fix: Deprecate OC_Template, add proper template manager instead

Signed-off-by: Côme Chilliet <come.chilliet@nextcloud.com>

7 files changed, 400 insertions, 327 deletions

diff --git a/lib/base.php b/lib/base.php
index 44b78ff713e..618b392e337 100644
--- a/lib/base.php
+++ b/lib/base.php
@@ -21,6 +21,7 @@ use OCP\IUserSession;
 use OCP\Security\Bruteforce\IThrottler;
 use OCP\Server;
 use OCP\Share;
+use OCP\Template\ITemplateManager;
 use OCP\User\Events\UserChangedEvent;
 use OCP\User\Events\UserDeletedEvent;
 use OCP\Util;
@@ -208,7 +209,7 @@ class OC {
 				echo $l->t('See %s', [ $urlGenerator->linkToDocs('admin-config') ]) . "\n";
 				exit;
 			} else {
-				OC_Template::printErrorPage(
+				Server::get(ITemplateManager::class)->printErrorPage(
 					$l->t('Cannot write into "config" directory!'),
 					$l->t('This can usually be fixed by giving the web server write access to the config directory.') . ' '
 					. $l->t('But, if you prefer to keep config.php file read only, set the option "config_is_read_only" to true in it.') . ' '
@@ -244,7 +245,7 @@ class OC {
 			header('Retry-After: 120');
 
 			// render error page
-			$template = new OC_Template('', 'update.user', 'guest');
+			$template = Server::get(ITemplateManager::class)->getTemplate('', 'update.user', 'guest');
 			\OCP\Util::addScript('core', 'maintenance');
 			\OCP\Util::addStyle('core', 'guest');
 			$template->printPage();
@@ -300,7 +301,7 @@ class OC {
 			$serverVersion = \OCP\Server::get(\OCP\ServerVersion::class);
 
 			// render error page
-			$template = new OC_Template('', 'update.use-cli', 'guest');
+			$template = Server::get(ITemplateManager::class)->getTemplate('', 'update.use-cli', 'guest');
 			$template->assign('productName', 'nextcloud'); // for now
 			$template->assign('version', $serverVersion->getVersionString());
 			$template->assign('tooBig', $tooBig);
@@ -327,7 +328,7 @@ class OC {
 		/** @var \OC\App\AppManager $appManager */
 		$appManager = Server::get(\OCP\App\IAppManager::class);
 
-		$tmpl = new OC_Template('', 'update.admin', 'guest');
+		$tmpl = Server::get(ITemplateManager::class)->getTemplate('', 'update.admin', 'guest');
 		$tmpl->assign('version', \OCP\Server::get(\OCP\ServerVersion::class)->getVersionString());
 		$tmpl->assign('isAppsOnlyUpgrade', $isAppsOnlyUpgrade);
 
@@ -420,7 +421,7 @@ class OC {
 		} catch (Exception $e) {
 			Server::get(LoggerInterface::class)->error($e->getMessage(), ['app' => 'base','exception' => $e]);
 			//show the user a detailed error page
-			OC_Template::printExceptionErrorPage($e, 500);
+			Server::get(ITemplateManager::class)->printExceptionErrorPage($e, 500);
 			die();
 		}
 
