<?php

/**
 * PayAnyWay - WHMCS Payment Gateway Module
 *
 * WHMCS Gateway Module Developer Documentation:
 *
 * @see https://developers.whmcs.com/payment-gateways/
 */

const CMS_NAME = 'WHMCS';
const MODULE_NAME = 'payanyway';
const MODULE_VERSION = '1.0.0';

const TRANSACTION_ID_STRING_DELIMITER = '|';

const PAYMENT_URL_PROD = 'https://www.payanyway.ru/assistant.htm';
const PAYMENT_URL_DEMO = 'https://demo.moneta.ru/assistant.htm';

const DESCRIPTION_MAX_LENGTH = 500;

const INVENTORY_ITEM_NAME_MAX_LENGTH = 128;
const INVENTORY_ITEM_DEFAULT_PAYMENT_METHOD = 'full_payment';
const INVENTORY_ITEM_DEFAULT_PAYMENT_OBJECT = 'service';
const INVENTORY_ITEM_DEFAULT_QUANTITY = 1;
const INVENTORY_ITEM_DEFAULT_MEASURE = 'unit';
const INVENTORY_ITEM_DEFAULT_VAT_TAG = '1105'; // none

const MODULE_PAYMENT_FEE = 0.0;

if (!defined('WHMCS')) {
    die('This file cannot be accessed directly');
}

/**
 * Module metadata for WHMCS gateway registration.
 *
 * @return array<string, mixed>
 */
function payanyway_MetaData()
{
    return [
        'DisplayName' => 'PayAnyWay',
        'APIVersion' => '1.1',
        'DisableLocalCreditCardInput' => true,
        'TokenisedStorage' => false,
    ];
}

/**
 * Define gateway configuration options.
 *
 * The fields you define here determine the configuration options that are
 * presented to administrator users when activating and configuring your
 * payment gateway module for use.
 *
 * @return array<string, mixed>
 */
function payanyway_config()
{
    return [
        'FriendlyName' => [
            'Type' => 'System',
            'Value' => 'PayAnyWay',
        ],
        'mnt_id' => [
            'FriendlyName' => 'Account Number',
            'Type' => 'text',
            'Size' => '20',
            'Default' => '',
            'Description' => 'Enter your account number provided by PayAnyWay ',
        ],
        'mnt_dataintegrity_code' => [
            'FriendlyName' => 'Code of data integrity verification',
            'Type' => 'text',
            'Size' => '20',
            'Default' => '',
            'Description' => 'Enter your integrity code provided by PayAnyWay',
        ],
        'mnt_test_mode' => [
            'FriendlyName' => 'Test Mode',
            'Type' => 'yesno',
            'Description' => 'Tick to enable test mode',
        ],
    ];
}

/**
 * Generate a PayAnyWay payment link for a WHMCS invoice.
 *
 * Creates a payment preference via PayAnyWay and returns an
 * anchor tag (<a>) pointing to the hosted checkout page. WHMCS will render
 * this HTML inside the invoice payment section.
 *
 * @param array<string, mixed> $params Standard WHMCS gateway params array.
 *                                     See: https://developers.whmcs.com/payment-gateways/third-party-gateway/
 * @return string HTML output to display on the invoice page.
 */
function payanyway_link(array $params)
{
    try {
        // Gateway Configuration Parameters
        $mntId = payanyway_getPayAnyWayMntIdOrFail($params);
        $testMode = !empty($params['mnt_test_mode']) ? '1' : '0';
        $integrityCode = payanyway_getPayAnyWayIntegrityCodeOrFail($params);

        // Invoice Parameters
        $invoiceId = payanyway_getWhmcsInvoiceIdOrFail($params);
        $amount = payanyway_getWhmcsInvoiceAmountOrFail($params);
        $formatAmount = payanyway_formatAmount($amount);
        $currency = payanyway_getWhmcsInvoiceCurrencyOrFail($params);

        // System Parameters
        $langPayNow = payanyway_getOptionalStringWithDefault($params, 'langpaynow', 'Pay Now');
        $whmcsVersion = payanyway_getOptionalString($params, 'whmcsVersion');

