Namespace and ClassPath rewrites

2022-11-18 18:06:46 +01:00
parent c277aababc
commit 951ff14c5f
217 changed files with 1017 additions and 936 deletions
--- a/Core/Elements/Body.class.php
+++ b/Core/Elements/Body.class.php
@@ -0,0 +1,9 @@
+<?php
+
+namespace Core\Elements;
+
+abstract class Body extends View {
+  public function __construct($document) {
+    parent::__construct($document);
+  }
+}
--- a/Core/Elements/Document.class.php
+++ b/Core/Elements/Document.class.php
@@ -0,0 +1,152 @@
+<?php
+
+namespace Core\Elements;
+
+use Core\Configuration\Settings;
+use Core\Driver\Logger\Logger;
+use Core\Driver\SQL\SQL;
+use Core\Objects\Context;
+use Core\Objects\lang\LanguageModule;
+use Core\Objects\Router\DocumentRoute;
+use Core\Objects\Router\Router;
+use Core\Objects\DatabaseEntity\User;
+use Core\Objects\Search\Searchable;
+use Core\Objects\Search\SearchQuery;
+use Core\Objects\Search\SearchResult;
+
+abstract class Document {
+
+  protected Router $router;
+  private Logger $logger;
+  protected bool $databaseRequired;
+  private bool $cspEnabled;
+  private ?string $cspNonce;
+  private array $cspWhitelist;
+  private string $domain;
+  protected bool $searchable;
+
+  public function __construct(Router $router) {
+    $this->router = $router;
+    $this->cspEnabled = false;
+    $this->cspNonce = null;
+    $this->databaseRequired = true;
+    $this->cspWhitelist = [];
+    $this->domain = $this->getSettings()->getBaseUrl();
+    $this->logger = new Logger("Document", $this->getSQL());
+    $this->searchable = false;
+  }
+
+  public abstract function getTitle(): string;
+
+  public function isSearchable(): bool {
+    return $this->searchable;
+  }
+
+  public function getLogger(): Logger {
+    return $this->logger;
+  }
+
+  public function getUser(): ?User {
+    return $this->getContext()->getUser();
+  }
+
+  public function getContext(): Context {
+    return $this->router->getContext();
+  }
+
+  public function getSQL(): ?SQL {
+    return $this->getContext()->getSQL();
+  }
+
+  public function getSettings(): Settings {
+    return $this->getContext()->getSettings();
+  }
+
+  public function getCSPNonce(): ?string {
+    return $this->cspNonce;
+  }
+
+  public function isCSPEnabled(): bool {
+    return $this->cspEnabled;
+  }
+
+  public function enableCSP() {
+    $this->cspEnabled = true;
+    $this->cspNonce = generateRandomString(16, "base62");
+  }
+
+  public function getRouter(): Router {
+    return $this->router;
+  }
+
+  public function addCSPWhitelist(string $path) {
+    $urlParts = parse_url($path);
+    if (!$urlParts || !isset($urlParts["host"])) {
+      $this->cspWhitelist[] = $this->domain . $path;
+    } else {
+      $this->cspWhitelist[] = $path;
+    }
+  }
+
+  public function loadLanguageModule(LanguageModule|string $module) {
+    $language = $this->getContext()->getLanguage();
+    $language->loadModule($module);
+  }
+
+  public function sendHeaders() {
+    if ($this->cspEnabled) {
+      $cspWhiteList = implode(" ", $this->cspWhitelist);
+      $csp = [
+        "default-src $cspWhiteList 'self'",
+        "object-src 'none'",
+        "base-uri 'self'",
+        "style-src 'self' 'unsafe-inline'",
+        "img-src 'self' 'unsafe-inline' data: https:;",
+        "script-src $cspWhiteList 'nonce-$this->cspNonce'"
+      ];
+      if ($this->getSettings()->isRecaptchaEnabled()) {
+        $csp[] = "frame-src https://www.google.com/ 'self'";
+      }
+
+      $compiledCSP = implode("; ", $csp);
+      header("Content-Security-Policy: $compiledCSP;");
+    }
+  }
+
+  public abstract function getCode(array $params = []);
+
+  public function load(array $params = []): string {
+
+    if ($this->databaseRequired) {
+      $sql = $this->getSQL();
+      if (is_null($sql)) {
+        return "Database is not configured yet.";
+      } else if (!$sql->isConnected()) {
+        return "Database is not connected: " . $sql->getLastError();
+      }
+    }
+
+
+    $code =  $this->getCode($params);
+    $this->sendHeaders();
+    return $code;
+  }
+
+  public function doSearch(SearchQuery $query, DocumentRoute $route): array {
+    $code = $this->getCode();
+    $results = Searchable::searchHtml($code, $query);
+    return array_map(function ($res) use ($route) {
