<?php
/**
 * @copyright Copyright (c) 2016, ownCloud, Inc.
 *
 * @author Arthur Schiwon <blizzz@arthur-schiwon.de>
 * @author Björn Schießle <bjoern@schiessle.org>
 * @author Christoph Wurst <christoph@winzerhof-wurst.at>
 * @author Daniel Calviño Sánchez <danxuliu@gmail.com>
 * @author Frank Karlitschek <frank@karlitschek.de>
 * @author Jakob Sack <mail@jakobsack.de>
 * @author Joas Schilling <coding@schilljs.com>
 * @author Jörn Friedrich Dreyer <jfd@butonic.de>
 * @author Julius Härtl <jus@bitgrid.net>
 * @author Ko- <k.stoffelen@cs.ru.nl>
 * @author Michael Gapczynski <GapczynskiM@gmail.com>
 * @author Morris Jobke <hey@morrisjobke.de>
 * @author Nicolai Ehemann <en@enlightened.de>
 * @author Piotr Filiciak <piotr@filiciak.pl>
 * @author Robin Appelman <robin@icewind.nl>
 * @author Robin McCorkell <robin@mccorkell.me.uk>
 * @author Roeland Jago Douma <roeland@famdouma.nl>
 * @author Thibaut GRIDEL <tgridel@free.fr>
 * @author Thomas Müller <thomas.mueller@tmit.eu>
 * @author Valdnet <47037905+Valdnet@users.noreply.github.com>
 * @author Victor Dubiniuk <dubiniuk@owncloud.com>
 * @author Vincent Petry <vincent@nextcloud.com>
 *
 * @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/>
 *
 */
use bantu\IniGetWrapper\IniGetWrapper;
use OC\Files\View;
use OC\Streamer;
use OCP\EventDispatcher\IEventDispatcher;
use OCP\Files\Events\BeforeDirectFileDownloadEvent;
use OCP\Files\Events\BeforeZipCreatedEvent;
use OCP\Lock\ILockingProvider;

/**
 * Class for file server access
 */
class OC_Files {
	public const FILE = 1;
	public const ZIP_FILES = 2;
	public const ZIP_DIR = 3;

	public const UPLOAD_MIN_LIMIT_BYTES = 1048576; // 1 MiB


	private static string $multipartBoundary = '';

	private static function getBoundary(): string {
		if (empty(self::$multipartBoundary)) {
			self::$multipartBoundary = md5((string)mt_rand());
		}
		return self::$multipartBoundary;
	}

	/**
	 * @param string $filename
	 * @param string $name
	 * @param array $rangeArray ('from'=>int,'to'=>int), ...
	 */
	private static function sendHeaders($filename, $name, array $rangeArray): void {
		OC_Response::setContentDispositionHeader($name, 'attachment');
		header('Content-Transfer-Encoding: binary', true);
		header('Expires: 0');
		header("Cache-Control: must-revalidate, post-check=0, pre-check=0");
		$fileSize = \OC\Files\Filesystem::filesize($filename);
		$type = \OC::$server->getMimeTypeDetector()->getSecureMimeType(\OC\Files\Filesystem::getMimeType($filename));
		if ($fileSize > -1) {
			if (!empty($rangeArray)) {
				http_response_code(206);
				header('Accept-Ranges: bytes', true);
				if (count($rangeArray) > 1) {
					$type = 'multipart/byteranges; boundary='.self::getBoundary();
				// no Content-Length header here
				} else {
					header(sprintf('Content-Range: bytes %d-%d/%d', $rangeArray[0]['from'], $rangeArray[0]['to'], $fileSize), true);
					OC_Response::setContentLengthHeader($rangeArray[0]['to'] - $rangeArray[0]['from'] + 1);
				}
			} else {
				OC_Response::setContentLengthHeader($fileSize);
			}
		}
		header('Content-Type: '.$type, true);
		header('X-Accel-Buffering: no');
	}

	/**
	 * return the content of a file or return a zip file containing multiple files
	 *
	 * @param string $dir
	 * @param string $files ; separated list of files to download
	 * @param array $params ; 'head' boolean to only send header of the request ; 'range' http range header
	 */
	public static function get($dir, $files, $params = null) {
		OC_Util::setupFS();
		$view = \OC\Files\Filesystem::getView();
		$getType = self::FILE;
		$filename = $dir;
		try {
			if (is_array($files) && count($files) === 1) {
				$files = $files[0];
			}

			if (!is_array($files)) {
				$filename = $dir . '/' . $files;
				if (!$view->is_dir($filename)) {
					self::getSingleFile($view, $dir, $files, is_null($params) ? [] : $params);
					return;
				}
			}

