<?php

/**
 * SPDX-FileCopyrightText: 2016-2024 Nextcloud GmbH and Nextcloud contributors
 * SPDX-FileCopyrightText: 2016 ownCloud, Inc.
 * SPDX-License-Identifier: AGPL-3.0-only
 */
namespace OCA\DAV\Connector\Sabre;

/**
 * ownCloud
 *
 * @author Vincent Petry
 * @copyright 2014 Vincent Petry <pvince81@owncloud.com>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU AFFERO GENERAL PUBLIC LICENSE
 * License as published by the Free Software Foundation; either
 * version 3 of the License, or any later version.
 *
 * This library 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 library.  If not, see <http://www.gnu.org/licenses/>.
 *
 */
use OCP\EventDispatcher\IEventDispatcher;
use OCP\ITagManager;
use OCP\ITags;
use OCP\IUserSession;
use Sabre\DAV\ICollection;
use Sabre\DAV\PropFind;
use Sabre\DAV\PropPatch;

class TagsPlugin extends \Sabre\DAV\ServerPlugin {

	// namespace
	public const NS_OWNCLOUD = 'http://owncloud.org/ns';
	public const TAGS_PROPERTYNAME = '{http://owncloud.org/ns}tags';
	public const FAVORITE_PROPERTYNAME = '{http://owncloud.org/ns}favorite';
	public const TAG_FAVORITE = '_$!<Favorite>!$_';

	/**
	 * Reference to main server object
	 *
	 * @var \Sabre\DAV\Server
	 */
	private $server;

	/**
	 * @var ITags
	 */
	private $tagger;

	/**
	 * Array of file id to tags array
	 * The null value means the cache wasn't initialized.
	 *
	 * @var array
	 */
	private $cachedTags;
	private array $cachedDirectories;

	/**
	 * @param \Sabre\DAV\Tree $tree tree
	 * @param ITagManager $tagManager tag manager
	 */
	public function __construct(
		private \Sabre\DAV\Tree $tree,
		private ITagManager $tagManager,
		private IEventDispatcher $eventDispatcher,
		private IUserSession $userSession,
	) {
		$this->tagger = null;
		$this->cachedTags = [];
	}

	/**
	 * This initializes the plugin.
	 *
	 * This function is called by \Sabre\DAV\Server, after
	 * addPlugin is called.
	 *
	 * This method should set up the required event subscriptions.
	 *
	 * @param \Sabre\DAV\Server $server
	 * @return void
	 */
	public function initialize(\Sabre\DAV\Server $server) {
		$server->xml->namespaceMap[self::NS_OWNCLOUD] = 'oc';
		$server->xml->elementMap[self::TAGS_PROPERTYNAME] = TagList::class;

		$this->server = $server;
		$this->server->on('preloadCollection', $this->preloadCollection(...));
		$this->server->on('propFind', [$this, 'handleGetProperties']);
		$this->server->on('propPatch', [$this, 'handleUpdateProperties']);
		$this->server->on('preloadProperties', [$this, 'handlePreloadProperties']);
	}

	/**
	 * Returns the tagger
	 *
	 * @return ITags tagger
	 */
	private function getTagger() {
		if (!$this->tagger) {
			$this->tagger = $this->tagManager->load('files');
		}
		return $this->tagger;
	}

	/**
	 * Returns tags and favorites.
	 *
	 * @param integer $fileId file id
	 * @return array list($tags, $favorite) with $tags as tag array
	 *               and $favorite is a boolean whether the file was favorited
	 */
	private function getTagsAndFav($fileId) {
		$isFav = false;
		$tags = $this->getTags($fileId);
		if ($tags) {
			$favPos = array_search(self::TAG_FAVORITE, $tags, true);
			if ($favPos !== false) {
				$isFav = true;
				unset($tags[$favPos]);
			}
		}
		return [$tags, $isFav];
	}

	/**
	 * Returns tags for the given file id
	 *
	 * @param integer $fileId file id
	 * @return array list of tags for that file
	 */
	private function getTags($fileId) {
		if (isset($this->cachedTags[$fileId])) {
			return $this->cachedTags[$fileId];
		} else {
			$tags = $this->getTagger()->getTagsForObjects([$fileId]);
			if ($tags !== false) {
				if (empty($tags)) {
					return [];
				}
				return current($tags);
			}
		}
		return null;
	}