+      return new SearchResult($route->getUrl(), $this->getTitle(), $res["text"]);
+    }, $results);
+  }
+
+  public function createScript($type, $src, $content = ""): Script {
+    $script = new Script($type, $src, $content);
+
+    if ($this->isCSPEnabled()) {
+      $script->setNonce($this->getCSPNonce());
+    }
+
+    return $script;
+  }
+}
--- a/Core/Elements/EmptyHead.class.php
+++ b/Core/Elements/EmptyHead.class.php
@@ -0,0 +1,26 @@
+<?php
+
+namespace Core\Elements;
+
+class EmptyHead extends Head {
+
+  public function __construct($document) {
+    parent::__construct($document);
+  }
+
+  protected function initSources() {
+  }
+
+  protected function initMetas(): array {
+    return array(
+    );
+  }
+
+  protected function initRawFields(): array {
+    return array();
+  }
+
+  protected function initTitle(): string {
+    return "";
+  }
+}
--- a/Core/Elements/Head.class.php
+++ b/Core/Elements/Head.class.php
@@ -0,0 +1,110 @@
+<?php
+
+namespace Core\Elements;
+
+abstract class Head extends View {
+
+  protected array $sources;
+  protected string $title;
+  protected array $metas;
+  protected array $rawFields;
+  protected array $keywords;
+  protected string $description;
+  protected string $baseUrl;
+
+  function __construct($document) {
+    parent::__construct($document);
+    $this->sources = array();
+    $this->searchable = false;
+    $this->metas = $this->initMetas();
+    $this->rawFields = $this->initRawFields();
+    $this->title = $this->initTitle();
+    $this->initSources();
+    $this->init();
+  }
+
+  protected abstract function initSources();
+  protected abstract function initMetas(): array;
+  protected abstract function initRawFields(): array;
+  protected abstract function initTitle(): string;
+
+  protected function init() {
+    $this->keywords = array();
+    $this->description = "";
+    $this->baseUrl = "";
+  }
+
+  public function setBaseUrl($baseUrl) { $this->baseUrl = $baseUrl; }
+  public function setDescription($description) { $this->description = $description; }
+  public function setKeywords($keywords) { $this->keywords = $keywords; }
+  public function setTitle($title) { $this->title = $title; }
+  public function getSources(): array { return $this->sources; }
+  public function addScript($type, $url, $js = '') { $this->sources[] = new Script($type, $url, $js); }
+  public function addRawField($rawField) { $this->rawFields[] = $rawField; }
+  public function addMeta($aMeta) { $this->metas[] = $aMeta; }
+  public function addLink($rel, $href, $type = "") { $this->sources[] = new Link($rel, $href, $type); }
+  public function addKeywords($keywords) { $this->keywords = array_merge($this->keywords, $keywords); }
+  public function getTitle(): string { return $this->title; }
+
+  public function addCSS($href, $type = Link::MIME_TEXT_CSS)  { $this->sources[] = new Link(Link::STYLESHEET, $href, $type); }
+  public function addStyle($style) { $this->sources[] = new Style($style); }
+  public function addJS($url) { $this->sources[] = new Script(Script::MIME_TEXT_JAVASCRIPT, $url, ""); }
+  public function addJSCode($code) { $this->sources[] = new Script(Script::MIME_TEXT_JAVASCRIPT, "", $code); }
+
+  public function loadFontawesome() {
+    $this->addCSS(Link::FONTAWESOME);
+  }
+
+  public function loadGoogleRecaptcha($siteKey) {
+    $this->addJS("https://www.google.com/recaptcha/api.js?render=$siteKey");
+  }
+
+  public function loadJQuery() {
+    $this->addJS(Script::JQUERY);
+  }
+
+  public function loadBootstrap() {
+    $this->addCSS(Link::BOOTSTRAP);
+    $this->addJS(Script::BOOTSTRAP);
+  }
+
+  public function getCode(): string {
+    $content = [];
+
+    // meta tags
+    foreach($this->metas as $meta) {
+      $content[] = html_tag_short("meta", $meta);
+    }
+
+    // description
+    if(!empty($this->description)) {
+      $content[] = html_tag_short("meta", ["name" => "description", "content" => $this->description]);
+    }
+
+    // keywords
+    if(!empty($this->keywords)) {
+      $keywords = implode(", ", $this->keywords);
+      $content[] = html_tag_short("meta", ["name" => "keywords", "content" => $keywords]);
+    }
+
+    // base tag
+    if(!empty($this->baseUrl)) {
+      $content[] = html_tag_short("base", ["href" => $this->baseUrl]);
+    }
+
+    // title
+    $content[] = html_tag("title", [], $this->title);
