FM / Services

/home/suroeste/public_html/payments.transportessuroeste.com/src/Services/

/home/suroeste/public_html/payments.transportessuroeste.com/src/Services

Name	Size	Mode	Actions
ClientDatabaseService.php	4444	0644	edit dl rm
EncryptionService.php	3867	0644	edit dl rm
LogService.php	9678	0644	edit dl rm
PaymentService.php	28357	0644	edit dl rm

Edit: /home/suroeste/public_html/payments.transportessuroeste.com/src/Services/PaymentService.php (28357B)

<?php
/**
 * ============================================================================
 * PAYMENT SERVICE - Integración con ePayco Smart Checkout v2
 * ============================================================================
 */

namespace TransportesSuroeste\Services;

use TransportesSuroeste\Models\Database;
use TransportesSuroeste\Exceptions\PaymentException;

class PaymentService
{
    private Database $db;
    private EncryptionService $encryption;
    private $epayco = null;
    private ?string $apifyToken = null;

private const APIFY_LOGIN_URL = 'https://apify.epayco.co/login';
    private const APIFY_SESSION_URL = 'https://apify.epayco.co/payment/session/create';
    private const SMART_CHECKOUT_URL = 'https://checkout.epayco.co';

public function __construct()
    {
        $this->db = Database::getInstance();
        $this->encryption = new EncryptionService();
    }

private function getEpayco()
    {
        if ($this->epayco === null) {
            if (!class_exists('Epayco\Epayco')) {
                throw new PaymentException('SDK ePayco no instalado. Ejecute: composer require epayco/epayco-php');
            }
            
            set_error_handler(function($errno, $errstr) {
                return (strpos($errstr, 'deprecated') !== false || $errno === E_DEPRECATED);
            });
            
            try {
                $this->epayco = new \Epayco\Epayco(array(
                    "apiKey" => EPAYCO_CONFIG['public_key'],
                    "privateKey" => EPAYCO_CONFIG['private_key'],
                    "lenguage" => EPAYCO_CONFIG['language'],
                    "test" => EPAYCO_CONFIG['test_mode']
                ));
            } finally {
                restore_error_handler();
            }
        }
        return $this->epayco;
    }

/**
     * Ejecutar método de ePayco suprimiendo deprecations
     */
    private function callEpayco(callable $callback)
    {
        $oldErrorReporting = error_reporting();
        error_reporting($oldErrorReporting & ~E_DEPRECATED & ~E_USER_DEPRECATED);
        
        try {
            return @$callback();
        } finally {
            error_reporting($oldErrorReporting);
        }
    }

/**
     * Obtener token de autenticación de Apify
     */
    private function getApifyToken(): string
    {
        if ($this->apifyToken !== null) {
            return $this->apifyToken;
        }

$credentials = base64_encode(EPAYCO_CONFIG['public_key'] . ':' . EPAYCO_CONFIG['private_key']);

$ch = curl_init(self::APIFY_LOGIN_URL);
        curl_setopt_array($ch, [
            CURLOPT_POST => true,
            CURLOPT_RETURNTRANSFER => true,
            CURLOPT_HTTPHEADER => [
                'Content-Type: application/json',
                'Authorization: Basic ' . $credentials
            ],
            CURLOPT_TIMEOUT => 30,
            CURLOPT_SSL_VERIFYPEER => true
        ]);

$response = curl_exec($ch);
        $httpCode = curl_getinfo($ch, CURLINFO_HTTP_CODE);
        $error = curl_error($ch);
        curl_close($ch);

if ($error) {
            LogService::error('epayco', 'Error cURL en login Apify', ['error' => $error]);
            throw new PaymentException('Error de conexión con ePayco: ' . $error);
        }

$data = json_decode($response, true);

if ($httpCode !== 200 || empty($data['token'])) {
            LogService::error('epayco', 'Error autenticación Apify', [
                'http_code' => $httpCode,
                'response' => $response
            ]);
            throw new PaymentException('Error de autenticación con ePayco');
        }

$this->apifyToken = $data['token'];
        return $this->apifyToken;
    }

/**
     * Crear sesión de Smart Checkout v2
     */
    private function createSmartCheckoutSession(array $data, string $internalRef, string $transactionUuid): array
    {
        $token = $this->getApifyToken();

