/**
 * @brief Display Adaptive TMO
 *
 * From:
 * Rafal Mantiuk, Scott Daly, Louis Kerofsky.
 * Display Adaptive Tone Mapping.
 * To appear in: ACM Transactions on Graphics (Proc. of SIGGRAPH'08) 27 (3)
 * http://www.mpi-inf.mpg.de/resources/hdr/datmo/
 *
 * This file is a part of LuminanceHDR package, based on pfstmo.
 * ---------------------------------------------------------------------- 
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program 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 General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 * ---------------------------------------------------------------------- 
 * 
 * @author Rafal Mantiuk, <mantiuk@gmail.com>
 *
 * $Id: display_function.cpp,v 1.3 2008/06/16 18:42:58 rafm Exp $
 */

#include <math.h>
#include <assert.h>
#include <string.h>
#include <stdlib.h>

#include "Libpfs/pfs.h"

#include "arch/string.h"
#include "display_function.h"

// ========== GGBA Display Function ==============

DisplayFunctionGGBA::DisplayFunctionGGBA( float gamma, float L_max, float L_black, float E_amb, float screen_refl ) 
{
  init( gamma, L_max, L_black, E_amb, screen_refl );
}

void DisplayFunctionGGBA::init( float gamma, float L_max, float L_black, float E_amb, float screen_refl )
{
  this->gamma = gamma;
  this->L_max = L_max;
  this->L_black = L_black;
  this->E_amb = E_amb;
  this->screen_refl = screen_refl;
  this->L_offset = L_black + screen_refl/M_PI*E_amb;
}

DisplayFunctionGGBA::DisplayFunctionGGBA( const char *predefined )
{
  if( !strcasecmp( predefined, "lcd_office" ) ) {
    init( 2.2f, 100, 0.8, 400, 0.01 );
  } else if( !strcasecmp( predefined, "lcd" ) ) {
    init( 2.2f, 200, 0.8, 60, 0.01 );
  } else if( !strcasecmp( predefined, "lcd_bright" ) ) {
    init( 2.6f, 500, 0.5, 10, 0.01 );
  } else if( !strcasecmp( predefined, "crt" ) ) {
    init( 2.2f, 80, 1, 60, 0.02 );
  } else {
    throw pfs::Exception( "Unknown display type. Recognized types: lcd_office, lcd, lcd_bright, crt." );
  }
}

void DisplayFunctionGGBA::print( FILE *fh )
{
  fprintf( fh, "Display function: gamma-gain-black-ambient\n" );
  fprintf( fh, "   gamma = %g\t L_max = %g\t L_black = %g\n", (double)gamma, (double)L_max, (double)L_black );
  fprintf( fh, "   E_amb = %g\t k     = %g\n", (double)E_amb, (double)screen_refl );
}

float DisplayFunctionGGBA::inv_display( float L )
{
  if( L < L_offset ) L = L_offset;
  if( L > (L_offset+L_max) ) L = L_offset + L_max;
  return powf( (L - L_offset)/(L_max-L_black), 1/gamma );
}

float DisplayFunctionGGBA::display( float pix )
{
  assert( pix >= 0 && pix <= 1 );
  return pow( pix, gamma ) * (L_max-L_black) + L_offset;
}

#ifdef __USE_SSE__

v4sf DisplayFunctionGGBA::inv_display( v4sf L )
{
  const v4sf voffset = _mm_set1_ps(L_offset);
  const v4sf vmax = _mm_set1_ps(L_max);
  L = _mm_max_ps(L, voffset);
  L = _mm_min_ps(L, voffset+vmax);
  return _mm_pow_ps((L - voffset)/(vmax-_mm_set1_ps(L_black)), _mm_set1_ps(1.0f/gamma));
}

v4sf DisplayFunctionGGBA::display( v4sf pix )
{
  return _mm_pow_ps(pix, _mm_set1_ps(gamma)) * (_mm_set1_ps(L_max)-_mm_set1_ps(L_black)) + _mm_set1_ps(L_offset);
}

#endif

// ========== LUT Display Function ==============

static const int max_lut_size = 4096;

DisplayFunctionLUT::DisplayFunctionLUT( const char *file_name ) : pix_lut( NULL ), L_lut( NULL )
{
  FILE *fh = fopen( file_name, "r" );
  if( fh == NULL )
    throw pfs::Exception( "Cannot open lookup-table file" );

