Sort app scripts topologically by its dependencies

Implement a proper topological sorting algorithm. Based on the
implementation by https://github.com/marcj/topsort.php

Logs an error in case a circular dependency is detected.

Fixes: #30278

Signed-off-by: Jonas Meurer <jonas@freesources.org>

2 files changed, 202 insertions, 0 deletions

diff --git a/lib/private/AppScriptDependency.php b/lib/private/AppScriptDependency.php
new file mode 100644
index 00000000000..35878e85b49
--- /dev/null
+++ b/lib/private/AppScriptDependency.php
@@ -0,0 +1,97 @@
+<?php
+/**
+ * @copyright Copyright (c) 2021, Jonas Meurer <jonas@freesources.org>
+ *
+ * @author Jonas Meurer <jonas@freesources.org>
+ *
+ * @license GNU AGPL version 3 or any later version
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+namespace OC;
+
+class AppScriptDependency {
+	/** @var string */
+	private $id;
+
+	/** @var array */
+	private $deps;
+
+	/** @var bool */
+	private $visited;
+
+	/**
+	 * @param string $id
+	 * @param array $deps
+	 * @param bool $visited
+	 */
+	public function __construct(string $id, array $deps = [], bool $visited = false) {
+		$this->setId($id);
+		$this->setDeps($deps);
+		$this->setVisited($visited);
+	}
+
+	/**
+	 * @return string
+	 */
+	public function getId(): string {
+		return $this->id;
+	}
+
+	/**
+	 * @param string $id
+	 */
+	public function setId(string $id): void {
+		$this->id = $id;
+	}
+
+	/**
+	 * @return array
+	 */
+	public function getDeps(): array {
+		return $this->deps;
+	}
+
+	/**
+	 * @param array $deps
+	 */
+	public function setDeps(array $deps): void {
+		$this->deps = $deps;
+	}
+
+	/**
+	 * @param string $dep
+	 */
+	public function addDep(string $dep): void {
+		if (!in_array($dep, $this->deps, true)) {
+			$this->deps[] = $dep;
+		}
+	}
+
+	/**
+	 * @return bool
+	 */
+	public function isVisited(): bool {
+		return $this->visited;
+	}
+
+	/**
+	 * @param bool $visited
+	 */
+	public function setVisited(bool $visited): void {
+		$this->visited = $visited;
+	}
+}
diff --git a/lib/private/AppScriptSort.php b/lib/private/AppScriptSort.php
new file mode 100644
index 00000000000..c42d02d485d
--- /dev/null
+++ b/lib/private/AppScriptSort.php
@@ -0,0 +1,105 @@
+<?php
+/**
+ * @copyright Copyright (c) 2021, Jonas Meurer <jonas@freesources.org>
+ *
+ * @author Jonas Meurer <jonas@freesources.org>
+ *
+ * @license GNU AGPL version 3 or any later version
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+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;
+	}
+}