			$name = 'download';
			if (is_array($files)) {
				$getType = self::ZIP_FILES;
				$basename = basename($dir);
				if ($basename) {
					$name = $basename;
				}

				$filename = $dir . '/' . $name;
			} else {
				$filename = $dir . '/' . $files;
				$getType = self::ZIP_DIR;
				// downloading root ?
				if ($files !== '') {
					$name = $files;
				}
			}

			self::lockFiles($view, $dir, $files);
			$numberOfFiles = 0;
			$fileSize = 0;

			/* Calculate filesize and number of files */
			if ($getType === self::ZIP_FILES) {
				$fileInfos = [];
				foreach ($files as $file) {
					$fileInfo = \OC\Files\Filesystem::getFileInfo($dir . '/' . $file);
					if ($fileInfo) {
						$fileSize += $fileInfo->getSize();
						$fileInfos[] = $fileInfo;
					}
				}
				$numberOfFiles = self::getNumberOfFiles($fileInfos);
			} elseif ($getType === self::ZIP_DIR) {
				$fileInfo = \OC\Files\Filesystem::getFileInfo($dir . '/' . $files);
				if ($fileInfo) {
					$fileSize = $fileInfo->getSize();
					$numberOfFiles = self::getNumberOfFiles([$fileInfo]);
				}
			}

			//Dispatch an event to see if any apps have problem with download
			$event = new BeforeZipCreatedEvent($dir, is_array($files) ? $files : [$files]);
			$dispatcher = \OCP\Server::get(IEventDispatcher::class);
			$dispatcher->dispatchTyped($event);
			if ((!$event->isSuccessful()) || $event->getErrorMessage() !== null) {
				throw new \OC\ForbiddenException($event->getErrorMessage());
			}

			$streamer = new Streamer(\OC::$server->getRequest(), $fileSize, $numberOfFiles);
			OC_Util::obEnd();

			$streamer->sendHeaders($name);
			$executionTime = (int)OC::$server->get(IniGetWrapper::class)->getNumeric('max_execution_time');
			if (!str_contains(@ini_get('disable_functions'), 'set_time_limit')) {
				@set_time_limit(0);
			}
			ignore_user_abort(true);

			if ($getType === self::ZIP_FILES) {
				foreach ($files as $file) {
					$file = $dir . '/' . $file;
					if (\OC\Files\Filesystem::is_file($file)) {
						$userFolder = \OC::$server->getRootFolder()->get(\OC\Files\Filesystem::getRoot());
						$file = $userFolder->get($file);
						if ($file instanceof \OC\Files\Node\File) {
							try {
								$fh = $file->fopen('r');
							} catch (\OCP\Files\NotPermittedException $e) {
								continue;
							}
							$fileSize = $file->getSize();
							$fileTime = $file->getMTime();
						} else {
							// File is not a file? …
							\OC::$server->getLogger()->debug(
								'File given, but no Node available. Name {file}',
								[ 'app' => 'files', 'file' => $file ]
							);
							continue;
						}
						$streamer->addFileFromStream($fh, $file->getName(), $fileSize, $fileTime);
						fclose($fh);
					} elseif (\OC\Files\Filesystem::is_dir($file)) {
						$streamer->addDirRecursive($file);
					}
				}
			} elseif ($getType === self::ZIP_DIR) {
				$file = $dir . '/' . $files;
				$streamer->addDirRecursive($file);
			}
			$streamer->finalize();
			set_time_limit($executionTime);
			self::unlockAllTheFiles($dir, $files, $getType, $view, $filename);
		} catch (\OCP\Lock\LockedException $ex) {
			self::unlockAllTheFiles($dir, $files, $getType, $view, $filename);
			OC::$server->getLogger()->logException($ex);
			$l = \OC::$server->getL10N('lib');
			$hint = method_exists($ex, 'getHint') ? $ex->getHint() : '';
			\OC_Template::printErrorPage($l->t('File is currently busy, please try again later'), $hint, 200);
		} catch (\OCP\Files\ForbiddenException $ex) {
			self::unlockAllTheFiles($dir, $files, $getType, $view, $filename);
			OC::$server->getLogger()->logException($ex);
			$l = \OC::$server->getL10N('lib');
			\OC_Template::printErrorPage($l->t('Cannot download file'), $ex->getMessage(), 200);
		} catch (\OCP\Files\ConnectionLostException $ex) {
			self::unlockAllTheFiles($dir, $files, $getType, $view, $filename);
			OC::$server->getLogger()->logException($ex, ['level' => \OCP\ILogger::DEBUG]);
			/* We do not print anything here, the connection is already closed */
			die();
		} catch (\Exception $ex) {
			self::unlockAllTheFiles($dir, $files, $getType, $view, $filename);
			OC::$server->getLogger()->logException($ex);
			$l = \OC::$server->getL10N('lib');
			$hint = method_exists($ex, 'getHint') ? $ex->getHint() : '';
			if ($event && $event->getErrorMessage() !== null) {
				$hint .= ' ' . $event->getErrorMessage();
			}
			\OC_Template::printErrorPage($l->t('Cannot download file'), $hint, 200);
		}
	}

