<?php

class Skin_Utils
{
    /**
     * Converts an HSV color value to RGB. Conversion formula
     * adapted from http://en.wikipedia.org/wiki/HSV_color_space.
     * Assumes h, s, and v are contained in the set [0, 1] and
     * returns r, g, and b in the set [0, 255].
     *
     */
    static public function hsvToRgb($h, $s, $v)
    {
        $r = $g = $b = 0;

        if ($h > 1)
            $h /= 360;

        $i = floor($h * 6);
        $f = $h * 6 - $i;
        $p = $v * (1 - $s);
        $q = $v * (1 - $f * $s);
        $t = $v * (1 - (1 - $f) * $s);

        switch($i % 6)
        {
            case 0: $r = $v; $g = $t; $b = $p; break;
            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;
        }

        $r = round($r * 255);
        $g = round($g * 255);
        $b = round($b * 255);

        return array(
            'r' =>  $r,
            'g' =>  $g,
            'b' =>  $b,
            'hex'=> '#' . str_pad(dechex($r), 2, '0', STR_PAD_LEFT)
                . str_pad(dechex($g), 2, '0', STR_PAD_LEFT)
                . str_pad(dechex($b), 2, '0', STR_PAD_LEFT),
        );
    }

    static public function rgbHexToDec($hex)
    {
        if (strlen($hex) == 4)
        {
            $hex = $hex[1] . $hex[1] . $hex[2] . $hex[2] . $hex[3] . $hex[3];
        }
        elseif (strlen($hex) == 7)
        {
            $hex = substr($hex, 1);
        }
        elseif (strlen($hex) == 3)
        {
            $hex = $hex[0] . $hex[0] . $hex[1] . $hex[1] . $hex[2] . $hex[2];
        }
        elseif (strlen($hex) != 6)
        {
            throw new Exception("Invalid string length for RGB value '$hex'");
        }

        $b = hexdec(substr($hex, 4, 2));
        $g = hexdec(substr($hex, 2, 2));
        $r = hexdec(substr($hex, 0, 2));

        return array($r, $g, $b);
    }

    /**
     * Converts an RGB color value to HSV. Conversion formula
     * adapted from http://en.wikipedia.org/wiki/HSV_color_space.
     * Assumes r, g, and b are contained in the set [0, 255] and
     * returns h, s, and v in the set [0, 1].
     *
     * @param   Number  r       The red color value
     * @param   Number  g       The green color value
     * @param   Number  b       The blue color value
     * @return  Array           The HSV representation
     */
    static public function rgbToHsv($r, $g = null, $b = null)
    {
        if (is_string($r) && is_null($g) && is_null($b))
        {
            list($r, $g, $b) = self::rgbHexToDec($r);
        }

        $r /= 255;
        $g /= 255;
        $b /= 255;
        $max = max($r, $g, $b);
        $min = min($r, $g, $b);
        $h = $s = $v = $max;

        $d = $max - $min;
        $s = ($max == 0) ? 0 : $d / $max;

        if($max == $min)
        {
            $h = 0; // achromatic
        }
        else
        {
            switch($max)
            {
                case $r: $h = ($g - $b) / $d + ($g < $b ? 6 : 0); break;
                case $g: $h = ($b - $r) / $d + 2; break;
                case $b: $h = ($r - $g) / $d + 4; break;
            }
            $h /= 6;
        }

        return array($h * 360, $s, $v);
    }

    static public function listFonts()
    {
        return array(
            'Sans serif'=>  'Arial, Helvetica, sans-serif',
            'Comics'    =>  '\'Comic Sans MS\', cursive',
            'Courier'   =>  '\'Courier New\', Courier, monospace',
            'Serif'     =>  '\'Times New Roman\', Times, serif',
            'Georgia'   =>  'Georgia, serif',
            //'Trebuchet' =>  '\'Trebuchet MS\', Helvetica, sans-serif',
        );
    }
}

?>