<?php
/**
 * @author Joas Schilling <coding@schilljs.com>
 * @author Morris Jobke <hey@morrisjobke.de>
 * @author Olivier Paroz <github@oparoz.com>
 * @author Robin Appelman <icewind@owncloud.com>
 * @author Thomas Müller <thomas.mueller@tmit.eu>
 * @author Vincent Petry <pvince81@owncloud.com>
 * @author Lorenzo Perone <lorenzo.perone@yellowspace.net>
 *
 * @copyright Copyright (c) 2018, ownCloud GmbH
 * @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\AppFramework\Middleware\Security\Exceptions\NotLoggedInException;
use OCP\Files\IRootFolder;
use OCP\IConfig;
use OCP\IImage;
use OCP\IPreview;
use OCP\IUserSession;
use OCP\Preview\IProvider;
use OCP\Preview\IProvider2;

class PreviewManager implements IPreview {
	/** @var IConfig */
	protected $config;

	/** @var bool */
	protected $providerListDirty = false;

	/** @var bool */
	protected $registeredCoreProviders = false;

	/** @var array */
	protected $providers = [];

	/** @var array mime type => support status */
	protected $mimeTypeSupportMap = [];

	/** @var array */
	protected $defaultProviders;

	/** @var IRootFolder */
	private $rootFolder;

	/** @var IUserSession */
	private $userSession;

	/**
	 * Constructor
	 *
	 * @param IConfig $config
	 * @param IRootFolder $rootFolder
	 * @param IUserSession $userSession
	 */
	public function __construct(IConfig $config, IRootFolder $rootFolder, IUserSession $userSession) {
		$this->config = $config;
		$this->rootFolder = $rootFolder;
		$this->userSession = $userSession;
	}

	/**
	 * In order to improve lazy loading a closure can be registered which will be
	 * called in case preview providers are actually requested
	 *
	 * $callable has to return an instance of \OCP\Preview\IProvider
	 *
	 * @param string $mimeTypeRegex Regex with the mime types that are supported by this provider
	 * @param \Closure $callable
	 * @return void
	 */
	public function registerProvider($mimeTypeRegex, \Closure $callable) {
		if (!$this->config->getSystemValue('enable_previews', true)) {
			return;
		}

		if (!isset($this->providers[$mimeTypeRegex])) {
			$this->providers[$mimeTypeRegex] = [];
		}
		$this->providers[$mimeTypeRegex][] = $callable;
		$this->providerListDirty = true;
	}

	/**
	 * Get all providers
	 * @return array
	 */
	public function getProviders() {
		if (!$this->config->getSystemValue('enable_previews', true)) {
			return [];
		}

		$this->registerCoreProviders();
		if ($this->providerListDirty) {
			$keys = \array_map('strlen', \array_keys($this->providers));
			\array_multisort($keys, SORT_DESC, $this->providers);
			$this->providerListDirty = false;
		}

		return $this->providers;
	}

	/**
	 * Does the manager have any providers
	 * @return bool
	 */
	public function hasProviders() {
		$this->registerCoreProviders();
		return !empty($this->providers);
	}

	/**
	 * return a preview of a file
	 *
	 * @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 boolean $scaleUp Scale smaller images up to the thumbnail size or not. Might look ugly
	 * @return IImage
	 * @throws NotLoggedInException
	 * @throws \OCP\Files\NotFoundException
	 * @throws \Exception
	 */
	public function createPreview($file, $maxX = 100, $maxY = 75, $scaleUp = false) {
		$user = $this->userSession->getUser();
		if ($user === null) {
			throw new NotLoggedInException();
		}
		$file = $this->rootFolder->getUserFolder($user->getUID())->getParent()->get($file);
		$preview = new Preview('', '', $file, $maxX, $maxY, $scaleUp);
		return $preview->getPreview();
	}

	/**
	 * returns true if the passed mime type is supported
	 *
	 * @param string $mimeType
	 * @return boolean
	 */
	public function isMimeSupported($mimeType = '*') {
		if (!$this->config->getSystemValue('enable_previews', true)) {
			return false;
		}

		if (isset($this->mimeTypeSupportMap[$mimeType])) {
			return $this->mimeTypeSupportMap[$mimeType];
		}

		$this->registerCoreProviders();
		$providerMimeTypes = \array_keys($this->providers);
		foreach ($providerMimeTypes as $supportedMimeType) {
			if (\preg_match($supportedMimeType, $mimeType)) {
				$this->mimeTypeSupportMap[$mimeType] = true;
				return true;
			}
		}
		$this->mimeTypeSupportMap[$mimeType] = false;
		return false;
	}
	
