/* A small, easy-to-understand C++ library written to convert colorspaces
 * Will convert RGB to HSV or HSL and back to RGB
 * Note on the colors:
 * R,G,B are ints [0,255]
 * S,V,L are floats [0,1]
 * H is a float [0,360)
 *
 * Requires the CImg library header file (testing code used version 1.3.1)
 * http://cimg.sourceforge.net/
 *
 * Written by Alex Kuhl
 * http://www.alexkuhl.org/code
 * Licensed under a Creative Commons Attribution-Share Alike 3.0 Unported License. 
 * Must keep this entire notice in both this file and derivative works
 */

#pragma once

#include <cmath>
#include <algorithm>
#include <vector>
#include <iostream>
#include "CImg.h"

using namespace std ;
using namespace cimg_library ;

void rgb_to_hsl( int r, int g, int b, float& h, float& s, float& l )
{
	float fr = r/255.0, fg = g/255.0, fb = b/255.0 ;
	int imax = max( max( r, g ), b ) ;
	int imin = min( min( r, g ), b ) ;
	float fmax = imax/255.0 ;
	float fmin = imin/255.0 ;
	float multiplier = ( imin == imax ) ? 0.0 : 60/( fmax - fmin ) ;
		
	if( r == imax ) 	// red is dominant
	{
		h = ( multiplier*( fg - fb ) + 360 ) ;
		if( h >= 360 ) h -= 360 ;	// take quick modulus, % doesn't work with floats
	}
	else if( g == imax )// green is dominant
		h = multiplier*( fb - fr ) + 120 ;
	else				// blue is dominant
		h = multiplier*( fr - fg ) + 240 ;	
	l = .5*( fmax + fmin ) ;
	if( imax == imin )
		s = 0.0 ;
	else if( l <= .5 )
		s = ( fmax - fmin )/( 2*l ) ;
	else
		s = ( fmax - fmin )/( 2 - 2*l ) ;
}

void hsl_to_rgb( float h, float s, float l, int& r, int& g, int& b )
{
	float q ;
	if( l < .5 )
		q = l*( 1 + s ) ;
	else
		q = l + s - ( l*s ) ;
	float p = 2*l - q ;
	h /= 360 ;
	// t holds r, g, and b values
	float t[ 3 ] = { h + 1/3.0, h, h - 1/3.0 } ;
	for( int i = 0 ; i < 3 ; ++i )
	{
		if( t[ i ] < 0 )
			t[ i ] += 1 ;
		else if( t[ i ] > 1 )
			t[ i ] -= 1 ;
		// calculate the color
		if( t[ i ] < 1.0/6.0 )
			t[ i ] = p + ( ( q - p )*6*t[ i ] ) ;
		else if( 1.0/6.0 <= t[ i ] && t[ i ] < .5 )
			t[ i ] = q ;
		else if( .5 <= t[ i ] && t[ i ] < 2.0/3.0 )
			t[ i ] = p + ( ( q - p )*6*( 2.0/3.0 - t[ i ] ) ) ;
		else
			t[ i ] = p ;
	}	
	r = round( t[ 0 ]*255 ) ;
	g = round( t[ 1 ]*255 ) ;
	b = round( t[ 2 ]*255 ) ;
}

void rgb_to_hsv( int r, int g, int b, float& h, float& s, float& v )
{
	float fr = r/255.0, fg = g/255.0, fb = b/255.0 ;
	int imax = max( max( r, g ), b ) ;
	int imin = min( min( r, g ), b ) ;
	float fmax = imax/255.0 ;
	float fmin = imin/255.0 ;
	float multiplier = ( imin == imax ) ? 0.0 : 60/( fmax - fmin ) ;
		
	if( r == imax ) 	// red is dominant
	{
		h = ( multiplier*( fg - fb ) + 360 ) ;
		if( h >= 360 ) h -= 360 ;	// take quick modulus, % doesn't work with floats
	}
	else if( g == imax )// green is dominant
		h = multiplier*( fb - fr ) + 120 ;
	else				// blue is dominant
		h = multiplier*( fr - fg ) + 240 ;	
	if( imax == 0 )
		s = 0 ;
	else
		s = 1 - ( fmin/fmax ) ;
	v = fmax ;
}
 
void hsv_to_rgb( float h, float s, float v, int& r, int& g, int& b )
{
	h /= 60 ;
	int hi = (int)h ;
	float f = h - hi ;
	// all the following *255 are to move from [0,1] to [0,255] domains
	// because rgb are assumed [0,255] integers
	int p = round( v*( 1 - s )*255 ) ;
	int q = round( v*( 1 - f*s )*255 ) ;
	int t = round( v*( 1 - ( 1 - f )*s )*255 ) ;
	int iv = round( v*255 ) ;
	switch( hi )
	{
		case 0:
			r = iv ; g = t ; b = p ;
			break ;
		case 1:
			r = q ; g = iv ; b = p ;
			break ;
		case 2:
			r = p ; g = iv ; b = t ;
			break ;
		case 3:
			r = p ; g = q ; b = iv ;
			break ;
		case 4:
			r = t ; g = p ; b = iv ;
			break ;
		case 5:
			r = iv ; g = p ; b = q ;
			break ;
	}
}