@@ -659,7 +660,7 @@ class OC {
 			if ($config->getSystemValueBool('debug', false)) {
 				set_error_handler([$errorHandler, 'onAll'], E_ALL);
 				if (\OC::$CLI) {
-					$exceptionHandler = ['OC_Template', 'printExceptionErrorPage'];
+					$exceptionHandler = [Server::get(ITemplateManager::class), 'printExceptionErrorPage'];
 				}
 			} else {
 				set_error_handler([$errorHandler, 'onError']);
@@ -702,7 +703,7 @@ class OC {
 					http_response_code(503);
 					OC_Util::addStyle('guest');
 					try {
-						OC_Template::printGuestPage('', 'error', ['errors' => $errors]);
+						Server::get(ITemplateManager::class)->printGuestPage('', 'error', ['errors' => $errors]);
 						exit;
 					} catch (\Exception $e) {
 						// In case any error happens when showing the error page, we simply fall back to posting the text.
@@ -781,7 +782,7 @@ class OC {
 		// Check whether the sample configuration has been copied
 		if ($systemConfig->getValue('copied_sample_config', false)) {
 			$l = Server::get(\OCP\L10N\IFactory::class)->get('lib');
-			OC_Template::printErrorPage(
+			Server::get(ITemplateManager::class)->printErrorPage(
 				$l->t('Sample configuration detected'),
 				$l->t('It has been detected that the sample configuration has been copied. This can break your installation and is unsupported. Please read the documentation before performing changes on config.php'),
 				503
@@ -1094,7 +1095,7 @@ class OC {
 				logger('core')->emergency($e->getMessage(), ['exception' => $e]);
 			}
 			$l = Server::get(\OCP\L10N\IFactory::class)->get('lib');
-			OC_Template::printErrorPage(
+			Server::get(ITemplateManager::class)->printErrorPage(
 				'404',
 				$l->t('The page could not be found on the server.'),
 				404
diff --git a/lib/private/Template/Base.php b/lib/private/Template/Base.php
index 602c8e6257e..35c2bf596ad 100644
--- a/lib/private/Template/Base.php
+++ b/lib/private/Template/Base.php
@@ -12,7 +12,7 @@ use Throwable;
 
 class Base {
 	private $template; // The template
-	private $vars; // Vars
+	private array $vars = [];
 
 	/** @var \OCP\IL10N */
 	private $l10n;
@@ -59,11 +59,9 @@ class Base {
 	}
 
 	/**
-	 * @param string $serverRoot
-	 * @param string $theme
 	 * @return string[]
 	 */
-	protected function getCoreTemplateDirs($theme, $serverRoot) {
+	protected function getCoreTemplateDirs(string $theme, string $serverRoot): array {
 		return [
 			$serverRoot . '/themes/' . $theme . '/core/templates/',
 			$serverRoot . '/core/templates/',
@@ -105,42 +103,29 @@ class Base {
 
 	/**
 	 * Prints the proceeded template
-	 * @return bool
 	 *
 	 * This function proceeds the template and prints its output.
 	 */
-	public function printPage() {
+	public function printPage(): void {
 		$data = $this->fetchPage();
-		if ($data === false) {
-			return false;
-		} else {
-			print $data;
-			return true;
-		}
+		print $data;
 	}
 
 	/**
 	 * Process the template
 	 *
-	 * @param array|null $additionalParams
-	 * @return string This function processes the template.
-	 *
 	 * This function processes the template.
 	 */
-	public function fetchPage($additionalParams = null) {
+	public function fetchPage(?array $additionalParams = null): string {
 		return $this->load($this->template, $additionalParams);
 	}
 