+
+    // src tags
+    foreach($this->sources as $src) {
+      $content[] = $src->getCode();
+    }
+
+    //
+    foreach ($this->rawFields as $raw) {
+      $content[] = $raw;
+    }
+
+    return html_tag("head", [], $content, false);
+  }
+}
--- a/Core/Elements/HtmlDocument.class.php
+++ b/Core/Elements/HtmlDocument.class.php
@@ -0,0 +1,71 @@
+<?php
+
+namespace Core\Elements;
+
+use Core\Objects\Router\Router;
+
+class HtmlDocument extends Document {
+
+  protected ?Head $head;
+  protected ?Body $body;
+  private ?string $activeView;
+
+  public function __construct(Router $router, $headClass, $bodyClass, ?string $view = NULL) {
+    parent::__construct($router);
+    $this->head = $headClass ? new $headClass($this) : null;
+    $this->body = $bodyClass ? new $bodyClass($this) : null;
+    $this->activeView = $view;
+  }
+
+  public function getHead(): ?Head { return $this->head; }
+  public function getBody(): ?Body { return $this->body; }
+
+  public function getView() : ?View {
+
+    if ($this->activeView === null) {
+      return null;
+    }
+
+    $view = parseClass($this->activeView);
+    $file = getClassPath($view);
+    if (!file_exists($file) || !is_subclass_of($view, View::class)) {
+      return null;
+    }
+
+    return new $view($this);
+  }
+
+  public function getRequestedView(): string {
+    return $this->activeView;
+  }
+
+  function getCode(array $params = []): string {
+    // generate body first, so we can modify head
+    $body = $this->body->getCode();
+
+    if ($this->isCSPEnabled()) {
+      foreach ($this->head->getSources() as $element) {
+        if ($element instanceof Script || $element instanceof Link) {
+          $element->setNonce($this->getCSPNonce());
+        }
+      }
+    }
+
+    $head = $this->head->getCode();
+    $lang = $this->getContext()->getLanguage();
+
+    $code = "<!DOCTYPE html>";
+    $code .= html_tag("html", ["lang" => $lang->getShortCode()], $head . $body, false);
+
+    return $code;
+  }
+
+
+  public function getTitle(): string {
+    if ($this->head !== null) {
+      return $this->head->getTitle();
+    }
+
+    return "Untitled Document";
+  }
+}
--- a/Core/Elements/Link.class.php
+++ b/Core/Elements/Link.class.php
@@ -0,0 +1,43 @@
+<?php
+
+namespace Core\Elements;
+
+class Link extends StaticView {
+
+  const STYLESHEET    = "stylesheet";
+  const MIME_TEXT_CSS = "text/css";
+
+  const FONTAWESOME = "/css/fontawesome.min.css";
+  const BOOTSTRAP   = "/css/bootstrap.min.css";
+  const CORE        = "/css/style.css";
+  const ACCOUNT       = "/css/account.css";
+
+  private string $type;
+  private string $rel;
+  private string $href;
+  private ?string $nonce;
+
+  function __construct($rel, $href, $type = "") {
+    $this->href = $href;
+    $this->type = $type;
+    $this->rel = $rel;
+    $this->nonce = null;
+  }
+
+  function getCode(): string {
+    $attributes = ["rel" => $this->rel, "href" => $this->href];
+
+    if (!empty($this->type)) {
+      $attributes["type"] = $this->type;
+    }
+    if (!empty($this->nonce)) {
+      $attributes["nonce"] = $this->nonce;
+    }
+
+    return html_tag_short("link", $attributes);
+  }
+
+  public function setNonce(string $nonce) {
+    $this->nonce = $nonce;
+  }
+}
--- a/Core/Elements/Script.class.php
+++ b/Core/Elements/Script.class.php
@@ -0,0 +1,45 @@
+<?php
+
+namespace Core\Elements;
+
+class Script extends StaticView {
+
+  const MIME_TEXT_JAVASCRIPT    = "text/javascript";
+
+  const CORE      = "/js/script.js";
+  const JQUERY    = "/js/jquery.min.js";
+  const INSTALL   = "/js/install.js";
+  const BOOTSTRAP = "/js/bootstrap.bundle.min.js";
+  const ACCOUNT   = "/js/account.js";
+  const FONTAWESOME = "/js/fontawesome-all.min.js";
+
+  private string $type;
+  private string $content;
+  private string $src;
+  private ?string $nonce;
+
+  function __construct($type, $src, $content = "") {
+    $this->src = $src;
+    $this->type = $type;
+    $this->content = $content;
+    $this->nonce = null;
+  }
+
+  function getCode(): string {
+    $attributes = ["type" => $this->type];
+    if (!empty($this->src)) {
+      $attributes["src"] = $this->src;
+    }
+
+    if (!empty($this->nonce)) {
+      $attributes["nonce"] = $this->nonce;
+    }
+
+    // TODO: do we need to escape the content here?
