Move more from \OC to PSR-4

* \OC\OCSClient
* \OC\Preview
* \OC\PreviewManager
* \OC\Repair
* \OC\RepairException
* \OC\Search
* \OC\ServerContainer
* \OC\ServerNotAvailableException
* \OC\ServiceUnavailableException
* \OC\Setup
* \OC\Streamer
* \OC\SubAdmin
* \OC\SystemConfig
* \OC\TagManager
* \OC\Tags
* \OC\TempManager
* \OC\TemplateLayout
* \OC\URLGenerator
* \OC\Updater

1 files changed, 1337 insertions, 0 deletions

diff --git a/lib/private/Preview.php b/lib/private/Preview.php
new file mode 100644
index 00000000000..4fca56dd984
--- /dev/null
+++ b/lib/private/Preview.php
@@ -0,0 +1,1337 @@
+<?php
+/**
+ * @author Björn Schießle <schiessle@owncloud.com>
+ * @author Frank Karlitschek <frank@owncloud.org>
+ * @author Georg Ehrke <georg@owncloud.com>
+ * @author Joas Schilling <nickvergessen@owncloud.com>
+ * @author Jörn Friedrich Dreyer <jfd@butonic.de>
+ * @author Lukas Reschke <lukas@owncloud.com>
+ * @author Morris Jobke <hey@morrisjobke.de>
+ * @author Olivier Paroz <github@oparoz.com>
+ * @author Robin Appelman <icewind@owncloud.com>
+ * @author Roeland Jago Douma <rullzer@owncloud.com>
+ * @author Thomas Müller <thomas.mueller@tmit.eu>
+ * @author Tobias Kaminsky <tobias@kaminsky.me>
+ *
+ * @copyright Copyright (c) 2016, ownCloud, Inc.
+ * @license AGPL-3.0
+ *
+ * This code is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License, version 3,
+ * as published by the Free Software Foundation.
+ *
+ * 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, version 3,
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>
+ *
+ */
+namespace OC;
+
+use OC\Preview\Provider;
+use OCP\Files\FileInfo;
+use OCP\Files\NotFoundException;
+
+class Preview {
+	//the thumbnail folder
+	const THUMBNAILS_FOLDER = 'thumbnails';
+
+	const MODE_FILL = 'fill';
+	const MODE_COVER = 'cover';
+
+	//config
+	private $maxScaleFactor;
+	/** @var int maximum width allowed for a preview */
+	private $configMaxWidth;
+	/** @var int maximum height allowed for a preview */
+	private $configMaxHeight;
+
+	//fileview object
+	private $fileView = null;
+	private $userView = null;
+
+	//vars
+	private $file;
+	private $maxX;
+	private $maxY;
+	private $scalingUp;
+	private $mimeType;
+	private $keepAspect = false;
+	private $mode = self::MODE_FILL;
+
+	//used to calculate the size of the preview to generate
+	/** @var int $maxPreviewWidth max width a preview can have */
+	private $maxPreviewWidth;
+	/** @var int $maxPreviewHeight max height a preview can have */
+	private $maxPreviewHeight;
+	/** @var int $previewWidth calculated width of the preview we're looking for */
+	private $previewWidth;
+	/** @var int $previewHeight calculated height of the preview we're looking for */
+	private $previewHeight;
+
+	//filemapper used for deleting previews
+	// index is path, value is fileinfo
+	static public $deleteFileMapper = array();
+	static public $deleteChildrenMapper = array();
+
+	/**
+	 * preview images object
+	 *
+	 * @var \OCP\IImage
+	 */
+	private $preview;
+
+	/**
+	 * @var \OCP\Files\FileInfo
+	 */
+	protected $info;
+
+	/**
+	 * check if thumbnail or bigger version of thumbnail of file is cached
+	 *
+	 * @param string $user userid - if no user is given, OC_User::getUser will be used
+	 * @param string $root path of root
+	 * @param string $file The path to the file where you want a thumbnail from
+	 * @param int $maxX The maximum X size of the thumbnail. It can be smaller depending on the
+	 *     shape of the image
+	 * @param int $maxY The maximum Y size of the thumbnail. It can be smaller depending on the
+	 *     shape of the image
+	 * @param bool $scalingUp Disable/Enable upscaling of previews
+	 *
+	 * @throws \Exception
+	 * @return mixed (bool / string)
+	 *                    false if thumbnail does not exist
+	 *                    path to thumbnail if thumbnail exists
+	 */
+	public function __construct(
+		$user = '',
+		$root = '/',
+		$file = '', $maxX = 1,
+		$maxY = 1,
+		$scalingUp = true
+	) {
+		//init fileviews
+		if ($user === '') {
+			$user = \OC_User::getUser();
+		}
+		$this->fileView = new \OC\Files\View('/' . $user . '/' . $root);
+		$this->userView = new \OC\Files\View('/' . $user);
+
+		//set config
+		$sysConfig = \OC::$server->getConfig();
+		$this->configMaxWidth = $sysConfig->getSystemValue('preview_max_x', 2048);
+		$this->configMaxHeight = $sysConfig->getSystemValue('preview_max_y', 2048);
+		$this->maxScaleFactor = $sysConfig->getSystemValue('preview_max_scale_factor', 2);
+
+		//save parameters
+		$this->setFile($file);
+		$this->setMaxX((int)$maxX);
+		$this->setMaxY((int)$maxY);
+		$this->setScalingUp($scalingUp);
+
+		$this->preview = null;
+
+		//check if there are preview backends
+		if (!\OC::$server->getPreviewManager()
+						 ->hasProviders()
+			&& \OC::$server->getConfig()
+						   ->getSystemValue('enable_previews', true)
