<?php

/**
 * WHMCS hooks for the VirtFusion module.
 *
 * HOW HOOKS WORK IN WHMCS
 * -----------------------
 * add_hook('EventName', $priority, $callback) registers $callback to fire on
 * the named event. WHMCS discovers hook files by walking modules/servers/*
 * /hooks.php and modules/addons/* /hooks.php on every page load, then invokes
 * every registered hook for the current event.
 *
 * Hooks run IN-REQUEST — there's no queue or background worker. Anything
 * expensive in a hook (like an external API call) blocks the user's page
 * load. For that reason we only do:
 *   - Fast in-process work (building DOM snippets, validating session state)
 *   - Scheduled work on DailyCronJob where "in-request" means the cron worker,
 *     not a user session
 *
 * HOOKS REGISTERED HERE
 * ---------------------

 *   DailyCronJob                — PowerDNS reconciliation across all services
 *   AfterCronJob                — Every-2-hour stock recalculation safety net
 *   AfterModuleCreate           — Stock refresh + order auto-accept after a VPS provisions
 *   AfterModuleTerminate        — Stock refresh after a VPS is destroyed
 *   ClientAreaPageCart          — Lazy per-product stock refresh during the order flow
 *   ShoppingCartValidateCheckout — blocks checkout until OS is selected
 *   ClientAreaFooterOutput      — injects the OS/SSH-key gallery on order form
 *
 * FAILURE SEMANTICS
 * -----------------
 * Every hook wraps its body in try/catch and silently absorbs any exception.
 * A hook that throws would potentially break the entire WHMCS request for
 * all users, not just this module — so we log and swallow, preferring
 * degraded functionality over site-wide breakage.
 */

use WHMCS\Database\Capsule;
use WHMCS\Module\Server\VirtFusionDirect\Cache;
use WHMCS\Module\Server\VirtFusionDirect\ConfigureService;
use WHMCS\Module\Server\VirtFusionDirect\Database;
use WHMCS\Module\Server\VirtFusionDirect\Log;
use WHMCS\Module\Server\VirtFusionDirect\Module;
use WHMCS\Module\Server\VirtFusionDirect\PowerDns\Config as PowerDnsConfig;
use WHMCS\Module\Server\VirtFusionDirect\PowerDns\PtrManager;
use WHMCS\Module\Server\VirtFusionDirect\StockControl;

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

/**
 * Daily PowerDNS reconciliation.
 *
 * Walks every managed service and creates any missing PTRs (never overwrites existing
 * values — cron is additive-only). Requires the VirtFusion DNS addon to be activated
 * and enabled; otherwise short-circuits immediately.
 *
 * All error handling lives inside reconcileAll(); this wrapper just logs any escape
 * without disturbing the rest of the daily cron run.
 */
add_hook('DailyCronJob', 1, function ($vars) {
    try {
        if (PowerDnsConfig::isEnabled()) {
            (new PtrManager)->reconcileAll();
        }
    } catch (Throwable $e) {
        Log::insert('PowerDns:DailyCronJob', [], $e->getMessage());
    }
});

/**
 * Every-~2-hour stock recalculation safety net.
 *
 * Events (AfterModuleCreate/Terminate) cover every capacity change driven
 * through WHMCS. But an operator can also create/destroy VMs directly in the
 * VirtFusion panel — no WHMCS hook fires for that, so stock qty would drift
 * until the next cart-page visit or the next event-driven refresh. This hook
 * closes that blind spot.
 *
 * AfterCronJob fires on every main WHMCS cron invocation (typically every
 * 5 minutes). Cache::get on the rate-limit key means the hook is effectively
 * free on the 99% of invocations where no recalc is due — one cache read,
 * return. The actual recalc only runs when the key has expired.
 *
 * Interval: 2 hours. Tunable via the STOCK_CRON_INTERVAL_SECONDS constant
 * below. Short enough that out-of-band VirtFusion panel changes surface the
 * same business day; long enough that the storefront isn't writing
 * tblproducts.qty every five minutes.
 *
 * FAIL-SAFE: StockControl::recalculateAll() returns a map of productId =>
 * qty|null, where null means the orchestrator left qty UNTOUCHED (transient
 * API failure, missing CP, etc.). Our catch here only fires on truly unexpected
 * errors that escape the orchestrator itself.
 */
const STOCK_CRON_INTERVAL_SECONDS = 2 * 3600;   // 2 hours

add_hook('AfterCronJob', 5, function ($vars) {
    try {
        $rateKey = 'stockrefresh:cron';
        if (Cache::get($rateKey) !== null) {
            return;
        }
        Cache::set($rateKey, 1, STOCK_CRON_INTERVAL_SECONDS);

