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See Release Notes

  • Bug fixes for general core bugs in 3.11.x will end 14 Nov 2022 (12 months plus 6 months extension).
  • Bug fixes for security issues in 3.11.x will end 13 Nov 2023 (18 months plus 12 months extension).
  • PHP version: minimum PHP 7.3.0 Note: minimum PHP version has increased since Moodle 3.10. PHP 7.4.x is supported too.

Differences Between: [Versions 311 and 402] [Versions 311 and 403] [Versions 39 and 311]

   1  <?php
   2  // This file is part of Moodle - http://moodle.org/
   3  //
   4  // Moodle is free software: you can redistribute it and/or modify
   5  // it under the terms of the GNU General Public License as published by
   6  // the Free Software Foundation, either version 3 of the License, or
   7  // (at your option) any later version.
   8  //
   9  // Moodle is distributed in the hope that it will be useful,
  10  // but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  // GNU General Public License for more details.
  13  //
  14  // You should have received a copy of the GNU General Public License
  15  // along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
  16  
  17  /**
  18   * Nextcloud repository plugin library.
  19   *
  20   * @package    repository_nextcloud
  21   * @copyright  2017 Project seminar (Learnweb, University of Münster)
  22   * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or
  23   */
  24  
  25  use repository_nextcloud\issuer_management;
  26  use repository_nextcloud\ocs_client;
  27  
  28  defined('MOODLE_INTERNAL') || die();
  29  
  30  require_once($CFG->dirroot . '/repository/lib.php');
  31  require_once($CFG->libdir . '/webdavlib.php');
  32  
  33  /**
  34   * Nextcloud repository class.
  35   *
  36   * @package    repository_nextcloud
  37   * @copyright  2017 Project seminar (Learnweb, University of Münster)
  38   * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  39   */
  40  class repository_nextcloud extends repository {
  41      /**
  42       * OAuth 2 client
  43       * @var \core\oauth2\client
  44       */
  45      private $client = null;
  46  
  47      /**
  48       * OAuth 2 Issuer
  49       * @var \core\oauth2\issuer
  50       */
  51      private $issuer = null;
  52  
  53      /**
  54       * Additional scopes needed for the repository. Currently, nextcloud does not actually support/use scopes, so
  55       * this is intended as a hint at required functionality and will help declare future scopes.
  56       */
  57      const SCOPES = 'files ocs';
  58  
  59      /**
  60       * Webdav client which is used for webdav operations.
  61       *
  62       * @var \webdav_client
  63       */
  64      private $dav = null;
  65  
  66      /**
  67       * Basepath for WebDAV operations
  68       * @var string
  69       */
  70      private $davbasepath;
  71  
  72      /**
  73       * OCS client that uses the Open Collaboration Services REST API.
  74       * @var ocs_client
  75       */
  76      private $ocsclient;
  77  
  78      /**
  79       * @var oauth2_client System account client.
  80       */
  81      private $systemoauthclient = false;
  82  
  83      /**
  84       * OCS systemocsclient that uses the Open Collaboration Services REST API.
  85       * @var ocs_client
  86       */
  87      private $systemocsclient = null;
  88  
  89      /**
  90       * Name of the folder for controlled links.
  91       * @var string
  92       */
  93      private $controlledlinkfoldername;
  94  
  95      /**
  96       * Curl instance that can be used to fetch file from nextcloud instance.
  97       * @var curl
  98       */
  99      private $curl;
 100  
 101      /**
 102       * repository_nextcloud constructor.
 103       *
 104       * @param int $repositoryid
 105       * @param bool|int|stdClass $context
 106       * @param array $options
 107       */
 108      public function __construct($repositoryid, $context = SYSCONTEXTID, $options = array()) {
 109          parent::__construct($repositoryid, $context, $options);
 110          try {
 111              // Issuer from repository instance config.
 112              $issuerid = $this->get_option('issuerid');
 113              $this->issuer = \core\oauth2\api::get_issuer($issuerid);
 114          } catch (dml_missing_record_exception $e) {
 115              // A repository is marked as disabled when no issuer is present.
 116              $this->disabled = true;
 117              return;
 118          }
 119  
 120          try {
 121              // Load the webdav endpoint and parse the basepath.
 122              $webdavendpoint = issuer_management::parse_endpoint_url('webdav', $this->issuer);
 123              // Get basepath without trailing slash, because future uses will come with a leading slash.
 124              $basepath = $webdavendpoint['path'];
 125              if (strlen($basepath) > 0 && substr($basepath, -1) === '/') {
 126                  $basepath = substr($basepath, 0, -1);
 127              }
 128              $this->davbasepath = $basepath;
 129          } catch (\repository_nextcloud\configuration_exception $e) {
 130              // A repository is marked as disabled when no webdav_endpoint is present
 131              // or it fails to parse, because all operations concerning files
 132              // rely on the webdav endpoint.
 133              $this->disabled = true;
 134              return;
 135          }
 136          $this->controlledlinkfoldername = $this->get_option('controlledlinkfoldername');
 137  
 138          if (!$this->issuer) {
 139              $this->disabled = true;
 140              return;
 141          } else if (!$this->issuer->get('enabled')) {
 142              // In case the Issuer is not enabled, the repository is disabled.
