<?php
declare(strict_types=1);

namespace Esun\Catalog\Model;

use Esun\Catalog\Setup\Patch\Data\AddMixStepPricesAttribute;
use Magento\Catalog\Model\Product;
use Magento\Customer\Model\Group;
use Magento\Framework\Serialize\Serializer\Json;

class MixStepPriceProvider
{
    public function __construct(private readonly Json $json)
    {
    }

    public function getRules(Product $parentProduct, int $customerGroupId): array
    {
        $rows = $parentProduct->getData(AddMixStepPricesAttribute::ATTRIBUTE_CODE);
        if (is_string($rows) && trim($rows) !== '') {
            try {
                $rows = $this->json->unserialize($rows);
            } catch (\InvalidArgumentException) {
                $rows = [];
            }
        }
        if (!is_array($rows)) {
            return [];
        }

        $rules = [];
        foreach ($rows as $row) {
            if (!is_array($row) || (isset($row['enabled']) && !(bool)$row['enabled'])) {
                continue;
            }

            $ruleGroupId = (int)($row['customer_group_id'] ?? Group::CUST_GROUP_ALL);
            if ($ruleGroupId !== Group::CUST_GROUP_ALL && $ruleGroupId !== $customerGroupId) {
                continue;
            }

            $quantity = (int)($row['qty'] ?? 0);
            $value = (float)($row['value'] ?? 0);
            $priceType = (string)($row['price_type'] ?? 'percent');
            if ($quantity < 2 || $value <= 0 || !in_array($priceType, ['percent', 'fixed'], true)) {
                continue;
            }

            $specificity = $ruleGroupId === $customerGroupId ? 1 : 0;
            if (isset($rules[$quantity]) && $rules[$quantity]['specificity'] > $specificity) {
                continue;
            }
            $rules[$quantity] = [
                'qty' => $quantity,
                'price_type' => $priceType,
                'value' => $value,
                'specificity' => $specificity,
            ];
        }

        ksort($rules);
        return array_map(static function (array $rule): array {
            unset($rule['specificity']);
            return $rule;
        }, array_values($rules));
    }

    public function getActiveRule(array $rules, float $quantity): ?array
    {
        $activeRule = null;
        foreach ($rules as $rule) {
            if ($quantity >= (float)$rule['qty']) {
                $activeRule = $rule;
            }
        }

        return $activeRule;
    }

    public function calculateUnitPrice(float $basePrice, ?array $rule): float
    {
        if (!$rule) {
            return max(0, $basePrice);
        }
        if (($rule['price_type'] ?? '') === 'fixed') {
            return max(0, min($basePrice, (float)$rule['value']));
        }

        return max(0, $basePrice * (1 - ((float)$rule['value'] / 100)));
    }
}