        (new StockControl)->recalculateAll();
    } catch (Throwable $e) {
        Log::insert('StockControl:AfterCronJob', [], $e->getMessage());
    }
});

/**
 * Post-provision: auto-accept the originating order and refresh stock.
 *
 * Fires after every successful VirtFusion CreateAccount. Two responsibilities,
 * independent try/catch blocks so a failure in one doesn't short-circuit the other:
 *
 *   1. AUTO-ACCEPT — if the service's parent order is still 'Pending' (admin
 *      hasn't manually accepted yet), call WHMCS's AcceptOrder API with
 *      autosetup=false (we already provisioned, don't re-trigger CreateAccount).
 *      This closes the loop for installs that rely on pending-order workflows
 *      for non-VF products but want VF provisions to auto-advance.
 *
 *   2. STOCK REFRESH — a new VM just consumed memory/cpu/disk/IPv4 on the
 *      target hypervisor group. Bust the grpres:{id} cache and recalculate
 *      every stock-controlled product. A shared 30 s rate-limit key prevents
 *      a burst of 10 parallel provisions from triggering 10 full recalcs.
 *
 * Filtering by moduletype='VirtFusionDirect' keeps this hook harmless for
 * unrelated products that happen to share the WHMCS install.
 */
add_hook('AfterModuleCreate', 1, function ($vars) {
    if (($vars['params']['moduletype'] ?? '') !== 'VirtFusionDirect') {
        return;
    }

    // Part 1: auto-accept the originating order if still Pending.
    try {
        $serviceId = (int) ($vars['params']['serviceid'] ?? 0);
        if ($serviceId > 0) {
            $hosting = Capsule::table('tblhosting')->where('id', $serviceId)->first();
            $orderId = $hosting ? (int) ($hosting->orderid ?? 0) : 0;
            if ($orderId > 0) {
                $order = Capsule::table('tblorders')->where('id', $orderId)->first();
                if ($order && strcasecmp((string) $order->status, 'Pending') === 0) {
                    $resp = localAPI('AcceptOrder', [
                        'orderid' => $orderId,
                        'autosetup' => false,   // already provisioned; don't re-run CreateAccount
                        'sendemail' => true,
                    ]);
                    Log::insert(
                        'AutoAcceptOrder',
                        ['orderid' => $orderId, 'serviceid' => $serviceId],
                        $resp,
                    );
                }
            }
        }
    } catch (Throwable $e) {
        Log::insert('AutoAcceptOrder:fail', ['serviceID' => $vars['params']['serviceid'] ?? null], $e->getMessage());
    }

    // Part 2: refresh stock (capacity just decreased).
    try {
        if (Cache::get('stockrefresh:event') === null) {
            Cache::set('stockrefresh:event', 1, 30);

            $groupId = (int) ($vars['params']['configoption1'] ?? 0);
            if ($groupId > 0) {
                Cache::forget('grpres:' . $groupId);
            }

            (new StockControl)->recalculateAll();
        }
    } catch (Throwable $e) {
        Log::insert('StockControl:AfterModuleCreate', ['serviceID' => $vars['params']['serviceid'] ?? null], $e->getMessage());
    }
});

/**
 * Post-termination stock refresh.
 *
 * A destroyed VM just freed memory/cpu/disk/IPv4 on the target hypervisor group.
 * Refresh so the storefront reflects the restored capacity immediately. Shares
 * the 30 s rate-limit key with AfterModuleCreate — a provision-then-terminate in
 * quick succession only triggers one full recalc.
 */
add_hook('AfterModuleTerminate', 1, function ($vars) {
    if (($vars['params']['moduletype'] ?? '') !== 'VirtFusionDirect') {
        return;
    }

    try {
        if (Cache::get('stockrefresh:event') !== null) {
            return;
        }
        Cache::set('stockrefresh:event', 1, 30);

        $groupId = (int) ($vars['params']['configoption1'] ?? 0);
        if ($groupId > 0) {
            Cache::forget('grpres:' . $groupId);
        }

