Cómo integrar Factura Electrónica ARCA (ex AFIP) WSFEv1 en Argentina: creá tu facturador sin programar con MIA (alojado en su propia VPS) o conectalo en PHP 8.4 y WooCommerce

# 1. Generar la clave privada RSA de 2048 bits (proteger con chmod 600)
openssl genrsa -out afip_privada.key 2048
chmod 600 afip_privada.key

# 2. Generar el Certificate Signing Request (CSR) con el formato exacto exigido por ARCA
openssl req -new -key afip_privada.key \
  -subj "/C=AR/O=MiEmpresaSRL/CN=facturador/serialNumber=CUIT 30123456789" \
  -out afip_pedido.csr

<?php
declare(strict_types=1);

final class ArcaFacturador
{
    private string $cuit;
    private string $certPath;
    private string $keyPath;
    private string $cacheDir;
    private bool $production;

    public function __construct(
        string $cuit,
        string $certPath,
        string $keyPath,
        string $cacheDir,
        bool $production = true
    ) {
        $this->cuit       = preg_replace('/\D/', '', $cuit);
        $this->certPath   = $certPath;
        $this->keyPath    = $keyPath;
        $this->cacheDir   = rtrim($cacheDir, '/');
        $this->production = $production;
    }

    /**
     * Obtiene Token y Sign de WSAA reutilizando el caché local durante 12 horas
     */
    public function obtenerTicketAcceso(string $service = 'wsfe'): array
    {
        $taFile = $this->cacheDir . '/ta_' . $service . '_' . ($this->production ? 'prod' : 'homo') . '.xml';

        if (is_file($taFile)) {
            $xml = @simplexml_load_file($taFile);
            if ($xml && isset($xml->header->expirationTime)) {
                $exp = strtotime((string)$xml->header->expirationTime);
                if ($exp > (time() + 600)) {
                    return [
                        'token' => (string)$xml->credentials->token,
                        'sign'  => (string)$xml->credentials->sign,
                    ];
                }
            }
        }

        // Generar TRA (Ticket de Requerimiento de Acceso)
        $traFile = $this->cacheDir . '/tra_' . bin2hex(random_bytes(6)) . '.xml';
        $cmsFile = $traFile . '.cms';
        $now     = time();

        $traXml = '<?xml version="1.0" encoding="UTF-8"?>'
            . '<loginTicketRequest version="1.0">'
            . '<header>'
            . '<uniqueId>' . $now . '</uniqueId>'
            . '<generationTime>' . gmdate('c', $now - 600) . '</generationTime>'
            . '<expirationTime>' . gmdate('c', $now + 600) . '</expirationTime>'
            . '</header>'
            . '<service>' . htmlspecialchars($service, ENT_XML1) . '</service>'
            . '</loginTicketRequest>';

        file_put_contents($traFile, $traXml, LOCK_EX);

        $signed = openssl_pkcs7_sign(
            $traFile,
            $cmsFile,
            'file://' . $this->certPath,
            ['file://' . $this->keyPath, ''],
            [],
            PKCS7_BINARY | PKCS7_NOATTR
        );
        @unlink($traFile);

        if (!$signed) {
            throw new RuntimeException('Error al firmar TRA con OpenSSL: ' . openssl_error_string());
        }

        $cmsRaw   = file_get_contents($cmsFile);
        @unlink($cmsFile);
        $parts    = preg_split("/\r?\n\r?\n/", $cmsRaw, 2);
        $cmsClean = trim($parts[1] ?? '');

        $wsaaWsdl = $this->production
            ? 'https://wsaa.afip.gov.ar/ws/services/LoginCms?WSDL'
            : 'https://wsaahomo.afip.gov.ar/ws/services/LoginCms?WSDL';

        $client = new SoapClient($wsaaWsdl, [
            'soap_version' => SOAP_1_2,
            'exceptions'   => true,
            'trace'        => false,
            'cache_wsdl'   => WSDL_CACHE_DISK,
        ]);

        $response = $client->loginCms(['in0' => $cmsClean]);
        $taXmlStr = (string)$response->loginCmsReturn;
        file_put_contents($taFile, $taXmlStr, LOCK_EX);
        @chmod($taFile, 0600);

        $xml = simplexml_load_string($taXmlStr);
        return [
            'token' => (string)$xml->credentials->token,
            'sign'  => (string)$xml->credentials->sign,
        ];
    }

