export class ColorService {
       /**
        * http://stackoverflow.com/questions/2353211/hsl-to-rgb-color-conversion
        *
        * Converts an HSL color value to RGB. Conversion formula
        * adapted from http://en.wikipedia.org/wiki/HSL_color_space.
        * Assumes h, s, and l are contained in the set [0, 1] and
        * returns r, g, and b in the set [0, 255].
        *
        * @param   Number  h       The hue
        * @param   Number  s       The saturation
        * @param   Number  l       The lightness
        * @return  Array           The RGB representation
        */
       hslToRgb(h, s, l) {
           var r, g, b;

           if (s == 0) {
               r = g = b = l; // achromatic
           } else {
               function 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) * (2 / 3 - t) * 6;
                   return p;
               }

               var q = l < 0.5 ? l * (1 + s) : l + s - l * s;
               var p = 2 * l - q;
               r = hue2rgb(p, q, h + 1 / 3);
               g = hue2rgb(p, q, h);
               b = hue2rgb(p, q, h - 1 / 3);
           }

           return [Math.floor(r * 255), Math.floor(g * 255), Math.floor(b * 255)];
       }

       // convert a number to a color using hsl
       numberToColorHsl(i) {
           // as the function expects a value between 0 and 1, and red = 0° and green = 120°
           // we convert the input to the appropriate hue value
           var hue = i * 100 * 1.2 / 360;
           // we convert hsl to rgb (saturation 100%, lightness 50%)
           var rgb = this.hslToRgb(hue, .9, .4);
           // we format to css value and return
           return 'rgb(' + rgb[0] + ',' + rgb[1] + ',' + rgb[2] + ')';
       }
}