	/**
	 * @param string $rangeHeaderPos
	 * @param int|float $fileSize
	 * @return array $rangeArray ('from'=>int,'to'=>int), ...
	 */
	private static function parseHttpRangeHeader($rangeHeaderPos, $fileSize): array {
		$rArray = explode(',', $rangeHeaderPos);
		$minOffset = 0;
		$ind = 0;

		$rangeArray = [];

		foreach ($rArray as $value) {
			$ranges = explode('-', $value);
			if (is_numeric($ranges[0])) {
				if ($ranges[0] < $minOffset) { // case: bytes=500-700,601-999
					$ranges[0] = $minOffset;
				}
				if ($ind > 0 && $rangeArray[$ind - 1]['to'] + 1 == $ranges[0]) { // case: bytes=500-600,601-999
					$ind--;
					$ranges[0] = $rangeArray[$ind]['from'];
				}
			}

			if (is_numeric($ranges[0]) && is_numeric($ranges[1]) && $ranges[0] < $fileSize && $ranges[0] <= $ranges[1]) {
				// case: x-x
				if ($ranges[1] >= $fileSize) {
					$ranges[1] = $fileSize - 1;
				}
				$rangeArray[$ind++] = [ 'from' => $ranges[0], 'to' => $ranges[1], 'size' => $fileSize ];
				$minOffset = $ranges[1] + 1;
				if ($minOffset >= $fileSize) {
					break;
				}
			} elseif (is_numeric($ranges[0]) && $ranges[0] < $fileSize) {
				// case: x-
				$rangeArray[$ind++] = [ 'from' => $ranges[0], 'to' => $fileSize - 1, 'size' => $fileSize ];
				break;
			} elseif (is_numeric($ranges[1])) {
				// case: -x
				if ($ranges[1] > $fileSize) {
					$ranges[1] = $fileSize;
				}
				$rangeArray[$ind++] = [ 'from' => $fileSize - $ranges[1], 'to' => $fileSize - 1, 'size' => $fileSize ];
				break;
			}
		}
		return $rangeArray;
	}

	/**
	 * @param View $view
	 * @param string $name
	 * @param string $dir
	 * @param array $params ; 'head' boolean to only send header of the request ; 'range' http range header
	 * @throws \OC\ForbiddenException
	 */
	private static function getSingleFile($view, $dir, $name, $params) {
		$filename = $dir . '/' . $name;
		$file = null;

		try {
			$userFolder = \OC::$server->getRootFolder()->get(\OC\Files\Filesystem::getRoot());
			$file = $userFolder->get($filename);
			if (!$file instanceof \OC\Files\Node\File || !$file->isReadable()) {
				http_response_code(403);
				die('403 Forbidden');
			}
			$fileSize = $file->getSize();
		} catch (\OCP\Files\NotPermittedException $e) {
			http_response_code(403);
			die('403 Forbidden');
		} catch (\OCP\Files\InvalidPathException $e) {
			http_response_code(403);
			die('403 Forbidden');
		} catch (\OCP\Files\NotFoundException $e) {
			http_response_code(404);
			$tmpl = new OC_Template('', '404', 'guest');
			$tmpl->printPage();
			exit();
		}

		OC_Util::obEnd();
		$view->lockFile($filename, ILockingProvider::LOCK_SHARED);