+		) {
+			\OCP\Util::writeLog('core', 'No preview providers exist', \OCP\Util::ERROR);
+			throw new \Exception('No preview providers');
+		}
+	}
+
+	/**
+	 * returns the path of the file you want a thumbnail from
+	 *
+	 * @return string
+	 */
+	public function getFile() {
+		return $this->file;
+	}
+
+	/**
+	 * returns the max width of the preview
+	 *
+	 * @return integer
+	 */
+	public function getMaxX() {
+		return $this->maxX;
+	}
+
+	/**
+	 * returns the max height of the preview
+	 *
+	 * @return integer
+	 */
+	public function getMaxY() {
+		return $this->maxY;
+	}
+
+	/**
+	 * returns whether or not scalingup is enabled
+	 *
+	 * @return bool
+	 */
+	public function getScalingUp() {
+		return $this->scalingUp;
+	}
+
+	/**
+	 * returns the name of the thumbnailfolder
+	 *
+	 * @return string
+	 */
+	public function getThumbnailsFolder() {
+		return self::THUMBNAILS_FOLDER;
+	}
+
+	/**
+	 * returns the max scale factor
+	 *
+	 * @return string
+	 */
+	public function getMaxScaleFactor() {
+		return $this->maxScaleFactor;
+	}
+
+	/**
+	 * returns the max width set in ownCloud's config
+	 *
+	 * @return integer
+	 */
+	public function getConfigMaxX() {
+		return $this->configMaxWidth;
+	}
+
+	/**
+	 * returns the max height set in ownCloud's config
+	 *
+	 * @return integer
+	 */
+	public function getConfigMaxY() {
+		return $this->configMaxHeight;
+	}
+
+	/**
+	 * Returns the FileInfo object associated with the file to preview
+	 *
+	 * @return false|Files\FileInfo|\OCP\Files\FileInfo
+	 */
+	protected function getFileInfo() {
+		$absPath = $this->fileView->getAbsolutePath($this->file);
+		$absPath = Files\Filesystem::normalizePath($absPath);
+		if (array_key_exists($absPath, self::$deleteFileMapper)) {
+			$this->info = self::$deleteFileMapper[$absPath];
+		} else if (!$this->info) {
+			$this->info = $this->fileView->getFileInfo($this->file);
+		}
+
+		return $this->info;
+	}
+
+
+	/**
+	 * @return array|null
+	 */
+	private function getChildren() {
+		$absPath = $this->fileView->getAbsolutePath($this->file);
+		$absPath = Files\Filesystem::normalizePath($absPath);
+
+		if (array_key_exists($absPath, self::$deleteChildrenMapper)) {
+			return self::$deleteChildrenMapper[$absPath];
+		}
+
+		return null;
+	}
+
+	/**
+	 * Sets the path of the file you want a preview of
+	 *
+	 * @param string $file
+	 * @param \OCP\Files\FileInfo|null $info
+	 *
+	 * @return \OC\Preview
+	 */
+	public function setFile($file, $info = null) {
+		$this->file = $file;
+		$this->info = $info;
+
+		if ($file !== '') {
+			$this->getFileInfo();
+			if ($this->info instanceof \OCP\Files\FileInfo) {
+				$this->mimeType = $this->info->getMimetype();
+			}
+		}
+
+		return $this;
+	}
+
+	/**
+	 * Forces the use of a specific media type
+	 *
+	 * @param string $mimeType
+	 */
+	public function setMimetype($mimeType) {
+		$this->mimeType = $mimeType;
+	}
+
+	/**
+	 * Sets the max width of the preview. It's capped by the maximum allowed size set in the
+	 * configuration
+	 *
+	 * @param int $maxX
+	 *
+	 * @throws \Exception
+	 * @return \OC\Preview
+	 */
+	public function setMaxX($maxX = 1) {
+		if ($maxX <= 0) {
+			throw new \Exception('Cannot set width of 0 or smaller!');
+		}
+		$configMaxX = $this->getConfigMaxX();
+		$maxX = $this->limitMaxDim($maxX, $configMaxX, 'maxX');
+		$this->maxX = $maxX;
+
+		return $this;
+	}
+
+	/**
+	 * Sets the max height of the preview. It's capped by the maximum allowed size set in the
+	 * configuration
+	 *
+	 * @param int $maxY
+	 *
+	 * @throws \Exception
+	 * @return \OC\Preview
+	 */
+	public function setMaxY($maxY = 1) {
+		if ($maxY <= 0) {
+			throw new \Exception('Cannot set height of 0 or smaller!');
+		}
+		$configMaxY = $this->getConfigMaxY();
+		$maxY = $this->limitMaxDim($maxY, $configMaxY, 'maxY');
+		$this->maxY = $maxY;
+
+		return $this;
+	}
+
+	/**
+	 * Sets whether we're allowed to scale up when generating a preview. It's capped by the maximum
+	 * allowed scale factor set in the configuration
+	 *
+	 * @param bool $scalingUp
+	 *
+	 * @return \OC\Preview
+	 */
+	public function setScalingup($scalingUp) {
+		if ($this->getMaxScaleFactor() === 1) {
+			$scalingUp = false;
+		}
+		$this->scalingUp = $scalingUp;
+
+		return $this;
+	}
+
+	/**
+	 * Set whether to cover or fill the specified dimensions
+	 *
+	 * @param string $mode
+	 *
+	 * @return \OC\Preview
+	 */
+	public function setMode($mode) {
+		$this->mode = $mode;
+
+		return $this;
+	}
+
+	/**
+	 * Sets whether we need to generate a preview which keeps the aspect ratio of the original file
+	 *
+	 * @param bool $keepAspect
+	 *
+	 * @return \OC\Preview
+	 */
+	public function setKeepAspect($keepAspect) {
+		$this->keepAspect = $keepAspect;
+
+		return $this;
+	}
+
+	/**
+	 * Makes sure we were given a file to preview and that it exists in the filesystem