 143              $this->disabled = true;
 144              return;
 145          } else if (!issuer_management::is_valid_issuer($this->issuer)) {
 146              // Check if necessary endpoints are present.
 147              $this->disabled = true;
 148              return;
 149          }
 150  
 151          $this->ocsclient = new ocs_client($this->get_user_oauth_client());
 152          $this->curl = new curl();
 153      }
 154  
 155      /**
 156       * Get or initialise an oauth client for the system account.
 157       *
 158       * @return false|oauth2_client False if initialisation was unsuccessful, otherwise an initialised client.
 159       */
 160      private function get_system_oauth_client() {
 161          if ($this->systemoauthclient === false) {
 162              try {
 163                  $this->systemoauthclient = \core\oauth2\api::get_system_oauth_client($this->issuer);
 164              } catch (\moodle_exception $e) {
 165                  $this->systemoauthclient = false;
 166              }
 167          }
 168          return $this->systemoauthclient;
 169      }
 170  
 171      /**
 172       * Get or initialise an ocs client for the system account.
 173       *
 174       * @return null|ocs_client Null if initialisation was unsuccessful, otherwise an initialised client.
 175       */
 176      private function get_system_ocs_client() {
 177          if ($this->systemocsclient === null) {
 178              try {
 179                  $systemoauth = $this->get_system_oauth_client();
 180                  if (!$systemoauth) {
 181                      return null;
 182                  }
 183                  $this->systemocsclient = new ocs_client($systemoauth);
 184              } catch (\moodle_exception $e) {
 185                  $this->systemocsclient = null;
 186              }
 187          }
 188          return $this->systemocsclient;
 189      }
 190  
 191      /**
 192       * Initiates the webdav client.
 193       *
 194       * @throws \repository_nextcloud\configuration_exception If configuration is missing (endpoints).
 195       */
 196      private function initiate_webdavclient() {
 197          if ($this->dav !== null) {
 198              return $this->dav;
 199          }
 200  
 201          $webdavendpoint = issuer_management::parse_endpoint_url('webdav', $this->issuer);
 202  
 203          // Selects the necessary information (port, type, server) from the path to build the webdavclient.
 204          $server = $webdavendpoint['host'];
 205          if ($webdavendpoint['scheme'] === 'https') {
 206              $webdavtype = 'ssl://';
 207              $webdavport = 443;
 208          } else if ($webdavendpoint['scheme'] === 'http') {
 209              $webdavtype = '';
 210              $webdavport = 80;
 211          }
 212  
 213          // Override default port, if a specific one is set.
 214          if (isset($webdavendpoint['port'])) {
 215              $webdavport = $webdavendpoint['port'];
 216          }
 217  
 218          // Authentication method is `bearer` for OAuth 2. Pass token of authenticated client, too.
 219          $this->dav = new \webdav_client($server, '', '', 'bearer', $webdavtype,
 220              $this->get_user_oauth_client()->get_accesstoken()->token);
 221  
 222          $this->dav->port = $webdavport;
 223          $this->dav->debug = false;
 224          return $this->dav;
 225      }
 226  
 227      /**
 228       * This function does exactly the same as in the WebDAV repository. The only difference is, that
 229       * the nextcloud OAuth2 client uses OAuth2 instead of Basic Authentication.
 230       *
 231       * @param string $reference relative path to the file.
 232       * @param string $title title of the file.
 233       * @return array|bool returns either the moodle path to the file or false.
 234       */
 235      public function get_file($reference, $title = '') {
 236          // Normal file.
 237          $reference = urldecode($reference);
 238  
 239          // Prepare a file with an arbitrary name - cannot be $title because of special chars (cf. MDL-57002).
 240          $path = $this->prepare_file(uniqid());
 241          $this->initiate_webdavclient();
 242          if (!$this->dav->open()) {
 243              return false;
 244          }
 245          $this->dav->get_file($this->davbasepath . $reference, $path);
 246          $this->dav->close();
 247  
 248          return array('path' => $path);
 249      }
 250  
 251      /**
 252       * This function does exactly the same as in the WebDAV repository. The only difference is, that
 253       * the nextcloud OAuth2 client uses OAuth2 instead of Basic Authentication.
 254       *
 255       * @param string $path relative path to the directory or file.
 256       * @param string $page page number (given multiple pages of elements).
 257       * @return array directory properties.
 258       */
 259      public function get_listing($path='', $page = '') {
 260          if (empty($path)) {
 261              $path = '/';
 262          }
 263  
 264          $ret = $this->get_listing_prepare_response($path);
 265  
 266          // Before any WebDAV method can be executed, a WebDAV client socket needs to be opened
 267          // which connects to the server.
 268          $this->initiate_webdavclient();
 269          if (!$this->dav->open()) {
 270              return $ret;
 271          }
 272  
 273          // Since the paths which are received from the PROPFIND WebDAV method are url encoded
 274          // (because they depict actual web-paths), the received paths need to be decoded back
 275          // for the plugin to be able to work with them.
