@author mr.doob / http://mrdoob.com/

Ported to Dart from JS by: @author rob silverton / http://www.unwrong.com/

class Color {

 double _r;
 double _g;
 double _b;

 set r(num r) { _r = r.toDouble();}
 get r => _r;

 set g(num g) { _g = g.toDouble();}
 get g => _g;

 set b(num b) { _b = b.toDouble();}
 get b => _b;

 int get _rr => (r*255).floor();
 int get _gg => (g*255).floor();
 int get _bb => (b*255).floor();

 Color( [num hex] )
     : _r = 1.0,
       _g = 1.0,
       _b = 1.0 {

   if ( hex is num ) setHex( hex );
 }

 Color copy( Color color ) {
   r = color.r;
   g = color.g;
   b = color.b;

   return this;
 }

 Color copyGammaToLinear( Color color ) {
   r = color.r * color.r;
   g = color.g * color.g;
   b = color.b * color.b;

   return this;
 }

 Color copyLinearToGamma( Color color ) {
   num x = Math.sqrt( color.r );

   r = Math.sqrt( color.r );
   g = Math.sqrt( color.g );
   b = Math.sqrt( color.b );

   return this;
 }

 Color convertGammaToLinear() {
   var _r = r, _g = g, _b = b;

   r = _r * _r;
   g = _g * _g;
   b = _b * _b;

   return this;
 }

 Color convertLinearToGamma() {
   r = Math.sqrt( r );
   g = Math.sqrt( g );
   b = Math.sqrt( b );
   return this;
 }

 Color setRGB( num newR, num newG, num newB ) {
   r = newR.toDouble();
   g = newG.toDouble();
   b = newB.toDouble();

   return this;
 }

 Color setHSV( num h, num s, num v ) {
   // based on MochiKit implementation by Bob Ippolito
   // h,s,v ranges are < 0.0 - 1.0 >
   num i, f, p, q, t;

   if ( v == 0 ) {
     r = g = b = 0.0;
   } else {
     i = ( h * 6 ).floor();
     f = ( h * 6 ) - i;
     p = v * ( 1 - s );
     q = v * ( 1 - ( s * f ) );
     t = v * ( 1 - ( s * ( 1 - f ) ) );

     switch ( i ) {
       case 1: r = q; g = v; b = p; break;
       case 2: r = p; g = v; b = t; break;
       case 3: r = p; g = q; b = v; break;
       case 4: r = t; g = p; b = v; break;
       case 5: r = v; g = p; b = q; break;
       case 6: // fall through
       case 0: r = v; g = t; b = p; break;
     }
   }

   return this;
 }

 Color setHSL( h, s, l ) {

   // h,s,l ranges are in 0.0 - 1.0

   if ( s == 0 ) {

     r = g = b = l;

   } else {

     var hue2rgb = ( p, q, t ) {

       if ( t < 0 ) t += 1;
       if ( t > 1 ) t -= 1;
       if ( t < 1 / 6 ) return p + ( q - p ) * 6 * t;
       if ( t < 1 / 2 ) return q;
       if ( t < 2 / 3 ) return p + ( q - p ) * 6 * ( 2 / 3 - t );
       return p;

     };

     var p = l <= 0.5 ? l * ( 1 + s ) : l + s - ( l * s );
     var q = ( 2 * l ) - p;

     this.r = hue2rgb( q, p, h + 1 / 3 );
     this.g = hue2rgb( q, p, h );
     this.b = hue2rgb( q, p, h - 1 / 3 );

   }

   return this;

 }

 get HSL {
   // h,s,l ranges are in 0.0 - 1.0

   var r = this.r, g = this.g, b = this.b;

   var max = Math.max(Math.max( r, g), b );
   var min = Math.min(Math.min( r, g), b );

   var hue, saturation;
   var lightness = ( min + max ) / 2.0;

   if ( min == max ) {

     hue = 0;
     saturation = 0;

   } else {

     var delta = max - min;

     saturation = lightness <= 0.5 ? delta / ( max + min ) : delta / ( 2 - max - min );

     if (max == r) {
       hue = ( g - b ) / delta + ( g < b ? 6 : 0 );
     } else if (max == g) {
       hue = ( b - r ) / delta + 2;
     } else if (max == b) {
       hue = ( r - g ) / delta + 4;
     }

     hue /= 6;

   }

   return [hue, saturation, lightness];

 }

 Color offsetHSL( h, s, l ) {

   var hsl = this.HSL;

   hsl[0] += h; hsl[1] += s; hsl[2] += l;

   setHSL( hsl[0], hsl[1], hsl[2] );

   return this;

 }

 Color setHex( num hex ) {
   var h = hex.floor().toInt();
   r = ( (h&0xFF0000)>>16 ) / 255;
   g = ( (h&0x00FF00)>>8 ) / 255;
   b = (h&0x0000FF) / 255;
   return this;
 }

 num getHex() {
   num h = (_rr<<16)^(_gg<<8)^(_bb);
   return h;
 }

 String getContextStyle() {
   // TODO: this is a little bit of a mess. We should stay consistent between
   // how r,g,b is set. Something in CanvasRender is setting them to doubles
   // when they should be int's. We could add setter/getter's to handle this

   return 'rgb(${_rr},${_gg},${_bb})';
 }

 Color clone() {
   return new Color().setRGB( r, g, b);
 }
}