        (new StockControl)->recalculateAll();
    } catch (Throwable $e) {
        Log::insert('StockControl:AfterModuleTerminate', ['serviceID' => $vars['params']['serviceid'] ?? null], $e->getMessage());
    }
});

/**
 * Lazy stock refresh on order-flow cart pages.
 *
 * Keeps "hot" products fresh between daily cron runs without a polling loop: when a
 * customer lands on a cart page for a specific product, we opportunistically recalculate
 * that product's qty. If the upstream grpres:{id} cache is warm (populated in the last
 * 120 s by an earlier view or the daily cron), recalculateForProduct does no HTTP calls
 * and just re-writes the same qty — effectively free.
 *
 * WHY ClientAreaPageCart (not ClientAreaPageProductDetails)
 * ---------------------------------------------------------
 * ClientAreaPageProductDetails fires on the My Services → product-details view for an
 * EXISTING service, which is the wrong place — the stock number only matters during
 * pre-order. ClientAreaPageCart fires on every cart/order page (product browse, config,
 * checkout) and WHMCS consults tblproducts.qty on each of those, so this is where a
 * fresh number pays off.
 *
 * RATE LIMIT
 * ----------
 * 60 s per product (stockrefresh:{pid}). Short enough that a busy product refreshes
 * near-continuously across viewers; long enough that two customers arriving within the
 * same second don't trigger two identical DB UPDATEs. The pid check below filters this
 * hook to only fire when a specific product is known — generic cart pages (templatefile=
 * "cart.tpl") pass no pid and are no-ops.
 */
add_hook('ClientAreaPageCart', 1, function ($vars) {
    try {
        $productId = (int) ($vars['pid'] ?? $vars['productid'] ?? ($vars['productinfo']['pid'] ?? 0));
        if ($productId <= 0) {
            return null;
        }

        $rateKey = 'stockrefresh:' . $productId;
        if (Cache::get($rateKey) !== null) {
            return null;
        }
        Cache::set($rateKey, 1, 60);

        (new StockControl)->recalculateForProduct($productId);
    } catch (Throwable $e) {
        Log::insert('StockControl:ClientAreaPageCart', ['pid' => $vars['pid'] ?? null], $e->getMessage());
    }

    return null;
});

/**
 * Shopping Cart Validation Hook
 *
 * Validates that an operating system has been selected before checkout
 * for all VirtFusion products in the cart.
 */
add_hook('ShoppingCartValidateCheckout', 1, function ($vars) {
    $errors = [];

    try {
        if (! isset($_SESSION['cart']['products']) || ! is_array($_SESSION['cart']['products'])) {
            return $errors;
        }

        foreach ($_SESSION['cart']['products'] as $key => $product) {
            $pid = $product['pid'] ?? null;
            if (! $pid) {
                continue;
            }

            $dbProduct = Capsule::table('tblproducts')
                ->where('id', $pid)
                ->where('servertype', 'VirtFusionDirect')
                ->first();

            if (! $dbProduct) {
                continue;
            }

            // Check if Initial Operating System custom field has a value
            if (isset($product['customfields']) && is_array($product['customfields'])) {
                $osSelected = false;
                $customFields = Capsule::table('tblcustomfields')
                    ->where('relid', $pid)
                    ->where('type', 'product')
                    ->get();

                foreach ($customFields as $field) {
                    if (strtolower(str_replace(' ', '', $field->fieldname)) === 'initialoperatingsystem') {
                        $fieldValue = $product['customfields'][$field->id] ?? '';
                        if (! empty($fieldValue) && is_numeric($fieldValue)) {
                            $osSelected = true;
                        }
                        break;
                    }
                }

                if (! $osSelected) {
                    $errors[] = 'Please select an Operating System for your VPS order.';
                }
            }
        }
    } catch (Exception $e) {
        // Don't block checkout on internal errors
    }

    return $errors;
});

/**
 * Client Area Footer Output Hook
 *
 * Dynamically converts hidden text fields for OS templates and SSH keys
 * into dropdown selects populated from the VirtFusion API.
 * Works with all WHMCS themes by using vanilla JavaScript and standard form-control classes.
 */
add_hook('ClientAreaFooterOutput', 1, function ($vars) {
    if (! isset($vars['productinfo']['module']) || $vars['productinfo']['module'] !== 'VirtFusionDirect') {
        return null;
    }

    try {
        $cs = new ConfigureService;