 276          $ls = $this->dav->ls($this->davbasepath . urldecode($path));
 277          $this->dav->close();
 278  
 279          // The method get_listing return all information about all child files/folders of the
 280          // current directory. If no information was received, the directory must be empty.
 281          if (!is_array($ls)) {
 282              return $ret;
 283          }
 284  
 285          // Process WebDAV output and convert it into Moodle format.
 286          $ret['list'] = $this->get_listing_convert_response($path, $ls);
 287          return $ret;
 288  
 289      }
 290  
 291      /**
 292       * Use OCS to generate a public share to the requested file.
 293       * This method derives a download link from the public share URL.
 294       *
 295       * @param string $url relative path to the chosen file
 296       * @return string the generated download link.
 297       * @throws \repository_nextcloud\request_exception If nextcloud responded badly
 298       *
 299       */
 300      public function get_link($url) {
 301          // Create a read only public link, remember no update possible in this file/folder.
 302          $ocsparams = [
 303              'path' => $url,
 304              'shareType' => ocs_client::SHARE_TYPE_PUBLIC,
 305              'publicUpload' => false,
 306              'permissions' => ocs_client::SHARE_PERMISSION_READ
 307              ];
 308  
 309          $response = $this->ocsclient->call('create_share', $ocsparams);
 310          $xml = simplexml_load_string($response);
 311  
 312          if ($xml === false ) {
 313              throw new \repository_nextcloud\request_exception(array('instance' => $this->get_name(),
 314                  'errormessage' => get_string('invalidresponse', 'repository_nextcloud')));
 315          }
 316  
 317          if ((string)$xml->meta->status !== 'ok') {
 318              throw new \repository_nextcloud\request_exception(array('instance' => $this->get_name(), 'errormessage' => sprintf(
 319                  '(%s) %s', $xml->meta->statuscode, $xml->meta->message)));
 320          }
 321  
 322          // Take the share link and convert it into a download link.
 323          return ((string)$xml->data[0]->url) . '/download';
 324      }
 325  
 326      /**
 327       * This method does not do any translation of the file source.
 328       *
 329       * @param string $source source of the file, returned by repository as 'source' and received back from user (not cleaned)
 330       * @return string file reference, ready to be stored or json encoded string for public link reference
 331       */
 332      public function get_file_reference($source) {
 333          $usefilereference = optional_param('usefilereference', false, PARAM_BOOL);
 334          if ($usefilereference) {
 335              return json_encode([
 336                  'type' => 'FILE_REFERENCE',
 337                  'link' => $this->get_link($source),
 338              ]);
 339          }
 340          // The simple relative path to the file is enough.
 341          return $source;
 342      }
 343  
 344      /**
 345       * Called when a file is selected as a "access control link".
 346       * Invoked at MOODLE/repository/repository_ajax.php
 347       *
 348       * This is called at the point the reference files are being copied from the draft area to the real area.
 349       * What is done here is transfer ownership to the system user (by copying) then delete the intermediate share
 350       * used for that. Finally update the reference to point to new file name.
 351       *
 352       * @param string $reference this reference is generated by repository::get_file_reference()
 353       * @param context $context the target context for this new file.
 354       * @param string $component the target component for this new file.
 355       * @param string $filearea the target filearea for this new file.
 356       * @param string $itemid the target itemid for this new file.
 357       * @return string updated reference (final one before it's saved to db).
 358       * @throws \repository_nextcloud\configuration_exception
 359       * @throws \repository_nextcloud\request_exception
 360       * @throws coding_exception
 361       * @throws moodle_exception
 362       * @throws repository_exception
 363       */
 364      public function reference_file_selected($reference, $context, $component, $filearea, $itemid) {
 365          $source = json_decode($reference);
 366  
 367          if (is_object($source)) {
 368              if ($source->type != 'FILE_CONTROLLED_LINK') {
 369                  // Only access controlled links need special handling; we are done.
 370                  return $reference;
 371              }
 372              if (!empty($source->usesystem)) {
 373                  // If we already copied this file to the system account - we are done.
 374                  return $reference;
 375              }
 376          }
 377  
 378          // Check this issuer is enabled.
 379          if ($this->disabled || $this->get_system_oauth_client() === false || $this->get_system_ocs_client() === null) {
 380              throw new repository_exception('cannotdownload', 'repository');
 381          }
 382  
 383          $linkmanager = new \repository_nextcloud\access_controlled_link_manager($this->ocsclient, $this->get_system_oauth_client(),
 384              $this->get_system_ocs_client(), $this->issuer, $this->get_name());
 385  
 386          // Get the current user.
 387          $userauth = $this->get_user_oauth_client();
 388          if ($userauth === false) {
 389              $details = get_string('cannotconnect', 'repository_nextcloud');
 390              throw new \repository_nextcloud\request_exception(array('instance' => $this->get_name(), 'errormessage' => $details));
 391          }
 392          // 1. Share the File with the system account.
