<?php
/**
 * @author Adam Williamson <awilliam@redhat.com>
 * @author Arthur Schiwon <blizzz@arthur-schiwon.de>
 * @author Bart Visscher <bartv@thisnet.nl>
 * @author Christopher Schäpers <kondou@ts.unde.re>
 * @author Francesco Rovelli <francesco.rovelli@gmail.com>
 * @author Jörn Friedrich Dreyer <jfd@butonic.de>
 * @author Lukas Reschke <lukas@statuscode.ch>
 * @author Michael Gapczynski <GapczynskiM@gmail.com>
 * @author Morris Jobke <hey@morrisjobke.de>
 * @author Philipp Kapfer <philipp.kapfer@gmx.at>
 * @author Robin Appelman <icewind@owncloud.com>
 * @author Robin McCorkell <robin@mccorkell.me.uk>
 * @author Thomas Müller <thomas.mueller@tmit.eu>
 * @author Vincent Petry <pvince81@owncloud.com>
 * @author Martin Mattel <github@diemattels.at>
 *
 * @copyright Copyright (c) 2017, 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 OCA\Files_External\Lib\Storage;

use Google\Service\Drive;
use Google\Service\Drive\DriveFile;
use GuzzleHttp\Exception\RequestException;
use Icewind\Streams\IteratorDirectory;
use Icewind\Streams\RetryWrapper;

class Google extends \OCP\Files\Storage\StorageAdapter {
	private $client;
	private $id;
	private $root;
	private $service;
	private $driveFiles;

	private static $tempFiles = [];

	private $defaultFieldsForFile;
	private $defaultFieldsForFolderScan;

	// Google Doc mimetypes
	public const FOLDER = 'application/vnd.google-apps.folder';
	public const DOCUMENT = 'application/vnd.google-apps.document';
	public const SPREADSHEET = 'application/vnd.google-apps.spreadsheet';
	public const DRAWING = 'application/vnd.google-apps.drawing';
	public const PRESENTATION = 'application/vnd.google-apps.presentation';
	public const MAP = 'application/vnd.google-apps.map';

	public function __construct($params) {
		if (isset($params['configured']) && $params['configured'] === 'true'
			&& isset($params['client_id'], $params['client_secret'], $params['token'])

		) {
			$this->client = new \Google_Client([
				'retry' => [
					'retries' => 5,
					// keep other retry params as default
				]
			]);
			$this->client->setClientId($params['client_id']);
			$this->client->setClientSecret($params['client_secret']);
			$this->client->setScopes(['https://www.googleapis.com/auth/drive']);
			$this->client->setAccessToken(\json_decode($params['token'], true));

			// note: API connection is lazy
			$this->service = new Drive($this->client);
			$token = \json_decode($params['token'], true);
			$this->id = 'google::'.\substr($params['client_id'], 0, 30).$token['created'];
			$this->root = isset($params['root']) ? $params['root'] : '';
		} else {
			throw new \Exception('Creating Google storage failed');
		}
	}

	/**
	 * @return boolean
	 */
	public function usePartFile() {
		return false;
	}

	public function getId() {
		if ($this->root === '') {
			return $this->id;
		} else {
			return "{$this->id}/{$this->root}";
		}
	}

	private function getDefaultFieldsForFile() {
		if ($this->defaultFieldsForFile === null) {
			$this->defaultFieldsForFile = \implode(',', [
				'id',
				'name',
				'mimeType',
				'parents',
				'capabilities/canEdit',
				'size',
				'viewedByMeTime',
				'createdTime',
				'modifiedTime',
			]);
		}
		return $this->defaultFieldsForFile;
	}

	private function getDefaultFieldsForFolderScan() {
		if ($this->defaultFieldsForFolderScan === null) {
			$this->defaultFieldsForFolderScan = \implode(',', [
				'incompleteSearch',
				'nextPageToken',
				"files({$this->getDefaultFieldsForFile()})",  // ask for the same fields to cache info
			]);
		}
		return $this->defaultFieldsForFolderScan;
	}

