1, 'name' => 'Widget', 'price' => 9.99, 'featured' => true, 'inStock' => true],
['id' => 2, 'name' => 'Gadget', 'price' => 19.99, 'featured' => false, 'inStock' => true],
['id' => 3, 'name' => 'Sprocket', 'price' => 4.50, 'featured' => false, 'inStock' => false],
['id' => 4, 'name' => 'Gizmo', 'price' => 29.99, 'featured' => true, 'inStock' => true],
];
$TYPES = ['counter', 'products', 'cart', 'user', 'notice'];
// ---------------------------------------------------------------------------
// Helpers
// ---------------------------------------------------------------------------
/** Send a JSON array of Statum directives and stop. */
function statum_respond(array $directives): void
{
header('Content-Type: application/vnd.statum+json');
header('Cache-Control: no-store');
echo json_encode($directives, JSON_PRETTY_PRINT);
exit;
}
/** Wrap a snapshot in a trivial (unsigned) frame. */
function frame(array $snapshot): array
{
return ['content' => json_encode($snapshot), 'signer' => 'demo', 'signature' => ''];
}
/** Stable per-type slot key, kept in the session. */
function key_for(string $type): string
{
if (!isset($_SESSION['keys'][$type])) {
$_SESSION['keys'][$type] = 'k_' . $type;
}
return $_SESSION['keys'][$type];
}
/**
* Build a snapshot for a type. `always` makes transmit_after == as_at so the
* client sends the base64 frame on every request (demonstrating that path).
*/
function make_snapshot(string $type, string $scope, array $public, array $opts = []): array
{
$now = gmdate('Y-m-d\TH:i:s\Z');
return [
'as_at' => $now,
'slot' => ['key' => key_for($type), 'scope' => $scope, 'type' => $type],
'transmit_after' => !empty($opts['always']) ? $now : gmdate('Y-m-d\TH:i:s\Z', time() + 60),
'invalid_after' => gmdate('Y-m-d\TH:i:s\Z', time() + 600),
'private' => $opts['private'] ?? '',
'public' => $public,
];
}
function set_dir(array $snapshot): array
{
return ['type' => 'set', 'snapshot_frame' => frame($snapshot)];
}
function clear_dir(string $key): array
{
return ['type' => 'clear', 'key' => $key];
}
function product_by_id($id): ?array
{
global $CATALOG;
foreach ($CATALOG as $p) {
if ((string)$p['id'] === (string)$id) return $p;
}
return null;
}
// ---------------------------------------------------------------------------
// Public-data builders
// ---------------------------------------------------------------------------
function build_counter(): array
{
$v = $_SESSION['counter'] ?? 0;
return [
'value' => $v,
'high' => $v > 5,
'increment' => ['uri' => '/api/counter/inc', 'method' => 'POST'],
'decrement' => ['uri' => '/api/counter/dec', 'method' => 'POST'],
'reset' => ['uri' => '/api/counter/reset', 'method' => 'POST'],
'add' => ['uri' => '/api/counter/add', 'method' => 'POST'],
];
}
function build_products(): array
{
global $CATALOG;
$items = [];
foreach ($CATALOG as $p) {
$pid = (string)$p['id'];
$items[] = [
'id' => $pid,
'name' => $p['name'],
'price' => $p['price'],
'featured' => $p['featured'],
'inStock' => $p['inStock'],
// Per-item context rides in `private`; the client echoes it back
// via the X-Statum-Private header (no stm-data expression needed).
'addToCartAction' => [
'uri' => '/api/cart/add',
'method' => 'POST',
'private' => base64_encode('id=' . $pid),
],
];
}
return ['items' => $items];
}
function build_cart(): array
{
$cart = $_SESSION['cart'] ?? [];
$count = 0;
$total = 0.0;
$lines = [];
foreach ($cart as $id => $qty) {
$p = product_by_id($id);
if (!$p) continue;
$count += $qty;
$total += $p['price'] * $qty;
$lines[] = ['id' => (string)$id, 'name' => $p['name'], 'qty' => $qty, 'price' => $p['price']];
}
return [
'count' => $count,
'total' => round($total, 2),
'empty' => $count === 0,
'items' => $lines,
'checkoutAction' => ['uri' => '/api/cart/checkout', 'method' => 'POST'],
'clearAction' => ['uri' => '/api/cart/clear', 'method' => 'POST'],
];
}
function build_user(): array
{
$role = $_SESSION['role'] ?? 'guest';
$names = ['guest' => 'Guest', 'member' => 'Member Mike', 'admin' => 'Admin Alice'];
return [
'role' => $role,
'name' => $names[$role] ?? 'Guest',
'toggleAction' => ['uri' => '/api/user/toggle', 'method' => 'POST'],
'resetAllAction' => ['uri' => '/api/reset-all', 'method' => 'POST'],
];
}
function build_notice(): array
{
return [
'html' => $_SESSION['notice'] ?? 'No notice set.',
'setAction' => ['uri' => '/api/notice/set', 'method' => 'POST'],
'failAction' => ['uri' => '/api/notice/fail', 'method' => 'POST'],
];
}
/** Build the snapshot for a type with its demo scope/options. */
function snap(string $type): ?array
{
switch ($type) {
case 'counter': return make_snapshot('counter', 'session', build_counter());
case 'products': return make_snapshot('products', 'session', build_products());
case 'cart': return make_snapshot('cart', 'session', build_cart(), ['always' => true]);
case 'user': return make_snapshot('user', 'session', build_user());
case 'notice': return make_snapshot('notice', 'flow', build_notice());
}
return null;
}
function all_directives(): array
{
global $TYPES;
$dirs = [];
foreach ($TYPES as $t) {
$s = snap($t);
if ($s) $dirs[] = set_dir($s);
}
return $dirs;
}
// ---------------------------------------------------------------------------
// Router
// ---------------------------------------------------------------------------
$method = $_SERVER['REQUEST_METHOD'];
$path = parse_url($_SERVER['REQUEST_URI'], PHP_URL_PATH);
// Static assets.