	/**
	 * Returns all registered MimeTypes as an array
	 *
	 * @return string[]
	 */
	public function getSupportedMimes() {
		$supportedMimes = [];
		$this->registerCoreProviders();
		$mimeRegexArray = \array_keys($this->providers);
		// Now trim start/stop regexp delimiters
		foreach ($mimeRegexArray as $mimeRegex) {
			$supportedMimes[] = \trim($mimeRegex, '/');
		}
		return $supportedMimes;
	}

	/**
	 * Check if a preview can be generated for a file
	 *
	 * @param \OCP\Files\FileInfo $file
	 * @return bool
	 */
	public function isAvailable(\OCP\Files\FileInfo $file) {
		if (!$this->config->getSystemValue('enable_previews', true)) {
			return false;
		}

		$this->registerCoreProviders();
		if (!$this->isMimeSupported($file->getMimetype())) {
			return false;
		}

		$mount = $file->getMountPoint();
		if ($mount and !$mount->getOption('previews', true)) {
			return false;
		}

		foreach ($this->providers as $supportedMimeType => $providers) {
			if (\preg_match($supportedMimeType, $file->getMimetype())) {
				foreach ($providers as $closure) {
					$provider = $closure();
					if (!($provider instanceof IProvider) && !($provider instanceof IProvider2)) {
						continue;
					}

					/** @var $provider IProvider */
					if ($provider->isAvailable($file)) {
						return true;
					}
				}
			}
		}
		return false;
	}

	/**
	 * List of enabled default providers
	 *
	 * The following providers are enabled by default:
	 *  - OC\Preview\PNG
	 *  - OC\Preview\JPEG
	 *  - OC\Preview\WEBP
	 *  - OC\Preview\GIF
	 *  - OC\Preview\BMP
	 *  - OC\Preview\XBitmap
	 *  - OC\Preview\MarkDown
	 *  - OC\Preview\MP3
	 *  - OC\Preview\TXT
	 *
	 * The following providers are disabled by default due to performance or privacy concerns:
	 *  - OC\Preview\Font
	 *  - OC\Preview\Illustrator
	 *  - OC\Preview\Movie
	 *  - OC\Preview\MSOfficeDoc
	 *  - OC\Preview\MSOffice2003
	 *  - OC\Preview\MSOffice2007
	 *  - OC\Preview\OpenDocument
	 *  - OC\Preview\StarOffice
	 *  - OC\Preview\PDF
	 *  - OC\Preview\Photoshop
	 *  - OC\Preview\Postscript
	 *  - OC\Preview\SVG
	 *  - OC\Preview\TIFF
	 *
	 * @return array
	 */
	protected function getEnabledDefaultProvider() {
		if ($this->defaultProviders !== null) {
			return $this->defaultProviders;
		}

		$imageProviders = [
			'OC\Preview\PNG',
			'OC\Preview\JPEG',
			'OC\Preview\WEBP',
			'OC\Preview\GIF',
			'OC\Preview\BMP',
			'OC\Preview\Heic',
			'OC\Preview\XBitmap',
			'OC\Preview\SGI',
		];

		$this->defaultProviders = $this->config->getSystemValue('enabledPreviewProviders', \array_merge([
			'OC\Preview\MarkDown',
			'OC\Preview\MP3',
			'OC\Preview\TXT',
		], $imageProviders));

		if (\in_array('OC\Preview\Image', $this->defaultProviders)) {
			$this->defaultProviders = \array_merge($this->defaultProviders, $imageProviders);
		}
		$this->defaultProviders = \array_unique($this->defaultProviders);
		return $this->defaultProviders;
	}

	/**
	 * Register the default providers (if enabled)
	 *
	 * @param string $class
	 * @param string $mimeType
	 */
	protected function registerCoreProvider($class, $mimeType, $options = []) {
		if (\in_array(\trim($class, '\\'), $this->getEnabledDefaultProvider())) {
			$this->registerProvider($mimeType, function () use ($class, $options) {
				return new $class($options);
			});
		}
	}

	/**
	 * Register the default providers (if enabled)
	 */
	protected function registerCoreProviders() {
		if ($this->registeredCoreProviders) {
			return;
		}
		$this->registeredCoreProviders = true;

		$this->registerCoreProvider('OC\Preview\TXT', '/text\/plain/');
		$this->registerCoreProvider('OC\Preview\MarkDown', '/text\/(x-)?markdown/');
		$this->registerCoreProvider('OC\Preview\PNG', '/image\/png/');
		$this->registerCoreProvider('OC\Preview\JPEG', '/image\/jpeg/');
		$this->registerCoreProvider('OC\Preview\WEBP', '/image\/webp/');
		$this->registerCoreProvider('OC\Preview\GIF', '/image\/gif/');
		$this->registerCoreProvider('OC\Preview\BMP', '/image\/bmp/');
		$this->registerCoreProvider('OC\Preview\XBitmap', '/image\/x-xbitmap/');
		$this->registerCoreProvider('OC\Preview\MP3', '/audio\/mpeg/');