        $url = ('1' === $testMode) ? PAYMENT_URL_DEMO : PAYMENT_URL_PROD;

        $subscriberId = payanyway_getSubscriberId($params);
        $signature = md5($mntId . $invoiceId . $formatAmount . $currency . $subscriberId . $testMode . $integrityCode);

        $postFields = array(
            'MNT_ID' => $mntId,
            'MNT_TRANSACTION_ID' => payanyway_createTransactionId($invoiceId),
            'MNT_AMOUNT' => $formatAmount,
            'MNT_CURRENCY_CODE' => $currency,
            'MNT_TEST_MODE' => '0',
            'MNT_DESCRIPTION' => payanyway_getDescription($invoiceId, $params),
            'MNT_SUBSCRIBER_ID' => $subscriberId,
            'MNT_SIGNATURE' => $signature,
            'MNT_CMS' => payanyway_getCmsModuleVersion($whmcsVersion),
        );

        $htmlOutput = '<form method="post" action="' . $url . '">';
        foreach ($postFields as $key => $value) {
            $value = htmlspecialchars($value, ENT_QUOTES | ENT_HTML5, 'UTF-8');
            $htmlOutput .= '<input type="hidden" name="' . $key . '" value="' . $value . '" />';
        }

        $htmlOutput .= '<input type="submit" value="' . $langPayNow . '" />';
        $htmlOutput .= '</form>';

        return $htmlOutput;
    } catch (\Exception $e) {
        return '<p style="color:red;"><strong>Error:</strong> '
            . htmlspecialchars($e->getMessage(), ENT_QUOTES | ENT_HTML5, 'UTF-8') . '</p>';
    }
}

/**
 * WHMCS PayAnyWay Payment Gateway Helper Functions
 */

/**
 * @param array<string, mixed> $data
 * @return int
 * @throws \InvalidArgumentException
 */
function payanyway_getPayAnyWayMntIdOrFail(array $data)
{
    $mntId = payanyway_getOptionalInt($data, 'mnt_id');
    if (null === $mntId) {
        throw new \InvalidArgumentException(
            'PayAnyWay module is not configured properly. '
            . 'Please set Account Number in WHMCS Admin → Payment Gateways.'
        );
    }

    return $mntId;
}

/**
 * @param array<string, mixed> $data
 * @return string
 * @throws \InvalidArgumentException
 */
function payanyway_getPayAnyWayIntegrityCodeOrFail(array $data)
{
    $integrityCode = payanyway_getOptionalString($data, 'mnt_dataintegrity_code');
    if (null === $integrityCode) {
        throw new \InvalidArgumentException(
            'PayAnyWay module is not configured properly. '
            . 'Please set Code of Data Integrity Verification in WHMCS Admin → Payment Gateways.'
        );
    }

    return $integrityCode;
}

/**
 * @param array<string, mixed> $data
 * @return int
 * @throws \InvalidArgumentException
 */
function payanyway_getWhmcsInvoiceIdOrFail(array $data)
{
    $invoiceId = payanyway_getOptionalInt($data, 'invoiceid');
    if (null === $invoiceId) {
        throw new \InvalidArgumentException('Missing or invalid invoice ID (integer required)');
    }

    return $invoiceId;
}

/**
 * @param array<string, mixed> $data
 * @return float
 * @throws \InvalidArgumentException
 */
function payanyway_getWhmcsInvoiceAmountOrFail(array $data)
{
    $amount = payanyway_getOptionalFloat($data, 'amount');
    if (null === $amount) {
        throw new \InvalidArgumentException('Missing or invalid invoice amount (float required).');
    }

    return $amount;
}

/**
 * @param array<string, mixed> $data
 * @return string
 * @throws \InvalidArgumentException
 */
function payanyway_getWhmcsInvoiceCurrencyOrFail(array $data)
{
    $supportedCurrencies = array('RUB');

    $currency = payanyway_getOptionalString($data, 'currency');
    if (null === $currency) {
        $supported = implode(', ', $supportedCurrencies);
        throw new \InvalidArgumentException(
            'Missing currency code. Module supports only: ' . $supported
        );
    }

