<?php
class SwedishSocialSecurityNumber {

    private $_socialSecurityNumber;
    private $_year;
    private $_month;
    private $_day;
    private $_code;
    private $_isOver100;

    public function __construct($socialSecurityNumber) {
        $this->_socialSecurityNumber = $socialSecurityNumber;
        $this->_isOver100 = false;

        if (!$this->hasTheRightPattern()) {
            throw new \Exception("The SSN has to have the format YYNNDD-XXXX or YYMMDD+XXXX");
        }

        $this->_year = substr($this->_socialSecurityNumber, 0, 2);
        $this->_month = substr($this->_socialSecurityNumber, 2, 2);
        $this->_day = substr($this->_socialSecurityNumber, 4, 2);

        if (substr($this->_socialSecurityNumber, 6, 1) == "+") {
            $this->_isOver100 = true;
        }

        $this->_code = substr($this->_socialSecurityNumber, 7, 4);

        if (!$this->isDateValid()) {
            throw new \Exception("The date is invalid or is fictional");
        }

        if ($this->getCheckSum() != substr($this->_socialSecurityNumber, 10, 11)) {
            throw new \Exception("The control number is not valid");
        }

    }
    public function getDay() {return $this->_day;}
    public function getMonth() {return $this->_month;}
    public function getYear() {return $this->_year;}
    public function getCode() {return $this->_code;}
    public function isOver100() {return $this->_isOver100;}
    public function getSocialSecurityNumber() {return $this->_socialSecurityNumber;}

    public function isFemale() {
        $num = intval(substr($this->_socialSecurityNumber, 9, 1));
        if (($num % 2) == 0) {
            return true;
        }

        return false;
    }

    public function isMale() {
        return !$this->isFemale();
    }

    public function getCheckSum() {
        $temp = null;
        $variegated = 2;
        $list = [];

        for ($i = 0; $i < strlen($this->_socialSecurityNumber) - 1; $i++) {
            if ($i == 6) {
                continue;
            }

            $temp = $this->_socialSecurityNumber[$i];
            $temp = $temp * $variegated;

            $tempStr = strval($temp);
            for ($j = 0; $j < strlen($tempStr); $j++) {
                $list[] = intval($tempStr[$j]);
            }

            $variegated = $variegated == 2 ? 1 : 2;
        }

        return (10 - (array_sum($list) % 10));
    }

    public function getFullYear() {
        $currentYear = date("Y");
        $retValue = null;

        if ($this->_year < 10) {
            $retValue = substr($currentYear, 0, 2) . "0" . $this->_year;
        } else {
            $retValue = substr($currentYear, 0, 2) . $this->_year;
        }

        if ($this->_isOver100) {
            return $retValue - 100;
        }

        if ($retValue > $currentYear) {
            return $retValue - 100;
        }

        return $retValue;

    }

    private function isDateValid() {
        $date = strtotime("{$this->getFullYear()}-{$this->_month}-{$this->_day}");
        $year = date('Y', $date);
        $month = date('m', $date);
        $day = date('d', $date);

        $currentDate = strtotime(date("Y-m-d"));

        if ($date > $currentDate) {
            return false;
        }

        if ($this->getFullYear() == $year && $this->_month == $month && $this->_day == $day) {
            return true;
        }

        return false;
    }

    private function hasTheRightPattern() {
        if (!preg_match("/^[0-9]{2}[0-1][0-9][0-3][0-9][-|+][0-9]{4}$/", $this->_socialSecurityNumber)) {
            return false;
        }

        return true;
    }
}