public function init_form_fields() {
    $this->form_fields = array(
        'enabled' => array(
            'title' => __('Enable/Disable', 'woocommerce'),
            'type' => 'checkbox',
            'label' => __('Enable Selcom Payments', 'woocommerce'),
            'default' => 'yes'
        ),
        'title' => array(
            'title' => __('Title', 'woocommerce'),
            'type' => 'text',
            'description' => __('This controls the title which the user sees during checkout.', 'woocommerce'),
            'default' => __('Pay via mobile phone or card', 'woocommerce'),
            'desc_tip' => true,
        ),
        'description' => array(
            'title' => __('Customer Message', 'woocommerce'),
            'type' => 'textarea',
            'default' => 'Pay directly from your mobile phone or card',
            'description' => 'This controls the description which the user sees during checkout.',
        ),
        'merchant_id' => array(
            'title' => __('Vendor/Merchant ID', 'woocommerce'),
            'type' => 'text',
            'description' => __('Your merchant id received from Selcom.', $this->id),
            'default' => '',
            'desc_tip' => true,
        ),
        'api_key' => array(
            'title' => __('API Key', 'woocommerce'),
            'type' => 'text',
            'description' => __('Your API Key received from Selcom.', $this->id),
            'default' => '',
            'desc_tip' => true,
        ),
        'secret_key' => array(
            'title' => __('Secret Key', 'woocommerce'),
            'type' => 'text',
            'description' => __('Your Secret Key received from Selcom.', $this->id),
            'default' => '',
            'desc_tip' => true,
        ),
        'api_url' => array(
            'title' => __('API URL', 'woocommerce'),
            'type' => 'text',
            'description' => __('Base URL for Selcom API (e.g., https://apigw.selcommobile.com). Contact Selcom support to confirm.', $this->id),
            'default' => 'https://apigw.selcommobile.com',
            'desc_tip' => true,
        ),
        'prefix' => array(
            'title' => __('Unique Vendor Prefix', 'woocommerce'),
            'type' => 'text',
            'description' => __('Vendor prefix for auto-generated transaction IDs.', $this->id),
            'default' => 'YAT',
            'desc_tip' => true,
        )
    );
}

public function process_payment($order_id) {
    global $woocommerce;

    // Get an instance of the WC_Order object
    $order = new WC_Order($order_id);

    // Selcom API prerequisites
    $apiKey = $this->api_key;
    $apiSecret = $this->api_secret;
    $baseUrl = rtrim($this->api_url, '/'); // Ensure no trailing slash
    $vendorPrefix = $this->prefix;
    date_default_timezone_set('Africa/Dar_es_Salaam');

    // Validate required fields
    if (empty($apiKey) || empty($apiSecret) || empty($this->vendor) || empty($baseUrl)) {
        wc_add_notice(__('Error: Selcom API credentials are not configured correctly.', 'woocommerce'), 'error');
        return array('result' => 'failure');
    }

    // Test API URL reachability with endpoint
    $testUrl = $baseUrl . '/checkout/create-order';
    error_log('Selcom: Testing API URL: ' . $testUrl);
    $headers = array(
        'Authorization' => 'SELCOM ' . base64_encode($apiKey),
        'Accept' => 'application/json',
    );
    $testResponse = wp_remote_get($testUrl, array(
        'timeout' => 5,
        'headers' => $headers,
    ));
    if (is_wp_error($testResponse)) {
        $error_message = $testResponse->get_error_message();
        error_log('Selcom: API URL test failed: ' . $error_message);
        wc_add_notice(__('Error: Cannot connect to Selcom API (' . $error_message . '). Please verify the API URL or contact Selcom support at support@selcom.net.', 'woocommerce'), 'error');
        return array('result' => 'failure');
    }
    $httpCode = wp_remote_retrieve_response_code($testResponse);
    if ($httpCode >= 400) {
        $response_body = wp_remote_retrieve_body($testResponse);
        error_log('Selcom: API URL test failed: HTTP ' . $httpCode . ' | Response: ' . $response_body);
        wc_add_notice(__('Error: Selcom API returned an error (HTTP ' . $httpCode . '). Please verify the API URL or contact Selcom support at support@selcom.net.', 'woocommerce'), 'error');
        return array('result' => 'failure');
    }

    // Log raw phone number
    error_log('Selcom: Raw billing phone from order: ' . $order->get_billing_phone());