 	/**
 	 * doing the actual work
 	 *
-	 * @param string $file
-	 * @param array|null $additionalParams
-	 * @return string content
-	 *
 	 * Includes the template file, fetches its output
 	 */
-	protected function load($file, $additionalParams = null) {
+	protected function load(string $file, ?array $additionalParams = null): string {
 		// Register the variables
 		$_ = $this->vars;
 		$l = $this->l10n;
diff --git a/lib/private/Template/Template.php b/lib/private/Template/Template.php
new file mode 100644
index 00000000000..78865ceee5c
--- /dev/null
+++ b/lib/private/Template/Template.php
@@ -0,0 +1,172 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * SPDX-FileCopyrightText: 2016-2024 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-FileCopyrightText: 2016 ownCloud, Inc.
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+namespace OC\Template;
+
+use OC\TemplateLayout;
+use OCP\AppFramework\Http\TemplateResponse;
+use OCP\Template\ITemplate;
+
+require_once __DIR__ . '/../legacy/template/functions.php';
+
+class Template extends Base implements ITemplate {
+	/** @var string */
+	private $renderAs; // Create a full page?
+
+	/** @var string */
+	private $path; // The path to the template
+
+	/** @var array */
+	private $headers = []; //custom headers
+
+	/** @var string */
+	protected $app; // app id
+
+	/**
+	 * Constructor
+	 *
+	 * @param string $app app providing the template
+	 * @param string $name of the template file (without suffix)
+	 * @param string $renderAs If $renderAs is set, will try to
+	 *                         produce a full page in the according layout. For
+	 *                         now, $renderAs can be set to "guest", "user" or
+	 *                         "admin".
+	 * @param bool $registerCall = true
+	 */
+	public function __construct(
+		$app,
+		$name,
+		$renderAs = TemplateResponse::RENDER_AS_BLANK,
+		$registerCall = true,
+	) {
+		$theme = OC_Util::getTheme();
+
+		$requestToken = (OC::$server->getSession() && $registerCall) ? \OCP\Util::callRegister() : '';
+		$cspNonce = \OCP\Server::get(\OC\Security\CSP\ContentSecurityPolicyNonceManager::class)->getNonce();
+
+		$parts = explode('/', $app); // fix translation when app is something like core/lostpassword
+		$l10n = \OC::$server->getL10N($parts[0]);
+		/** @var \OCP\Defaults $themeDefaults */
+		$themeDefaults = \OCP\Server::get(\OCP\Defaults::class);
+
+		[$path, $template] = $this->findTemplate($theme, $app, $name);
+
+		// Set the private data
+		$this->renderAs = $renderAs;
+		$this->path = $path;
+		$this->app = $app;
+
+		parent::__construct(
+			$template,
+			$requestToken,
+			$l10n,
+			$themeDefaults,
+			$cspNonce,
+		);
+	}
+
+
+	/**
+	 * find the template with the given name
+	 * @param string $name of the template file (without suffix)
+	 *
+	 * Will select the template file for the selected theme.
+	 * Checking all the possible locations.
+	 * @param string $theme
+	 * @param string $app
+	 * @return string[]
+	 */
+	protected function findTemplate($theme, $app, $name) {
+		// Check if it is a app template or not.
+		if ($app !== '') {
+			$dirs = $this->getAppTemplateDirs($theme, $app, OC::$SERVERROOT, OC_App::getAppPath($app));
+		} else {
+			$dirs = $this->getCoreTemplateDirs($theme, OC::$SERVERROOT);
+		}
+		$locator = new \OC\Template\TemplateFileLocator($dirs);
+		$template = $locator->find($name);
+		$path = $locator->getPath();
+		return [$path, $template];
+	}
+
+	/**
+	 * Add a custom element to the header
+	 * @param string $tag tag name of the element
+	 * @param array $attributes array of attributes for the element
+	 * @param string $text the text content for the element. If $text is null then the
+	 *                     element will be written as empty element. So use "" to get a closing tag.
+	 */
+	public function addHeader($tag, $attributes, $text = null) {
+		$this->headers[] = [
+			'tag' => $tag,
+			'attributes' => $attributes,
+			'text' => $text
+		];
+	}
+
+	/**
+	 * Process the template
+	 * @return string
+	 *
+	 * This function process the template. If $this->renderAs is set, it
+	 * will produce a full page.