        $templates_data = $cs->fetchTemplates(
            $cs->fetchPackageByDbId($vars['productinfo']['pid']) ?? $cs->fetchPackageId($vars['productinfo']['name']),
        );

        if (empty($templates_data)) {
            return null;
        }

        $vfServer = Capsule::table('tblservers')
            ->where('type', 'VirtFusionDirect')
            ->where('disabled', 0)
            ->first();
        $baseUrl = $vfServer ? rtrim('https://' . $vfServer->hostname, '/') : '';

        $galleryData = [
            'baseUrl' => $baseUrl,
            'categories' => Module::groupOsTemplates($templates_data['data'] ?? [], true),
        ];

        $sshKeys = [];
        $sshKeysOptions = [];
        if (isset($vars['loggedinuser']) && $vars['loggedinuser']) {
            $sshKeysData = $cs->getUserSshKeys($vars['loggedinuser']);
            if ($sshKeysData && isset($sshKeysData['data'])) {
                $sshKeysOptions = array_values(array_filter(array_map(function ($sshKey) {
                    if ($sshKey['enabled'] === false) {
                        return null;
                    }

                    return [
                        'id' => $sshKey['id'],
                        'name' => htmlspecialchars($sshKey['name'], ENT_QUOTES, 'UTF-8'),
                    ];
                }, $sshKeysData['data'])));
            }
        }

        $osID = array_values(array_filter(array_map(function ($option) {
            if ($option['textid'] === 'initialoperatingsystem') {
                return $option['id'];
            }
        }, $vars['customfields'] ?? [])));

        $sshID = array_values(array_filter(array_map(function ($option) {
            if ($option['textid'] === 'initialsshkey') {
                return $option['id'];
            }
        }, $vars['customfields'] ?? [])));

        $osFieldId = $osID[0] ?? null;
        $sshFieldId = $sshID[0] ?? null;

        if ($osFieldId === null) {
            return null;
        }

        $systemUrl = Database::getSystemUrl();

        return '
    <link href="' . htmlspecialchars($systemUrl, ENT_QUOTES, 'UTF-8') . 'modules/servers/VirtFusionDirect/templates/css/module.css?v=' . time() . '" rel="stylesheet">
    <script src="' . htmlspecialchars($systemUrl, ENT_QUOTES, 'UTF-8') . 'modules/servers/VirtFusionDirect/templates/js/keygen.js?v=' . time() . "\"></script>
    <script>
    document.addEventListener('DOMContentLoaded', function() {
        var osGalleryData = " . json_encode($galleryData, JSON_THROW_ON_ERROR | JSON_HEX_TAG | JSON_HEX_AMP | JSON_HEX_APOS | JSON_HEX_QUOT) . ';
        var sshKeys = ' . json_encode($sshKeysOptions, JSON_THROW_ON_ERROR | JSON_HEX_TAG | JSON_HEX_AMP | JSON_HEX_APOS | JSON_HEX_QUOT) . ";

        var osInputField = document.querySelector('[name=\"customfield[" . (int) $osFieldId . "]\"]');
        var sshInputField = " . ($sshFieldId !== null ? "document.querySelector('[name=\"customfield[" . (int) $sshFieldId . "]\"]')" : 'null') . ';
        var sshInputLabel = ' . ($sshFieldId !== null ? "document.querySelector('[for=\"customfield" . (int) $sshFieldId . "\"]')" : 'null') . ";

        if (!osInputField) return;

        // Brand color map (must match vfOsBrandColors in module.js)
        var brandColors = {
            'ubuntu':'#E95420','debian':'#A81D33','rocky':'#10B981','centos':'#932279',
            'almalinux':'#0F4266','alma':'#0F4266','windows':'#0078D4','fedora':'#51A2DA',
            'arch':'#1793D1','opensuse':'#73BA25','suse':'#73BA25','freebsd':'#AB2B28',
            'oracle':'#F80000','rhel':'#EE0000','red hat':'#EE0000','cloudlinux':'#0095D9',
            'gentoo':'#54487A','slackware':'#000','nixos':'#7EBAE4','alpine':'#0D597F'
        };
        function getBrandColor(name) {
            var l = (name || '').toLowerCase();
            for (var k in brandColors) { if (l.indexOf(k) !== -1) return brandColors[k]; }
            return '#6c757d';
        }