	/**
	 * Transform an external path to one originating from the virtual root.
	 * @param $path string the path relative to the virtual root directory
	 * @return string a path starting at the real root of Google Drive
	 */
	private function getAbsolutePath($path) {
		if ($path === '.') {
			$path = '';
		}
		$path = "{$this->root}/{$path}";
		return \trim($path, '/');
	}

	/**
	 * Get elements of the relative path given.
	 * The path is relative, in case a subfolder is used.
	 * Returns false on failure.
	 * @param string $path
	 * @return DriveFile|false
	 */
	private function getDriveFile($path) {
		return $this->getInternalDriveFile($this->getAbsolutePath($path));
	}

	/**
	 * Get the elements of the absolute path in case a subfolder is used.
	 * Returns false on failure.
	 * @param string $path
	 * @return DriveFile|false
	 */
	private function getInternalDriveFile($path) {
		// Remove leading and trailing slashes
		$path = \trim($path, '/');
		if ($path === '.') {
			$path = '';
		}
		if (isset($this->driveFiles[$path])) {
			return $this->driveFiles[$path];
		} elseif ($path === '') {
			$root = $this->service->files->get('root', [
				'fields' => $this->getDefaultFieldsForFile(),
			]);
			$this->driveFiles[$path] = $root;
			return $root;
		} else {
			// Google Drive SDK does not have methods for retrieving files by path
			// Instead we must find the id of the parent folder of the file
			$parentId = $this->getInternalDriveFile('')->getId();
			$folderNames = \explode('/', $path);
			$path = '';
			// Loop through each folder of this path to get to the file
			foreach ($folderNames as $name) {
				// Reconstruct path from beginning
				if ($path === '') {
					$path .= $name;
				} else {
					$path .= '/'.$name;
				}
				if (isset($this->driveFiles[$path])) {
					$parentId = $this->driveFiles[$path]->getId();
				} else {
					$q = "name='" . \str_replace("'", "\\'", $name) . "' and '" . \str_replace("'", "\\'", $parentId) . "' in parents and trashed = false";
					$result = $this->service->files->listFiles([
						'q' => $q,
						'fields' => $this->getDefaultFieldsForFolderScan(),
					])->getFiles();

					if (!empty($result)) {
						// Google Drive allows files with the same name, ownCloud doesn't
						if (\count($result) > 1) {
							$this->onDuplicateFileDetected($path);
							return false;
						} else {
							$file = \current($result);
							$this->driveFiles[$path] = $file;
							$parentId = $file->getId();
						}
					} else {
						// Google Docs have no extension in their title, so try without extension
						$pos = \strrpos($path, '.');
						if ($pos !== false) {
							$pathWithoutExt = \substr($path, 0, $pos);
							$file = $this->getInternalDriveFile($pathWithoutExt);
							if ($file && $this->isGoogleDocFile($file)) {
								// Switch cached Google\Service\Drive\DriveFile to the correct index
								unset($this->driveFiles[$pathWithoutExt]);
								$this->driveFiles[$path] = $file;
								$parentId = $file->getId();
							} else {
								return false;
							}
						} else {
							return false;
						}
					}
				}
			}
			return $this->driveFiles[$path];
		}
	}

	/**
	 * Set the Google\Service\Drive\DriveFile object in the cache
	 * @param string $path
	 * @param DriveFile|false $file
	 */
	private function setDriveFile($path, $file) {
		$this->setDriveFileHelper($this->getAbsolutePath($path), $file);
	}

	/**
	 * Set the Google\Service\Drive\DriveFile object in the cache
	 * @param string $path
	 * @param DriveFile|false $file
	 */
	private function setDriveFileHelper($path, $file) {
		$path = \trim($path, '/');
		$this->driveFiles[$path] = $file;
		if ($file === false) {
			// Remove all children
			$len = \strlen($path);
			foreach ($this->driveFiles as $key => $file) {
				if (\substr($key, 0, $len) === $path) {
					unset($this->driveFiles[$key]);
				}
			}
		}
	}

