1 files changed, 89 insertions, 0 deletions
diff --git a/lib/private/AppScriptSort.php b/lib/private/AppScriptSort.php
new file mode 100644
index 00000000000..134dad100dc
--- /dev/null
+++ b/lib/private/AppScriptSort.php
@@ -0,0 +1,89 @@
+<?php
+
+/**
+ * SPDX-FileCopyrightText: 2021 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+
+namespace OC;
+
+use Psr\Log\LoggerInterface;
+
+/**
+ * Sort scripts topologically by their dependencies
+ * Implementation based on https://github.com/marcj/topsort.php
+ */
+class AppScriptSort {
+	/** @var LoggerInterface */
+	private $logger;
+
+	public function __construct(LoggerInterface $logger) {
+		$this->logger = $logger;
+	}
+
+	/**
+	 * Recursive topological sorting
+	 *
+	 * @param AppScriptDependency $app
+	 * @param array $parents
+	 * @param array $scriptDeps
+	 * @param array $sortedScriptDeps
+	 */
+	private function topSortVisit(
+		AppScriptDependency $app,
+		array &$parents,
+		array &$scriptDeps,
+		array &$sortedScriptDeps): void {
+		// Detect and log circular dependencies
+		if (isset($parents[$app->getId()])) {
+			$this->logger->error('Circular dependency in app scripts at app ' . $app->getId());
+		}
+
+		// If app has not been visited
+		if (!$app->isVisited()) {
+			$parents[$app->getId()] = true;
+			$app->setVisited(true);
+
+			foreach ($app->getDeps() as $dep) {
+				if ($app->getId() === $dep) {
+					// Ignore dependency on itself
+					continue;
+				}
+
+				if (isset($scriptDeps[$dep])) {
+					$newParents = $parents;
+					$this->topSortVisit($scriptDeps[$dep], $newParents, $scriptDeps, $sortedScriptDeps);
+				}
+			}
+
+			$sortedScriptDeps[] = $app->getId();
+		}
+	}
+
+	/**
+	 * @return array scripts sorted by dependencies
+	 */
+	public function sort(array $scripts, array $scriptDeps): array {
+		// Sort scriptDeps into sortedScriptDeps
+		$sortedScriptDeps = [];
+		foreach ($scriptDeps as $app) {
+			$parents = [];
+			$this->topSortVisit($app, $parents, $scriptDeps, $sortedScriptDeps);
+		}
+
+		// Sort scripts into sortedScripts based on sortedScriptDeps order
+		$sortedScripts = [];
+		foreach ($sortedScriptDeps as $app) {
+			$sortedScripts[$app] = $scripts[$app] ?? [];
+		}
+
+		// Add remaining scripts
+		foreach (array_keys($scripts) as $app) {
+			if (!isset($sortedScripts[$app])) {
+				$sortedScripts[$app] = $scripts[$app];
+			}
+		}
+
+		return $sortedScripts;
+	}
+}