/* ALTA --- Analysis of Bidirectional Reflectance Distribution Functions

   Copyright (C) 2013 Inria

   This file is part of ALTA.

   This Source Code Form is subject to the terms of the Mozilla Public
   License, v. 2.0.  If a copy of the MPL was not distributed with this
   file, You can obtain one at http://mozilla.org/MPL/2.0/.  */

#ifndef EXR_IO_H_
#define EXR_IO_H_
/*
 * Author: Cyril Soler
 */


#include <stdexcept>

#include <ImfRgbaFile.h>
#include <ImfArray.h>

template<typename FType>
class t_EXR_IO
{
	public:
		static bool LoadEXR(const char *filename,int& W,int& H, FType *& pix,int nC=3) 
		{
			Imf::RgbaInputFile file(filename);
			Imath::Box2i dw = file.dataWindow();

			W = dw.max.x - dw.min.x + 1;
			H = dw.max.y - dw.min.y + 1;

			Imf::Array2D<Imf::Rgba> pixels;
			pixels.resizeErase(H, W);

			file.setFrameBuffer (&pixels[0][0] - dw.min.x - dw.min.y * W, 1, W);
			file.readPixels (dw.min.y, dw.max.y);

			pix = new FType[W*H*3] ;

			switch(nC)
			{
				case 3: for(int i=0;i<H;++i)
							  for(int j=0;j<W;++j)
							  {
								  pix[3*(j+i*W)+0] = pixels[H-i-1][j].r ;
								  pix[3*(j+i*W)+1] = pixels[H-i-1][j].g ;
								  pix[3*(j+i*W)+2] = pixels[H-i-1][j].b ;
							  }
						  break ;

				case 1: for(int i=0;i<H;++i)
							  for(int j=0;j<W;++j)
								  pix[j+i*W] = 0.3*pixels[H-i-1][j].r + 0.59*pixels[H-i-1][j].g + 0.11*pixels[H-i-1][j].b ;
						  break ;
				default:
						  throw std::runtime_error("Unexpected case in EXR_IO.") ;
			}
			return true ;
		}

		static bool SaveEXR(const char *filename,int W,int H, const FType *pix,int nC=3)
		{
			Imf::Array2D<Imf::Rgba> pixels(H,W);

			/* Convert separated channel representation to per pixel representation */

			switch(nC)
			{
				case 3:
					for (int row=0;row<H;row++) 
						for(int i=0;i<W;i++) 
						{
							Imf::Rgba &p = pixels[H-row-1][i];

							p.r = pix[3*(i+row*W)+0] ;
							p.g = pix[3*(i+row*W)+1] ;
							p.b = pix[3*(i+row*W)+2] ;
							p.a = 1.0 ;
						}
					break ;

				case 1:
					for (int row=0;row<H;row++) 
						for(int i=0;i<W;i++) 
						{
							Imf::Rgba &p = pixels[H-row-1][i];

							p.r = pix[i+row*W] ;
							p.g = pix[i+row*W] ;
							p.b = pix[i+row*W] ;
							p.a = FType(1.0) ;
						}
					break ;
				default:
					throw std::runtime_error("Unexpected case in EXR_IO.") ;
			}

			Imf::RgbaOutputFile file(filename, W, H, Imf::WRITE_RGBA);
			file.setFrameBuffer(&pixels[0][0], 1, W);
			file.writePixels(H);

			return true ;
		}
};

typedef t_EXR_IO<float> EXR_IO ;


#endif