+	 */
+	public function fetchPage($additionalParams = null) {
+		$data = parent::fetchPage($additionalParams);
+
+		if ($this->renderAs) {
+			$page = new TemplateLayout($this->renderAs, $this->app);
+
+			if (is_array($additionalParams)) {
+				foreach ($additionalParams as $key => $value) {
+					$page->assign($key, $value);
+				}
+			}
+
+			// Add custom headers
+			$headers = '';
+			foreach (OC_Util::$headers as $header) {
+				$headers .= '<' . \OCP\Util::sanitizeHTML($header['tag']);
+				if (strcasecmp($header['tag'], 'script') === 0 && in_array('src', array_map('strtolower', array_keys($header['attributes'])))) {
+					$headers .= ' defer';
+				}
+				foreach ($header['attributes'] as $name => $value) {
+					$headers .= ' ' . \OCP\Util::sanitizeHTML($name) . '="' . \OCP\Util::sanitizeHTML($value) . '"';
+				}
+				if ($header['text'] !== null) {
+					$headers .= '>' . \OCP\Util::sanitizeHTML($header['text']) . '</' . \OCP\Util::sanitizeHTML($header['tag']) . '>';
+				} else {
+					$headers .= '/>';
+				}
+			}
+
+			$page->assign('headers', $headers);
+
+			$page->assign('content', $data);
+			return $page->fetchPage($additionalParams);
+		}
+
+		return $data;
+	}
+
+	/**
+	 * Include template
+	 *
+	 * @param string $file
+	 * @param array|null $additionalParams
+	 * @return string returns content of included template
+	 *
+	 * Includes another template. use <?php echo $this->inc('template'); ?> to
+	 * do this.
+	 */
+	public function inc($file, $additionalParams = null) {
+		return $this->load($this->path . $file . '.php', $additionalParams);
+	}
+}
diff --git a/lib/private/Template/TemplateManager.php b/lib/private/Template/TemplateManager.php
new file mode 100644
index 00000000000..db8d83c1bf9
--- /dev/null
+++ b/lib/private/Template/TemplateManager.php
@@ -0,0 +1,162 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * SPDX-FileCopyrightText: 2025 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+
+namespace OC\Template;
+
+use OCP\App\IAppManager;
+use OCP\AppFramework\Http\Events\BeforeTemplateRenderedEvent;
+use OCP\AppFramework\Http\TemplateResponse;
+use OCP\EventDispatcher\IEventDispatcher;
+use OCP\IRequest;
+use OCP\Server;
+use Psr\Log\LoggerInterface;
+
+class TemplateManager {
+	public function __construct(
+		private IAppManager $appManager,
+		private IEventDispatcher $eventDispatcher,
+	) {
+	}
+
+	public function getTemplate(string $app, string $name, string $renderAs = TemplateResponse::RENDER_AS_BLANK, bool $registerCall = true): ITemplate {
+		return new Template($app, $name, $renderAs, $registerCall);
+	}
+
+	/**
+	 * Shortcut to print a simple page for guests
+	 * @param string $application The application we render the template for
+	 * @param string $name Name of the template
+	 * @param array $parameters Parameters for the template
+	 */
+	public function printGuestPage(string $application, string $name, array $parameters = []): void {
+		$content = new Template($application, $name, $name === 'error' ? $name : 'guest');
+		foreach ($parameters as $key => $value) {
+			$content->assign($key, $value);
+		}
+		$content->printPage();
+	}
+
+	/**
+	 * Print a fatal error page and terminates the script
+	 * @param string $error_msg The error message to show
+	 * @param string $hint An optional hint message - needs to be properly escape
+	 */
+	public function printErrorPage(string $error_msg, string $hint = '', int $statusCode = 500): never {
+		if ($this->appManager->isEnabledForUser('theming') && !$this->appManager->isAppLoaded('theming')) {
+			$this->appManager->loadApp('theming');
+		}
+
+		if ($error_msg === $hint) {
+			// If the hint is the same as the message there is no need to display it twice.
+			$hint = '';
+		}
+		$errors = [['error' => $error_msg, 'hint' => $hint]];
+
+		http_response_code($statusCode);
+		try {
+			// Try rendering themed html error page
+			$response = new TemplateResponse(
+				'',
+				'error',
+				['errors' => $errors],
+				TemplateResponse::RENDER_AS_ERROR,
+				$statusCode,
+			);
+			$event = new BeforeTemplateRenderedEvent(false, $response);