+	 *
+	 * @return bool
+	 */
+	public function isFileValid() {
+		$file = $this->getFile();
+		if ($file === '') {
+			\OCP\Util::writeLog('core', 'No filename passed', \OCP\Util::DEBUG);
+
+			return false;
+		}
+
+		if (!$this->getFileInfo() instanceof FileInfo) {
+			\OCP\Util::writeLog('core', 'File:"' . $file . '" not found', \OCP\Util::DEBUG);
+
+			return false;
+		}
+
+		return true;
+	}
+
+	/**
+	 * Deletes the preview of a file with specific width and height
+	 *
+	 * This should never delete the max preview, use deleteAllPreviews() instead
+	 *
+	 * @return bool
+	 */
+	public function deletePreview() {
+		$fileInfo = $this->getFileInfo();
+		if ($fileInfo !== null && $fileInfo !== false) {
+			$fileId = $fileInfo->getId();
+
+			$previewPath = $this->buildCachePath($fileId);
+			if (!strpos($previewPath, 'max')) {
+				return $this->userView->unlink($previewPath);
+			}
+		}
+
+		return false;
+	}
+
+	/**
+	 * Deletes all previews of a file
+	 */
+	public function deleteAllPreviews() {
+		$toDelete = $this->getChildren();
+		$toDelete[] = $this->getFileInfo();
+
+		foreach ($toDelete as $delete) {
+			if ($delete instanceof FileInfo) {
+				/** @var \OCP\Files\FileInfo $delete */
+				$fileId = $delete->getId();
+
+				// getId() might return null, e.g. when the file is a
+				// .ocTransferId*.part file from chunked file upload.
+				if (!empty($fileId)) {
+					$previewPath = $this->getPreviewPath($fileId);
+					$this->userView->deleteAll($previewPath);
+					$this->userView->rmdir($previewPath);
+				}
+			}
+		}
+	}
+
+	/**
+	 * Checks if a preview matching the asked dimensions or a bigger version is already cached
+	 *
+	 *    * We first retrieve the size of the max preview since this is what we be used to create
+	 * all our preview. If it doesn't exist we return false, so that it can be generated
+	 *    * Using the dimensions of the max preview, we calculate what the size of the new
+	 * thumbnail should be
+	 *    * And finally, we look for a suitable candidate in the cache
+	 *
+	 * @param int $fileId fileId of the original file we need a preview of
+	 *
+	 * @return string|false path to the cached preview if it exists or false
+	 */
+	public function isCached($fileId) {
+		if (is_null($fileId)) {
+			return false;
+		}
+
+		/**
+		 * Phase 1: Looking for the max preview
+		 */
+		$previewPath = $this->getPreviewPath($fileId);
+		// We currently can't look for a single file due to bugs related to #16478
+		$allThumbnails = $this->userView->getDirectoryContent($previewPath);
+		list($maxPreviewWidth, $maxPreviewHeight) = $this->getMaxPreviewSize($allThumbnails);
+
+		// Only use the cache if we have a max preview
+		if (!is_null($maxPreviewWidth) && !is_null($maxPreviewHeight)) {
+
+			/**
+			 * Phase 2: Calculating the size of the preview we need to send back
+			 */
+			$this->maxPreviewWidth = $maxPreviewWidth;
+			$this->maxPreviewHeight = $maxPreviewHeight;
+
+			list($previewWidth, $previewHeight) = $this->simulatePreviewDimensions();
+			if (empty($previewWidth) || empty($previewHeight)) {
+				return false;
+			}
+
+			$this->previewWidth = $previewWidth;
+			$this->previewHeight = $previewHeight;
+
+			/**
+			 * Phase 3: We look for a preview of the exact size
+			 */
+			// This gives us a calculated path to a preview of asked dimensions
+			// thumbnailFolder/fileId/<maxX>-<maxY>(-max|-with-aspect).png
+			$preview = $this->buildCachePath($fileId, $previewWidth, $previewHeight);
+
+			// This checks if we have a preview of those exact dimensions in the cache
+			if ($this->thumbnailSizeExists($allThumbnails, basename($preview))) {
+				return $preview;
+			}
+
+			/**
+			 * Phase 4: We look for a larger preview, matching the aspect ratio
+			 */
+			if (($this->getMaxX() >= $maxPreviewWidth)
+				&& ($this->getMaxY() >= $maxPreviewHeight)
+			) {
+				// The preview we-re looking for is the exact size or larger than the max preview,
+				// so return that
+				return $this->buildCachePath($fileId, $maxPreviewWidth, $maxPreviewHeight);
+			} else {
+				// The last resort is to look for something bigger than what we've calculated,
+				// but still smaller than the max preview
+				return $this->isCachedBigger($fileId, $allThumbnails);
+			}
+		}
+
+		return false;
+	}
+
+	/**
+	 * Returns the dimensions of the max preview
+	 *
+	 * @param FileInfo[] $allThumbnails the list of all our cached thumbnails
+	 *
+	 * @return int[]
+	 */
+	private function getMaxPreviewSize($allThumbnails) {
+		$maxPreviewX = null;
+		$maxPreviewY = null;
+
+		foreach ($allThumbnails as $thumbnail) {
+			$name = $thumbnail['name'];
+			if (strpos($name, 'max')) {
+				list($maxPreviewX, $maxPreviewY) = $this->getDimensionsFromFilename($name);
+				break;
+			}
+		}
+
+		return [$maxPreviewX, $maxPreviewY];
+	}
+
+	/**
