1 files changed, 116 insertions, 0 deletions
diff --git a/apps/theming/lib/Service/ThemeInjectionService.php b/apps/theming/lib/Service/ThemeInjectionService.php
new file mode 100644
index 00000000000..873d388081c
--- /dev/null
+++ b/apps/theming/lib/Service/ThemeInjectionService.php
@@ -0,0 +1,116 @@
+<?php
+
+/**
+ * SPDX-FileCopyrightText: 2022 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+namespace OCA\Theming\Service;
+
+use OCA\Theming\ITheme;
+use OCA\Theming\Themes\DefaultTheme;
+use OCA\Theming\Util;
+use OCP\IConfig;
+use OCP\IURLGenerator;
+use OCP\IUserSession;
+
+class ThemeInjectionService {
+
+	private ?string $userId;
+
+	public function __construct(
+		private IURLGenerator $urlGenerator,
+		private ThemesService $themesService,
+		private DefaultTheme $defaultTheme,
+		private Util $util,
+		private IConfig $config,
+		IUserSession $userSession,
+	) {
+		if ($userSession->getUser() !== null) {
+			$this->userId = $userSession->getUser()->getUID();
+		} else {
+			$this->userId = null;
+		}
+	}
+
+	public function injectHeaders(): void {
+		$themes = $this->themesService->getThemes();
+		$defaultTheme = $themes[$this->defaultTheme->getId()];
+		$mediaThemes = array_filter($themes, function ($theme) {
+			// Check if the theme provides a media query
+			return (bool)$theme->getMediaQuery();
+		});
+
+		// Default theme fallback
+		$this->addThemeHeaders($defaultTheme);
+
+		// Themes applied by media queries
+		foreach ($mediaThemes as $theme) {
+			$this->addThemeHeaders($theme, true, $theme->getMediaQuery());
+		}
+
+		// Themes
+		foreach ($this->themesService->getThemes() as $theme) {
+			// Ignore default theme as already processed first
+			if ($theme->getId() === $this->defaultTheme->getId()) {
+				continue;
+			}
+			$this->addThemeHeaders($theme, false);
+		}
+
+		// Meta headers
+		$this->addThemeMetaHeaders($themes);
+	}
+
+	/**
+	 * Inject theme header into rendered page
+	 *
+	 * @param ITheme $theme the theme
+	 * @param bool $plain request the :root syntax
+	 * @param string $media media query to use in the <link> element
+	 */
+	private function addThemeHeaders(ITheme $theme, bool $plain = true, ?string $media = null): void {
+		$linkToCSS = $this->urlGenerator->linkToRoute('theming.Theming.getThemeStylesheet', [
+			'themeId' => $theme->getId(),
+			'plain' => $plain,
+			'v' => $this->util->getCacheBuster(),
+		]);
+		\OCP\Util::addHeader('link', [
+			'rel' => 'stylesheet',
+			'media' => $media,
+			'href' => $linkToCSS,
+			'class' => 'theme'
+		]);
+	}
+
+	/**
+	 * Inject meta headers into rendered page
+	 *
+	 * @param ITheme[] $themes the theme
+	 */
+	private function addThemeMetaHeaders(array $themes): void {
+		$metaHeaders = [];
+
+		// Meta headers
+		foreach ($this->themesService->getThemes() as $theme) {
+			if (!empty($theme->getMeta())) {
+				foreach ($theme->getMeta() as $meta) {
+					if (!isset($meta['name']) || !isset($meta['content'])) {
+						continue;
+					}
+
+					if (!isset($metaHeaders[$meta['name']])) {
+						$metaHeaders[$meta['name']] = [];
+					}
+					$metaHeaders[$meta['name']][] = $meta['content'];
+				}
+			}
+		}
+
+		foreach ($metaHeaders as $name => $content) {
+			\OCP\Util::addHeader('meta', [
+				'name' => $name,
+				'content' => join(' ', array_unique($content)),
+			]);
+		}
+	}
+}