 393          $responsecreateshare = $linkmanager->create_share_user_sysaccount($reference);
 394          if ($responsecreateshare['statuscode'] == 403) {
 395              // File has already been shared previously => find file in system account and use that.
 396              $responsecreateshare = $linkmanager->find_share_in_sysaccount($reference);
 397          }
 398  
 399          // 2. Create a unique path in the system account.
 400          $createdfolder = $linkmanager->create_folder_path_access_controlled_links($context, $component, $filearea,
 401              $itemid);
 402  
 403          // 3. Copy File to the new folder path.
 404          $linkmanager->transfer_file_to_path($responsecreateshare['filetarget'], $createdfolder, 'copy');
 405  
 406          // 4. Delete the share.
 407          $linkmanager->delete_share_dataowner_sysaccount($responsecreateshare['shareid']);
 408  
 409          // Update the returned reference so that the stored_file in moodle points to the newly copied file.
 410          $filereturn = new stdClass();
 411          $filereturn->type = 'FILE_CONTROLLED_LINK';
 412          $filereturn->link = $createdfolder . $responsecreateshare['filetarget'];
 413          $filereturn->name = $reference;
 414          $filereturn->usesystem = true;
 415          $filereturn = json_encode($filereturn);
 416  
 417          return $filereturn;
 418      }
 419  
 420      /**
 421       * Repository method that serves the referenced file (created e.g. via get_link).
 422       * All parameters are there for compatibility with superclass, but they are ignored.
 423       *
 424       * @param stored_file $storedfile
 425       * @param int $lifetime (ignored)
 426       * @param int $filter (ignored)
 427       * @param bool $forcedownload (ignored)
 428       * @param array $options additional options affecting the file serving
 429       * @throws \repository_nextcloud\configuration_exception
 430       * @throws \repository_nextcloud\request_exception
 431       * @throws coding_exception
 432       * @throws moodle_exception
 433       */
 434      public function send_file($storedfile, $lifetime=null , $filter=0, $forcedownload=false, array $options = null) {
 435          $repositoryname = $this->get_name();
 436          $reference = json_decode($storedfile->get_reference());
 437  
 438          // If the file is a reference which means its a public link in nextcloud.
 439          if ($reference->type === 'FILE_REFERENCE') {
 440              // This file points to the public link just fetch the latest one from nextcloud repo.
 441              redirect($reference->link);
 442          }
 443  
 444          // 1. assure the client and user is logged in.
 445          if (empty($this->client) || $this->get_system_oauth_client() === false || $this->get_system_ocs_client() === null) {
 446              $details = get_string('contactadminwith', 'repository_nextcloud',
 447                  get_string('noclientconnection', 'repository_nextcloud'));
 448              throw new \repository_nextcloud\request_exception(array('instance' => $repositoryname, 'errormessage' => $details));
 449          }
 450  
 451          // Download for offline usage. This is strictly read-only, so the file need not be shared.
 452          if (!empty($options['offline'])) {
 453              // Download from system account and provide the file to the user.
 454              $linkmanager = new \repository_nextcloud\access_controlled_link_manager($this->ocsclient,
 455                  $this->get_system_oauth_client(), $this->get_system_ocs_client(), $this->issuer, $repositoryname);
 456  
 457              // Create temp path, then download into it.
 458              $filename = basename($reference->link);
 459              $tmppath = make_request_directory() . '/' . $filename;
 460              $linkmanager->download_for_offline_usage($reference->link, $tmppath);
 461  
 462              // Output the obtained file to the user and remove it from disk.
 463              send_temp_file($tmppath, $filename);
 464  
 465              // That's all.
 466              return;
 467          }
 468  
 469          if (!$this->client->is_logged_in()) {
 470              $this->print_login_popup(['style' => 'margin-top: 250px'], $options['embed']);
 471              return;
 472          }
 473  
 474          // Determining writeability of file from the using context.
 475          // Variable $info is null|\file_info. file_info::is_writable is only true if user may write for any reason.
 476          $fb = get_file_browser();
 477          $context = context::instance_by_id($storedfile->get_contextid(), MUST_EXIST);
 478          $info = $fb->get_file_info($context,
 479              $storedfile->get_component(),
 480              $storedfile->get_filearea(),
 481              $storedfile->get_itemid(),
 482              $storedfile->get_filepath(),
 483              $storedfile->get_filename());
 484          $maywrite = !empty($info) && $info->is_writable();
 485  
 486          $this->initiate_webdavclient();
 487  
 488          // Create the a manager to handle steps.
 489          $linkmanager = new \repository_nextcloud\access_controlled_link_manager($this->ocsclient, $this->get_system_oauth_client(),
 490              $this->get_system_ocs_client(), $this->issuer, $repositoryname);
 491  
 492          // 2. Check whether user has folder for files otherwise create it.
 493          $linkmanager->create_storage_folder($this->controlledlinkfoldername, $this->dav);
 494  
 495          $userinfo = $this->client->get_userinfo();
 496          $username = $userinfo['username'];
 497  
 498          // Creates a share between the systemaccount and the user.