+	 * Check if a specific thumbnail size is cached
+	 *
+	 * @param FileInfo[] $allThumbnails the list of all our cached thumbnails
+	 * @param string $name
+	 * @return bool
+	 */
+	private function thumbnailSizeExists(array $allThumbnails, $name) {
+
+		foreach ($allThumbnails as $thumbnail) {
+			if ($name === $thumbnail->getName()) {
+				return true;
+			}
+		}
+
+		return false;
+	}
+
+	/**
+	 * Determines the size of the preview we should be looking for in the cache
+	 *
+	 * @return integer[]
+	 */
+	private function simulatePreviewDimensions() {
+		$askedWidth = $this->getMaxX();
+		$askedHeight = $this->getMaxY();
+
+		if ($this->keepAspect) {
+			list($newPreviewWidth, $newPreviewHeight) =
+				$this->applyAspectRatio($askedWidth, $askedHeight);
+		} else {
+			list($newPreviewWidth, $newPreviewHeight) = $this->fixSize($askedWidth, $askedHeight);
+		}
+
+		return [(int)$newPreviewWidth, (int)$newPreviewHeight];
+	}
+
+	/**
+	 * Resizes the boundaries to match the aspect ratio
+	 *
+	 * @param int $askedWidth
+	 * @param int $askedHeight
+	 *
+	 * @param int $originalWidth
+	 * @param int $originalHeight
+	 * @return integer[]
+	 */
+	private function applyAspectRatio($askedWidth, $askedHeight, $originalWidth = 0, $originalHeight = 0) {
+		if(!$originalWidth){
+			$originalWidth= $this->maxPreviewWidth;
+		}
+		if (!$originalHeight) {
+			$originalHeight = $this->maxPreviewHeight;
+		}
+		$originalRatio = $originalWidth / $originalHeight;
+		// Defines the box in which the preview has to fit
+		$scaleFactor = $this->scalingUp ? $this->maxScaleFactor : 1;
+		$askedWidth = min($askedWidth, $originalWidth * $scaleFactor);
+		$askedHeight = min($askedHeight, $originalHeight * $scaleFactor);
+
+		if ($askedWidth / $originalRatio < $askedHeight) {
+			// width restricted
+			$askedHeight = round($askedWidth / $originalRatio);
+		} else {
+			$askedWidth = round($askedHeight * $originalRatio);
+		}
+
+		return [(int)$askedWidth, (int)$askedHeight];
+	}
+
+	/**
+	 * Resizes the boundaries to cover the area
+	 *
+	 * @param int $askedWidth
+	 * @param int $askedHeight
+	 * @param int $previewWidth
+	 * @param int $previewHeight
+	 * @return integer[]
+	 */
+	private function applyCover($askedWidth, $askedHeight, $previewWidth, $previewHeight) {
+		$originalRatio = $previewWidth / $previewHeight;
+		// Defines the box in which the preview has to fit
+		$scaleFactor = $this->scalingUp ? $this->maxScaleFactor : 1;
+		$askedWidth = min($askedWidth, $previewWidth * $scaleFactor);
+		$askedHeight = min($askedHeight, $previewHeight * $scaleFactor);
+
+		if ($askedWidth / $originalRatio > $askedHeight) {
+			// height restricted
+			$askedHeight = round($askedWidth / $originalRatio);
+		} else {
+			$askedWidth = round($askedHeight * $originalRatio);
+		}
+
+		return [(int)$askedWidth, (int)$askedHeight];
+	}
+
+	/**
+	 * Makes sure an upscaled preview doesn't end up larger than the max dimensions defined in the
+	 * config
+	 *
+	 * @param int $askedWidth
+	 * @param int $askedHeight
+	 *
+	 * @return integer[]
+	 */
+	private function fixSize($askedWidth, $askedHeight) {
+		if ($this->scalingUp) {
+			$askedWidth = min($this->configMaxWidth, $askedWidth);
+			$askedHeight = min($this->configMaxHeight, $askedHeight);
+		}
+
+		return [(int)$askedWidth, (int)$askedHeight];
+	}
+
+	/**
+	 * Checks if a bigger version of a file preview is cached and if not
+	 * return the preview of max allowed dimensions
+	 *
+	 * @param int $fileId fileId of the original image
+	 * @param FileInfo[] $allThumbnails the list of all our cached thumbnails
+	 *
+	 * @return string path to bigger thumbnail
+	 */
+	private function isCachedBigger($fileId, $allThumbnails) {
+		// This is used to eliminate any thumbnail narrower than what we need
+		$maxX = $this->getMaxX();
+
+		//array for usable cached thumbnails
+		$possibleThumbnails = $this->getPossibleThumbnails($allThumbnails);
+
+		foreach ($possibleThumbnails as $width => $path) {
+			if ($width < $maxX) {
+				continue;
+			} else {
+				return $path;
+			}
+		}
+
+		// At this stage, we didn't find a preview, so we return the max preview
+		return $this->buildCachePath($fileId, $this->maxPreviewWidth, $this->maxPreviewHeight);
+	}
+
+	/**
+	 * Get possible bigger thumbnails of the given image with the proper aspect ratio
+	 *
+	 * @param FileInfo[] $allThumbnails the list of all our cached thumbnails
+	 *
+	 * @return string[] an array of paths to bigger thumbnails
+	 */
+	private function getPossibleThumbnails($allThumbnails) {
+		if ($this->keepAspect) {
+			$wantedAspectRatio = (float)($this->maxPreviewWidth / $this->maxPreviewHeight);
+		} else {
+			$wantedAspectRatio = (float)($this->getMaxX() / $this->getMaxY());
+		}
+
+		//array for usable cached thumbnails
+		$possibleThumbnails = array();
+		foreach ($allThumbnails as $thumbnail) {
