public function process_payment( $order_id ) {
    $order = wc_get_order( $order_id );

    // 1) Monta array de produtos com subtotal da linha
    $items    = $order->get_items();
    $products = array();
    foreach ( $items as $item_id => $item ) {
        $product_id   = $item->get_product_id();
        $product_name = $item->get_name();
        $quantity     = intval( $item->get_quantity() );
        
        // Subtotal da linha (quantidade × preço unitário)
        $line_subtotal = floatval( $order->get_line_subtotal( $item, false ) );
        
        $products[]   = array(
            'id'       => (string) $product_id,
            'name'     => $product_name,
            'quantity' => $quantity,
            'price'    => $line_subtotal, // Subtotal da linha
        );
    }

    // 2) Recupera e sanitiza CPF (somente dígitos)
    $raw_document   = isset( $_POST['billing_cpf'] ) ? wc_clean( $_POST['billing_cpf'] ) : '';
    $documentDigits = preg_replace( '/\D/', '', $raw_document );

    // 3) Calcula valores do pedido
    $subtotal     = floatval( $order->get_subtotal() );           // R$ 319,92
    $total        = floatval( $order->get_total() );              // R$ 271,93
    $shipping_fee = floatval( $order->get_shipping_total() );     // R$ 0,00
    $discount     = $subtotal - $total + $shipping_fee;           // R$ 47,99
    
    // 4) Monta o payload - Testando diferentes abordagens
    $payload = array(
        'identifier'  => $this->generate_identifier(),
        'amount'      => $subtotal,        // Subtotal dos produtos
        'shippingFee' => $shipping_fee,    // Taxa de entrega
        'extraFee'    => 0.0,
        'discount'    => $discount,        // Desconto aplicado
        'client'      => array(
            'name'     => $order->get_billing_first_name() . ' ' . $order->get_billing_last_name(),
            'email'    => $order->get_billing_email(),
            'phone'    => $order->get_billing_phone(),
            'document' => $documentDigits,
        ),
        'products'    => $products,
        'splits'      => array(),
        'dueDate'     => date( 'Y-m-d', strtotime( '+' . apply_filters( 'wc_safirapay_pix_due_days', 1 ) . ' days' ) ),
        'metadata'    => new stdClass(),
        'callbackUrl' => esc_url_raw( $this->get_return_url( $order ) ),
    );

    $json_payload = wp_json_encode( $payload, JSON_UNESCAPED_UNICODE );
    $endpoint     = 'https://app.safirapag.com/api/v1/gateway/pix/receive';

    // 5) Debug detalhado
    $debug_info = array(
        'order_id' => $order_id,
        'subtotal_wc' => $subtotal,
        'total_wc' => $total,
        'shipping_wc' => $shipping_fee,
        'discount_calculated' => $discount,
        'validation' => array(
            'subtotal_minus_discount_plus_shipping' => ($subtotal - $discount + $shipping_fee),
            'should_equal_total' => $total,
            'matches' => (abs(($subtotal - $discount + $shipping_fee) - $total) < 0.01) ? 'YES' : 'NO'
        ),
        'payload' => $payload
    );
    
    $debug_path = ABSPATH . 'safirapay_debug.txt';
    file_put_contents( $debug_path, "=== TENTATIVA " . date('Y-m-d H:i:s') . " ===\n" . print_r($debug_info, true) . "\n\n", FILE_APPEND );

    // 6) Chamada à API
    $args = array(
        'method'      => 'POST',
        'timeout'     => 45,
        'headers'     => array(
            'Content-Type' => 'application/json',
            'x-public-key' => $this->public_key,
            'x-secret-key' => $this->secret_key,
        ),
        'body'        => $json_payload,
    );

    $response  = wp_remote_post( $endpoint, $args );
    $http_code = wp_remote_retrieve_response_code( $response );
    $body      = wp_remote_retrieve_body( $response );
    $result    = json_decode( $body, true );

    // 7) Log da resposta da API
    file_put_contents( ABSPATH . 'safirapay_response.txt', 
        "=== RESPONSE " . date('Y-m-d H:i:s') . " ===\n" . 
        "HTTP Code: " . $http_code . "\n" .
        "Response: " . $body . "\n\n", 
        FILE_APPEND 
    );

    // 8) Verifica erros de conexão
    if ( is_wp_error( $response ) ) {
        if ( $this->logging ) {
            error_log( 'Erro SafiraPay PIX (WP_Error): ' . $response->get_error_message() );
        }
        wc_add_notice( __( 'SafiraPay PIX falhou: Problema de conexão.', 'wc-safirapay' ), 'error' );
        return array( 'result' => 'failure' );
    }

    // 9) Aceita HTTP 200 OU 201 como sucesso
    if ( $http_code !== 200 && $http_code !== 201 ) {
        if ( $this->logging ) {
            error_log( sprintf( 'Erro SafiraPay PIX – HTTP Code: %s', $http_code ) );
            error_log( sprintf( 'Erro SafiraPay PIX – Response body: %s', $body ) );
        }

        $mensagem = 'SafiraPay PIX falhou: ';
        if ( isset( $result['errorCode'] ) && isset( $result['message'] ) ) {
            $mensagem .= $result['errorCode'] . ' – ' . $result['message'];
            if ( isset( $result['details'] ) ) {
                file_put_contents( ABSPATH . 'pix_error_details.txt', print_r( $result['details'], true ) );
                $mensagem .= ' Detalhes: ' . wp_json_encode( $result['details'] );
            }
        } else {
            $mensagem .= 'Erro genérico ao criar cobrança PIX.';
        }
        wc_add_notice( $mensagem, 'error' );
        return array( 'result' => 'failure' );
    }

    // 10) Sucesso
    update_post_meta( $order_id, '_safirapay_pix_response', $result );
    $order->update_status( 'on-hold', __( 'Aguardando pagamento PIX', 'wc-safirapay' ) );
    wc_reduce_stock_levels( $order_id );
    WC()->cart->empty_cart();

    return array(
        'result'   => 'success',
        'redirect' => $this->get_return_url( $order ),
    );
}