  L_lut = new float[max_lut_size];
  pix_lut = new float[max_lut_size];

  const size_t max_line = 100;
  char buf[max_line];

  int i = 0;
  while( fgets( buf, max_line, fh ) != NULL ) {
    float p_buf, L_buf;
    if( sscanf( buf, "%f%*[ ,;]%f\n", &p_buf, &L_buf ) != 2 )
      continue;
    if( p_buf < 0 || p_buf > 1 )
      throw pfs::Exception( "Improper LUT: pixel values must be from 0 to 1" );    
    if( L_buf <= 0 )
      throw pfs::Exception( "Improper LUT: luminance must be greater than 0" );    
    L_lut[i] = log10( L_buf );
    pix_lut[i] = p_buf;
    i++;
    if( i >= max_lut_size )
      throw pfs::Exception( "LUT too large (more than 4096 entries)" );    
  }
  lut_size = i;
  if( pix_lut[0] != 0 || pix_lut[lut_size-1]!= 1 )
      throw pfs::Exception( "The first and last LUT entries for pixel value should be 0 and 1" );    
}

DisplayFunctionLUT::~DisplayFunctionLUT()
{
  delete []pix_lut;
  delete []L_lut;
}

inline float bin_search_interp( float x, const float *lut_x, const float *lut_y, const int lutSize )
{
  if( x <= lut_x[0] )
    return lut_y[0];
  if( x >= lut_x[lutSize-1] )
    return lut_y[lutSize-1];
  
  size_t l = 0, r = lutSize;
  while( true ) {
    size_t m = (l+r)/2;
    if( m == l ) break;
    if( x < lut_x[m] )
      r = m;
    else
      l = m;
  }
  return lut_y[l] + (lut_y[l+1]-lut_y[l])*(x-lut_x[l]);
}
  
float DisplayFunctionLUT::inv_display( float L )
{
  return bin_search_interp( log10( L ), L_lut, pix_lut, lut_size );
}

float DisplayFunctionLUT::display( float pix )
{
  return pow( 10, bin_search_interp( pix, pix_lut, L_lut, lut_size ) );  
}

void DisplayFunctionLUT::print( FILE *fh )
{
  fprintf( fh, "Display function: lookup-table\n" );
  fprintf( fh, "   L_min = %g \tL_max = %g\n", (double)pow( 10, L_lut[0] ), (double)pow( 10, L_lut[lut_size-1] ) );
}

// ========== Command line parsing ==============
/*
DisplayFunction *createDisplayFunctionFromArgs( int &argc, char* argv[] )
{
  DisplayFunction *df = 0;
  
    for( int i=1 ; i<argc; i++ )
    {
      if( !strcmp( argv[i], "--display-function" ) || !strcmp( argv[i], "-d" )  ) {
        if( i+1 >= argc )
          throw pfs::Exception( "missing display function specification" );

        float gamma = 2.2f, L_max = 100.f, L_black = 1.f, k = 0.01, E_amb = 50;
        bool GGBA_model = true;
        char *token;
        token = strtok( argv[i+1], ":" );
        while( token != NULL ) {
          if( !strncmp( token, "pd=", 3 )  ) {
              df = new DisplayFunctionGGBA( token+3 );
              GGBA_model = false;
              break;
          } else if( !strncmp( token, "lut=", 4 )  ) {
              df = new DisplayFunctionLUT( token+4 );
              GGBA_model = false;
              break;
          } else if( !strncmp( token, "g=", 2 ) ) {
            gamma = strtod( token+2, NULL );
          } else if( !strncmp( token, "l=", 2 ) ) {
            L_max = strtod( token+2, NULL );
          } else if( !strncmp( token, "b=", 2 ) ) {
            L_black = strtod( token+2, NULL );
          } else if( !strncmp( token, "k=", 2 ) ) {
            k = strtod( token+2, NULL );
          } else if( !strncmp( token, "a=", 2 ) ) {
            E_amb = strtod( token+2, NULL );
          } else {
            throw pfs::Exception( "Bad display type specification" );
          }            
          token = strtok( NULL, ":" );
        }
        if( GGBA_model )
          df = new DisplayFunctionGGBA( gamma, L_max, L_black, E_amb, k );
        
        removeCommandLineArg( argc, argv, i, 2 );
        break;
      }
    }
    return df;
}

static void removeCommandLineArg( int &argc, char* argv[],
  int firstArgToRemove, int numArgsToRemove )
{
  assert( firstArgToRemove+numArgsToRemove <= argc );
  if( argc-firstArgToRemove-numArgsToRemove > 0 ) {
    for( int i = firstArgToRemove; i < argc-numArgsToRemove; i++ )
      argv[i] = argv[i+numArgsToRemove];
  }

  argc -= numArgsToRemove;
}

*/