		// SVG, Office and Bitmap require imagick
		// Either use the additional library mentioned below when using imagick 6, or use imagick 7
		// which does not need this library. See the installation and preview documentation for more details.
		// Install `libmagickcore-6.q16-3-extra` additional to the imagick library when using SVG.
		// This library adds imagick support for SVG, WMF, OpenEXR, DjVu and Graphviz:
		
		if (\extension_loaded('imagick')) {
			$imagickProviders = [
				'SVG'	=> ['mimetype' => '/image\/svg\+xml/', 'class' => '\OC\Preview\SVG'],
				'TIFF'	=> ['mimetype' => '/image\/tiff/', 'class' => '\OC\Preview\TIFF'],
				'PDF'	=> ['mimetype' => '/application\/pdf/', 'class' => '\OC\Preview\PDF'],
				'AI'	=> ['mimetype' => '/application\/illustrator/', 'class' => '\OC\Preview\Illustrator'],
				'PSD'	=> ['mimetype' => '/application\/x-photoshop/', 'class' => '\OC\Preview\Photoshop'],
				'EPS'	=> ['mimetype' => '/application\/postscript/', 'class' => '\OC\Preview\Postscript'],
				'TTF'	=> ['mimetype' => '/application\/(?:font-sfnt|x-font$)/', 'class' => '\OC\Preview\Font'],
				'HEIF'	=> ['mimetype' => '/image\/heif/', 'class' => '\OC\Preview\Heic'],
				'HEIC'	=> ['mimetype' => '/image\/heic/', 'class' => '\OC\Preview\Heic'],
				'SGI'	=> ['mimetype' => '/image\/sgi/', 'class' => '\OC\Preview\SGI'],
			];

			foreach ($imagickProviders as $queryFormat => $provider) {
				$class = $provider['class'];
				if (!\in_array(\trim($class, '\\'), $this->getEnabledDefaultProvider())) {
					continue;
				}

				if (\count(\Imagick::queryFormats($queryFormat)) === 1) {
					$this->registerCoreProvider($class, $provider['mimetype']);
				}
			}

			if (\count(\Imagick::queryFormats('PDF')) === 1) {
				// Office previews are only supported if either LibreOffice or OpenOffice is installed on the server
				if (\OC_Helper::is_function_enabled('shell_exec')) {
					$officeFound = \is_string($this->config->getSystemValue('preview_libreoffice_path', null));

					if (!$officeFound) {
						//let's see if there is libreoffice or openoffice on this machine
						$whichLibreOffice = \shell_exec('command -v libreoffice');
						$officeFound = !empty($whichLibreOffice);
						if (!$officeFound) {
							$whichOpenOffice = \shell_exec('command -v openoffice');
							$officeFound = !empty($whichOpenOffice);
						}
					}

					if ($officeFound) {
						$this->registerCoreProvider('\OC\Preview\MSOfficeDoc', '/application\/msword/');
						$this->registerCoreProvider('\OC\Preview\MSOffice2003', '/application\/vnd.ms-.*/');
						$this->registerCoreProvider('\OC\Preview\MSOffice2007', '/application\/vnd.openxmlformats-officedocument.*/');
						$this->registerCoreProvider('\OC\Preview\OpenDocument', '/application\/vnd.oasis.opendocument.*/');
						$this->registerCoreProvider('\OC\Preview\StarOffice', '/application\/vnd.sun.xml.*/');
					}
				}
			}
		}

		// Video requires avconv or ffmpeg to be installed on the server
		if (\in_array('OC\Preview\Movie', $this->getEnabledDefaultProvider())) {
			$avconvBinary = \OC_Helper::findBinaryPath('avconv');
			$ffmpegBinary = ($avconvBinary) ? null : \OC_Helper::findBinaryPath('ffmpeg');
			$atomicParsleyBinary = \OC_Helper::findBinaryPath('AtomicParsley');

			// FIXME // a bit hacky but didn't want to use subclasses
			$registerProvider = false;
			if ($avconvBinary !== null) {
				\OC\Preview\Movie::$avconvBinary = $avconvBinary;
				$registerProvider = true;
			}
			if ($ffmpegBinary !== null) {
				\OC\Preview\Movie::$ffmpegBinary = $ffmpegBinary;
				$registerProvider = true;
			}
			if ($atomicParsleyBinary !== null) {
				\OC\Preview\Movie::$atomicParsleyBinary = $atomicParsleyBinary;
				$registerProvider = true;
			}
			if ($registerProvider === true) {
				$this->registerCoreProvider('\OC\Preview\Movie', '/video\/.*/');
			}
		}
	}
}