+			$this->eventDispatcher->dispatchTyped($event);
+			print($response->render());
+		} catch (\Throwable $e1) {
+			$logger = \OCP\Server::get(LoggerInterface::class);
+			$logger->error('Rendering themed error page failed. Falling back to un-themed error page.', [
+				'app' => 'core',
+				'exception' => $e1,
+			]);
+
+			try {
+				// Try rendering unthemed html error page
+				$content = new Template('', 'error', 'error', false);
+				$content->assign('errors', $errors);
+				$content->printPage();
+			} catch (\Exception $e2) {
+				// If nothing else works, fall back to plain text error page
+				$logger->error("$error_msg $hint", ['app' => 'core']);
+				$logger->error('Rendering un-themed error page failed. Falling back to plain text error page.', [
+					'app' => 'core',
+					'exception' => $e2,
+				]);
+
+				header('Content-Type: text/plain; charset=utf-8');
+				print("$error_msg $hint");
+			}
+		}
+		die();
+	}
+
+	/**
+	 * print error page using Exception details
+	 */
+	public function printExceptionErrorPage(\Throwable $exception, int $statusCode = 503): never {
+		$debug = false;
+		http_response_code($statusCode);
+		try {
+			$debug = Server::get(\OC\SystemConfig::class)->getValue('debug', false);
+			$serverLogsDocumentation = Server::get(\OC\SystemConfig::class)->getValue('documentation_url.server_logs', '');
+			$request = Server::get(IRequest::class);
+			$content = new Template('', 'exception', 'error', false);
+			$content->assign('errorClass', get_class($exception));
+			$content->assign('errorMsg', $exception->getMessage());
+			$content->assign('errorCode', $exception->getCode());
+			$content->assign('file', $exception->getFile());
+			$content->assign('line', $exception->getLine());
+			$content->assign('exception', $exception);
+			$content->assign('debugMode', $debug);
+			$content->assign('serverLogsDocumentation', $serverLogsDocumentation);
+			$content->assign('remoteAddr', $request->getRemoteAddress());
+			$content->assign('requestID', $request->getId());
+			$content->printPage();
+		} catch (\Exception $e) {
+			try {
+				$logger = \OCP\Server::get(LoggerInterface::class);
+				$logger->error($exception->getMessage(), ['app' => 'core', 'exception' => $exception]);
+				$logger->error($e->getMessage(), ['app' => 'core', 'exception' => $e]);
+			} catch (\Throwable $e) {
+				// no way to log it properly - but to avoid a white page of death we send some output
+				$this->printPlainErrorPage($e, $debug);
+
+				// and then throw it again to log it at least to the web server error log
+				throw $e;
+			}
+
+			$this->printPlainErrorPage($e, $debug);
+		}
+		die();
+	}
+
+	/**
+	 * @psalm-taint-escape has_quotes
+	 * @psalm-taint-escape html
+	 */
+	private function fakeEscapeForPlainText(string $str): string {
+		return $str;
+	}
+
+	private function printPlainErrorPage(\Throwable $exception, bool $debug = false): void {
+		header('Content-Type: text/plain; charset=utf-8');
+		print("Internal Server Error\n\n");
+		print("The server encountered an internal error and was unable to complete your request.\n");
+		print("Please contact the server administrator if this error reappears multiple times, please include the technical details below in your report.\n");
+		print("More details can be found in the server log.\n");
+
+		if ($debug) {
+			print("\n");
+			print($exception->getMessage() . ' ' . $exception->getFile() . ' at ' . $exception->getLine() . "\n");
+			print($this->fakeEscapeForPlainText($exception->getTraceAsString()));
+		}
+	}
+}
diff --git a/lib/private/legacy/OC_Template.php b/lib/private/legacy/OC_Template.php
index af363e0a41e..afa640632f8 100644
--- a/lib/private/legacy/OC_Template.php
+++ b/lib/private/legacy/OC_Template.php
@@ -5,209 +5,27 @@
  * SPDX-FileCopyrightText: 2016 ownCloud, Inc.
  * SPDX-License-Identifier: AGPL-3.0-only
  */
-use OC\TemplateLayout;
-use OCP\AppFramework\Http\Events\BeforeTemplateRenderedEvent;
-use OCP\AppFramework\Http\TemplateResponse;
-use OCP\EventDispatcher\IEventDispatcher;
-use Psr\Log\LoggerInterface;
+use OCP\Server;
+use OCP\Template\ITemplateManager;
 