$sessionData = [
            // Requeridos
            'checkout_version' => '2',
            'name' => APP_NAME ?? 'Transportes Suroeste',
            'description' => $data['description'] ?? 'Pago Transportes Suroeste',
            'invoice' => $internalRef,
            'currency' => $data['currency'] ?? 'COP',
            'amount' => (float)$data['amount'],
            'tax' => (float)($data['tax'] ?? 0),
            'taxBase' => (float)($data['tax_base'] ?? $data['amount']),
            'taxIco' => 0,
            'country' => 'CO',
            'lang' => 'ES',
            'test' => EPAYCO_CONFIG['test_mode'],

// URLs de respuesta
            'response' => $data['response_url'] ?? (APP_URL . '/payment/response') . '?tx=' . urlencode($transactionUuid),
            'confirmation' => APP_URL . '/api/v1/webhook/epayco',
            'method' => 'POST',

// Extras para identificar la transacción
            'extras' => [
                'extra1' => $data['ticket_reference'] ?? '',
                'extra2' => $transactionUuid,
                'extra3' => $internalRef,
                'extra4' => '',
                'extra5' => ''
            ],

// Billing - datos del comprador (ePayco requiere strings)
            'billing' => [
                'email' => (string)($data['payer_email'] ?? ''),
                'name' => (string)($data['payer_name'] ?? ''),
                'typeDoc' => (string)($data['payer_document_type'] ?? 'CC'),
                'numberDoc' => (string)($data['payer_document'] ?? ''),
                'mobilePhone' => (string)($data['payer_phone'] ?? ''),
                'callingCode' => '+57'
            ]
        ];

LogService::info('epayco', 'Datos sesión a enviar', [
            'invoice' => $sessionData['invoice'],
            'amount' => $sessionData['amount'],
            'currency' => $sessionData['currency'],
            'description' => $sessionData['description'] ?? '(null)',
            'billing_email' => $sessionData['billing']['email'] ?? '(null)',
            'billing_name' => $sessionData['billing']['name'] ?? '(null)',
            'billing_typeDoc' => $sessionData['billing']['typeDoc'] ?? '(null)',
            'test' => $sessionData['test']
        ]);

$ch = curl_init(self::APIFY_SESSION_URL);
        curl_setopt_array($ch, [
            CURLOPT_POST => true,
            CURLOPT_RETURNTRANSFER => true,
            CURLOPT_HTTPHEADER => [
                'Content-Type: application/json',
                'Authorization: Bearer ' . $token
            ],
            CURLOPT_POSTFIELDS => json_encode($sessionData),
            CURLOPT_TIMEOUT => 30,
            CURLOPT_SSL_VERIFYPEER => true
        ]);

$response = curl_exec($ch);
        $httpCode = curl_getinfo($ch, CURLINFO_HTTP_CODE);
        $error = curl_error($ch);
        curl_close($ch);

if ($error) {
            LogService::error('epayco', 'Error cURL creando sesión', ['error' => $error]);
            throw new PaymentException('Error de conexión con ePayco: ' . $error);
        }

$result = json_decode($response, true);

LogService::info('epayco', 'Respuesta crear sesión', [
            'http_code' => $httpCode,
            'response' => $result
        ]);

if ($httpCode !== 200 || empty($result['success']) || empty($result['data']['sessionId'])) {
            LogService::error('epayco', 'Error creando sesión Smart Checkout', [
                'http_code' => $httpCode,
                'response' => $response,
                'request_data' => json_encode($sessionData)
            ]);

$errorMsg = $result['textResponse'] ?? 'Error desconocido';
            // En debug, incluir detalles de ePayco para diagnosticar campos faltantes
            if (defined('APP_DEBUG') && APP_DEBUG) {
                $details = $result['data']['errors'] ?? $result['data'] ?? $result['errors'] ?? null;
                if ($details) {
                    $errorMsg .= ' | Detalles: ' . json_encode($details, JSON_UNESCAPED_UNICODE);
                }
                $errorMsg .= ' | HTTP: ' . $httpCode;
            }
            throw new PaymentException('Error al crear sesión de pago: ' . $errorMsg);
        }

return [
            'sessionId' => $result['data']['sessionId'],
            'token' => $result['data']['token'] ?? null
        ];
    }