 499          $responsecreateshare = $linkmanager->create_share_user_sysaccount($reference->link, $username, $maywrite);
 500  
 501          $statuscode = $responsecreateshare['statuscode'];
 502  
 503          if ($statuscode == 403) {
 504              $shareid = $linkmanager->get_shares_from_path($reference->link, $username);
 505          } else if ($statuscode == 100) {
 506              $filetarget = $linkmanager->get_share_information_from_shareid($responsecreateshare['shareid'], $username);
 507              $copyresult = $linkmanager->transfer_file_to_path($filetarget, $this->controlledlinkfoldername,
 508                  'move', $this->dav);
 509              if (!($copyresult == 201 || $copyresult == 412)) {
 510                  throw new \repository_nextcloud\request_exception(array('instance' => $repositoryname,
 511                      'errormessage' => get_string('couldnotmove', 'repository_nextcloud', $this->controlledlinkfoldername)));
 512              }
 513              $shareid = $responsecreateshare['shareid'];
 514          } else if ($statuscode == 997) {
 515              throw new \repository_nextcloud\request_exception(array('instance' => $repositoryname,
 516                  'errormessage' => get_string('notauthorized', 'repository_nextcloud')));
 517          } else {
 518              $details = get_string('filenotaccessed', 'repository_nextcloud');
 519              throw new \repository_nextcloud\request_exception(array('instance' => $repositoryname, 'errormessage' => $details));
 520          }
 521          $filetarget = $linkmanager->get_share_information_from_shareid((int)$shareid, $username);
 522  
 523          // Obtain the file from Nextcloud using a Bearer token authenticated connection because we cannot perform a redirect here.
 524          // The reason is that Nextcloud uses samesite cookie validation, i.e. a redirected request would not be authenticated.
 525          // (Also the browser might use the session of a Nextcloud user that is different from the one that is known to Moodle.)
 526          $filename = basename($filetarget);
 527          $tmppath = make_request_directory() . '/' . $filename;
 528          $this->dav->open();
 529  
 530          // Concat webdav path with file path.
 531          $webdavendpoint = issuer_management::parse_endpoint_url('webdav', $this->issuer);
 532          $filetarget = ltrim($filetarget, '/');
 533          $filetarget = $webdavendpoint['path'] . $filetarget;
 534  
 535          // Write file into temp location.
 536          if (!$this->dav->get_file($filetarget, $tmppath)) {
 537              $this->dav->close();
 538              throw new repository_exception('cannotdownload', 'repository');
 539          }
 540          $this->dav->close();
 541  
 542          // Output the obtained file to the user and remove it from disk.
 543          send_temp_file($tmppath, $filename);
 544      }
 545  
 546      /**
 547       * Which return type should be selected by default.
 548       *
 549       * @return int
 550       */
 551      public function default_returntype() {
 552          $setting = $this->get_option('defaultreturntype');
 553          $supported = $this->get_option('supportedreturntypes');
 554          if (($setting == FILE_INTERNAL && $supported !== 'external') || $supported === 'internal') {
 555              return FILE_INTERNAL;
 556          }
 557          return FILE_CONTROLLED_LINK;
 558      }
 559  
 560      /**
 561       * Return names of the general options.
 562       * By default: no general option name.
 563       *
 564       * @return array
 565       */
 566      public static function get_type_option_names() {
 567          return array();
 568      }
 569  
 570      /**
 571       * Function which checks whether the user is logged in on the Nextcloud instance.
 572       *
 573       * @return bool false, if no Access Token is set or can be requested.
 574       */
 575      public function check_login() {
 576          $client = $this->get_user_oauth_client();
 577          return $client->is_logged_in();
 578      }
 579  
 580      /**
 581       * Get a cached user authenticated oauth client.
 582       *
 583       * @param bool|moodle_url $overrideurl Use this url instead of the repo callback.
 584       * @return \core\oauth2\client
 585       */
 586      protected function get_user_oauth_client($overrideurl = false) {
 587          if ($this->client) {
 588              return $this->client;
 589          }
 590          if ($overrideurl) {
 591              $returnurl = $overrideurl;
 592          } else {
 593              $returnurl = new moodle_url('/repository/repository_callback.php');
 594              $returnurl->param('callback', 'yes');
 595              $returnurl->param('repo_id', $this->id);
 596              $returnurl->param('sesskey', sesskey());
 597          }
 598          $this->client = \core\oauth2\api::get_user_oauth_client($this->issuer, $returnurl, self::SCOPES, true);
 599          return $this->client;
 600      }
 601  
 602      /**
 603       * Prints a simple Login Button which redirects to an authorization window from Nextcloud.
 604       *
 605       * @return mixed login window properties.
 606       * @throws coding_exception
 607       */
 608      public function print_login() {
 609          $client = $this->get_user_oauth_client();
 610          $loginurl = $client->get_login_url();
 611          if ($this->options['ajax']) {
 612              $ret = array();
 613              $btn = new \stdClass();
 614              $btn->type = 'popup';
 615              $btn->url = $loginurl->out(false);
 616              $ret['login'] = array($btn);
 617              return $ret;
 618          } else {
 619              echo html_writer::link($loginurl, get_string('login', 'repository'),
 620                      array('target' => '_blank',  'rel' => 'noopener noreferrer'));
 621          }
 622      }
 623  
 624      /**
 625       * Deletes the held Access Token and prints the Login window.