        // Build gallery container
        var galleryWrap = document.createElement('div');
        galleryWrap.style.marginTop = '8px';

        var searchInput = document.createElement('input');
        searchInput.type = 'text';
        searchInput.className = 'form-control vf-os-search';
        searchInput.placeholder = 'Search templates...';
        galleryWrap.appendChild(searchInput);

        var galleryContainer = document.createElement('div');
        galleryContainer.setAttribute('id', 'vf-checkout-os-gallery');
        galleryContainer.style.marginTop = '8px';

        if (osGalleryData.categories && osGalleryData.categories.length > 0) {
            osGalleryData.categories.forEach(function(cat, ci) {
                var section = document.createElement('div');
                section.className = 'vf-os-category';

                var header = document.createElement('div');
                header.className = 'vf-os-category-header';
                var catColor = getBrandColor(cat.name);

                var catIcon = document.createElement('span');
                catIcon.className = 'vf-os-category-icon';
                if (cat.icon && osGalleryData.baseUrl) {
                    var catImg = document.createElement('img');
                    catImg.src = osGalleryData.baseUrl + '/img/logo/' + encodeURIComponent(cat.icon);
                    catImg.alt = '';
                    catImg.onerror = function() { this.parentNode.style.background = catColor; this.parentNode.textContent = (cat.name || '?')[0].toUpperCase(); };
                    catIcon.appendChild(catImg);
                } else if (cat.name === 'Other') {
                    catIcon.style.background = '#6c757d';
                    catIcon.innerHTML = '<svg width=\"16\" height=\"16\" viewBox=\"0 0 16 16\" fill=\"#fff\"><path d=\"M3 2a1 1 0 0 0-1 1v10a1 1 0 0 0 1 1h10a1 1 0 0 0 1-1V3a1 1 0 0 0-1-1H3zm1 2h8v2H4V4zm0 3h8v1H4V7zm0 2h5v1H4V9z\"/></svg>';
                } else {
                    catIcon.style.background = catColor;
                    catIcon.textContent = (cat.name || '?')[0].toUpperCase();
                }

                var catTitle = document.createElement('span');
                catTitle.textContent = cat.name + ' (' + cat.templates.length + ')';

                var arrow = document.createElement('span');
                arrow.className = 'vf-os-category-arrow';
                arrow.textContent = ci === 0 ? '\u25BC' : '\u25B6';

                header.appendChild(catIcon);
                header.appendChild(catTitle);
                header.appendChild(arrow);
                section.appendChild(header);

                var grid = document.createElement('div');
                grid.className = 'vf-os-grid';
                if (ci !== 0) grid.style.display = 'none';

                header.addEventListener('click', function() {
                    var isOpen = grid.style.display !== 'none';
                    // Collapse all
                    galleryContainer.querySelectorAll('.vf-os-grid').forEach(function(g) { g.style.display = 'none'; });
                    galleryContainer.querySelectorAll('.vf-os-category-arrow').forEach(function(a) { a.textContent = '\u25B6'; });
                    // Toggle this one
                    if (!isOpen) {
                        grid.style.display = '';
                        arrow.textContent = '\u25BC';
                    }
                });

                cat.templates.forEach(function(tpl) {
                    var fullLabel = tpl.name + (tpl.version ? ' ' + tpl.version : '') + (tpl.variant ? ' ' + tpl.variant : '');
                    var card = document.createElement('div');
                    card.className = 'vf-os-card' + (tpl.eol ? ' vf-os-card-eol' : '');
                    card.setAttribute('data-id', tpl.id);
                    card.setAttribute('data-search', fullLabel.toLowerCase());

                    var iconDiv = document.createElement('div');
                    iconDiv.className = 'vf-os-icon';
                    if (tpl.icon && osGalleryData.baseUrl) {
                        var tplImg = document.createElement('img');
                        tplImg.src = osGalleryData.baseUrl + '/img/logo/' + encodeURIComponent(tpl.icon);
                        tplImg.alt = '';
                        tplImg.onerror = function() { this.parentNode.style.background = catColor; this.parentNode.textContent = ''; var s = document.createElement('span'); s.textContent = (tpl.name || '?')[0].toUpperCase(); this.parentNode.appendChild(s); };
                        iconDiv.appendChild(tplImg);
                    } else {
                        iconDiv.style.background = catColor;
                        var sp = document.createElement('span');
                        sp.textContent = (tpl.name || '?')[0].toUpperCase();
                        iconDiv.appendChild(sp);
                    }
                    card.appendChild(iconDiv);

