final class FlowChart
{
    public const CAR_A = 1;
    public const CAR_B = 2;
    public const CAR_C = 3;

    public const WALK_RATE_A = 1;
    public const WALK_RATE_B = 2;
    public const WALK_RATE_C = 3;

    public const EXPANSION_RATE_A = 1;
    public const EXPANSION_RATE_B = 2;

    public const SPEED_A = 1;
    public const SPEED_B = 2;

    public const HUNGRY_A = 1;
    public const HUNGRY_B = 2;

    public const SMART_A = 1;
    public const SMART_B = 2;


    /**
     * @param $class
     * @param $expansionRate
     * @param $smart
     * @param $hungry
     * @param $hasCars
     * @param $speed
     * @param $walkTime
     * @return int
     */
    public function flowChart($class, $expansionRate, $smart, $hungry, $hasCars, $speed, $walkTime): ?int
    {
        $expansionRate = $this->expansionRateRule($expansionRate);
        $smart = $this->smartRule($smart);
        $hungry = $this->hungryRule($hungry);
        $hasCars = $this->hasCarsRule($hasCars);
        $walkTime = $this->walkRule($walkTime);

        switch ($class) {
            case 'A':
                return 1;
            case 'B':
                return 2;
            case 'C':
                return $this->checkRules(
                    3,
                    $this->smartRule($smart),
                    $this->hungryRule($hungry)
                );
            case 'D':
                return $this->checkRules(
                    6,
                    $this->smartRule($smart),
                    $this->hungryRule($hungry)
                    );
            case 'E':
                return $this->checkRules(
                    9,
                    $this->smartRule($smart),
                    $this->hungryRule($hungry),
                    $this->hasCarsRule($hasCars)
                );
            case 'F':
                return $this->checkRules(
                    13,
                    $this->smartRule($smart),
                    $this->hungryRule($hungry),
                    $this->hasCarsRule($hasCars),
                    $this->speedRule($speed),
                    $this->walkRule($walkTime),
                    true,
                    $this->expansionRateRule($expansionRate)
                );
            case 'G':
                return $this->checkRules(
                    25,
                    $this->smartRule($smart),
                    $this->hungryRule($hungry),
                    $this->hasCarsRule($hasCars),
                    $this->speedRule($speed),
                    $this->walkRule($walkTime)
                );
        }

        return null;
    }

    /**
     * @param $smart
     * @return int
     */
    private function smartRule($smart): int
    {
        if ($smart === 'Yes') {
            return self::SMART_A;
        }
        return self::SMART_B;
    }

    /**
     * @param $hungry
     * @return int
     */
    private function hungryRule($hungry): int
    {
        if ($hungry === 'Yes') {
            return self::HUNGRY_A;
        }
        return self::HUNGRY_B;
    }

    /**
     * @param $hasCars
     * @return int
     */
    private function hasCarsRule($hasCars): int
    {
        if ($hasCars > 1) {
            return self::CAR_A;
        }

        if ($hasCars === 1) {
            return self::CAR_B;
        }

        return self::CAR_C;
    }

    /**
     * @param $expansion
     * @return int
     */
    private function expansionRateRule($expansion): int
    {
        if ($expansion < 200) {
            return self::EXPANSION_RATE_A;
        }
        return self::EXPANSION_RATE_B;
    }

    /**
     * @param $speed
     * @return int
     */
    private function speedRule($speed): int
    {
        if ($speed <= 105) {
            return self::SPEED_A;
        }
        return self::SPEED_B;
    }

    /**
     * @param $walk
     * @return int
     */
    private function walkRule($walk): int
    {
        if ($walk < 100) {
            return self::WALK_RATE_A;
        }

        if ($walk > 100 && $walk < 106) {
            return self::WALK_RATE_B;
        }

        return self::WALK_RATE_C;
    }

    /**
     * @param $input
     * @param bool $smart
     * @param bool $hungry
     * @param bool $hasCars
     * @param bool $speed
     * @param bool $walk
     * @param bool $modifiedWalk
     * @param bool $expansionRate
     * @return int
     */
    public function checkRules(
        $input,
        $smart = false,
        $hungry = false,
        $hasCars = false,
        $speed = false,
        $walk = false,
        $modifiedWalk = false,
        $expansionRate = false
    ): int
    {
        if ($expansionRate) {
            switch ($expansionRate) {
                case self::EXPANSION_RATE_A:
                    break;
                case self::EXPANSION_RATE_B:
                    $input += 5;
            }
        }
        if ($smart) {
            switch ($smart) {
                case self::SMART_A:
                    break;
                case self::SMART_B:
                    ++$input;
            }
        }
        if ($hungry) {
            switch ($hungry) {
                case self::HUNGRY_A:
                    break;
                case self::HUNGRY_B:
                    ++$input;
            }
        }
        if ($hasCars && $speed && $modifiedWalk) {
            switch ($hasCars) {
                case self::CAR_A:
                    break;
                case self::CAR_B:
                    ++$input;
                    break;
                case self::CAR_C:
                    ++$input;
            }
            switch ($walk) {
                case self::WALK_RATE_A:
                    break;
                case self::WALK_RATE_B:
                    ++$input;
                    break;
                case self::WALK_RATE_C:
                    $input += 2;
            }
        } elseif ($hasCars && $speed) {
            switch ($hasCars) {
                case self::CAR_A:
                    break;
                case self::CAR_B:
                    ++$input;
                    break;
                case self::CAR_C:
                    $input += 2;
            }
            switch ($speed) {
                case self::SPEED_A:
                    break;
                case self::SPEED_B:
                    ++$input;
            }
            switch ($walk) {
                case self::WALK_RATE_A:
                    break;
                case self::WALK_RATE_C:
                    ++$input;
            }
        } elseif ($hasCars) {
            switch ($hasCars) {
                case self::CAR_B:
                    break;
                case self::CAR_C:
                    ++$input;
            }
        }
        return $input;
    }
}