<?php
declare(strict_types=1);

namespace Esun\FreeGift\Model\Config\Backend;

use Magento\Config\Model\Config\Backend\Serialized\ArraySerialized;
use Magento\Config\Model\ResourceModel\Config\Data as ConfigResource;
use Magento\Config\Model\ResourceModel\Config\Data\Collection as ConfigCollection;

class TierItems extends ArraySerialized
{
    protected function _construct(): void
    {
        $this->_setResourceModel(ConfigResource::class, ConfigCollection::class);
    }

    public function beforeSave()
    {
        $items = [];
        $value = $this->getValue();
        if (is_array($value)) {
            unset($value['__empty']);
            foreach ($value as $row) {
                if (!is_array($row)) {
                    continue;
                }

                $amount = max(0.0, (float)($row['amount'] ?? 0));
                $quantity = max(0, (int)($row['qty'] ?? 0));
                if ($quantity <= 0) {
                    continue;
                }

                $items[] = ['amount' => $amount, 'qty' => $quantity];
            }
        }

        usort($items, static fn (array $left, array $right): int => $left['amount'] <=> $right['amount']);
        $this->setValue($items);

        return parent::beforeSave();
    }
}