 require_once __DIR__ . '/template/functions.php';
 
 /**
  * This class provides the templates for ownCloud.
+ * @deprecated 32.0.0 Use \OCP\Template\ITemplateManager instead
  */
-class OC_Template extends \OC\Template\Base {
-	/** @var string */
-	private $renderAs; // Create a full page?
-
-	/** @var string */
-	private $path; // The path to the template
-
-	/** @var array */
-	private $headers = []; //custom headers
-
-	/** @var string */
-	protected $app; // app id
-
-	/**
-	 * Constructor
-	 *
-	 * @param string $app app providing the template
-	 * @param string $name of the template file (without suffix)
-	 * @param string $renderAs If $renderAs is set, OC_Template will try to
-	 *                         produce a full page in the according layout. For
-	 *                         now, $renderAs can be set to "guest", "user" or
-	 *                         "admin".
-	 * @param bool $registerCall = true
-	 */
-	public function __construct($app, $name, $renderAs = TemplateResponse::RENDER_AS_BLANK, $registerCall = true) {
-		$theme = OC_Util::getTheme();
-
-		$requestToken = (OC::$server->getSession() && $registerCall) ? \OCP\Util::callRegister() : '';
-		$cspNonce = \OCP\Server::get(\OC\Security\CSP\ContentSecurityPolicyNonceManager::class)->getNonce();
-
-		$parts = explode('/', $app); // fix translation when app is something like core/lostpassword
-		$l10n = \OC::$server->getL10N($parts[0]);
-		/** @var \OCP\Defaults $themeDefaults */
-		$themeDefaults = \OCP\Server::get(\OCP\Defaults::class);
-
-		[$path, $template] = $this->findTemplate($theme, $app, $name);
-
-		// Set the private data
-		$this->renderAs = $renderAs;
-		$this->path = $path;
-		$this->app = $app;
-
-		parent::__construct(
-			$template,
-			$requestToken,
-			$l10n,
-			$themeDefaults,
-			$cspNonce,
-		);
-	}
-
-
-	/**
-	 * find the template with the given name
-	 * @param string $name of the template file (without suffix)
-	 *
-	 * Will select the template file for the selected theme.
-	 * Checking all the possible locations.
-	 * @param string $theme
-	 * @param string $app
-	 * @return string[]
-	 */
-	protected function findTemplate($theme, $app, $name) {
-		// Check if it is a app template or not.
-		if ($app !== '') {
-			$dirs = $this->getAppTemplateDirs($theme, $app, OC::$SERVERROOT, OC_App::getAppPath($app));
-		} else {
-			$dirs = $this->getCoreTemplateDirs($theme, OC::$SERVERROOT);
-		}
-		$locator = new \OC\Template\TemplateFileLocator($dirs);
-		$template = $locator->find($name);
-		$path = $locator->getPath();
-		return [$path, $template];
-	}
-
-	/**
-	 * Add a custom element to the header
-	 * @param string $tag tag name of the element
-	 * @param array $attributes array of attributes for the element
-	 * @param string $text the text content for the element. If $text is null then the
-	 *                     element will be written as empty element. So use "" to get a closing tag.
-	 */
-	public function addHeader($tag, $attributes, $text = null) {
-		$this->headers[] = [
-			'tag' => $tag,
-			'attributes' => $attributes,
-			'text' => $text
-		];
-	}
-
-	/**
-	 * Process the template
-	 * @return string
-	 *
-	 * This function process the template. If $this->renderAs is set, it
-	 * will produce a full page.
-	 */
-	public function fetchPage($additionalParams = null) {
-		$data = parent::fetchPage($additionalParams);
-
-		if ($this->renderAs) {
-			$page = new TemplateLayout($this->renderAs, $this->app);
-
-			if (is_array($additionalParams)) {
-				foreach ($additionalParams as $key => $value) {
-					$page->assign($key, $value);
-				}
-			}
-
-			// Add custom headers
-			$headers = '';
-			foreach (OC_Util::$headers as $header) {
-				$headers .= '<' . \OCP\Util::sanitizeHTML($header['tag']);
-				if (strcasecmp($header['tag'], 'script') === 0 && in_array('src', array_map('strtolower', array_keys($header['attributes'])))) {
-					$headers .= ' defer';
-				}
-				foreach ($header['attributes'] as $name => $value) {
-					$headers .= ' ' . \OCP\Util::sanitizeHTML($name) . '="' . \OCP\Util::sanitizeHTML($value) . '"';
-				}
-				if ($header['text'] !== null) {
-					$headers .= '>' . \OCP\Util::sanitizeHTML($header['text']) . '</' . \OCP\Util::sanitizeHTML($header['tag']) . '>';
-				} else {
-					$headers .= '/>';
-				}
-			}
-
-			$page->assign('headers', $headers);
-
-			$page->assign('content', $data);
-			return $page->fetchPage($additionalParams);
-		}
-
-		return $data;
-	}
-
-	/**
-	 * Include template
-	 *
-	 * @param string $file
-	 * @param array|null $additionalParams
-	 * @return string returns content of included template
-	 *
-	 * Includes another template. use <?php echo $this->inc('template'); ?> to
-	 * do this.
-	 */
-	public function inc($file, $additionalParams = null) {
-		return $this->load($this->path . $file . '.php', $additionalParams);
-	}
-
-	/**
-	 * Shortcut to print a simple page for users
-	 * @param string $application The application we render the template for
-	 * @param string $name Name of the template
-	 * @param array $parameters Parameters for the template
-	 * @return boolean|null
-	 */
-	public static function printUserPage($application, $name, $parameters = []) {
-		$content = new OC_Template($application, $name, 'user');
-		foreach ($parameters as $key => $value) {
-			$content->assign($key, $value);
-		}
-		print $content->printPage();
-	}
-
-	/**
-	 * Shortcut to print a simple page for admins
-	 * @param string $application The application we render the template for
-	 * @param string $name Name of the template
-	 * @param array $parameters Parameters for the template
-	 * @return bool
-	 */
-	public static function printAdminPage($application, $name, $parameters = []) {
-		$content = new OC_Template($application, $name, 'admin');
-		foreach ($parameters as $key => $value) {
-			$content->assign($key, $value);
-		}
-		return $content->printPage();
-	}
-
+class OC_Template extends \OC\Template\Template {
 	/**
 	 * Shortcut to print a simple page for guests
 	 * @param string $application The application we render the template for
 	 * @param string $name Name of the template
 	 * @param array|string $parameters Parameters for the template
 	 * @return bool
+	 * @deprecated 32.0.0 Use \OCP\Template\ITemplateManager instead
 	 */
 	public static function printGuestPage($application, $name, $parameters = []) {
-		$content = new OC_Template($application, $name, $name === 'error' ? $name : 'guest');
-		foreach ($parameters as $key => $value) {
-			$content->assign($key, $value);
-		}
-		return $content->printPage();
+		Server::get(ITemplateManager::class)->printGuestPage($application, $name, $parameters);
+		return true;
 	}
 