                    var labelDiv = document.createElement('div');
                    labelDiv.className = 'vf-os-label';
                    labelDiv.textContent = tpl.name;
                    card.appendChild(labelDiv);

                    var verDiv = document.createElement('div');
                    verDiv.className = 'vf-os-version';
                    verDiv.textContent = (tpl.version || '') + (tpl.variant ? ' ' + tpl.variant : '');
                    card.appendChild(verDiv);

                    if (tpl.eol) {
                        var eolBadge = document.createElement('span');
                        eolBadge.className = 'vf-os-eol-badge';
                        eolBadge.textContent = 'EOL';
                        card.appendChild(eolBadge);
                    }

                    card.addEventListener('click', function() {
                        galleryContainer.querySelectorAll('.vf-os-card').forEach(function(c) { c.classList.remove('vf-os-card-selected'); });
                        card.classList.add('vf-os-card-selected');
                        osInputField.value = tpl.id;
                        galleryContainer.style.borderColor = '';
                    });

                    grid.appendChild(card);
                });

                section.appendChild(grid);
                galleryContainer.appendChild(section);
            });
        }

        galleryWrap.appendChild(galleryContainer);

        // Search handler
        searchInput.addEventListener('keyup', function() {
            var q = this.value.toLowerCase();
            galleryContainer.querySelectorAll('.vf-os-card').forEach(function(c) {
                c.style.display = c.getAttribute('data-search').indexOf(q) !== -1 ? '' : 'none';
            });
            galleryContainer.querySelectorAll('.vf-os-category').forEach(function(s) {
                var cards = s.querySelectorAll('.vf-os-card');
                var hasVisible = false;
                cards.forEach(function(c) { if (c.style.display !== 'none') hasVisible = true; });
                s.style.display = hasVisible ? '' : 'none';
            });
        });

        // Validation: red border if no selection on form submit
        var form = osInputField.closest('form');
        if (form) {
            form.addEventListener('submit', function(e) {
                if (!osInputField.value) {
                    galleryContainer.style.border = '2px solid #dc3545';
                    galleryContainer.style.borderRadius = '8px';
                    galleryContainer.style.padding = '4px';
                    galleryContainer.scrollIntoView({behavior: 'smooth', block: 'center'});
                }
            });
        }

        osInputField.parentNode.insertBefore(galleryWrap, osInputField.nextSibling);
        osInputField.style.display = 'none';

        // Handle SSH keys
        if (sshInputField) {
            // Create the paste-key textarea (hidden initially if keys exist)
            var sshPasteContainer = document.createElement('div');
            sshPasteContainer.setAttribute('id', 'vf-ssh-paste-container');
            sshPasteContainer.style.display = 'none';
            sshPasteContainer.style.marginTop = '8px';

            var pasteLabel = document.createElement('label');
            pasteLabel.textContent = 'Paste your SSH public key:';
            pasteLabel.style.display = 'block';
            pasteLabel.style.marginBottom = '4px';

            var pasteArea = document.createElement('textarea');
            pasteArea.className = 'form-control';
            pasteArea.setAttribute('id', 'vf-ssh-paste');
            pasteArea.setAttribute('rows', '3');
            pasteArea.setAttribute('placeholder', 'ssh-rsa AAAA... or ssh-ed25519 AAAA...');

            pasteArea.addEventListener('input', function() {
                sshInputField.value = this.value.trim();
            });

            sshPasteContainer.appendChild(pasteLabel);
            sshPasteContainer.appendChild(pasteArea);

            // Generate key button
            var generateBtn = document.createElement('button');
            generateBtn.type = 'button';
            generateBtn.className = 'btn btn-outline-secondary btn-sm';
            generateBtn.textContent = 'Generate a new key';
            generateBtn.style.marginTop = '8px';

