Clairance creatinine

<?php

namespace Medical\CoreBundle\Component\Tool;

class CreatinineCalculator
{
    const MDRD = 'MDRD';
    const COCKROFT = 'COCKROFT';

    /**
     * @return float
     */
    public static function compute($type, array $input)
    {
        if ($type === self::MDRD) {

            return self::computeMdrd($input);

        } else if ($type === self::COCKROFT) {

            return self::computeCockroft($input);

        } else {
            throw new \Exception('Cannot compute: allowed values are MDRD or COCKROFT');
        }
    }

    /**
     * @return float
     */
    public static function computeCockroft(array $input)
    {
        $k = ($input['sex'] === 'H') ? 1.23 : 1.04;

        // quick check if age is empty, it must be computed
        // from birthyear. Otherwise we onnly need the age so go on
        $input['age'] = self::validateAgeInput($input);

        // base creatinimie value must be in umol/L (id normalize mg/L input(s))
        $creat = self::toUmolCockroft($input);

        $cockroft = ( ((140 - $input['age']) / $creat) * floatval($input['weight']) * floatval($k) );
        $cockroft = round($cockroft, 2);

        return $cockroft;
    }

    /**
     * @return float
     */
    public static function computeMdrd(array $input)
    {
        // two different multipliers must be applied to the base result
        // depending on sex (male, female) or afro origin.
        // If not, assign a neutral multiplier to m1 and m2 (ie. 1)
        $m1 = ($input['sex'] === 'F') ? 0.742 : 1;
        $m2 = ($input['originAfro'] === true) ? 1.212 : 1;

        // base creatinimie value must be in umol/L (id normalize mg/L input(s))
        $creat = self::toUmolMdrd($input);

        $mdrd = 186 * pow( ($creat * 0.0113), -1.154) * pow($input['age'], -0.203) * $m1 * $m2;

        // @TODO A vérifier absolument !
        if ($input['creatinimieType'] === 'mg/L') {
            $mdrd = $mdrd * pow(88.5,-1.154);
        }

        return round($mdrd, 2);
    }

    public static function birthyearToAge($year)
    {
        $year = (int) $year;
        
        $now = new \DateTime();
        $fulldate = $year.'-01-01 00:00:01';
        $birthday = new \DateTime($fulldate);
        $interval = $now->diff($birthday);
        $age = $interval->format('%y');

        return $age;
    }

    public static function validateAgeInput(array $input)
    {
        if (empty($input['age']) && empty($input['year'])) {
            throw new \Exception('Only one of these fields can be empty: year or age');
        }

        return empty($input['age']) ? self::birthyearToAge($input['year']) : $input['age'];
    }

    public static function toUmolCockroft(array $input)
    {
        // base creatinimie value must be in umol/L (id normalize mg/L input(s))
        if ($input['creatinimieType'] === 'mg/L') {
            $creat = ($input['creatinimie'] / 10) * 88.4;
        } else {
            // value already in umol/L. Nice !
            $creat = $input['creatinimie'];
        }

        return $creat;
    }

    public static function toUmolMdrd(array $input)
    {
        // base creatinimie value must be in umol/L (id normalize mg/L input(s))
        if ($input['creatinimieType'] === 'mg/L') {
            $creat = $input['creatinimie'] / 10;
        } else {
            // value already in umol/L. Nice !
            $creat = $input['creatinimie'];
        }

        return $creat;
    }
}