		$rangeArray = [];

		if (isset($params['range']) && substr($params['range'], 0, 6) === 'bytes=') {
			$rangeArray = self::parseHttpRangeHeader(substr($params['range'], 6), $fileSize);
		}

		$dispatcher = \OCP\Server::get(IEventDispatcher::class);
		$event = new BeforeDirectFileDownloadEvent($filename);
		$dispatcher->dispatchTyped($event);

		if (!\OC\Files\Filesystem::isReadable($filename) || $event->getErrorMessage()) {
			if ($event->getErrorMessage()) {
				$msg = $event->getErrorMessage();
			} else {
				$msg = 'Access denied';
			}
			throw new \OC\ForbiddenException($msg);
		}

		self::sendHeaders($filename, $name, $rangeArray);

		if (isset($params['head']) && $params['head']) {
			return;
		}

		if (!empty($rangeArray)) {
			try {
				if (count($rangeArray) == 1) {
					$view->readfilePart($filename, $rangeArray[0]['from'], $rangeArray[0]['to']);
				} else {
					// check if file is seekable (if not throw UnseekableException)
					// we have to check it before body contents
					$view->readfilePart($filename, $rangeArray[0]['size'], $rangeArray[0]['size']);

					$type = \OC::$server->getMimeTypeDetector()->getSecureMimeType(\OC\Files\Filesystem::getMimeType($filename));

					foreach ($rangeArray as $range) {
						echo "\r\n--".self::getBoundary()."\r\n".
						 "Content-type: ".$type."\r\n".
						 "Content-range: bytes ".$range['from']."-".$range['to']."/".$range['size']."\r\n\r\n";
						$view->readfilePart($filename, $range['from'], $range['to']);
					}
					echo "\r\n--".self::getBoundary()."--\r\n";
				}
			} catch (\OCP\Files\UnseekableException $ex) {
				// file is unseekable
				header_remove('Accept-Ranges');
				header_remove('Content-Range');
				http_response_code(200);
				self::sendHeaders($filename, $name, []);
				$view->readfile($filename);
			}
		} else {
			$view->readfile($filename);
		}
	}

	/**
	 * Returns the total (recursive) number of files and folders in the given
	 * FileInfos.
	 *
	 * @param \OCP\Files\FileInfo[] $fileInfos the FileInfos to count
	 * @return int the total number of files and folders
	 */
	private static function getNumberOfFiles($fileInfos) {
		$numberOfFiles = 0;

		$view = new View();

		while ($fileInfo = array_pop($fileInfos)) {
			$numberOfFiles++;

			if ($fileInfo->getType() === \OCP\Files\FileInfo::TYPE_FOLDER) {
				$fileInfos = array_merge($fileInfos, $view->getDirectoryContent($fileInfo->getPath()));
			}
		}

		return $numberOfFiles;
	}

	/**
	 * @param View $view
	 * @param string $dir
	 * @param string[]|string $files
	 */
	public static function lockFiles($view, $dir, $files) {
		if (!is_array($files)) {
			$file = $dir . '/' . $files;
			$files = [$file];
		}
		foreach ($files as $file) {
			$file = $dir . '/' . $file;
			$view->lockFile($file, ILockingProvider::LOCK_SHARED);
			if ($view->is_dir($file)) {
				$contents = $view->getDirectoryContent($file);
				$contents = array_map(function ($fileInfo) use ($file) {
					/** @var \OCP\Files\FileInfo $fileInfo */
					return $file . '/' . $fileInfo->getName();
				}, $contents);
				self::lockFiles($view, $dir, $contents);
			}
		}
	}

	/**
	 * @param string $dir
	 * @param $files
	 * @param integer $getType
	 * @param View $view
	 * @param string $filename
	 */
	private static function unlockAllTheFiles($dir, $files, $getType, $view, $filename) {
		if ($getType === self::FILE) {
			$view->unlockFile($filename, ILockingProvider::LOCK_SHARED);
		}
		if ($getType === self::ZIP_FILES) {
			foreach ($files as $file) {
				$file = $dir . '/' . $file;
				$view->unlockFile($file, ILockingProvider::LOCK_SHARED);
			}
		}
		if ($getType === self::ZIP_DIR) {
			$file = $dir . '/' . $files;
			$view->unlockFile($file, ILockingProvider::LOCK_SHARED);
		}
	}
}