+			$name = rtrim($thumbnail['name'], '.png');
+			list($x, $y, $aspectRatio) = $this->getDimensionsFromFilename($name);
+			if (abs($aspectRatio - $wantedAspectRatio) >= 0.000001
+				|| $this->unscalable($x, $y)
+			) {
+				continue;
+			}
+			$possibleThumbnails[$x] = $thumbnail['path'];
+		}
+
+		ksort($possibleThumbnails);
+
+		return $possibleThumbnails;
+	}
+
+	/**
+	 * Looks at the preview filename from the cache and extracts the size of the preview
+	 *
+	 * @param string $name
+	 *
+	 * @return array<int,int,float>
+	 */
+	private function getDimensionsFromFilename($name) {
+		$size = explode('-', $name);
+		$x = (int)$size[0];
+		$y = (int)$size[1];
+		$aspectRatio = (float)($x / $y);
+
+		return array($x, $y, $aspectRatio);
+	}
+
+	/**
+	 * @param int $x
+	 * @param int $y
+	 *
+	 * @return bool
+	 */
+	private function unscalable($x, $y) {
+
+		$maxX = $this->getMaxX();
+		$maxY = $this->getMaxY();
+		$scalingUp = $this->getScalingUp();
+		$maxScaleFactor = $this->getMaxScaleFactor();
+
+		if ($x < $maxX || $y < $maxY) {
+			if ($scalingUp) {
+				$scaleFactor = $maxX / $x;
+				if ($scaleFactor > $maxScaleFactor) {
+					return true;
+				}
+			} else {
+				return true;
+			}
+		}
+
+		return false;
+	}
+
+	/**
+	 * Returns a preview of a file
+	 *
+	 * The cache is searched first and if nothing usable was found then a preview is
+	 * generated by one of the providers
+	 *
+	 * @return \OCP\IImage
+	 */
+	public function getPreview() {
+		if (!is_null($this->preview) && $this->preview->valid()) {
+			return $this->preview;
+		}
+
+		$this->preview = null;
+		$fileInfo = $this->getFileInfo();
+		if ($fileInfo === null || $fileInfo === false) {
+			return new \OC_Image();
+		}
+
+		$fileId = $fileInfo->getId();
+		$cached = $this->isCached($fileId);
+		if ($cached) {
+			$this->getCachedPreview($fileId, $cached);
+		}
+
+		if (is_null($this->preview)) {
+			$this->generatePreview($fileId);
+		}
+
+		// We still don't have a preview, so we send back an empty object
+		if (is_null($this->preview)) {
+			$this->preview = new \OC_Image();
+		}
+
+		return $this->preview;
+	}
+
+	/**
+	 * Sends the preview, including the headers to client which requested it
+	 *
+	 * @param null|string $mimeTypeForHeaders the media type to use when sending back the reply
+	 *
+	 * @throws NotFoundException
+	 */
+	public function showPreview($mimeTypeForHeaders = null) {
+		// Check if file is valid
+		if ($this->isFileValid() === false) {
+			throw new NotFoundException('File not found.');
+		}
+
+		if (is_null($this->preview)) {
+			$this->getPreview();
+		}
+		if ($this->preview instanceof \OCP\IImage) {
+			if ($this->preview->valid()) {
+				\OCP\Response::enableCaching(3600 * 24); // 24 hours
+			} else {
+				$this->getMimeIcon();
+			}
+			$this->preview->show($mimeTypeForHeaders);
+		}
+	}
+
+	/**
+	 * Retrieves the preview from the cache and resizes it if necessary
+	 *
+	 * @param int $fileId fileId of the original image
+	 * @param string $cached the path to the cached preview
+	 */
+	private function getCachedPreview($fileId, $cached) {
+		$stream = $this->userView->fopen($cached, 'r');
+		$this->preview = null;
+		if ($stream) {
+			$image = new \OC_Image();
+			$image->loadFromFileHandle($stream);
+
+			$this->preview = $image->valid() ? $image : null;
+
+			if (!is_null($this->preview)) {
+				// Size of the preview we calculated
+				$maxX = $this->previewWidth;
+				$maxY = $this->previewHeight;
+				// Size of the preview we retrieved from the cache
+				$previewX = (int)$this->preview->width();
+				$previewY = (int)$this->preview->height();
+
+				// We don't have an exact match
+				if ($previewX !== $maxX || $previewY !== $maxY) {
+					$this->resizeAndStore($fileId);
+				}
+			}
+
+			fclose($stream);
+		}
+	}
+
+	/**
+	 * Resizes, crops, fixes orientation and stores in the cache
+	 *
+	 * @param int $fileId fileId of the original image
+	 */
+	private function resizeAndStore($fileId) {
+		$image = $this->preview;
+		if (!($image instanceof \OCP\IImage)) {
+			\OCP\Util::writeLog(
+				'core', '$this->preview is not an instance of \OCP\IImage', \OCP\Util::DEBUG
+			);
+
+			return;
+		}
+		$previewWidth = (int)$image->width();
+		$previewHeight = (int)$image->height();
+		$askedWidth = $this->getMaxX();
+		$askedHeight = $this->getMaxY();
+
+		if ($this->mode === self::MODE_COVER) {
+			list($askedWidth, $askedHeight) =
+				$this->applyCover($askedWidth, $askedHeight, $previewWidth, $previewHeight);
+		}
+
+		/**
+		 * Phase 1: If required, adjust boundaries to keep aspect ratio
+		 */
+		if ($this->keepAspect) {
+			list($askedWidth, $askedHeight) =
+				$this->applyAspectRatio($askedWidth, $askedHeight, $previewWidth, $previewHeight);
+		}
+
+		/**
+		 * Phase 2: Resizes preview to try and match requirements.