 626       *
 627       * @return array login window properties.
 628       */
 629      public function logout() {
 630          $client = $this->get_user_oauth_client();
 631          $client->log_out();
 632          return parent::logout();
 633      }
 634  
 635      /**
 636       * Sets up access token after the redirection from Nextcloud.
 637       */
 638      public function callback() {
 639          $client = $this->get_user_oauth_client();
 640          // If an Access Token is stored within the client, it has to be deleted to prevent the addition
 641          // of an Bearer authorization header in the request method.
 642          $client->log_out();
 643  
 644          // This will upgrade to an access token if we have an authorization code and save the access token in the session.
 645          $client->is_logged_in();
 646      }
 647  
 648      /**
 649       * Create an instance for this plug-in
 650       *
 651       * @param string $type the type of the repository
 652       * @param int $userid the user id
 653       * @param stdClass $context the context
 654       * @param array $params the options for this instance
 655       * @param int $readonly whether to create it readonly or not (defaults to not)
 656       * @return mixed
 657       * @throws dml_exception
 658       * @throws required_capability_exception
 659       */
 660      public static function create($type, $userid, $context, $params, $readonly=0) {
 661          require_capability('moodle/site:config', context_system::instance());
 662          return parent::create($type, $userid, $context, $params, $readonly);
 663      }
 664  
 665      /**
 666       * This method adds a select form and additional information to the settings form..
 667       *
 668       * @param \moodleform $mform Moodle form (passed by reference)
 669       * @return bool|void
 670       * @throws coding_exception
 671       * @throws dml_exception
 672       */
 673      public static function instance_config_form($mform) {
 674          if (!has_capability('moodle/site:config', context_system::instance())) {
 675              $mform->addElement('static', null, '',  get_string('nopermissions', 'error', get_string('configplugin',
 676                  'repository_nextcloud')));
 677              return false;
 678          }
 679  
 680          // Load configured issuers.
 681          $issuers = core\oauth2\api::get_all_issuers();
 682          $types = array();
 683  
 684          // Validates which issuers implement the right endpoints. WebDav is necessary for Nextcloud.
 685          $validissuers = [];
 686          foreach ($issuers as $issuer) {
 687              $types[$issuer->get('id')] = $issuer->get('name');
 688              if (\repository_nextcloud\issuer_management::is_valid_issuer($issuer)) {
 689                  $validissuers[] = $issuer->get('name');
 690              }
 691          }
 692  
 693          // Render the form.
 694          $url = new \moodle_url('/admin/tool/oauth2/issuers.php');
 695          $mform->addElement('static', null, '', get_string('oauth2serviceslink', 'repository_nextcloud', $url->out()));
 696  
 697          $mform->addElement('select', 'issuerid', get_string('chooseissuer', 'repository_nextcloud'), $types);
 698          $mform->addRule('issuerid', get_string('required'), 'required', null, 'issuer');
 699          $mform->addHelpButton('issuerid', 'chooseissuer', 'repository_nextcloud');
 700          $mform->setType('issuerid', PARAM_INT);
 701  
 702          // All issuers that are valid are displayed seperately (if any).
 703          if (count($validissuers) === 0) {
 704              $mform->addElement('static', null, '', get_string('no_right_issuers', 'repository_nextcloud'));
 705          } else {
 706              $mform->addElement('static', null, '', get_string('right_issuers', 'repository_nextcloud',
 707                  implode(', ', $validissuers)));
 708          }
 709  
 710          $mform->addElement('text', 'controlledlinkfoldername', get_string('foldername', 'repository_nextcloud'));
 711          $mform->addHelpButton('controlledlinkfoldername', 'foldername', 'repository_nextcloud');
 712          $mform->setType('controlledlinkfoldername', PARAM_TEXT);
 713          $mform->setDefault('controlledlinkfoldername', 'Moodlefiles');
 714  
 715          $mform->addElement('static', null, '', get_string('fileoptions', 'repository_nextcloud'));
 716          $choices = [
 717              'both' => get_string('both', 'repository_nextcloud'),
 718              'internal' => get_string('internal', 'repository_nextcloud'),
 719              'external' => get_string('external', 'repository_nextcloud'),
 720          ];
 721          $mform->addElement('select', 'supportedreturntypes', get_string('supportedreturntypes', 'repository_nextcloud'), $choices);
 722  
 723          $choices = [
 724              FILE_INTERNAL => get_string('internal', 'repository_nextcloud'),
 725              FILE_CONTROLLED_LINK => get_string('external', 'repository_nextcloud'),
 726          ];
 727          $mform->addElement('select', 'defaultreturntype', get_string('defaultreturntype', 'repository_nextcloud'), $choices);
 728      }
 729  
 730      /**
 731       * Save settings for repository instance
 732       *
 733       * @param array $options settings
 734       * @return bool
 735       */
 736      public function set_option($options = array()) {
 737          $options['issuerid'] = clean_param($options['issuerid'], PARAM_INT);
 738          $options['controlledlinkfoldername'] = clean_param($options['controlledlinkfoldername'], PARAM_TEXT);
 739  
 740          $ret = parent::set_option($options);
 741          return $ret;
 742      }
 743  
 744      /**
 745       * Names of the plugin settings
 746       *
 747       * @return array
 748       */
 749      public static function get_instance_option_names() {
 750          return ['issuerid', 'controlledlinkfoldername',
 751              'defaultreturntype', 'supportedreturntypes'];
 752      }
 753  
 754      /**
 755       * Method to define which file-types are supported (hardcoded can not be changed in Admin Menu)
 756       *
 757       * By default FILE_INTERNAL is supported. In case a system account is connected and an issuer exist,
 758       * FILE_CONTROLLED_LINK is supported.
