<?php
declare(strict_types=1);

namespace Esun\FileManager\Model\Config\Backend;

use Magento\Framework\App\Config\Value;
use Magento\Framework\Exception\LocalizedException;
use Esun\FileManager\Model\Security\FilePolicy;

class AllowedExtensions extends Value
{
    /**
     * @throws LocalizedException
     */
    public function beforeSave(): self
    {
        $value = strtolower((string) $this->getValue());
        $extensions = preg_split('/[\s,]+/', $value, -1, PREG_SPLIT_NO_EMPTY) ?: [];
        if (!$extensions) {
            throw new LocalizedException(__('At least one allowed extension is required.'));
        }

        foreach ($extensions as $extension) {
            if (!preg_match('/^[a-z0-9]+$/', $extension)) {
                throw new LocalizedException(__('Invalid extension: %1', $extension));
            }
            if (in_array($extension, FilePolicy::BLOCKED_EXTENSIONS, true)) {
                throw new LocalizedException(__('The extension %1 is always forbidden.', $extension));
            }
            if (!in_array($extension, FilePolicy::getSupportedExtensions(), true)) {
                throw new LocalizedException(
                    __('The extension %1 does not have a secure MIME policy.', $extension)
                );
            }
        }

        $this->setValue(implode(',', array_values(array_unique($extensions))));

        return parent::beforeSave();
    }
}