 	/**
@@ -215,123 +33,21 @@ class OC_Template extends \OC\Template\Base {
 	 * @param string $error_msg The error message to show
 	 * @param string $hint An optional hint message - needs to be properly escape
 	 * @param int $statusCode
-	 * @suppress PhanAccessMethodInternal
+	 * @return never
+	 * @deprecated 32.0.0 Use \OCP\Template\ITemplateManager instead
 	 */
 	public static function printErrorPage($error_msg, $hint = '', $statusCode = 500) {
-		if (\OC::$server->getAppManager()->isEnabledForUser('theming') && !\OC_App::isAppLoaded('theming')) {
-			\OC_App::loadApp('theming');
-		}
-
-
-		if ($error_msg === $hint) {
-			// If the hint is the same as the message there is no need to display it twice.
-			$hint = '';
-		}
-		$errors = [['error' => $error_msg, 'hint' => $hint]];
-
-		http_response_code($statusCode);
-		try {
-			// Try rendering themed html error page
-			$response = new TemplateResponse(
-				'',
-				'error',
-				['errors' => $errors],
-				TemplateResponse::RENDER_AS_ERROR,
-				$statusCode,
-			);
-			$event = new BeforeTemplateRenderedEvent(false, $response);
-			\OC::$server->get(IEventDispatcher::class)->dispatchTyped($event);
-			print($response->render());
-		} catch (\Throwable $e1) {
-			$logger = \OCP\Server::get(LoggerInterface::class);
-			$logger->error('Rendering themed error page failed. Falling back to un-themed error page.', [
-				'app' => 'core',
-				'exception' => $e1,
-			]);
-
-			try {
-				// Try rendering unthemed html error page
-				$content = new \OC_Template('', 'error', 'error', false);
-				$content->assign('errors', $errors);
-				$content->printPage();
-			} catch (\Exception $e2) {
-				// If nothing else works, fall back to plain text error page
-				$logger->error("$error_msg $hint", ['app' => 'core']);
-				$logger->error('Rendering un-themed error page failed. Falling back to plain text error page.', [
-					'app' => 'core',
-					'exception' => $e2,
-				]);
-
-				header('Content-Type: text/plain; charset=utf-8');
-				print("$error_msg $hint");
-			}
-		}
-		die();
+		Server::get(ITemplateManager::class)->printErrorPage($error_msg, $hint, $statusCode);
 	}
 