+    return html_tag("script", $attributes, $this->content, false);
+  }
+
+  public function setNonce(string $nonce) {
+    $this->nonce = $nonce;
+  }
+}
--- a/Core/Elements/SimpleBody.class.php
+++ b/Core/Elements/SimpleBody.class.php
@@ -0,0 +1,17 @@
+<?php
+
+namespace Core\Elements;
+
+abstract class SimpleBody extends Body {
+
+  public function __construct($document) {
+    parent::__construct($document);
+  }
+
+  public function getCode(): string {
+    $content = $this->getContent();
+    return html_tag("body", [], $content, false);
+  }
+
+  protected abstract function getContent(): string;
+}
--- a/Core/Elements/StaticView.class.php
+++ b/Core/Elements/StaticView.class.php
@@ -0,0 +1,13 @@
+<?php
+
+namespace Core\Elements;
+
+abstract class StaticView {
+
+  public abstract function getCode();
+
+  public function __toString() {
+    return $this->getCode();
+  }
+
+}
--- a/Core/Elements/Style.class.php
+++ b/Core/Elements/Style.class.php
@@ -0,0 +1,17 @@
+<?php
+
+namespace Core\Elements;
+
+class Style extends StaticView {
+
+  private string $style;
+
+  function __construct($style) {
+    $this->style = $style;
+  }
+
+  function getCode(): string {
+    // TODO: do we need to escape the content here?
+    return html_tag("style", [], $this->style, false);
+  }
+}
--- a/Core/Elements/TemplateDocument.class.php
+++ b/Core/Elements/TemplateDocument.class.php
@@ -0,0 +1,124 @@
+<?php
+
+namespace Core\Elements;
+
+use Core\Objects\CustomTwigFunctions;
+use Core\Objects\Router\DocumentRoute;
+use Core\Objects\Router\Router;
+use Core\Objects\Search\Searchable;
+use Core\Objects\Search\SearchQuery;
+use Core\Objects\Search\SearchResult;
+use Twig\Environment;
+use Twig\Error\LoaderError;
+use Twig\Error\RuntimeError;
+use Twig\Error\SyntaxError;
+use Twig\Loader\FilesystemLoader;
+
+class TemplateDocument extends Document {
+
+  const TEMPLATE_PATH = WEBROOT . '/Core/Templates';
+
+  private string $templateName;
+  protected array $parameters;
+  private Environment $twigEnvironment;
+  private FilesystemLoader $twigLoader;
+  protected string $title;
+
+  public function __construct(Router $router, string $templateName, array $params = []) {
+    parent::__construct($router);
+    $this->title = "Untitled Document";
+    $this->templateName = $templateName;
+    $this->parameters = $params;
+    $this->twigLoader = new FilesystemLoader(self::TEMPLATE_PATH);
+    $this->twigEnvironment = new Environment($this->twigLoader, [
+      'cache' => WEBROOT . '/core/Cache/Templates/',
+      'auto_reload' => true
+    ]);
+    $this->twigEnvironment->addExtension(new CustomTwigFunctions());
+  }
+
+  public function getTitle(): string {
+    return $this->title;
+  }
+
+  protected function getTemplateName(): string {
+    return $this->templateName;
+  }
+
+  protected function loadParameters() {
+
+  }
+
+  protected function setTemplate(string $file) {
+    $this->templateName = $file;
+  }
+
+  public function getCode(array $params = []): string {
+    $this->loadParameters();
+    return $this->renderTemplate($this->templateName, $this->parameters);
+  }
+
+  public function renderTemplate(string $name, array $params = []): string {
+    try {
+
+      $context = $this->getContext();
+      $session = $context->getSession();
+      $settings = $this->getSettings();
+      $language = $context->getLanguage();
+
+      $urlParts = parse_url($this->getRouter()->getRequestedUri());
+
+      $params = array_replace_recursive([
+        "user" => [
+          "lang" => $language->getShortCode(),
+          "loggedIn" => $session !== null,
+          "session" => ($session ? [
+            "csrfToken" => $session->getCsrfToken()
+          ] : null)