 759       *
 760       * FILE_INTERNAL - the file is uploaded/downloaded and stored directly within the Moodle file system.
 761       * FILE_CONTROLLED_LINK - creates a copy of the file in Nextcloud from which private shares to permitted users will be
 762       * created. The file itself can not be changed any longer by the owner.
 763       *
 764       * @return int return type bitmask supported
 765       */
 766      public function supported_returntypes() {
 767          // We can only support references if the system account is connected.
 768          if (!empty($this->issuer) && $this->issuer->is_system_account_connected()) {
 769              $setting = $this->get_option('supportedreturntypes');
 770              if ($setting === 'internal') {
 771                  return FILE_INTERNAL;
 772              } else if ($setting === 'external') {
 773                  return FILE_CONTROLLED_LINK;
 774              } else {
 775                  return FILE_CONTROLLED_LINK | FILE_INTERNAL | FILE_REFERENCE;
 776              }
 777          } else {
 778              return FILE_INTERNAL | FILE_REFERENCE;
 779          }
 780      }
 781  
 782  
 783      /**
 784       * Take the WebDAV `ls()' output and convert it into a format that Moodle's filepicker understands.
 785       *
 786       * @param string $dirpath Relative (urlencoded) path of the folder of interest.
 787       * @param array $ls Output by WebDAV
 788       * @return array Moodle-formatted list of directory contents; ready for use as $ret['list'] in get_listings
 789       */
 790      private function get_listing_convert_response($dirpath, $ls) {
 791          global $OUTPUT;
 792          $folders = array();
 793          $files = array();
 794          $parsedurl = issuer_management::parse_endpoint_url('webdav', $this->issuer);
 795          $basepath = rtrim('/' . ltrim($parsedurl['path'], '/ '), '/ ');
 796  
 797          foreach ($ls as $item) {
 798              if (!empty($item['lastmodified'])) {
 799                  $item['lastmodified'] = strtotime($item['lastmodified']);
 800              } else {
 801                  $item['lastmodified'] = null;
 802              }
 803  
 804              // Extracting object title from absolute path: First remove Nextcloud basepath.
 805              $item['href'] = substr(urldecode($item['href']), strlen($basepath));
 806              // Then remove relative path to current folder.
 807              $title = substr($item['href'], strlen($dirpath));
 808  
 809              if (!empty($item['resourcetype']) && $item['resourcetype'] == 'collection') {
 810                  // A folder.
 811                  if ($dirpath == $item['href']) {
 812                      // Skip "." listing.
 813                      continue;
 814                  }
 815  
 816                  $folders[strtoupper($title)] = array(
 817                      'title' => rtrim($title, '/'),
 818                      'thumbnail' => $OUTPUT->image_url(file_folder_icon(90))->out(false),
 819                      'children' => array(),
 820                      'datemodified' => $item['lastmodified'],
 821                      'path' => $item['href']
 822                  );
 823              } else {
 824                  // A file.
 825                  $size = !empty($item['getcontentlength']) ? $item['getcontentlength'] : '';
 826                  $files[strtoupper($title)] = array(
 827                      'title' => $title,
 828                      'thumbnail' => $OUTPUT->image_url(file_extension_icon($title, 90))->out(false),
 829                      'size' => $size,
 830                      'datemodified' => $item['lastmodified'],
 831                      'source' => $item['href']
 832                  );
 833              }
 834          }
 835          ksort($files);
 836          ksort($folders);
 837          return array_merge($folders, $files);
 838      }
 839  
 840      /**
 841       * Print the login in a popup.
 842       *
 843       * @param array|null $attr Custom attributes to be applied to popup div.
 844       */
 845      private function print_login_popup($attr = null, $embed = false) {
 846          global $OUTPUT, $PAGE;
 847  
 848          if ($embed) {
 849              $PAGE->set_pagelayout('embedded');
 850          }
 851  
 852          $this->client = $this->get_user_oauth_client();
 853          $url = new moodle_url($this->client->get_login_url());
 854          $state = $url->get_param('state') . '&reloadparent=true';
 855          $url->param('state', $state);
 856  
 857          echo $OUTPUT->header();
 858  
 859          $button = new single_button($url, get_string('logintoaccount', 'repository', $this->get_name()),
 860              'post', true);
 861          $button->add_action(new popup_action('click', $url, 'Login'));
 862          $button->class = 'mdl-align';
 863          $button = $OUTPUT->render($button);
 864          echo html_writer::div($button, '', $attr);
 865  
 866          echo $OUTPUT->footer();
 867      }
 868  
 869      /**
 870       * Prepare response of get_listing; namely
 871       * - defining setting elements,
 872       * - filling in the parent path of the currently-viewed directory.