+		 * Takes the scaling ratio into consideration
+		 */
+		list($newPreviewWidth, $newPreviewHeight) = $this->scale(
+			$image, $askedWidth, $askedHeight, $previewWidth, $previewHeight
+		);
+
+		// The preview has been resized and should now have the asked dimensions
+		if ($newPreviewWidth === $askedWidth && $newPreviewHeight === $askedHeight) {
+			$this->storePreview($fileId, $newPreviewWidth, $newPreviewHeight);
+
+			return;
+		}
+
+		/**
+		 * Phase 3: We're still not there yet, so we're clipping and filling
+		 * to match the asked dimensions
+		 */
+		// It turns out the scaled preview is now too big, so we crop the image
+		if ($newPreviewWidth >= $askedWidth && $newPreviewHeight >= $askedHeight) {
+			$this->crop($image, $askedWidth, $askedHeight, $newPreviewWidth, $newPreviewHeight);
+			$this->storePreview($fileId, $askedWidth, $askedHeight);
+
+			return;
+		}
+
+		// At least one dimension of the scaled preview is too small,
+		// so we fill the space with a transparent background
+		if (($newPreviewWidth < $askedWidth || $newPreviewHeight < $askedHeight)) {
+			$this->cropAndFill(
+				$image, $askedWidth, $askedHeight, $newPreviewWidth, $newPreviewHeight
+			);
+			$this->storePreview($fileId, $askedWidth, $askedHeight);
+
+			return;
+		}
+
+		// The preview is smaller, but we can't touch it
+		$this->storePreview($fileId, $newPreviewWidth, $newPreviewHeight);
+	}
+
+	/**
+	 * Calculates the new dimensions of the preview
+	 *
+	 * The new dimensions can be larger or smaller than the ones of the preview we have to resize
+	 *
+	 * @param \OCP\IImage $image
+	 * @param int $askedWidth
+	 * @param int $askedHeight
+	 * @param int $previewWidth
+	 * @param int $previewHeight
+	 *
+	 * @return int[]
+	 */
+	private function scale($image, $askedWidth, $askedHeight, $previewWidth, $previewHeight) {
+		$scalingUp = $this->getScalingUp();
+		$maxScaleFactor = $this->getMaxScaleFactor();
+
+		$factorX = $askedWidth / $previewWidth;
+		$factorY = $askedHeight / $previewHeight;
+
+		if ($factorX >= $factorY) {
+			$factor = $factorX;
+		} else {
+			$factor = $factorY;
+		}
+
+		if ($scalingUp === false) {
+			if ($factor > 1) {
+				$factor = 1;
+			}
+		}
+
+		// We cap when upscaling
+		if (!is_null($maxScaleFactor)) {
+			if ($factor > $maxScaleFactor) {
+				\OCP\Util::writeLog(
+					'core', 'scale factor reduced from ' . $factor . ' to ' . $maxScaleFactor,
+					\OCP\Util::DEBUG
+				);
+				$factor = $maxScaleFactor;
+			}
+		}
+
+		$newPreviewWidth = round($previewWidth * $factor);
+		$newPreviewHeight = round($previewHeight * $factor);
+
+		$image->preciseResize($newPreviewWidth, $newPreviewHeight);
+		$this->preview = $image;
+
+		return [$newPreviewWidth, $newPreviewHeight];
+	}
+
+	/**
+	 * Crops a preview which is larger than the dimensions we've received
+	 *
+	 * @param \OCP\IImage $image
+	 * @param int $askedWidth
+	 * @param int $askedHeight
+	 * @param int $previewWidth
+	 * @param int $previewHeight
+	 */
+	private function crop($image, $askedWidth, $askedHeight, $previewWidth, $previewHeight = null) {
+		$cropX = floor(abs($askedWidth - $previewWidth) * 0.5);
+		//don't crop previews on the Y axis, this sucks if it's a document.