	/**
	 * Write a log message to inform about duplicate file names
	 * @param string $path
	 */
	private function onDuplicateFileDetected($path) {
		$about = $this->service->about->get([
			'fields' => 'user/displayName',
		]);
		$user = $about->getUser()->getDisplayName();
		\OCP\Util::writeLog(
			'files_external',
			'Ignoring duplicate file name: '.$path.' on Google Drive for Google user: '.$user,
			\OCP\Util::INFO
		);
	}

	/**
	 * Generate file extension for a Google Doc, choosing Open Document formats for download
	 * @param string $mimetype
	 * @return string
	 */
	private function getGoogleDocExtension($mimetype) {
		if ($mimetype === self::DOCUMENT) {
			return 'odt';
		} elseif ($mimetype === self::SPREADSHEET) {
			return 'ods';
		} elseif ($mimetype === self::DRAWING) {
			return 'jpg';
		} elseif ($mimetype === self::PRESENTATION) {
			// Download as .odp is not available
			return 'pdf';
		} else {
			return '';
		}
	}

	/**
	 * Returns whether the given drive file is a Google Doc file
	 *
	 * @param DriveFile
	 *
	 * @return true if the file is a Google Doc file, false otherwise
	 */
	private function isGoogleDocFile($file) {
		return $this->getGoogleDocExtension($file->getMimeType()) !== '';
	}

	public function mkdir($path) {
		if (!$this->is_dir($path)) {
			$parentFolder = $this->getDriveFile(\dirname($path));
			if ($parentFolder) {
				$folder = new DriveFile();
				$folder->setName(\basename($path));
				$folder->setMimeType(self::FOLDER);
				$folder->setParents([$parentFolder->getId()]);
				$result = $this->service->files->create($folder, ['fields' => $this->getDefaultFieldsForFile()]);
				if ($result) {
					$this->setDriveFile($path, $result);
				}
				return (bool)$result;
			}
		}
		return false;
	}

	public function rmdir($path) {
		if (!$this->isDeletable($path)) {
			return false;
		}
		if (\trim($path, '/') === '') {
			$dir = $this->opendir($path);
			if (\is_resource($dir)) {
				while (($file = \readdir($dir)) !== false) {
					if (!\OC\Files\Filesystem::isIgnoredDir($file)) {
						if (!$this->unlink($path.'/'.$file)) {
							return false;
						}
					}
				}
				\closedir($dir);
			}
			$this->driveFiles = [];
			return true;
		} else {
			return $this->unlink($path);
		}
	}

	public function opendir($path) {
		$folder = $this->getDriveFile($path);
		if ($folder) {
			$files = [];
			$duplicates = [];
			$pageToken = true;
			while ($pageToken) {
				$params = [];
				if ($pageToken !== true) {
					$params['pageToken'] = $pageToken;
				}
				$params['q'] = "'" . \str_replace("'", "\\'", $folder->getId()) . "' in parents and trashed = false";
				$params['fields'] = $this->getDefaultFieldsForFolderScan();
				$children = $this->service->files->listFiles($params);
				foreach ($children->getFiles() as $child) {
					$name = $child->getName();
					// Check if this is a Google Doc i.e. no extension in name
					$extension = $child->getFileExtension();
					if (empty($extension)) {
						if ($child->getMimeType() === self::MAP) {
							continue; // No method known to transfer map files, ignore it
						} elseif ($child->getMimeType() !== self::FOLDER) {
							$extension = $this->getGoogleDocExtension($child->getMimeType());
							// don't append an empty extension as they will create broken paths
							if ($extension !== '') {
								$name .= ".{$extension}";
							}
						}
					}
					if ($path === '') {
						$filepath = $name;
					} else {
						$filepath = $path.'/'.$name;
					}
					// Google Drive allows files with the same name, ownCloud doesn't
					// Prevent opendir() from returning any duplicate files
					$key = \array_search($name, $files);
					if ($key !== false || isset($duplicates[$filepath])) {
						if (!isset($duplicates[$filepath])) {
							$duplicates[$filepath] = true;
							$this->setDriveFile($filepath, false);
							unset($files[$key]);
							$this->onDuplicateFileDetected($filepath);
						}
					} else {
						// Cache the Google\Service\Drive\DriveFile for future use
						$this->setDriveFile($filepath, $child);
						$files[] = $name;
					}
				}
				$pageToken = $children->getNextPageToken();
			}
			return IteratorDirectory::wrap($files);
		} else {
			return false;
		}
	}