/**
     * Crear transacción y generar link de pago de ePayco Smart Checkout v2
     */
    public function createPayment(array $data, array $client): array
    {
        // Verificar si ya existe una transaccion activa para este ticket
        $existing = $this->db->fetchOne(
            "SELECT transaction_uuid, status FROM transactions
             WHERE ticket_reference = :ticket AND client_id = :client
             AND status IN ('pending', 'approved')
             LIMIT 1",
            ['ticket' => $data['ticket_reference'], 'client' => $client['id']]
        );

if ($existing) {
            $msg = $existing['status'] === 'approved'
                ? 'Este ticket ya tiene un pago aprobado'
                : 'Ya existe una transaccion pendiente para este ticket. Consulte su estado con GET /api/v1/payments/ticket/' . $data['ticket_reference'];
            throw new PaymentException($msg, 409);
        }

$this->db->beginTransaction();

try {
            $transactionUuid = $this->encryption->generateUuid();
            $internalRef = 'TS' . date('Ymd') . strtoupper(bin2hex(random_bytes(4)));
            
            $signature = $this->encryption->sign(json_encode([
                'ticket' => $data['ticket_reference'],
                'amount' => $data['amount'],
                'client' => $client['uuid'],
                'time' => time()
            ]));

// Crear sesión de Smart Checkout v2
            $checkoutSession = $this->createSmartCheckoutSession($data, $internalRef, $transactionUuid);
            
            // Guardar transacción en BD
            $transactionId = $this->db->insert('transactions', [
                'transaction_uuid' => $transactionUuid,
                'client_id' => $client['id'],
                'ticket_reference' => $data['ticket_reference'],
                'internal_reference' => $internalRef,
                'epayco_session_id' => $checkoutSession['sessionId'],
                'amount' => $data['amount'],
                'currency' => $data['currency'] ?? 'COP',
                'tax' => $data['tax'] ?? 0,
                'tax_base' => $data['tax_base'] ?? $data['amount'],
                'status' => 'pending',
                'payer_email' => $this->encryption->encrypt($data['payer_email']),
                'payer_document_type' => $data['payer_document_type'],
                'payer_document' => $this->encryption->encrypt($data['payer_document']),
                'payer_name' => $this->encryption->encrypt($data['payer_name']),
                'payer_phone' => isset($data['payer_phone']) ? $this->encryption->encrypt($data['payer_phone']) : null,
                'description' => $data['description'],
                'ip_address' => LogService::getClientIp(),
                'user_agent' => $_SERVER['HTTP_USER_AGENT'] ?? 'Unknown',
                'request_signature' => $signature,
                'extra_data' => json_encode($data['extra_data'] ?? []),
                'expires_at' => date('Y-m-d H:i:s', time() + TRANSACTION_CONFIG['timeout'])
            ]);

$this->db->insert('transaction_status_history', [
                'transaction_id' => $transactionId,
                'previous_status' => null,
                'new_status' => 'pending',
                'changed_by' => 'system',
                'ip_address' => LogService::getClientIp()
            ]);

// Generar URL del checkout
            $paymentUrl =  APP_URL . '/payment/checkout' . '?sessionId=' . $checkoutSession['sessionId'] . '&uuid=' . $transactionUuid;

LogService::transaction($transactionUuid, 'CREATE', 'pending', [
                'ticket' => $data['ticket_reference'],
                'amount' => $data['amount'],
                'sessionId' => $checkoutSession['sessionId']
                
            ]);

$this->db->commit();

return [
                'transaction_uuid' => $transactionUuid,
                'internal_reference' => $internalRef,
                'ticket_reference' => $data['ticket_reference'],
                'amount' => $data['amount'],
                'currency' => $data['currency'] ?? 'COP',
                'status' => 'pending',
                'payment_url' => $paymentUrl,
                'session_id' => $checkoutSession['sessionId'],
                'expires_at' => date('Y-m-d H:i:s', time() + TRANSACTION_CONFIG['timeout']),
                'created_at' => date('Y-m-d H:i:s')
            ];

} catch (\TransportesSuroeste\Exceptions\DatabaseException $e) {
            $this->db->rollback();
            LogService::error('transactions', 'Error BD creando pago', [
                'error' => $e->getMessage(),
                'db_code' => $e->getDbErrorCode(),
                'constraint' => $e->getConstraintName(),
                'ticket' => $data['ticket_reference'] ?? null
            ]);