+        ],
+        "site" => [
+          "name" => $settings->getSiteName(),
+          "url" => [
+            "base" => $settings->getBaseUrl(),
+            "path" => $urlParts["path"],
+            "query" => $urlParts["query"] ?? "",
+            "fragment" => $urlParts["fragment"] ?? ""
+          ],
+          "lastModified" => date(L('Y-m-d H:i:s'), @filemtime(implode(DIRECTORY_SEPARATOR, [self::TEMPLATE_PATH, $name]))),
+          "registrationEnabled" => $settings->isRegistrationAllowed(),
+          "title" => $this->title,
+          "recaptcha" => [
+            "key" => $settings->isRecaptchaEnabled() ? $settings->getRecaptchaSiteKey() : null,
+            "enabled" => $settings->isRecaptchaEnabled(),
+          ],
+          "csp" => [
+            "nonce" => $this->getCSPNonce(),
+            "enabled" => $this->isCSPEnabled()
+          ]
+        ]
+      ], $params);
+      return $this->twigEnvironment->render($name, $params);
+    } catch (LoaderError | RuntimeError | SyntaxError $e) {
+      return "<b>Error rendering twig template: " . htmlspecialchars($e->getMessage()) . "</b>";
+    }
+  }
+
+  protected function loadView(string $class): array {
+    $view = new $class($this);
+    $view->loadParameters($this->parameters);
+    if ($view->getTitle()) {
+      $this->title = $view->getTitle();
+    }
+    return $this->parameters;
+  }
+
+  public function doSearch(SearchQuery $query, DocumentRoute $route): array {
+    $this->loadParameters();
+    $viewParams = $this->parameters["view"] ?? [];
+    $siteTitle = $this->parameters["site"]["title"] ?? $this->title;
+    $results = Searchable::searchArray($viewParams, $query);
+    return array_map(function ($res) use ($siteTitle, $route) {
+      return new SearchResult($route->getUrl(), $siteTitle, $res["text"]);
+    }, $results);
+  }
+}
--- a/Core/Elements/TemplateView.class.php
+++ b/Core/Elements/TemplateView.class.php
@@ -0,0 +1,39 @@
+<?php
+
+namespace Core\Elements;
+
+abstract class TemplateView extends View {
+
+  protected array $keywords = [];
+  protected string $description = "";
+
+  public function __construct(TemplateDocument $document) {
+    parent::__construct($document);
+    $this->title = "";
+  }
+
+  protected function getParameters(): array {
+    return [];
+  }
+
+  public function loadParameters(array &$parameters) {
+
+    $siteParameters = [
+      "title" => $this->title,
+      "description" => $this->description,
+      "keywords" => $this->keywords
+    ];
+
+    foreach ($siteParameters as $key => $value) {
+      if ($value) {
+        $parameters["site"][$key] = $value;
+      }
+    }
+
+    $parameters["view"] = $this->getParameters();
+  }
+
+  public function getCode(): string {
+    return $this->getDocument()->getCode();
+  }
+}
--- a/Core/Elements/View.class.php
+++ b/Core/Elements/View.class.php
@@ -0,0 +1,146 @@
+<?php
+
+namespace Core\Elements;
+
+abstract class View extends StaticView {
+
+  private Document $document;
+  private bool $loadView;
+  protected string $title;
+  protected array $langModules;
+
+  public function __construct(Document $document, bool $loadView = true) {
+    $this->document = $document;
+    $this->title = "Untitled View";
+    $this->langModules = array();
+    $this->loadView = $loadView;
+  }
+
+  public function getTitle(): string { return $this->title; }
+  public function getDocument(): Document { return $this->document; }
+
+  public function getSiteName(): string {
+    return $this->getDocument()->getSettings()->getSiteName();
+  }
+
+  protected function load(string $viewClass) : string {
+    try {
+      $reflectionClass = new \ReflectionClass($viewClass);