if ($path === '/statum.js') {
header('Content-Type: application/javascript');
readfile(__DIR__ . '/../js/statum.js');
exit;
}
// The page itself.
if ($path === '/' || $path === '/index.html') {
header('Content-Type: text/html; charset=utf-8');
readfile(__DIR__ . '/index.html');
exit;
}
// Landing page after a (post) checkout navigation.
if ($path === '/api/checkout-done') {
header('Content-Type: text/html; charset=utf-8');
$order = htmlspecialchars($_GET['order'] ?? 'UNKNOWN');
echo "Checkout" .
"" .
"Order $order placed
This page was reached via a statum post directive.
" .
"Back to the demo
";
exit;
}
// --- Statum endpoints -------------------------------------------------------
if ($path === '/_statum/entrypoint') {
statum_respond(all_directives());
}
if ($path === '/_statum/slots') {
// Pre-flight target: refresh each type whose frame the client sent back.
$body = json_decode(file_get_contents('php://input'), true);
$dirs = [];
if (is_array($body)) {
foreach ($body as $fr) {
$snap = json_decode($fr['content'] ?? 'null', true);
$type = $snap['slot']['type'] ?? null;
if ($type) {
$s = snap($type);
if ($s) $dirs[] = set_dir($s);
}
}
}
statum_respond($dirs);
}
// --- Actions ----------------------------------------------------------------
if ($path === '/api/counter/inc' && $method === 'POST') {
$_SESSION['counter'] = ($_SESSION['counter'] ?? 0) + 1;
statum_respond([set_dir(snap('counter'))]);
}
if ($path === '/api/counter/dec' && $method === 'POST') {
$_SESSION['counter'] = ($_SESSION['counter'] ?? 0) - 1;
statum_respond([set_dir(snap('counter'))]);
}
if ($path === '/api/counter/reset' && $method === 'POST') {
$_SESSION['counter'] = 0;
statum_respond([set_dir(snap('counter'))]);
}
if ($path === '/api/counter/add' && $method === 'POST') {
$amount = intval($_POST['amount'] ?? 1);
$_SESSION['counter'] = ($_SESSION['counter'] ?? 0) + $amount;
statum_respond([set_dir(snap('counter'))]);
}
if ($path === '/api/cart/add' && $method === 'POST') {
$priv = $_SERVER['HTTP_X_STATUM_PRIVATE'] ?? '';
$raw = base64_decode($priv, true) ?: '';
if (preg_match('/id=([0-9]+)/', $raw, $m)) {
$id = $m[1];
$_SESSION['cart'][$id] = ($_SESSION['cart'][$id] ?? 0) + 1;
}
statum_respond([set_dir(snap('cart'))]);
}
if ($path === '/api/cart/clear' && $method === 'POST') {
$_SESSION['cart'] = [];
statum_respond([set_dir(snap('cart'))]);
}
if ($path === '/api/cart/checkout' && $method === 'POST') {
// A `post` directive performs a full-page navigating form POST last.
statum_respond([['type' => 'post', 'uri' => '/api/checkout-done', 'data' => ['order' => 'ORD-' . strtoupper(bin2hex(random_bytes(3)))]]]);
}
if ($path === '/api/user/toggle' && $method === 'POST') {
$order = ['guest', 'member', 'admin'];
$cur = array_search($_SESSION['role'] ?? 'guest', $order);
$_SESSION['role'] = $order[($cur + 1) % count($order)];
statum_respond([set_dir(snap('user'))]);
}
if ($path === '/api/notice/set' && $method === 'POST') {
$_SESSION['notice'] = 'Notice: updated at ' . date('H:i:s') . '
';
statum_respond([set_dir(snap('notice'))]);
}
if ($path === '/api/notice/fail' && $method === 'POST') {
statum_respond([['type' => 'error', 'message' => 'Intentional failure.', 'code' => 'DEMO_FAIL', 'data' => ['at' => date('c')]]]);
}
if ($path === '/api/reset-all' && $method === 'POST') {
$dirs = [];
foreach ($TYPES as $t) {
if (isset($_SESSION['keys'][$t])) $dirs[] = clear_dir($_SESSION['keys'][$t]);
}
session_unset();
$dirs[] = ['type' => 'navigate', 'uri' => '/'];
statum_respond($dirs);
}
// Fallback 404.
http_response_code(404);
header('Content-Type: text/plain');
echo "404 Not Found: $path";