Order parser

index.php

<?php

class Parser {

    CONST break = '^';

    protected function sorter($a, $b): int
    {

        return strlen($b) - strlen($a);

    }

    public function sortItems($items): array
    {
    
        usort($items, [$this, 'sorter']);

        return $items;

    }

    protected function getPositions(string $item, string $order): array
    {

        $positions  = [];

        $start      = 0;

        while(($pos = strpos(strtolower($order), strtolower($item), $start)) !== false) {

            $positions[] = $pos;

            $start = $pos + 1;

        }

        return $positions;

    }

    /**
     * Finds quantity for specific item
     *
     * @param $item
     * @param $order
     * @return int
     */
    public function findQuantity($item, $order): int
    {

        $result = 0;

        if(($position = strpos(strtolower($order), strtolower($item))) === false) {

            return $result;

        }

        foreach($this->getPositions($item, $order) as $pos) {

            $innerValue = '';

            $numberSeek = false;

            $position   = $pos + strlen($item);

            if( ! isset($order[$position])) {

                $result++;
                continue;

            }

            while(isset($order[$position])) {

                if($numberSeek && ! is_numeric($order[$position])) {
                    break;
                }


                if($order[$position] === ' ') {

                    $position++;
                    continue;

                }

                if ( ! is_numeric($order[$position]) || ctype_alpha($order[$position])) {

                    $result++;
                    break;

                }


                if( is_numeric($order[$position])) {

                    $numberSeek = true;
                    $innerValue .= $order[$position];

                }

                $position++;

            }

            $result += (int) $innerValue;

        }

        return (int) $result;

    }

    /**
     * Parse, group and calculate given order based on available
     * items and give order
     * 
     * @param array $items i.e. ['yes a', 'yes b']
     * @param string $order i.e. 'yes a 15, yes b 3'
     * @return array ['yes a' => 15, 'yes b' => 3]
     */
    public function parseOrder(array $items, string $order): array
    {
          
        $out    = [];

        $items  = $this->sortItems($items);

        $order  = strtolower($order);

        foreach($items as $item) {
    
            if(($pos = strpos(strtolower($order), strtolower($item))) !== false) {

                if( ! $quantity = $this->findQuantity($item, $order)) {

                    $quantity = 1;

                }

                $out[$item] = (isset($out[$item])) ? ($out[$item] += $quantity) : $quantity;

                $partial    = substr($order, $pos, strlen($item));

                $order      = str_replace($partial, self::break, $order);
    
            }
    
        }

        return $out;

    }


}