	public function stat($path) {
		$file = $this->getDriveFile($path);
		if ($file) {
			$stat = [];
			if ($this->filetype($path) === 'dir') {
				$stat['size'] = 0;
			} else {
				$stat['size'] = $file->getSize();
			}
			$stat['atime'] = \strtotime($file->getViewedByMeTime());
			$stat['mtime'] = \strtotime($file->getModifiedTime());
			$stat['ctime'] = \strtotime($file->getCreatedTime());
			return $stat;
		} else {
			return false;
		}
	}

	public function filetype($path) {
		if ($this->getAbsolutePath($path) === '') {
			return 'dir';
		} else {
			$file = $this->getDriveFile($path);
			if ($file) {
				if ($file->getMimeType() === self::FOLDER) {
					return 'dir';
				} else {
					return 'file';
				}
			} else {
				return false;
			}
		}
	}

	public function isUpdatable($path) {
		$file = $this->getDriveFile($path);
		if ($file) {
			return $file->getCapabilities()->getCanEdit();
		} else {
			return false;
		}
	}

	public function file_exists($path) {
		return (bool)$this->getDriveFile($path);
	}

	public function unlink($path) {
		$file = $this->getDriveFile($path);
		if ($file) {
			$toUpdate = new DriveFile();
			$toUpdate->setTrashed(true);
			// not interested in the 'fields' returned by the response
			$result = $this->service->files->update($file->getId(), $toUpdate);
			if ($result) {
				$this->setDriveFile($path, false);
			}
			return (bool)$result;
		} else {
			return false;
		}
	}

	public function rename($path1, $path2) {
		$file = $this->getDriveFile($path1);
		if ($file) {
			$newFile = $this->getDriveFile($path2);
			$toUpdate = new DriveFile();
			$addedParent = '';
			$removedParent = '';
			if (\dirname($path1) === \dirname($path2)) {
				if ($newFile) {
					// rename to the name of the target file, could be an office file without extension
					$toUpdate->setName($newFile->getName());
				} else {
					$toUpdate->setName(\basename(($path2)));
				}
			} else {
				// Change file parent
				$parentFolder1 = $this->getDriveFile(\dirname($path1));
				$parentFolder2 = $this->getDriveFile(\dirname($path2));
				if ($parentFolder2) {
					$removedParent = $parentFolder1->getId();
					$addedParent = $parentFolder2->getId();
				} else {
					return false;
				}
			}
			// We need to get the object for the existing file with the same
			// name (if there is one) before we do the patch. If oldfile
			// exists and is a directory we have to delete it before we
			// do the rename too.
			$oldfile = $this->getDriveFile($path2);
			if ($oldfile && $this->is_dir($path2)) {
				$this->rmdir($path2);
				$oldfile = false;
			}
			$result = $this->service->files->update($file->getId(), $toUpdate, [
				'fields' => $this->getDefaultFieldsForFile(),
				'addParents' => $addedParent,
				'removeParents' => $removedParent
			]);
			if ($result) {
				$this->setDriveFile($path1, false);
				$this->setDriveFile($path2, $result);
				if ($oldfile && $newFile) {
					// only delete if they have a different id (same id can happen for part files)
					if ($newFile->getId() !== $oldfile->getId()) {
						$this->service->files->delete($oldfile->getId());
					}
				}
			}
			return (bool)$result;
		} else {
			return false;
		}
	}