+		//$cropY = floor(abs($y - $newPreviewHeight) * 0.5);
+		$cropY = 0;
+		$image->crop($cropX, $cropY, $askedWidth, $askedHeight);
+		$this->preview = $image;
+	}
+
+	/**
+	 * Crops an image if it's larger than the dimensions we've received and fills the empty space
+	 * with a transparent background
+	 *
+	 * @param \OCP\IImage $image
+	 * @param int $askedWidth
+	 * @param int $askedHeight
+	 * @param int $previewWidth
+	 * @param int $previewHeight
+	 */
+	private function cropAndFill($image, $askedWidth, $askedHeight, $previewWidth, $previewHeight) {
+		if ($previewWidth > $askedWidth) {
+			$cropX = floor(($previewWidth - $askedWidth) * 0.5);
+			$image->crop($cropX, 0, $askedWidth, $previewHeight);
+			$previewWidth = $askedWidth;
+		}
+
+		if ($previewHeight > $askedHeight) {
+			$cropY = floor(($previewHeight - $askedHeight) * 0.5);
+			$image->crop(0, $cropY, $previewWidth, $askedHeight);
+			$previewHeight = $askedHeight;
+		}
+
+		// Creates a transparent background
+		$backgroundLayer = imagecreatetruecolor($askedWidth, $askedHeight);
+		imagealphablending($backgroundLayer, false);
+		$transparency = imagecolorallocatealpha($backgroundLayer, 0, 0, 0, 127);
+		imagefill($backgroundLayer, 0, 0, $transparency);
+		imagesavealpha($backgroundLayer, true);
+
+		$image = $image->resource();
+
+		$mergeX = floor(abs($askedWidth - $previewWidth) * 0.5);
+		$mergeY = floor(abs($askedHeight - $previewHeight) * 0.5);
+
+		// Pastes the preview on top of the background
+		imagecopy(
+			$backgroundLayer, $image, $mergeX, $mergeY, 0, 0, $previewWidth,
+			$previewHeight
+		);
+
+		$image = new \OC_Image($backgroundLayer);
+
+		$this->preview = $image;
+	}
+
+	/**
+	 * Saves a preview in the cache to speed up future calls
+	 *
+	 * Do not nullify the preview as it might send the whole process in a loop
+	 *
+	 * @param int $fileId fileId of the original image
+	 * @param int $previewWidth
+	 * @param int $previewHeight
+	 */
+	private function storePreview($fileId, $previewWidth, $previewHeight) {
+		if (empty($previewWidth) || empty($previewHeight)) {
+			\OCP\Util::writeLog(
+				'core', 'Cannot save preview of dimension ' . $previewWidth . 'x' . $previewHeight,
+				\OCP\Util::DEBUG
+			);
+
+		} else {
+			$cachePath = $this->buildCachePath($fileId, $previewWidth, $previewHeight);
+			$this->userView->file_put_contents($cachePath, $this->preview->data());
+		}
+	}
+
+	/**
+	 * Returns the path to a preview based on its dimensions and aspect
+	 *
+	 * @param int $fileId
+	 * @param int|null $maxX
+	 * @param int|null $maxY
+	 *
+	 * @return string
+	 */
+	private function buildCachePath($fileId, $maxX = null, $maxY = null) {
+		if (is_null($maxX)) {
+			$maxX = $this->getMaxX();
+		}
+		if (is_null($maxY)) {
+			$maxY = $this->getMaxY();
+		}
+
+		$previewPath = $this->getPreviewPath($fileId);
+		$previewPath = $previewPath . strval($maxX) . '-' . strval($maxY);
+		$isMaxPreview =
+			($maxX === $this->maxPreviewWidth && $maxY === $this->maxPreviewHeight) ? true : false;
+		if ($isMaxPreview) {
+			$previewPath .= '-max';
+		}
+		if ($this->keepAspect && !$isMaxPreview) {
+			$previewPath .= '-with-aspect';
+		}
+		if ($this->mode === self::MODE_COVER) {
+			$previewPath .= '-cover';
+		}
+		$previewPath .= '.png';
+
+		return $previewPath;
+	}
+
+	/**
+	 * Returns the path to the folder where the previews are stored, identified by the fileId
+	 *
+	 * @param int $fileId
+	 *
+	 * @return string
+	 */
+	private function getPreviewPath($fileId) {
+		return $this->getThumbnailsFolder() . '/' . $fileId . '/';
+	}
+
+	/**
+	 * Asks the provider to send a preview of the file which respects the maximum dimensions
+	 * defined in the configuration and after saving it in the cache, it is then resized to the
+	 * asked dimensions
+	 *
+	 * This is only called once in order to generate a large PNG of dimensions defined in the
+	 * configuration file. We'll be able to quickly resize it later on.
+	 * We never upscale the original conversion as this will be done later by the resizing
+	 * operation
+	 *
+	 * @param int $fileId fileId of the original image
+	 */
+	private function generatePreview($fileId) {
+		$file = $this->getFile();
+		$preview = null;
+
+		$previewProviders = \OC::$server->getPreviewManager()
+										->getProviders();
+		foreach ($previewProviders as $supportedMimeType => $providers) {
+			if (!preg_match($supportedMimeType, $this->mimeType)) {
+				continue;
+			}
+
+			foreach ($providers as $closure) {
+				$provider = $closure();
+				if (!($provider instanceof \OCP\Preview\IProvider)) {
+					continue;
+				}
+
+				\OCP\Util::writeLog(
+					'core', 'Generating preview for "' . $file . '" with "' . get_class($provider)
+							. '"', \OCP\Util::DEBUG
+				);
+
+				/** @var $provider Provider */
+				$preview = $provider->getThumbnail(
+					$file, $this->configMaxWidth, $this->configMaxHeight, $scalingUp = false,
+					$this->fileView
+				);
+
+				if (!($preview instanceof \OCP\IImage)) {
+					continue;
+				}
+
+				$this->preview = $preview;
+				$previewPath = $this->getPreviewPath($fileId);
+
+				if ($this->userView->is_dir($this->getThumbnailsFolder() . '/') === false) {
+					$this->userView->mkdir($this->getThumbnailsFolder() . '/');
+				}
+
+				if ($this->userView->is_dir($previewPath) === false) {
+					$this->userView->mkdir($previewPath);
+				}
+
+				// This stores our large preview so that it can be used in subsequent resizing requests
+				$this->storeMaxPreview($previewPath);
+
+				break 2;
+			}
+		}
+
+		// The providers have been kind enough to give us a preview
+		if ($preview) {
+			$this->resizeAndStore($fileId);
+		}
+	}
+
+	/**
+	 * Defines the media icon, for the media type of the original file, as the preview
+	 */
+	private function getMimeIcon() {
+		$image = new \OC_Image();
+		$mimeIconWebPath = \OC::$server->getMimeTypeDetector()->mimeTypeIcon($this->mimeType);
+		if (empty(\OC::$WEBROOT)) {
+			$mimeIconServerPath = \OC::$SERVERROOT . $mimeIconWebPath;
+		} else {
+			$mimeIconServerPath = str_replace(\OC::$WEBROOT, \OC::$SERVERROOT, $mimeIconWebPath);
+		}
+		$image->loadFromFile($mimeIconServerPath);
+
+		$this->preview = $image;
+	}
+
+	/**
+	 * Stores the max preview in the cache
+	 *
+	 * @param string $previewPath path to the preview
+	 */
+	private function storeMaxPreview($previewPath) {
+		$maxPreviewExists = false;
+		$preview = $this->preview;
+
+		$allThumbnails = $this->userView->getDirectoryContent($previewPath);
+		// This is so that the cache doesn't need emptying when upgrading
+		// Can be replaced by an upgrade script...