 	/**
 	 * print error page using Exception details
 	 * @param Exception|Throwable $exception
 	 * @param int $statusCode
-	 * @return bool|string
-	 * @suppress PhanAccessMethodInternal
+	 * @return never
+	 * @deprecated 32.0.0 Use \OCP\Template\ITemplateManager instead
 	 */
 	public static function printExceptionErrorPage($exception, $statusCode = 503) {
-		$debug = false;
-		http_response_code($statusCode);
-		try {
-			$debug = \OC::$server->getSystemConfig()->getValue('debug', false);
-			$serverLogsDocumentation = \OC::$server->getSystemConfig()->getValue('documentation_url.server_logs', '');
-			$request = \OC::$server->getRequest();
-			$content = new \OC_Template('', 'exception', 'error', false);
-			$content->assign('errorClass', get_class($exception));
-			$content->assign('errorMsg', $exception->getMessage());
-			$content->assign('errorCode', $exception->getCode());
-			$content->assign('file', $exception->getFile());
-			$content->assign('line', $exception->getLine());
-			$content->assign('exception', $exception);
-			$content->assign('debugMode', $debug);
-			$content->assign('serverLogsDocumentation', $serverLogsDocumentation);
-			$content->assign('remoteAddr', $request->getRemoteAddress());
-			$content->assign('requestID', $request->getId());
-			$content->printPage();
-		} catch (\Exception $e) {
-			try {
-				$logger = \OCP\Server::get(LoggerInterface::class);
-				$logger->error($exception->getMessage(), ['app' => 'core', 'exception' => $exception]);
-				$logger->error($e->getMessage(), ['app' => 'core', 'exception' => $e]);
-			} catch (Throwable $e) {
-				// no way to log it properly - but to avoid a white page of death we send some output
-				self::printPlainErrorPage($e, $debug);
-
-				// and then throw it again to log it at least to the web server error log
-				throw $e;
-			}
-
-			self::printPlainErrorPage($e, $debug);
-		}
-		die();
-	}
-
-	/**
-	 * @psalm-taint-escape has_quotes
-	 * @psalm-taint-escape html
-	 */
-	private static function fakeEscapeForPlainText(string $str): string {
-		return $str;
-	}
-
-	private static function printPlainErrorPage(\Throwable $exception, bool $debug = false): void {
-		header('Content-Type: text/plain; charset=utf-8');
-		print("Internal Server Error\n\n");
-		print("The server encountered an internal error and was unable to complete your request.\n");
-		print("Please contact the server administrator if this error reappears multiple times, please include the technical details below in your report.\n");
-		print("More details can be found in the server log.\n");
-
-		if ($debug) {
-			print("\n");
-			print($exception->getMessage() . ' ' . $exception->getFile() . ' at ' . $exception->getLine() . "\n");
-			print(self::fakeEscapeForPlainText($exception->getTraceAsString()));
-		}
+		Server::get(ITemplateManager::class)->printExceptionErrorPage($exception, $statusCode);
 	}
 }
diff --git a/lib/public/Template.php b/lib/public/Template.php
index 048697ffcc4..d9b3083319b 100644
--- a/lib/public/Template.php
+++ b/lib/public/Template.php
@@ -12,6 +12,7 @@ namespace OCP;
  * specific templates, add data and generate the html code
  *
  * @since 8.0.0
+ * @deprecated 32.0.0 Use \OCP\Template\ITemplateManager instead
  */
 class Template extends \OC_Template {
 	/**
diff --git a/lib/public/Template/ITemplateManager.php b/lib/public/Template/ITemplateManager.php
new file mode 100644
index 00000000000..267439d4070
--- /dev/null
+++ b/lib/public/Template/ITemplateManager.php
@@ -0,0 +1,36 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * SPDX-FileCopyrightText: 2025 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+
+namespace OCP\Template;
+
+use OCP\AppFramework\Http\TemplateResponse;
+
+interface ITemplateManager {
+	public function getTemplate(string $app, string $name, string $renderAs = TemplateResponse::RENDER_AS_BLANK, bool $registerCall = true): ITemplate;
+
+	/**
+	 * Shortcut to print a simple page for guests
+	 * @since 32.0.0
+	 */
+	public function printGuestPage(string $application, string $name, array $parameters = []): void;
+
+	/**
+	 * Print a fatal error page and terminates the script
+	 * @since 32.0.0
+	 * @param string $error_msg The error message to show
+	 * @param string $hint An optional hint message - needs to be properly escape
+	 */
+	public function printErrorPage(string $error_msg, string $hint = '', int $statusCode = 500): never;
+
+	/**
+	 * print error page using Exception details
+	 * @since 32.0.0
+	 */
+	public function printExceptionErrorPage(\Throwable $exception, int $statusCode = 503): never;
+}