	public function fopen($path, $mode) {
		$pos = \strrpos($path, '.');
		if ($pos !== false) {
			$ext = \substr($path, $pos);
		} else {
			$ext = '';
		}
		switch ($mode) {
			case 'r':
			case 'rb':
				$file = $this->getDriveFile($path);
				if ($file) {
					try {
						if (!$this->isGoogleDocFile($file)) {
							$content = $this->service->files->get($file->getId(), ['alt' => 'media']);
						} else {
							$content = $this->service->files->export($file->getId(), $this->getMimeType($path));
						}
						$contentBody = $content->getBody();
						$contentBody->seek(0);
						return RetryWrapper::wrap($contentBody->detach());
					} catch (RequestException $e) {
						if ($e->getResponse() !== null) {
							if ($e->getResponse()->getStatusCode() === 404) {
								return false;
							} else {
								throw $e;
							}
						} else {
							throw $e;
						}
					}
				}
				return false;
			case 'w':
			case 'wb':
			case 'a':
			case 'ab':
			case 'r+':
			case 'w+':
			case 'wb+':
			case 'a+':
			case 'x':
			case 'x+':
			case 'c':
			case 'c+':
				$tmpFile = \OCP\Files::tmpFile($ext);
				\OC\Files\Stream\Close::registerCallback($tmpFile, [$this, 'writeBack']);
				if ($this->file_exists($path)) {
					$source = $this->fopen($path, 'rb');
					\file_put_contents($tmpFile, $source);
				}
				self::$tempFiles[$tmpFile] = $path;
				return \fopen('close://'.$tmpFile, $mode);
		}
		return false;
	}

	public function writeBack($tmpFile) {
		if (isset(self::$tempFiles[$tmpFile])) {
			$path = self::$tempFiles[$tmpFile];
			$parentFolder = $this->getDriveFile(\dirname($path));
			if ($parentFolder) {
				$mimetype = \OC::$server->getMimeTypeDetector()->detect($tmpFile);
				$params = [
					'mimeType' => $mimetype,
					'uploadType' => 'media',
					'fields' => $this->getDefaultFieldsForFile(),
				];
				$result = false;

				$chunkSizeBytes = 10 * 1024 * 1024;

				$useChunking = false;
				$size = \filesize($tmpFile);
				if ($size > $chunkSizeBytes) {
					$useChunking = true;
				} else {
					$params['data'] = \file_get_contents($tmpFile);
				}

				if ($this->file_exists($path)) {
					$file = $this->getDriveFile($path);
					$this->client->setDefer($useChunking);
					$request = $this->service->files->update(
						$file->getId(),
						new DriveFile(),
						$params
					);
				} else {
					$file = new DriveFile();
					$file->setName(\basename($path));
					$file->setMimeType($mimetype);
					$file->setParents([$parentFolder->getId()]);
					$this->client->setDefer($useChunking);
					$request = $this->service->files->create($file, $params);
				}

				if ($useChunking) {
					// Create a media file upload to represent our upload process.
					$media = new \Google_Http_MediaFileUpload(
						$this->client,
						$request,
						'text/plain',
						null,
						true,
						$chunkSizeBytes
					);
					$media->setFileSize($size);

					// Upload the various chunks. $status will be false until the process is
					// complete.
					$status = false;
					$handle = \fopen($tmpFile, 'rb');
					while (!$status && !\feof($handle)) {
						$chunk = \fread($handle, $chunkSizeBytes);
						$status = $media->nextChunk($chunk);
					}

					// The final value of $status will be the data from the API for the object
					// that has been uploaded.
					$result = false;
					if ($status !== false) {
						$result = $status;
					}

