<?php

class Keyboard
{
    const KEYBOARD  = "1234567890qwertyuiopasdfghjkl;zxcvbnm,./";

    private function horizontalTransform($index)
    {
        if ($index < 10) {
            return 9 - $index;
        }

        if ($index < 20) {
            return 29 - $index;
        }

        if ($index < 30) {
            return 49 - $index;
        }

        if ($index < 40) {
            return 69 - $index;
        }
    }

    private function verticalTransform($index)
    {
        if ($index < 10) {
            return 30 + $index;
        }

        if ($index < 20) {
            return 10 + $index;
        }

        if ($index < 30) {
            return $index - 10;
        }

        if ($index < 40) {
            return $index - 30;
        }
    }

    private function shift($index, $shiftBy)
    {
        $newIndex = $index - $shiftBy;

        if ($newIndex >= 40) {
            return $newIndex % 40;
        }

        if ($newIndex < 0) {
            return $newIndex + 40;
        }

        return $newIndex;
    }
    private function transformCharacter($sequence, $index)
    {
        foreach (explode(',', $sequence) as $transformation) {
            if (is_numeric($transformation)) {
                $index = $this->shift($index, (int)$transformation);
            }

            if (strtoupper($transformation) == 'H') {
                $index = $this->horizontalTransform($index);
            }

            if (strtoupper($transformation) == 'V') {
                $index = $this->verticalTransform($index);
            }
        }
        return self::KEYBOARD[$index];
    }

    public function transformString($transformationSequence, $string) {
        $transformedCharacters = [];
        $transformedString = '';
        foreach (str_split(strtolower($string)) as $character) {
            $position = strpos(self::KEYBOARD, $character);
            if ($position !== false) {
                if (empty($transformedCharacters[$character])) {
                    $transformedCharacters[$character] = $this->transformCharacter($transformationSequence, $position);
                }
                $transformedString .= $transformedCharacters[$character];
           } else {
                $transformedString .= $character;
           }
        }
        return $transformedString;
    }
}

echo (new Keyboard)->transformString("H,V", "qqww");