    $currency = strtoupper($currency);
    if (!in_array($currency, $supportedCurrencies, true)) {
        $supported = implode(', ', $supportedCurrencies);
        throw new \InvalidArgumentException(
            "Unsupported currency code: '{$currency}'. Module supports only: {$supported}"
        );
    }

    return $currency;
}

/**
 * @param array<string, mixed> $data
 * @param string               $name
 * @return string
 * @throws \InvalidArgumentException
 */
function payanyway_getWhmcsVariableOrFail(array $data, $name)
{
    $var = payanyway_getOptionalString($data, $name);
    if (null === $var) {
        throw new \InvalidArgumentException(sprintf('WHMCS variable $params[\'%s\'] is not set.', $name));
    }

    return $var;
}

/**
 * @param array<string, mixed> $data
 * @param string               $key
 * @return int|null
 */
function payanyway_getOptionalInt(array $data, $key)
{
    if (!isset($data[$key]) || !is_numeric($data[$key])) {
        return null;
    }

    return (int)$data[$key];
}

/**
 * @param array<string, mixed> $data
 * @param string               $key
 * @return float|null
 */
function payanyway_getOptionalFloat(array $data, $key)
{
    if (!isset($data[$key]) || !is_numeric($data[$key])) {
        return null;
    }

    return (float)$data[$key];
}

/**
 * @param array<string, mixed> $data
 * @param string               $key
 * @return float
 * @throws \InvalidArgumentException
 */
function payanyway_getRequiredFloat(array $data, $key)
{
    if (!isset($data[$key])) {
        throw new \InvalidArgumentException('Missing required field ' . $key);
    }

    $value = $data[$key];
    if (!is_numeric($value)) {
        throw new \InvalidArgumentException(
            sprintf('Field "%s" must be a number, %s given', $key, gettype($value))
        );
    }

    return (float)$value;
}

/**
 * @param array<string, mixed> $data
 * @param string               $key
 * @return string
 * @throws \InvalidArgumentException
 */
function payanyway_getRequiredString(array $data, $key)
{
    if (!isset($data[$key])) {
        throw new \InvalidArgumentException('Missing required field ' . $key);
    }

    $value = $data[$key];
    if (!is_string($value)) {
        throw new \InvalidArgumentException(
            sprintf('Field "%s" must be a string, %s given', $key, gettype($value))
        );
    }

    if ('' === $value) {
        throw new \InvalidArgumentException(sprintf('Field "%s" must be a non-empty string', $key));
    }

    return $value;
}

/**
 * @param array<string, mixed> $data
 * @param string               $key
 * @return string|null
 */
function payanyway_getOptionalString(array $data, $key)
{
    if (!isset($data[$key])) {
        return null;
    }

    $value = $data[$key];

    return (is_string($value) && ('' !== trim($value))) ? $value : null;
}

/**
 * @param array<string, mixed> $data
 * @param string               $key
 * @param string               $default
 * @return string
 */
function payanyway_getOptionalStringWithDefault(array $data, $key, $default = '')
{
    $value = payanyway_getOptionalString($data, $key);

    return (null !== $value) ? $value : $default;
}

/**
 * @param float $amount
 * @return string
 */
function payanyway_formatAmount($amount)
{
    return number_format($amount, 2, '.', '');
}

/**
 * @param array<string, mixed> $data
 * @return string
 */
function payanyway_getSubscriberId(array $data)
{
    $email = isset($data['clientdetails']['email'])
        ? filter_var($data['clientdetails']['email'], FILTER_SANITIZE_EMAIL)
        : '';
    $phoneNumber = isset($data['clientdetails']['phonenumber'])
        ? preg_replace('/[^0-9+]/', '', $data['clientdetails']['phonenumber'])
        : '';

    return $email ?: $phoneNumber;
}

/**
 * @param int $invoiceId
 * @return string
 */
function payanyway_createTransactionId($invoiceId)
{
    $date = date('YmdHis');
    return $invoiceId . TRANSACTION_ID_STRING_DELIMITER . $date;
}