    /**
     * Autoriza una Factura Electrónica en WSFEv1 (incluye CondicionIVAReceptorId RG 5616)
     * $cbteTipo: 1 = Factura A | 6 = Factura B | 11 = Factura C
     * $condicionIvaReceptor: 1 = Resp. Inscripto | 5 = Consumidor Final | 6 = Monotributo | 4 = Exento
     */
    public function autorizarComprobante(
        int $ptoVta,
        int $cbteTipo,
        int $docTipo,
        int $docNro,
        int $condicionIvaReceptor,
        float $impNeto,
        float $impIva
    ): array {
        $ta = $this->obtenerTicketAcceso('wsfe');
        $wsfeWsdl = $this->production
            ? 'https://servicios1.afip.gov.ar/wsfev1/service.asmx?WSDL'
            : 'https://wswhomo.afip.gov.ar/wsfev1/service.asmx?WSDL';

        $client = new SoapClient($wsfeWsdl, [
            'soap_version' => SOAP_1_2,
            'exceptions'   => true,
            'cache_wsdl'   => WSDL_CACHE_DISK,
        ]);

        $auth = [
            'Token' => $ta['token'],
            'Sign'  => $ta['sign'],
            'Cuit'  => (float)$this->cuit,
        ];

        // 1. Consultar último número de comprobante autorizado
        $ult = $client->FECompUltimoAutorizado([
            'Auth'     => $auth,
            'PtoVta'   => $ptoVta,
            'CbteTipo' => $cbteTipo,
        ]);
        $proximoNro = (int)$ult->FECompUltimoAutorizadoResult->CbteNro + 1;
        $impTotal   = round($impNeto + $impIva, 2);
        $fechaHoy   = date('Ymd');

        // 2. Solicitar CAE en FECAESolicitar
        $det = [
            'Concepto'               => 1, // 1 = Productos, 2 = Servicios, 3 = Productos y Servicios
            'DocTipo'                => $docTipo, // 80 = CUIT, 96 = DNI, 99 = Consumidor Final
            'DocNro'                 => $docNro,
            'CbteDesde'              => $proximoNro,
            'CbteHasta'              => $proximoNro,
            'CbteFch'                => $fechaHoy,
            'ImpTotal'               => $impTotal,
            'ImpTotConc'             => 0.00,
            'ImpNeto'                => round($impNeto, 2),
            'ImpOpEx'                => 0.00,
            'ImpTrib'                => 0.00,
            'ImpIVA'                 => round($impIva, 2),
            'MonId'                  => 'PES',
            'MonCotiz'               => 1.00,
            'CondicionIVAReceptorId' => $condicionIvaReceptor, // Obligatorio RG 5616
        ];

        if ($impIva > 0) {
            $det['Iva'] = [
                'AlicIva' => [
                    [
                        'Id'      => 5, // 5 = 21%, 4 = 10.5%, 6 = 27%
                        'BaseImp' => round($impNeto, 2),
                        'Importe' => round($impIva, 2),
                    ]
                ]
            ];
        }

        $res = $client->FECAESolicitar([
            'Auth'      => $auth,
            'FeCAEReq'  => [
                'FeCabReq' => [
                    'CantReg'  => 1,
                    'PtoVta'   => $ptoVta,
                    'CbteTipo' => $cbteTipo,
                ],
                'FeDetReq' => [
                    'FECAEDetRequest' => [$det],
                ],
            ],
        ]);

        $detResp = $res->FECAESolicitarResult->FeDetResp->FECAEDetResponse;
        if (is_array($detResp)) {
            $detResp = $detResp[0];
        }

        if (($detResp->Resultado ?? 'R') !== 'A') {
            throw new RuntimeException('Comprobante rechazado por ARCA: ' . json_encode($res->FECAESolicitarResult));
        }

        $cae    = (string)$detResp->CAE;
        $caeVto = (string)$detResp->CAEFchVto;

        // 3. Generar URL del Código QR oficial RG 4892
        $qrPayload = [
            'ver'        => 1,
            'fecha'      => date('Y-m-d'),
            'cuit'       => (int)$this->cuit,
            'ptoVta'     => $ptoVta,
            'tipoCmp'    => $cbteTipo,
            'nroCmp'     => $proximoNro,
            'importe'    => $impTotal,
            'moneda'     => 'PES',
            'ctz'        => 1,
            'tipoDocRec' => $docTipo,
            'nroDocRec'  => $docNro,
            'tipoCodAut' => 'E',
            'codAut'     => (int)$cae,
        ];
        $qrUrl = 'https://www.afip.gob.ar/fe/qr/?p=' . base64_encode(json_encode($qrPayload, JSON_UNESCAPED_SLASHES));

        return [
            'nro_comprobante' => $proximoNro,
            'cae'             => $cae,
            'cae_vencimiento' => $caeVto,
            'qr_url_oficial'  => $qrUrl,
        ];
    }
}