	/**
	 * Prefetches tags for a list of file IDs and caches the results
	 *
	 * @param array $fileIds List of file IDs to prefetch tags for
	 * @return void
	 */
	private function prefetchTagsForFileIds(array $fileIds) {
		$tags = $this->getTagger()->getTagsForObjects($fileIds);
		if ($tags === false) {
			// the tags API returns false on error...
			$tags = [];
		}

		foreach ($fileIds as $fileId) {
			$this->cachedTags[$fileId] = $tags[$fileId] ?? [];
		}
	}

	/**
	 * Updates the tags of the given file id
	 *
	 * @param int $fileId
	 * @param array $tags array of tag strings
	 * @param string $path path of the file
	 */
	private function updateTags($fileId, $tags, string $path) {
		$tagger = $this->getTagger();
		$currentTags = $this->getTags($fileId);

		$newTags = array_diff($tags, $currentTags);
		foreach ($newTags as $tag) {
			if ($tag === self::TAG_FAVORITE) {
				continue;
			}
			$tagger->tagAs($fileId, $tag, $path);
		}
		$deletedTags = array_diff($currentTags, $tags);
		foreach ($deletedTags as $tag) {
			if ($tag === self::TAG_FAVORITE) {
				continue;
			}
			$tagger->unTag($fileId, $tag, $path);
		}
	}

	private function preloadCollection(PropFind $propFind, ICollection $collection):
	void {
		if (!($collection instanceof Node)) {
			return;
		}

		// need prefetch ?
		if ($collection instanceof Directory
			&& !isset($this->cachedDirectories[$collection->getPath()])
			&& (!is_null($propFind->getStatus(self::TAGS_PROPERTYNAME))
				|| !is_null($propFind->getStatus(self::FAVORITE_PROPERTYNAME))
			)) {
			// note: pre-fetching only supported for depth <= 1
			$folderContent = $collection->getChildren();
			$fileIds = [(int)$collection->getId()];
			foreach ($folderContent as $info) {
				$fileIds[] = (int)$info->getId();
			}
			$this->prefetchTagsForFileIds($fileIds);
			$this->cachedDirectories[$collection->getPath()] = true;
		}
	}

	/**
	 * Adds tags and favorites properties to the response,
	 * if requested.
	 *
	 * @param PropFind $propFind
	 * @param \Sabre\DAV\INode $node
	 * @return void
	 */
	public function handleGetProperties(
		PropFind $propFind,
		\Sabre\DAV\INode $node,
	) {
		if (!($node instanceof Node)) {
			return;
		}

		$isFav = null;

		$propFind->handle(self::TAGS_PROPERTYNAME, function () use (&$isFav, $node) {
			[$tags, $isFav] = $this->getTagsAndFav($node->getId());
			return new TagList($tags);
		});

		$propFind->handle(self::FAVORITE_PROPERTYNAME, function () use ($isFav, $node) {
			if (is_null($isFav)) {
				[, $isFav] = $this->getTagsAndFav($node->getId());
			}
			if ($isFav) {
				return 1;
			} else {
				return 0;
			}
		});
	}

	/**
	 * Updates tags and favorites properties, if applicable.
	 *
	 * @param string $path
	 * @param PropPatch $propPatch
	 *
	 * @return void
	 */
	public function handleUpdateProperties($path, PropPatch $propPatch) {
		$node = $this->tree->getNodeForPath($path);
		if (!($node instanceof Node)) {
			return;
		}

		$propPatch->handle(self::TAGS_PROPERTYNAME, function ($tagList) use ($node, $path) {
			$this->updateTags($node->getId(), $tagList->getTags(), $path);
			return true;
		});

		$propPatch->handle(self::FAVORITE_PROPERTYNAME, function ($favState) use ($node, $path) {
			if ((int)$favState === 1 || $favState === 'true') {
				$this->getTagger()->tagAs($node->getId(), self::TAG_FAVORITE, $path);
			} else {
				$this->getTagger()->unTag($node->getId(), self::TAG_FAVORITE, $path);
			}

			if (is_null($favState)) {
				// confirm deletion
				return 204;
			}

			return 200;
		});
	}

	public function handlePreloadProperties(array $nodes, array $requestProperties): void {
		if (
			!in_array(self::FAVORITE_PROPERTYNAME, $requestProperties, true)
			&& !in_array(self::TAGS_PROPERTYNAME, $requestProperties, true)
		) {
			return;
		}
		$this->prefetchTagsForFileIds(array_map(fn ($node) => $node->getId(), $nodes));
	}
}