// Traducir errores de BD a mensajes de negocio
            if ($e->isDuplicate()) {
                $friendlyMsg = match(true) {
                    str_contains($e->getConstraintName(), 'ticket') => 'Ya existe una transaccion para este ticket. Consulte su estado con GET /api/v1/payments/ticket/{reference}',
                    str_contains($e->getConstraintName(), 'internal_reference') => 'Error generando referencia interna, intente de nuevo',
                    str_contains($e->getConstraintName(), 'transaction_uuid') => 'Error generando identificador, intente de nuevo',
                    default => 'Ya existe un registro con estos datos'
                };
                throw new PaymentException($friendlyMsg, 409);
            }

throw new PaymentException('Error al procesar la transaccion. Intente de nuevo', $e->getHttpCode());
        } catch (\Exception $e) {
            $this->db->rollback();
            LogService::error('transactions', 'Error creando pago', ['error' => $e->getMessage()]);
            throw new PaymentException('Error al procesar la transaccion', 500);
        }
    }

/**
     * Reintentar pago fallido/rechazado - Crea nueva sesión ePayco y resetea la transacción
     */
    public function retryPayment(string $transactionUuid): array
    {
        $transaction = $this->db->fetchOne(
            "SELECT * FROM transactions WHERE transaction_uuid = :uuid",
            ['uuid' => $transactionUuid]
        );

if (!$transaction) {
            throw new PaymentException('Transacción no encontrada', 404);
        }

$retryableStatuses = ['rejected', 'failed'];
        if (!in_array($transaction['status'], $retryableStatuses)) {
            throw new PaymentException('Esta transacción no puede reintentarse (estado: ' . $transaction['status'] . ')', 422);
        }

$this->db->beginTransaction();

try {
            // Desencriptar datos del pagador para crear nueva sesión
            // Cast a string: decrypt() retorna mixed y ePayco requiere strings en billing
            $payerEmail = (string)$this->encryption->decrypt($transaction['payer_email']);
            $payerDocument = (string)$this->encryption->decrypt($transaction['payer_document']);
            $payerName = (string)$this->encryption->decrypt($transaction['payer_name']);
            $payerPhone = $transaction['payer_phone'] ? (string)$this->encryption->decrypt($transaction['payer_phone']) : '';

$sessionData = [
                'amount' => (float)$transaction['amount'],
                'currency' => $transaction['currency'] ?? 'COP',
                'tax' => (float)($transaction['tax'] ?? 0),
                'tax_base' => (float)($transaction['tax_base'] ?? $transaction['amount']),
                'description' => $transaction['description'] ?? 'Pago Transportes Suroeste',
                'ticket_reference' => $transaction['ticket_reference'],
                'payer_email' => $payerEmail,
                'payer_name' => $payerName,
                'payer_document_type' => $transaction['payer_document_type'] ?? 'CC',
                'payer_document' => $payerDocument,
                'payer_phone' => $payerPhone
            ];

// Crear nueva sesión de ePayco
            $checkoutSession = $this->createSmartCheckoutSession(
                $sessionData,
                $transaction['internal_reference'],
                $transaction['transaction_uuid']
            );

// Actualizar transacción con nueva sesión y resetear estado
            $this->db->update('transactions', [
                'epayco_session_id' => $checkoutSession['sessionId'],
                'status' => 'pending',
                'status_code' => null,
                'status_message' => null,
                'epayco_ref' => null,
                'epayco_transaction_id' => null,
                'payment_method' => null,
                'payment_method_type' => null,
                'card_last_four' => null,
                'card_brand' => null,
                'bank_name' => null,
                'response_signature' => null,
                'processed_at' => null,
                'expires_at' => date('Y-m-d H:i:s', time() + TRANSACTION_CONFIG['timeout'])
            ], 'id = :id', ['id' => $transaction['id']]);

// Registrar cambio de estado
            $this->db->insert('transaction_status_history', [
                'transaction_id' => $transaction['id'],
                'previous_status' => $transaction['status'],
                'new_status' => 'pending',
                'changed_by' => 'retry',
                'ip_address' => LogService::getClientIp()
            ]);

LogService::transaction($transaction['transaction_uuid'], 'RETRY', 'pending', [
                'previous_status' => $transaction['status'],
                'new_session' => $checkoutSession['sessionId']
            ]);