+      if ($reflectionClass->isSubclassOf(View::class) && $reflectionClass->isInstantiable()) {
+        $view = $reflectionClass->newInstanceArgs(array($this->getDocument()));
+        $view->loadView();
+        return $view;
+      }
+    } catch(\ReflectionException $e) {
+      $this->document->getLogger()->error("Error loading view: '$viewClass': " . $e->getMessage());
+    }
+
+    return "";
+  }
+
+  private function loadLanguageModules() {
+    $lang = $this->document->getContext()->getLanguage();
+    foreach ($this->langModules as $langModule) {
+      $lang->loadModule($langModule);
+    }
+  }
+
+  // Virtual Methods
+  public function loadView() { }
+
+  public function getCode(): string {
+
+    // Load translations
+    $this->loadLanguageModules();
+
+    // Load metadata + head (title, scripts, includes, ...)
+    if($this->loadView) {
+      $this->loadView();
+    }
+
+    return '';
+  }
+
+  // UI Functions
+  private function createList(array $items, string $tag, array $classes = []): string {
+
+    $attributes = [];
+    if (!empty($classes)) {
+      $attributes["class"] = implode(" ", $classes);
+    }
+
+    $content = array_map(function ($item) { return html_tag("li", [], $item, false); }, $items);
+    return html_tag_ex($tag, $attributes, $content, false);
+  }
+
+  public function createOrderedList(array $items=[], array $classes=[]): string {
+    return $this->createList($items, "ol", $classes);
+  }
+
+  public function createUnorderedList(array $items=[], array $classes=[]): string {
+    return $this->createList($items, "ul", $classes);
+  }
+
+  protected function createLink(string $link, $title=null, array $classes=[], bool $escapeTitle=true): string {
+    $attrs = ["href" => $link];
+    if (!empty($classes)) {
+      $attrs["class"] = implode(" ", $classes);
+    }
+
+    return html_tag("a", $attrs, $title ?? $link, $escapeTitle);
+  }
+
+  protected function createExternalLink(string $link, $title=null, bool $escapeTitle=true): string {
+    $attrs = ["href" => $link, "target" => "_blank", "rel" => "noopener noreferrer", "class" => "external"];
+    return html_tag("a", $attrs, $title ?? $link, $escapeTitle);
+  }
+
+  protected function createIcon($icon, $type="fas", $classes = []): string {
+    $classes = array_merge($classes, [$type, "fa-$icon"]);
+    if ($icon === "spinner" || $icon === "circle-notch") {
+      $classes[] = "fa-spin";
+    }
+
+    return html_tag("i", ["class" => implode(" ", $classes)]);
+  }
+
+  protected function createErrorText($text, $id="", $hidden=false): string {
+    return $this->createStatusText("danger", $text, $id, $hidden);
+  }
+
+  protected function createWarningText($text, $id="", $hidden=false): string {
+    return $this->createStatusText("warning", $text, $id, $hidden);
+  }
+
+  protected function createSuccessText($text, $id="", $hidden=false): string {
+    return $this->createStatusText("success", $text, $id, $hidden);
+  }
+
+  protected function createSecondaryText($text, $id="", $hidden=false): string {
+    return $this->createStatusText("secondary", $text, $id, $hidden);
+  }
+
+  protected function createInfoText($text, $id="", $hidden=false): string {
+    return $this->createStatusText("info", $text, $id, $hidden);
+  }
+
+  protected function createStatusText(string $type, $text, string $id="", bool $hidden=false, array $classes=[]): string {
+    $classes[] = "alert";
+    $classes[] = "alert-$type";
+
+    if ($hidden) {
+      $classes[] = "hidden";
+    }
+
+    $attributes = [
+      "class" => implode(" ", $classes),
+      "role" => "alert"
+    ];
+
+    if (!empty($id)) {
+      $attributes["id"] = $id;
+    }
+
+    return html_tag("div", $attributes, $text, false);
+  }
+}