            // Private key panel (hidden initially)
            var privKeyPanel = document.createElement('div');
            privKeyPanel.setAttribute('id', 'vf-privkey-panel');
            privKeyPanel.style.display = 'none';
            privKeyPanel.style.marginTop = '12px';
            privKeyPanel.style.border = '2px solid #dc3545';
            privKeyPanel.style.borderRadius = '6px';
            privKeyPanel.style.padding = '12px';

            var privKeyWarning = document.createElement('div');
            privKeyWarning.style.color = '#dc3545';
            privKeyWarning.style.fontWeight = 'bold';
            privKeyWarning.style.marginBottom = '8px';
            privKeyWarning.textContent = 'Private Key — Save This Now! It will not be shown again.';

            var privKeyArea = document.createElement('textarea');
            privKeyArea.className = 'form-control';
            privKeyArea.setAttribute('rows', '6');
            privKeyArea.setAttribute('readonly', 'readonly');
            privKeyArea.style.fontFamily = 'monospace';
            privKeyArea.style.fontSize = '12px';
            privKeyArea.style.marginBottom = '8px';

            var privKeyBtnRow = document.createElement('div');
            privKeyBtnRow.style.display = 'flex';
            privKeyBtnRow.style.gap = '8px';
            privKeyBtnRow.style.alignItems = 'center';
            privKeyBtnRow.style.flexWrap = 'wrap';

            var downloadBtn = document.createElement('button');
            downloadBtn.type = 'button';
            downloadBtn.className = 'btn btn-primary btn-sm';
            downloadBtn.textContent = 'Download';

            var copyBtn = document.createElement('button');
            copyBtn.type = 'button';
            copyBtn.className = 'btn btn-default btn-secondary btn-sm';
            copyBtn.textContent = 'Copy to Clipboard';

            var pubKeyConfirm = document.createElement('span');
            pubKeyConfirm.style.color = '#28a745';
            pubKeyConfirm.style.fontWeight = 'bold';
            pubKeyConfirm.textContent = 'Public key set automatically.';

            privKeyBtnRow.appendChild(downloadBtn);
            privKeyBtnRow.appendChild(copyBtn);
            privKeyBtnRow.appendChild(pubKeyConfirm);
            privKeyPanel.appendChild(privKeyWarning);
            privKeyPanel.appendChild(privKeyArea);
            privKeyPanel.appendChild(privKeyBtnRow);

            downloadBtn.addEventListener('click', function() {
                vfDownloadFile('id_ed25519', privKeyArea.value);
            });

            copyBtn.addEventListener('click', function() {
                navigator.clipboard.writeText(privKeyArea.value).then(function() {
                    copyBtn.textContent = 'Copied!';
                    setTimeout(function() { copyBtn.textContent = 'Copy to Clipboard'; }, 2000);
                });
            });

            // Error message for unsupported browsers
            var genErrorMsg = document.createElement('div');
            genErrorMsg.style.display = 'none';
            genErrorMsg.style.marginTop = '8px';
            genErrorMsg.style.color = '#dc3545';
            genErrorMsg.textContent = 'Your browser does not support Ed25519 key generation. Please paste your public key manually.';

            generateBtn.addEventListener('click', async function() {
                generateBtn.disabled = true;
                generateBtn.textContent = 'Generating...';
                try {
                    var keys = await vfGenerateSSHKey();
                    var sshSelect = document.getElementById('vf-ssh-select');
                    if (sshSelect) {
                        sshSelect.value = '__new__';
                        sshPasteContainer.style.display = 'block';
                    }
                    pasteArea.value = keys.publicKey;
                    sshInputField.value = keys.publicKey;
                    privKeyArea.value = keys.privateKey;
                    privKeyPanel.style.display = 'block';
                    genErrorMsg.style.display = 'none';
                } catch (e) {
                    genErrorMsg.style.display = 'block';
                    privKeyPanel.style.display = 'none';
                } finally {
                    generateBtn.disabled = false;
                    generateBtn.textContent = 'Generate a new key';
                }
            });

            if (sshKeys.length > 0) {
                var sshSelect = document.createElement('select');
                sshSelect.className = 'form-control';
                sshSelect.setAttribute('id', 'vf-ssh-select');

                var sshDefaultOption = document.createElement('option');
                sshDefaultOption.value = '';
                sshDefaultOption.text = '-- No SSH Key (Optional) --';
                sshSelect.appendChild(sshDefaultOption);

                sshKeys.forEach(function(sshkey) {
                    var option = document.createElement('option');
                    option.value = sshkey.id;
                    option.text = sshkey.name;
                    sshSelect.appendChild(option);
                });