+		foreach ($allThumbnails as $thumbnail) {
+			$name = rtrim($thumbnail['name'], '.png');
+			if (strpos($name, 'max')) {
+				$maxPreviewExists = true;
+				break;
+			}
+		}
+		// We haven't found the max preview, so we create it
+		if (!$maxPreviewExists) {
+			$previewWidth = $preview->width();
+			$previewHeight = $preview->height();
+			$previewPath = $previewPath . strval($previewWidth) . '-' . strval($previewHeight);
+			$previewPath .= '-max.png';
+			$this->userView->file_put_contents($previewPath, $preview->data());
+			$this->maxPreviewWidth = $previewWidth;
+			$this->maxPreviewHeight = $previewHeight;
+		}
+	}
+
+	/**
+	 * Limits a dimension to the maximum dimension provided as argument
+	 *
+	 * @param int $dim
+	 * @param int $maxDim
+	 * @param string $dimName
+	 *
+	 * @return integer
+	 */
+	private function limitMaxDim($dim, $maxDim, $dimName) {
+		if (!is_null($maxDim)) {
+			if ($dim > $maxDim) {
+				\OCP\Util::writeLog(
+					'core', $dimName . ' reduced from ' . $dim . ' to ' . $maxDim, \OCP\Util::DEBUG
+				);
+				$dim = $maxDim;
+			}
+		}
+
+		return $dim;
+	}
+
+	/**
+	 * @param array $args
+	 */
+	public static function post_write($args) {
+		self::post_delete($args, 'files/');
+	}
+
+	/**
+	 * @param array $args
+	 */
+	public static function prepare_delete_files($args) {
+		self::prepare_delete($args, 'files/');
+	}
+
+	/**
+	 * @param array $args
+	 * @param string $prefix
+	 */
+	public static function prepare_delete(array $args, $prefix = '') {
+		$path = $args['path'];
+		if (substr($path, 0, 1) === '/') {
+			$path = substr($path, 1);
+		}
+
+		$view = new \OC\Files\View('/' . \OC_User::getUser() . '/' . $prefix);
+
+		$absPath = Files\Filesystem::normalizePath($view->getAbsolutePath($path));
+		$fileInfo = $view->getFileInfo($path);
+		if($fileInfo === false) {
+			return;
+		}
+		self::addPathToDeleteFileMapper($absPath, $fileInfo);
+		if ($view->is_dir($path)) {
+			$children = self::getAllChildren($view, $path);
+			self::$deleteChildrenMapper[$absPath] = $children;
+		}
+	}
+
+	/**
+	 * @param string $absolutePath
+	 * @param \OCP\Files\FileInfo $info
+	 */
+	private static function addPathToDeleteFileMapper($absolutePath, $info) {
+		self::$deleteFileMapper[$absolutePath] = $info;
+	}
+
+	/**
+	 * @param \OC\Files\View $view
+	 * @param string $path
+	 *
+	 * @return array
+	 */
+	private static function getAllChildren($view, $path) {
+		$children = $view->getDirectoryContent($path);
+		$childrensFiles = array();
+
+		$fakeRootLength = strlen($view->getRoot());
+
+		for ($i = 0; $i < count($children); $i++) {
+			$child = $children[$i];
+
+			$childsPath = substr($child->getPath(), $fakeRootLength);
+
+			if ($view->is_dir($childsPath)) {
+				$children = array_merge(
+					$children,
+					$view->getDirectoryContent($childsPath)
+				);
+			} else {
+				$childrensFiles[] = $child;
+			}
+		}
+
+		return $childrensFiles;
+	}
+
+	/**
+	 * @param array $args
+	 */
+	public static function post_delete_files($args) {
+		self::post_delete($args, 'files/');
+	}
+
+	/**
+	 * @param array $args
+	 */
+	public static function post_delete_versions($args) {
+		self::post_delete($args, 'files/');
+	}
+
+	/**
+	 * @param array $args
+	 * @param string $prefix
+	 */
+	public static function post_delete($args, $prefix = '') {
+		$path = Files\Filesystem::normalizePath($args['path']);
+
+		$preview = new Preview(\OC_User::getUser(), $prefix, $path);
+		$preview->deleteAllPreviews();
+	}
+
+}