/api/src/Service/CalculatorService.php

<?php

namespace App\Service;

use App\Service\Exception\AriphmeticException;

class CalculatorService
{
    /**
     * @param array $data
     * @return array
     */
    public function resolve(array $data): array
    {

        return [];
    }


    /**
     * @throws AriphmeticException
     */
    function calculate($statement)
    {
        if (!is_string($statement)) {
            throw new AriphmeticException('Wrong type', 1);
        }
        $calcQueue = [];
        $operStack = [];
        $operPriority = [
            '(' => 0,
            ')' => 0,
            '+' => 1,
            '-' => 1,
            '*' => 2,
            '/' => 2,
        ];
        $token = '';
        foreach (str_split($statement) as $char) {
            if ($char >= '0' && $char <= '9') {
                $token .= $char;
            } else {
                if (strlen($token)) {
                    $calcQueue[] = $token;
                    $token = '';
                }
                if (isset($operPriority[$char])) {
                    if (')' == $char) {
                        while (!empty($operStack)) {
                            $oper = array_pop($operStack);
                            if ('(' == $oper) {
                                break;
                            }
                            $calcQueue[] = $oper;
                        }
                        if ('(' != $oper) {
                            throw new AriphmeticException('Unexpected ")"', 2);
                        }
                    } else {
                        while (!empty($operStack) && '(' != $char) {
                            $oper = array_pop($operStack);
                            if ($operPriority[$char] > $operPriority[$oper]) {
                                $operStack[] = $oper;
                                break;
                            }
                            if ('(' != $oper) {
                                $calcQueue[] = $oper;
                            }
                        }
                        $operStack[] = $char;
                    }
                } elseif (strpos(' ', $char) !== FALSE) {
                } else {
                    throw new AriphmeticException('Unexpected symbol "' . $char . '"', 3);
                }
            }

        }
        if (strlen($token)) {
            $calcQueue[] = $token;
            $token = '';
        }
        if (!empty($operStack)) {
            while ($oper = array_pop($operStack)) {
                if ('(' == $oper) {
                    throw new AriphmeticException('Unexpected "("', 4);
                }
                $calcQueue[] = $oper;
            }
        }
        $calcStack = array();

        foreach ($calcQueue as $token) {
            switch ($token) {
                case '+':
                    $arg2 = array_pop($calcStack);
                    $arg1 = array_pop($calcStack);
                    $calcStack[] = $arg1 + $arg2;
                    break;
                case '-':
                    $arg2 = array_pop($calcStack);
                    $arg1 = array_pop($calcStack);
                    $calcStack[] = $arg1 - $arg2;
                    break;
                case '*':
                    $arg2 = array_pop($calcStack);
                    $arg1 = array_pop($calcStack);
                    $calcStack[] = $arg1 * $arg2;
                    break;
                case '/':
                    $arg2 = array_pop($calcStack);
                    $arg1 = array_pop($calcStack);
                    $calcStack[] = $arg1 / $arg2;
                    break;
                default:
                    $calcStack[] = $token;
            }
        }
        return array_pop($calcStack);
    }
}