/**
 * @param string $transactionId
 * @return int|null
 */
function payanyway_getInvoiceIdFromTransactionId($transactionId) {
    $transactionIdData = explode(TRANSACTION_ID_STRING_DELIMITER, $transactionId, 2);

    return isset($transactionIdData[0]) ? (int)$transactionIdData[0] : null;
}

/**
 * @param int                  $invoiceId
 * @param array<string, mixed> $params
 * @return string
 */
function payanyway_getDescription($invoiceId, array $params)
{
    $clientFirstName = isset($params['clientdetails']['firstname']) ? $params['clientdetails']['firstname'] : '';
    $clientLastName = isset($params['clientdetails']['lastname']) ? $params['clientdetails']['lastname'] : '';
    $clientName = trim($clientFirstName . ' ' . $clientLastName);

    $description = "Payment for Invoice №{$invoiceId}";

    if ('' !== $clientName) {
        $description .= " from {$clientName}";
    }

    $originalDescription = isset($params['description']) ? $params['description'] : '';
    if ('' !== $originalDescription) {
        $description .= ': ' . htmlspecialchars($originalDescription, ENT_QUOTES, 'UTF-8');
    }

    return payanyway_validateString($description, DESCRIPTION_MAX_LENGTH);
}

/**
 * @param array<string, mixed> $requestData
 * @return array<string, mixed>
 */
function payanyway_getCallbackData(array $requestData)
{
    return array(
        'MNT_COMMAND' => payanyway_getOptionalStringWithDefault($requestData, 'MNT_COMMAND'),
        'MNT_ID' => payanyway_getRequiredString($requestData, 'MNT_ID'),
        'MNT_TRANSACTION_ID' => payanyway_getRequiredString($requestData, 'MNT_TRANSACTION_ID'),
        'MNT_OPERATION_ID' => payanyway_getOptionalStringWithDefault($requestData, 'MNT_OPERATION_ID'),
        'MNT_AMOUNT' => payanyway_getOptionalStringWithDefault($requestData, 'MNT_AMOUNT'),
        'MNT_CURRENCY_CODE' => payanyway_getRequiredString($requestData, 'MNT_CURRENCY_CODE'),
        'MNT_SUBSCRIBER_ID' => payanyway_getOptionalStringWithDefault($requestData, 'MNT_SUBSCRIBER_ID'),
        'MNT_TEST_MODE' => payanyway_getRequiredString($requestData, 'MNT_TEST_MODE'),
        'MNT_SIGNATURE' => payanyway_getRequiredString($requestData, 'MNT_SIGNATURE'),
    );
}

/**
 * @param array<string, mixed> $callbackData
 * @param array<string, mixed> $gatewayParams
 * @return void
 * @throws \Exception
 */
function payanyway_handleCheckCallback(array $callbackData, array $gatewayParams)
{
    $integrityCode = payanyway_getPayAnyWayIntegrityCodeOrFail($gatewayParams);
    if (!payanyway_checkSignature($callbackData, $callbackData['MNT_SIGNATURE'], $integrityCode)) {
        payanyway_sendResponse('FAIL');
    }

    $gatewayName = payanyway_getWhmcsVariableOrFail($gatewayParams, 'name');

    $rawInvoiceId = payanyway_getInvoiceIdFromTransactionId($callbackData['MNT_TRANSACTION_ID']);
    if (null === $rawInvoiceId) {
        payanyway_sendResponse('FAIL');
    }
    $invoiceId = checkCbInvoiceID($rawInvoiceId, $gatewayName);
    $invoiceDetails = payanyway_getInvoiceDetails($invoiceId);
    if (null === $invoiceDetails) {
        payanyway_sendResponse('FAIL');
    }

    $invoiceItems = payanyway_getInvoiceItems($invoiceDetails);
    $invoicePaymentStatus = (string)$invoiceDetails['status'];

    $xmlData = array(
        'MNT_ID' => payanyway_getPayAnyWayMntIdOrFail($gatewayParams),
        'MNT_TRANSACTION_ID' => $callbackData['MNT_TRANSACTION_ID'],
        'MNT_AMOUNT' => payanyway_formatAmount($invoiceDetails['total']),
        'MNT_CURRENCY_CODE' => $callbackData['MNT_CURRENCY_CODE'],
        'inventory' => payanyway_getInventoryJson($invoiceItems) ?: null,
        'client' => $callbackData['MNT_SUBSCRIBER_ID'],
        'sno' => null,
        'delivery' => null,
    );

    list($xmlData['MNT_RESULT_CODE'], $xmlData['MNT_DESCRIPTION']) = payanyway_determineCheckResult($callbackData, $invoicePaymentStatus);

    $xmlData['MNT_SIGNATURE'] = md5(
        $xmlData['MNT_RESULT_CODE'] .
        $xmlData['MNT_ID'] .
        $xmlData['MNT_TRANSACTION_ID'] .
        payanyway_getPayAnyWayIntegrityCodeOrFail($gatewayParams)
    );

    payanyway_sendResponse(payanyway_buildXMLResponse($xmlData));
}

/**
 * @param array<string, mixed> $callbackData
 * @param string               $invoicePaymentStatus
 * @return array
 * @throws \Exception
 */
function payanyway_determineCheckResult(array $callbackData, $invoicePaymentStatus)
{
    if (empty($callbackData['MNT_AMOUNT'])) {
        return array(100, "Invoice status is '{$invoicePaymentStatus}'");
    }

    if ('Paid' === $invoicePaymentStatus) {
        return array(200, 'Invoice Paid');
    }

    return array(402, "Invoice status is '{$invoicePaymentStatus}'");
}

/**
 * @param array<string, mixed> $callbackData
 * @param array<string, mixed> $gatewayParams
 * @param string               $gatewayModuleName
 * @return void
 * @throws \Exception
 */
function payanyway_handlePayCallback(array $callbackData, array $gatewayParams, $gatewayModuleName)
{
    $gatewayName = payanyway_getWhmcsVariableOrFail($gatewayParams, 'name');

    $rawInvoiceId = payanyway_getInvoiceIdFromTransactionId($callbackData['MNT_TRANSACTION_ID']);
    if (null === $rawInvoiceId) {
        payanyway_sendResponse('FAIL');
    }
    $invoiceId = checkCbInvoiceID($rawInvoiceId, $gatewayName);
    $invoiceDetails = payanyway_getInvoiceDetails($invoiceId);
    if (null === $invoiceDetails) {
        payanyway_sendResponse('FAIL');
    }
    $invoiceTotal = payanyway_formatAmount($invoiceDetails['total']);

    $shopData = array(
        'MNT_ID' => payanyway_getPayAnyWayMntIdOrFail($gatewayParams),
        'MNT_TRANSACTION_ID' => $callbackData['MNT_TRANSACTION_ID'],
        'MNT_OPERATION_ID' => $callbackData['MNT_OPERATION_ID'],
        'MNT_AMOUNT' => $invoiceTotal,
        'MNT_CURRENCY_CODE' => $callbackData['MNT_CURRENCY_CODE'],
        'MNT_SUBSCRIBER_ID' => $callbackData['MNT_SUBSCRIBER_ID'],
        'MNT_TEST_MODE' => $callbackData['MNT_TEST_MODE'],
    );

    $integrityCode = payanyway_getPayAnyWayIntegrityCodeOrFail($gatewayParams);
    if (!payanyway_checkSignature($shopData, $callbackData['MNT_SIGNATURE'], $integrityCode)) {
        payanyway_sendResponse('FAIL');
    }

    $invoiceItems = payanyway_getInvoiceItems($invoiceDetails);
    $invoicePaymentStatus = (string)$invoiceDetails['status'];

    $mntId = payanyway_getPayAnyWayMntIdOrFail($gatewayParams);
    $resultCode = 200;
    $xmlData = array(
        'MNT_ID' => $mntId,
        'MNT_TRANSACTION_ID' => $callbackData['MNT_TRANSACTION_ID'],
        'MNT_RESULT_CODE' => $resultCode,
        'MNT_SIGNATURE' => md5($resultCode . $mntId . $callbackData['MNT_TRANSACTION_ID'] . $integrityCode),
        'MNT_AMOUNT' => $invoiceTotal,
        'MNT_CURRENCY_CODE' => $callbackData['MNT_CURRENCY_CODE'],
        'MNT_DESCRIPTION' => ('Paid' !== $invoicePaymentStatus) ? 'Invoice success paid' : 'Invoice already paid',
        'inventory' => payanyway_getInventoryJson($invoiceItems) ?: null,
        'client' => $callbackData['MNT_SUBSCRIBER_ID'],
        'sno' => null,
        'delivery' => null,
    );

    if ('Paid' !== $invoicePaymentStatus) {
        $transactionId = $callbackData['MNT_OPERATION_ID'];
        checkCbTransID($transactionId); // if $transactionId exist, script die()
        if (!payanyway_existInvoiceTransaction($invoiceId, $transactionId)) {
            addInvoicePayment($invoiceId, $transactionId, $invoiceTotal, MODULE_PAYMENT_FEE, $gatewayModuleName);
            logTransaction($gatewayName, $callbackData, 'Success');
        }
    }

    payanyway_sendResponse(payanyway_buildXMLResponse($xmlData));
}

/**
 * @param array<string, mixed> $data
 * @param string               $callbackSignature
 * @param string               $integrityCode
 * @return bool
 */
function payanyway_checkSignature(array $data, $callbackSignature, $integrityCode)
{
    $baseFields = array(
        'MNT_ID',
        'MNT_TRANSACTION_ID',
        'MNT_OPERATION_ID',
        'MNT_AMOUNT',
        'MNT_CURRENCY_CODE',
        'MNT_SUBSCRIBER_ID',
        'MNT_TEST_MODE',
    );

    $fields = isset($data['MNT_COMMAND']) && ('CHECK' === $data['MNT_COMMAND'])
        ? array_merge(['MNT_COMMAND'], $baseFields)
        : $baseFields;

    $signatureString = array_reduce($fields, function ($carry, $field) use ($data) {
            return $carry . $data[$field];
        }, '') . $integrityCode;

    return hash_equals(md5($signatureString), $callbackSignature);
}

/**
 * @see https://developers.whmcs.com/api-reference/getinvoice/
 * @param int $invoiceId
 * @return array<string, mixed>|null
 */
function payanyway_getInvoiceDetails($invoiceId)
{
    $command = 'GetInvoice';
    $postData = array(
        'invoiceid' => $invoiceId,
    );

    $results = localAPI($command, $postData);
    if ($results['result'] !== 'success') {
        return null;
    }

    return $results;
}

/**
 * @param array<string, mixed> $invoiceDetails
 * @return array<string, mixed>|null
 */
function payanyway_getInvoiceItems(array $invoiceDetails)
{
    return (isset($invoiceDetails['items']['item']) && is_array($invoiceDetails['items']['item']))
        ? $invoiceDetails['items']['item']
        : null;
}

/**
 * @see https://developers.whmcs.com/api-reference/gettransactions/
 * @param int    $invoiceId
 * @param string $transactionId
 * @return bool
 */
function payanyway_existInvoiceTransaction($invoiceId, $transactionId)
{
    $results = localAPI('GetTransactions', array(
        'invoiceid' => $invoiceId,
        'transid' => $transactionId,
    ));

    if ($results['result'] !== 'success') {
        return false;
    }

    $transactions = isset($results['transactions']['transaction']) ? $results['transactions']['transaction'] : array();
    if (empty($transactions)) {
        return false;
    }

    foreach ($transactions as $transaction) {
        if (isset($transaction['transid']) && ($transaction['transid'] === $transactionId)) {
            return true;
        }
    }

    return false;
}

/**
 * @param array<string, mixed> $items
 * @return false|string
 */
function payanyway_getInventoryJson(array $items)
{
    $inventory = array();
    foreach ($items as $item) {
        $name = isset($item['description']) ? $item['description'] : '';
        $price = isset($item['amount']) ? (float)$item['amount'] : 0;
        $name = payanyway_validateString($name, INVENTORY_ITEM_NAME_MAX_LENGTH);

        $inventory[] = array(
            'name' => !empty($name) ? $name : 'Service',
            'price' => (float)payanyway_formatAmount($price),
            'quantity' => INVENTORY_ITEM_DEFAULT_QUANTITY,
            'vatTag' => INVENTORY_ITEM_DEFAULT_VAT_TAG,
            'pm' => INVENTORY_ITEM_DEFAULT_PAYMENT_METHOD,
            'po' => INVENTORY_ITEM_DEFAULT_PAYMENT_OBJECT,
            'measure' => INVENTORY_ITEM_DEFAULT_MEASURE,
        );
    }

    return json_encode($inventory, JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_SLASHES);
}

/**
 * @param array<string, mixed> $data
 * @return false|string
 * @throws \Exception
 */
function payanyway_buildXMLResponse(array $data)
{
    $dom = new \DOMDocument('1.0', 'UTF-8');
    $dom->formatOutput = false;

    $root = $dom->createElement('MNT_RESPONSE');
    $dom->appendChild($root);

    $requiredFields = array(
        'MNT_ID',
        'MNT_TRANSACTION_ID',
        'MNT_RESULT_CODE',
        'MNT_DESCRIPTION',
        'MNT_AMOUNT',
        'MNT_CURRENCY_CODE',
        'MNT_SIGNATURE',
    );

    foreach ($requiredFields as $field) {
        if (isset($data[$field]) && ($data[$field] !== '')) {
            $root->appendChild($dom->createElement($field, (string)$data[$field]));
        }
    }

    $attributes = $dom->createElement('MNT_ATTRIBUTES');
    $root->appendChild($attributes);

    $attributeMap = array(
        'INVENTORY' => isset($data['inventory']) ? $data['inventory'] : null,
        'CLIENT' => isset($data['client']) ? $data['client'] : null,
        'SNO' => isset($data['sno']) ? $data['sno'] : null,
        'DELIVERY' => isset($data['delivery']) ? $data['delivery'] : null,
    );

    foreach ($attributeMap as $key => $value) {
        if (!empty($value)) {
            $attrElement = $dom->createElement('ATTRIBUTE');
            $attrElement->appendChild($dom->createElement('KEY', $key));
            $attrElement->appendChild($dom->createElement('VALUE', (string)$value));
            $attributes->appendChild($attrElement);
        }
    }

    return $dom->saveXML();
}

/**
 * @param string|null $whmcsVersion
 * @return string
 */
function payanyway_getCmsModuleVersion($whmcsVersion)
{
    $whmcsVersion = isset($whmcsVersion) ? $whmcsVersion : '.unknown';

    return sprintf('%s v%s | %s v%s', CMS_NAME, $whmcsVersion, MODULE_NAME, MODULE_VERSION);
}

/**
 * @param string $value
 * @param int    $maxLength
 * @return string
 */
function payanyway_validateString($value, $maxLength)
{
    $maxLength = max(0, $maxLength);
    $value = payanyway_sanitizeString($value);

    if (mb_strlen($value, 'UTF-8') <= $maxLength) {
        return $value;
    }

    $trimLength = max(0, $maxLength - 3);
    return mb_substr($value, 0, $trimLength, 'UTF-8') . ($maxLength > 3 ? '...' : '');
}

/**
 * @param string $value
 * @return string
 */
function payanyway_sanitizeString($value)
{
    $decoded = html_entity_decode($value, ENT_QUOTES | ENT_HTML5, 'UTF-8');
    $cleaned = preg_replace('/[^\p{L}\p{N}\s.,()_№+-]/u', '', $decoded);
    $cleaned = str_replace(['&', '/', '\\', ';', '%', '#', '"', "'"], '', $cleaned);

    return trim(preg_replace('/\s+/', ' ', $cleaned));
}

/**
 * @param string $response
 * @param int    $statusCode
 * @return void
 */
function payanyway_sendResponse($response, $statusCode = 200)
{
    http_response_code($statusCode);

    if (strpos($response, '<?xml') === 0 || strpos($response, '<MNT_RESPONSE') !== false) {
        header('Content-Type: application/xml');
    } else {
        header('Content-Type: text/plain; charset=UTF-8');
    }

    echo $response;
    exit();
}