$this->db->commit();

$paymentUrl = APP_URL . '/payment/checkout?sessionId=' . $checkoutSession['sessionId'] . '&uuid=' . $transaction['transaction_uuid'];

return [
                'transaction_uuid' => $transaction['transaction_uuid'],
                'session_id' => $checkoutSession['sessionId'],
                'payment_url' => $paymentUrl
            ];

} catch (PaymentException $e) {
            $this->db->rollback();
            throw $e;
        } catch (\Exception $e) {
            $this->db->rollback();
            LogService::error('transactions', 'Error en reintento de pago', [
                'uuid' => $transactionUuid,
                'error' => $e->getMessage()
            ]);
            throw new PaymentException('Error al reintentar el pago. Intente de nuevo', 500);
        }
    }

/**
     * Obtener bancos PSE
     */
    public function getPseBanks(): array
    {
        try {
            $epayco = $this->getEpayco();
            
            $banks = $this->callEpayco(function() use ($epayco) {
                return $epayco->bank->pseBank();
            });
            
            if (!$banks->success || empty($banks->data)) {
                return [];
            }

return array_map(fn($bank) => [
                'bank_code' => $bank->bankCode,
                'bank_name' => $bank->bankName
            ], $banks->data);

} catch (\Exception $e) {
            LogService::error('pse', 'Error obteniendo bancos', ['error' => $e->getMessage()]);
            return [];
        }
    }

/**
     * Consultar estado de transacción
     */
    public function getTransactionStatus(string $identifier, string $type = 'uuid'): ?array
    {
        $where = match($type) {
            'uuid' => 'transaction_uuid = :id',
            'ticket' => 'ticket_reference = :id',
            'internal' => 'internal_reference = :id',
            'ref_payco' => 'epayco_session_id = :id',
            default => 'transaction_uuid = :id'
        };

$transaction = $this->db->fetchOne(
            "SELECT t.*, c.client_name FROM transactions t 
             JOIN api_clients c ON t.client_id = c.id WHERE {$where}",
            ['id' => $identifier]
        );

if (!$transaction) return null;

return [
            'transaction_uuid' => $transaction['transaction_uuid'],
            'internal_reference' => $transaction['internal_reference'],
            'ticket_reference' => $transaction['ticket_reference'],
            'amount' => (float)$transaction['amount'],
            'currency' => $transaction['currency'],
            'status' => $transaction['status'],
            'status_code' => $transaction['status_code'],
            'status_message' => $transaction['status_message'],
            'payment_method' => $transaction['payment_method'],
            'epayco_ref' => $transaction['epayco_ref'],
            'created_at' => $transaction['created_at'],
            'processed_at' => $transaction['processed_at']
        ];
    }

/**
     * Procesar callback/webhook de ePayco
     */
    public function processCallback(array $data): array
    {
        $refPayco = $data['x_ref_payco'] ?? null;
        $internalRef = $data['x_id_invoice'] ?? $data['x_extra3'] ?? null;
        $transactionUuid = $data['x_extra2'] ?? null;

LogService::info('callback', 'Callback ePayco', $data);

$transaction = null;
        
        if ($transactionUuid) {
            $transaction = $this->db->fetchOne(
                "SELECT * FROM transactions WHERE transaction_uuid = :uuid",
                ['uuid' => $transactionUuid]
            );
        }
        
        if (!$transaction && $internalRef) {
            $transaction = $this->db->fetchOne(
                "SELECT * FROM transactions WHERE internal_reference = :ref",
                ['ref' => $internalRef]
            );
        }
        
        if (!$transaction && $refPayco) {
            $transaction = $this->db->fetchOne(
                "SELECT * FROM transactions WHERE epayco_ref = :ref",
                ['ref' => $refPayco]
            );
        }

if (!$transaction) {
            throw new PaymentException('Transacción no encontrada');
        }

$status = $this->mapEpaycoStatus($data['x_response'] ?? 'Pendiente');