                // Add new key option
                var addNewOption = document.createElement('option');
                addNewOption.value = '__new__';
                addNewOption.text = 'Add new key...';
                sshSelect.appendChild(addNewOption);

                sshSelect.addEventListener('change', function() {
                    if (this.value === '__new__') {
                        sshPasteContainer.style.display = 'block';
                        sshInputField.value = '';
                    } else {
                        sshPasteContainer.style.display = 'none';
                        document.getElementById('vf-ssh-paste').value = '';
                        sshInputField.value = this.value;
                    }
                });

                sshInputField.parentNode.insertBefore(sshSelect, sshInputField.nextSibling);
                sshSelect.parentNode.insertBefore(sshPasteContainer, sshSelect.nextSibling);
                sshPasteContainer.parentNode.insertBefore(generateBtn, sshPasteContainer.nextSibling);
                generateBtn.parentNode.insertBefore(genErrorMsg, generateBtn.nextSibling);
                genErrorMsg.parentNode.insertBefore(privKeyPanel, genErrorMsg.nextSibling);
                sshInputField.style.display = 'none';
            } else {
                // No existing keys — show the paste textarea directly
                sshPasteContainer.style.display = 'block';
                sshInputField.parentNode.insertBefore(sshPasteContainer, sshInputField.nextSibling);
                sshPasteContainer.parentNode.insertBefore(generateBtn, sshPasteContainer.nextSibling);
                generateBtn.parentNode.insertBefore(genErrorMsg, generateBtn.nextSibling);
                genErrorMsg.parentNode.insertBefore(privKeyPanel, genErrorMsg.nextSibling);
                sshInputField.style.display = 'none';
            }
        }

        // Slider UI: enhance known configurable option selects with range sliders
        var sliderResourceNames = ['Memory', 'CPU Cores', 'Storage', 'Bandwidth', 'Inbound Network Speed', 'Outbound Network Speed'];
        var sliderUnits = {
            'Memory': 'MB', 'CPU Cores': 'Core(s)', 'Storage': 'GB',
            'Bandwidth': 'GB', 'Inbound Network Speed': 'Mbps', 'Outbound Network Speed': 'Mbps'
        };

        var configSelects = document.querySelectorAll('select[name^=\"configoption[\"]');
        configSelects.forEach(function(sel) {
            // Find the label for this select
            var label = null;
            var labelEl = sel.closest('.form-group, .row');
            if (labelEl) {
                label = labelEl.querySelector('label');
            }
            if (!label) return;

            var labelText = label.textContent.trim();
            var matchedResource = null;
            sliderResourceNames.forEach(function(name) {
                if (labelText.indexOf(name) !== -1) {
                    matchedResource = name;
                }
            });
            if (!matchedResource) return;

            var options = [];
            for (var i = 0; i < sel.options.length; i++) {
                options.push({
                    value: sel.options[i].value,
                    label: sel.options[i].text
                });
            }
            if (options.length < 2) return;

            var unit = sliderUnits[matchedResource] || '';

            // Create slider container
            var container = document.createElement('div');
            container.className = 'vf-slider-container';

            var valueDisplay = document.createElement('div');
            valueDisplay.className = 'vf-slider-value';
            valueDisplay.textContent = options[sel.selectedIndex || 0].label + (unit ? ' ' + unit : '');

            var slider = document.createElement('input');
            slider.type = 'range';
            slider.className = 'vf-slider form-range';
            slider.min = '0';
            slider.max = String(options.length - 1);
            slider.step = '1';
            slider.value = String(sel.selectedIndex || 0);

            slider.addEventListener('input', function() {
                var idx = parseInt(this.value);
                sel.selectedIndex = idx;
                valueDisplay.textContent = options[idx].label + (unit ? ' ' + unit : '');
                // Trigger change event on hidden select for WHMCS pricing
                var evt = new Event('change', { bubbles: true });
                sel.dispatchEvent(evt);
            });

            container.appendChild(valueDisplay);
            container.appendChild(slider);

            sel.parentNode.insertBefore(container, sel.nextSibling);
            sel.style.display = 'none';
        });
    });
    </script>
    ";
    } catch (Throwable $e) {
        // Silently fail - don't break the checkout page
        return null;
    }
});