    // Order array
    $minOrder = array(
        "vendor" => $this->vendor,
        "order_id" => $order->get_id(),
        "buyer_email" => $order->get_billing_email() ?: 'no-email@selcom.com', // Fallback for guest checkout
        "buyer_name" => trim($order->get_billing_first_name() . " " . $order->get_billing_last_name()),
        "buyer_phone" => '', // Will be set after normalization
        "amount" => (float) $order->get_total(),
        "webhook" => base64_encode(get_site_url() . '/wp-json/selcom-push/v2/selcomstat'),
        "currency" => "TZS",
        "no_of_items" => (int) $woocommerce->cart->cart_contents_count,
        "cancel_url" => base64_encode(get_site_url() . '/checkout'),
        "redirect_url" => base64_encode($this->get_return_url($order)),
        "payment_methods" => "ALL",
        "billing.firstname" => $order->get_billing_first_name() ?: 'Guest',
        "billing.lastname" => $order->get_billing_last_name() ?: 'User',
        "billing.address_1" => $order->get_billing_address_1() ?: 'Unknown',
        "billing.city" => $order->get_billing_city() ?: 'Dar es Salaam',
        "billing.state_or_region" => $order->get_billing_state() ?: 'Dar es Salaam',
        "billing.postcode_or_pobox" => $order->get_billing_postcode() ?: '94103',
        "billing.country" => $order->get_billing_country() ?: 'TZ',
        "billing.phone" => $order->get_billing_phone(),
    );

    // Normalize phone number
    $raw_phone = $order->get_billing_phone();
    $normalized_phone = preg_replace('/[^0-9]/', '', $raw_phone); // Remove non-digits
    if (substr($normalized_phone, 0, 1) === '0') {
        $normalized_phone = '255' . substr($normalized_phone, 1); // Convert 07xx to 2557xx
    } elseif (substr($normalized_phone, 0, 3) === '+255') {
        $normalized_phone = substr($normalized_phone, 1); // Convert +255 to 255
    }
    $minOrder['buyer_phone'] = $normalized_phone;

    // Log webhook URL
    error_log('Selcom: Webhook URL: ' . base64_decode($minOrder['webhook']));

    // Validate order data
    if (empty($minOrder['buyer_phone']) || !preg_match('/^255[0-9]{9}$/', $minOrder['buyer_phone'])) {
        error_log('Selcom: Invalid phone number provided: ' . $raw_phone);
        wc_add_notice(__('Error: Invalid or missing billing phone number. Please enter a valid Tanzanian phone number (e.g., 255123456789).', 'woocommerce'), 'error');
        return array('result' => 'failure');
    }

    // Send Order Request
    error_log('Selcom: Sending order request to: ' . $testUrl);
    $orderResponse = sendOrder($minOrder, $apiKey, $apiSecret, $baseUrl);

    // Log the full API response for debugging
    error_log('Selcom API Response: ' . print_r($orderResponse, true));

    // Based on the order response, continue implementing USSD Push
    if (!isset($orderResponse->result)) {
        $order->update_status('failed', __('Order failed: Invalid API response.', 'woocommerce'));
        wc_add_notice(__('Error: Selcom API returned an invalid response.', 'woocommerce'), 'error');
        return array('result' => 'failure');
    }

    if ($orderResponse->result == 'FAIL') {
        $order->update_status('failed', __('Order not created: ' . ($orderResponse->message ?? 'Unknown error'), 'woocommerce'));
        wc_add_notice(__('Error: ', 'woocommerce') . ($orderResponse->message ?? 'Order could not be created. Please try again or contact support.'), 'error');
        return array('result' => 'failure');
    } elseif ($orderResponse->result == 'SUCCESS') {
        $data1 = (array) $orderResponse->data;
        $data1 = (object) $data1[0];
        $payment_gateway_url = base64_decode($data1->payment_gateway_url);

        $order->update_status('pending', __('Order has been received, waiting for payment.', 'woocommerce'));
        wc_add_notice(__('Update: ', 'woocommerce') . 'Order has been created, waiting for payment completion.', 'success');

        return array(
            'result' => 'success',
            'redirect' => $payment_gateway_url
        );
    } elseif ($orderResponse->result == 'INPROGRESS' || $orderResponse->result == 'AMBIGOUS') {
        // Handle INPROGRESS or AMBIGOUS by scheduling a status check
        $order->update_status('pending', __('Order in progress, awaiting confirmation.', 'woocommerce'));
        wc_add_notice(__('Update: ', 'woocommerce') . 'Order is being processed, please wait.', 'success');

        // Schedule a status check (requires WP-Cron)
        wp_schedule_single_event(time() + 180, 'selcom_check_order_status', array($order->get_id(), $baseUrl, $apiKey, $apiSecret));

        return array(
            'result' => 'success',
            'redirect' => $this->get_return_url($order)
        );
    } else {
        $order->update_status('failed', __('Order failed: ' . ($orderResponse->message ?? 'Unknown error'), 'woocommerce'));
        wc_add_notice(__('Error: ', 'woocommerce') . ($orderResponse->message ?? 'Something went wrong with the order. Please try again.'), 'error');
        return array('result' => 'failure');
    }
}