$this->db->update('transactions', [
            'status' => $status,
            'status_code' => $data['x_cod_response'] ?? null,
            'status_message' => $data['x_response_reason_text'] ?? null,
            'epayco_ref' => $refPayco,
            'epayco_transaction_id' => $data['x_transaction_id'] ?? null,
            'payment_method' => $data['x_franchise'] ?? $data['x_bank_name'] ?? null,
            'payment_method_type' => !empty($data['x_bank_name']) ? 'pse' : 'credit_card',
            'bank_name' => $data['x_bank_name'] ?? null,
            'card_brand' => $data['x_franchise'] ?? null,
            'card_last_four' => !empty($data['x_cardnumber']) ? substr($data['x_cardnumber'], -4) : null,
            'response_signature' => $data['x_signature'] ?? null,
            'processed_at' => date('Y-m-d H:i:s')
        ], 'id = :id', ['id' => $transaction['id']]);

$this->db->insert('transaction_status_history', [
            'transaction_id' => $transaction['id'],
            'previous_status' => $transaction['status'],
            'new_status' => $status,
            'status_code' => $data['x_cod_response'] ?? null,
            'status_message' => $data['x_response_reason_text'] ?? null,
            'changed_by' => 'epayco',
            'ip_address' => LogService::getClientIp()
        ]);

LogService::transaction($transaction['transaction_uuid'], 'CALLBACK', $status);

// Actualizar estado de pago en BD del cliente (reservas_clientes)
        $this->updateClientPaymentStatus(
            $transaction['ticket_reference'] ?? $data['x_extra1'] ?? '',
            $status
        );

$this->sendWebhook($transaction['id']);

return [
            'status' => $status,
            'transaction_uuid' => $transaction['transaction_uuid'],
            'ticket_reference' => $transaction['ticket_reference']
        ];
    }

private function mapEpaycoStatus(string $response): string
    {
        return match(strtolower($response)) {
            'aceptada', 'aprobada', 'approved' => 'approved',
            'rechazada', 'rejected' => 'rejected',
            'pendiente', 'pending' => 'pending',
            'fallida', 'failed' => 'failed',
            'cancelada', 'cancelled' => 'cancelled',
            default => 'pending'
        };
    }

/**
     * Actualizar estado de pago en la BD del cliente (tabla reservas_clientes)
     *
     * Conecta a la BD externa del cliente y actualiza el campo estadopago
     * buscando por idreserva_cliente = ticket_reference.
     * Los errores se registran en log pero no interrumpen el flujo principal.
     */
    private function updateClientPaymentStatus(string $ticketReference, string $status): void
    {
        if (empty($ticketReference)) {
            LogService::error('client_db', 'ticket_reference vacío, no se puede actualizar BD del cliente');
            return;
        }

try {
            $clientDb = new ClientDatabaseService();
            $updated = $clientDb->updatePaymentStatus($ticketReference, $status);

if (!$updated) {
                LogService::warning('client_db', 'No se encontró registro en reservas_clientes', [
                    'idreserva_cliente' => $ticketReference,
                    'status' => $status
                ]);
            }
        } catch (\Exception $e) {
            LogService::error('client_db', 'Error actualizando BD del cliente', [
                'ticket_reference' => $ticketReference,
                'status' => $status,
                'error' => $e->getMessage()
            ]);
        }
    }

private function sendWebhook(int $transactionId): void
    {
        $transaction = $this->db->fetchOne(
            "SELECT t.*, c.webhook_url, c.webhook_secret FROM transactions t 
             JOIN api_clients c ON t.client_id = c.id WHERE t.id = :id",
            ['id' => $transactionId]
        );

if (!$transaction || empty($transaction['webhook_url'])) return;

$payload = json_encode([
            'event' => 'payment.updated',
            'transaction_uuid' => $transaction['transaction_uuid'],
            'ticket_reference' => $transaction['ticket_reference'],
            'status' => $transaction['status'],
            'amount' => $transaction['amount'],
            'payment_method' => $transaction['payment_method'],
            'epayco_ref' => $transaction['epayco_ref'],
            'timestamp' => time()
        ]);

$signature = hash_hmac('sha512', $payload, $transaction['webhook_secret'] ?? '');

$this->db->insert('webhook_deliveries', [
            'delivery_uuid' => $this->encryption->generateUuid(),
            'transaction_id' => $transactionId,
            'client_id' => $transaction['client_id'],
            'webhook_url' => $transaction['webhook_url'],
            'payload' => $this->encryption->encrypt($payload),
            'signature' => $signature,
            'status' => 'pending'
        ]);
    }
}

cmd: