printf("FORMAT=32-bit_rle_rgbe\n");
	file->printf("\n");
	file->printf("-Y %d +X %d\n", height, width);

	boost::scoped_array<RGBE> scanline(new RGBE[width]);

	for(int row = 0; row < height; row++)
	{
		if((width < MINELEN) | (width > MAXELEN))
		{
			for(int col = 0; col < width; col++)
			{
				GetRGBE(rgbe, image, col, row, gamma, dither);

				if(!file->write(&rgbe, sizeof(RGBE)))
					throw POV_EXCEPTION(kFileDataErr, "Failed to write data to HDR file");
			}
		}
		else
		{
			// put magic header
			file->Write_Byte(2);
			file->Write_Byte(2);
			file->Write_Byte(width >> 8);
			file->Write_Byte(width & 255);

			// convert pixels
			for(int col = 0; col < width; col++)
				GetRGBE(scanline[col], image, col, row, gamma, dither);

			// put components seperately
			for(int i = 0; i < 4; i++)
			{
				for(int col = 0; col < width; col += cnt)
				{
					int beg = 0;

					// find next run
					for(beg = col; beg < width; beg += cnt)
					{
						cnt = 1;
						while((cnt < 127) && (beg + cnt < width) && (scanline[beg + cnt][i] == scanline[beg][i]))
							cnt++;

						// long enough ?
						if(cnt >= MINRUN)
							break;
					}

					if(beg - col > 1 && beg - col < MINRUN)
					{
						c2 = col + 1;
						while(scanline[c2++][i] == scanline[col][i])
						{
							if(c2 == beg)
							{
								// short run
								file->Write_Byte(128 + beg - col);

								if(!file->Write_Byte(scanline[col][i]))
									throw POV_EXCEPTION(kFileDataErr, "Failed to write data to HDR file");

								col = beg;
								break;
							}
						}
					}
					while(col < beg)
					{
						// write non-run
						if((c2 = beg - col) > 128)
							c2 = 128;

						file->Write_Byte(c2);

						while(c2--)
						{
							if(!file->Write_Byte(scanline[col++][i]))
								throw POV_EXCEPTION(kFileDataErr, "Failed to write data to HDR file");
						}
					}
					if(cnt >= MINRUN)
					{
						// write run
						file->Write_Byte(128 + cnt);

						if(!file->Write_Byte(scanline[beg][i]))
							throw POV_EXCEPTION(kFileDataErr, "Failed to write data to HDR file");
					}
					else
						cnt = 0;
				}
			}
		}
	}
}

} // end of namespace HDR

} // end of namespace pov_base