					\fclose($handle);
				} else {
					$result = $request;
				}

				// Reset to the client to execute requests immediately in the future.
				$this->client->setDefer(false);

				if ($result) {
					$this->setDriveFile($path, $result);
				}
			}
			\unlink($tmpFile);
		}
	}

	public function getMimeType($path) {
		$file = $this->getDriveFile($path);
		if ($file) {
			$mimetype = $file->getMimeType();
			// Convert Google Doc mimetypes, choosing Open Document formats for download
			if ($mimetype === self::FOLDER) {
				return 'httpd/unix-directory';
			} elseif ($mimetype === self::DOCUMENT) {
				return 'application/vnd.oasis.opendocument.text';
			} elseif ($mimetype === self::SPREADSHEET) {
				return 'application/x-vnd.oasis.opendocument.spreadsheet';
			} elseif ($mimetype === self::DRAWING) {
				return 'image/jpeg';
			} elseif ($mimetype === self::PRESENTATION) {
				// Download as .odp is not available
				return 'application/pdf';
			} else {
				// use extension-based detection, could be an encrypted file
				return parent::getMimeType($path);
			}
		} else {
			return false;
		}
	}

	public function free_space($path) {
		$about = $this->service->about->get([
			'fields' => 'storageQuota(limit,usage)',
		]);
		$quotas = $about->getStorageQuota();
		return $quotas->getLimit() - $quotas->getUsage();
	}

	public function touch($path, $mtime = null) {
		$file = $this->getDriveFile($path);
		$toUpdate = new DriveFile();
		$result = false;
		if ($file) {
			if (isset($mtime)) {
				// This is just RFC3339, but frustratingly, GDrive's API *requires*
				// the fractions portion be present, while no handy PHP constant
				// for RFC3339 or ISO8601 includes it. So we do it ourselves.
				$toUpdate->setModifiedTime(\date('Y-m-d\TH:i:s.uP', $mtime));
			} else {
				$toUpdate->setModifiedTime(\date('Y-m-d\TH:i:s.uP'));
			}
			$result = $this->service->files->update(
				$file->getId(),
				$toUpdate,
				['fields' => $this->getDefaultFieldsForFile()]
			);
		} else {
			$parentFolder = $this->getDriveFile(\dirname($path));
			if ($parentFolder) {
				$toUpdate->setName(\basename($path));
				$toUpdate->setParents([$parentFolder->getId()]);
				$result = $this->service->files->create(
					$toUpdate,
					['fields' => $this->getDefaultFieldsForFile()]
				);
			}
		}
		if ($result) {
			$this->setDriveFile($path, $result);
		}
		return (bool)$result;
	}

	public function test() {
		if ($this->free_space('')) {
			return true;
		}
		return false;
	}

	public function hasUpdated($path, $time) {
		if ($this->is_file($path)) {
			return parent::hasUpdated($path, $time);
		}

		// follow similar approach than opendir
		// assume there won't be changes (common case), so optimize the request
		// although data won't be cached.
		$folder = $this->getDriveFile($path);
		if (!$folder) {
			// missing folder implies it changed
			return true;
		}

		$pageToken = true;
		while ($pageToken) {
			$params = [];
			if ($pageToken !== true) {
				$params['pageToken'] = $pageToken;
			}
			$params['q'] = "'" . \str_replace("'", "\\'", $folder->getId()) . "' in parents and trashed = false";
			$params['fields'] = 'incompleteSearch,nextPageToken,files(modifiedTime)';  // just need the mtime
			$children = $this->service->files->listFiles($params);
			if ($children->getIncompleteSearch()) {
				// if the search is incomplete, assume there is a change
				return true;
			}

			foreach ($children->getFiles() as $child) {
				$childMTime = \strtotime($child->getModifiedTime());
				if ($childMTime > $time) {
					// a child has changed since that time, no need to keep on going
					return true;
				}
			}
			$pageToken = $children->getNextPageToken();
		}
		return false;
	}

	/**
	 * check if curl is installed
	 */
	public static function checkDependencies() {
		return true;
	}
}