 873       *
 874       * @param string $path Relative path
 875       * @return array ret array for use as get_listing's $ret
 876       */
 877      private function get_listing_prepare_response($path) {
 878          $ret = [
 879              // Fetch the list dynamically. An AJAX request is sent to the server as soon as the user opens a folder.
 880              'dynload' => true,
 881              'nosearch' => true, // Disable search.
 882              'nologin' => false, // Provide a login link because a user logs into his/her private Nextcloud storage.
 883              'path' => array([ // Contains all parent paths to the current path.
 884                  'name' => $this->get_meta()->name,
 885                  'path' => '',
 886              ]),
 887              'defaultreturntype' => $this->default_returntype(),
 888              'manage' => $this->issuer->get('baseurl'), // Provide button to go into file management interface quickly.
 889              'list' => array(), // Contains all file/folder information and is required to build the file/folder tree.
 890              'filereferencewarning' => get_string('externalpubliclinkwarning', 'repository_nextcloud'),
 891          ];
 892  
 893          // If relative path is a non-top-level path, calculate all its parents' paths.
 894          // This is used for navigation in the file picker.
 895          if ($path != '/') {
 896              $chunks = explode('/', trim($path, '/'));
 897              $parent = '/';
 898              // Every sub-path to the last part of the current path is a parent path.
 899              foreach ($chunks as $chunk) {
 900                  $subpath = $parent . $chunk . '/';
 901                  $ret['path'][] = [
 902                      'name' => urldecode($chunk),
 903                      'path' => $subpath
 904                  ];
 905                  // Prepare next iteration.
 906                  $parent = $subpath;
 907              }
 908          }
 909          return $ret;
 910      }
 911  
 912      /**
 913       * When a controlled link is clicked in the file picker get the human readable info about this file.
 914       *
 915       * @param string $reference
 916       * @param int $filestatus
 917       * @return string
 918       */
 919      public function get_reference_details($reference, $filestatus = 0) {
 920          if ($this->disabled) {
 921              throw new repository_exception('cannotdownload', 'repository');
 922          }
 923          if (empty($reference)) {
 924              return get_string('unknownsource', 'repository');
 925          }
 926          $source = json_decode($reference);
 927          $path = '';
 928          if (!empty($source->usesystem) && !empty($source->name)) {
 929              $path = $source->name;
 930          }
 931  
 932          return $path;
 933      }
 934  
 935      /**
 936       * Synchronize the external file if there is an update happened to it.
 937       *
 938       * If the file has been updated in the nextcloud instance, this method
 939       * would take care of the file we copy into the moodle file pool.
 940       *
 941       * The call to this method reaches from stored_file::sync_external_file()
 942       *
 943       * @param stored_file $file
 944       * @return bool true if synced successfully else false if not ready to sync or reference link not set
 945       */
 946      public function sync_reference(stored_file $file):bool {
 947          global $CFG;
 948  
 949          if ($file->get_referencelastsync() + DAYSECS > time()) {
 950              // Synchronize once per day.
 951              return false;
 952          }
 953  
 954          $reference = json_decode($file->get_reference());
 955  
 956          if (!isset($reference->link)) {
 957              return false;
 958          }
 959  
 960          $url = $reference->link;
 961          if (file_extension_in_typegroup($file->get_filepath() . $file->get_filename(), 'web_image')) {
 962              $saveas = $this->prepare_file(uniqid());
 963              try {
 964                  $result = $this->curl->download_one($url, [], [
 965                      'filepath' => $saveas,
 966                      'timeout' => $CFG->repositorysyncimagetimeout,
 967                      'followlocation' => true,
 968                  ]);
 969  
 970                  $info = $this->curl->get_info();
 971  
 972                  if ($result === true && isset($info['http_code']) && $info['http_code'] === 200) {
 973                      $file->set_synchronised_content_from_file($saveas);
 974                      return true;
 975                  }
 976              } catch (Exception $e) {
 977                  // If the download fails lets download with get().
 978                  $this->curl->get($url, null, ['timeout' => $CFG->repositorysyncimagetimeout, 'followlocation' => true, 'nobody' => true]);
 979                  $info = $this->curl->get_info();
 980  
 981                  if (isset($info['http_code']) && $info['http_code'] === 200 &&
 982                      array_key_exists('download_content_length', $info) &&
 983                      $info['download_content_length'] >= 0) {
 984                          $filesize = (int)$info['download_content_length'];
 985                          $file->set_synchronized(null, $filesize);
 986                          return true;
 987                  }
 988  
 989                  $file->set_missingsource();
 990                  return true;
 991              }
 992          }
 993          return false;
 994      }
 995  }