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   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  /**
  19   * External notes API
  20   *
  21   * @package    core_notes
  22   * @category   external
  23   * @copyright  2011 Jerome Mouneyrac
  24   * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  25   */
  26  
  27  require_once("$CFG->libdir/externallib.php");
  28  require_once($CFG->dirroot . "/notes/lib.php");
  29  
  30  /**
  31   * Notes external functions
  32   *
  33   * @package    core_notes
  34   * @category   external
  35   * @copyright  2011 Jerome Mouneyrac
  36   * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  37   * @since Moodle 2.2
  38   */
  39  class core_notes_external extends external_api {
  40  
  41      /**
  42       * Returns description of method parameters
  43       *
  44       * @return external_function_parameters
  45       * @since Moodle 2.2
  46       */
  47      public static function create_notes_parameters() {
  48          return new external_function_parameters(
  49              array(
  50                  'notes' => new external_multiple_structure(
  51                      new external_single_structure(
  52                          array(
  53                              'userid' => new external_value(PARAM_INT, 'id of the user the note is about'),
  54                              'publishstate' => new external_value(PARAM_ALPHA, '\'personal\', \'course\' or \'site\''),
  55                              'courseid' => new external_value(PARAM_INT, 'course id of the note (in Moodle a note can only be created into a course, even for site and personal notes)'),
  56                              'text' => new external_value(PARAM_RAW, 'the text of the message - text or HTML'),
  57                              'format' => new external_format_value('text', VALUE_DEFAULT),
  58                              'clientnoteid' => new external_value(PARAM_ALPHANUMEXT, 'your own client id for the note. If this id is provided, the fail message id will be returned to you', VALUE_OPTIONAL),
  59                          )
  60                      )
  61                  )
  62              )
  63          );
  64      }
  65  
  66      /**
  67       * Create notes about some users
  68       * Note: code should be matching the /notes/edit.php checks
  69       * and the /user/addnote.php checks. (they are similar cheks)
  70       *
  71       * @param array $notes  An array of notes to create.
  72       * @return array (success infos and fail infos)
  73       * @since Moodle 2.2
  74       */
  75      public static function create_notes($notes = array()) {
  76          global $CFG, $DB;
  77  
  78          $params = self::validate_parameters(self::create_notes_parameters(), array('notes' => $notes));
  79  
  80          // Check if note system is enabled.
  81          if (!$CFG->enablenotes) {
  82              throw new moodle_exception('notesdisabled', 'notes');
  83          }
  84  
  85          // Retrieve all courses.
  86          $courseids = array();
  87          foreach ($params['notes'] as $note) {
  88              $courseids[] = $note['courseid'];
  89          }
  90          $courses = $DB->get_records_list("course", "id", $courseids);
  91  
  92          // Retrieve all users of the notes.
  93          $userids = array();
  94          foreach ($params['notes'] as $note) {
  95              $userids[] = $note['userid'];
  96          }
  97          list($sqluserids, $sqlparams) = $DB->get_in_or_equal($userids, SQL_PARAMS_NAMED, 'userid_');
  98          $users = $DB->get_records_select("user", "id " . $sqluserids . " AND deleted = 0", $sqlparams);
  99  
 100          $resultnotes = array();
 101          foreach ($params['notes'] as $note) {
 102  
 103              $success = true;
 104              $resultnote = array(); // The infos about the success of the operation.
 105  
 106              // Check the course exists.
 107              if (empty($courses[$note['courseid']])) {
 108                  $success = false;
 109                  $errormessage = get_string('invalidcourseid', 'error');
 110              } else {
 111                  // Ensure the current user is allowed to run this function.
 112                  $context = context_course::instance($note['courseid']);
 113                  self::validate_context($context);
 114                  require_capability('moodle/notes:manage', $context);
 115              }
 116  
 117              // Check the user exists.
 118              if (empty($users[$note['userid']])) {
 119                  $success = false;
 120                  $errormessage = get_string('invaliduserid', 'notes', $note['userid']);
 121              }
 122  
 123              // Build the resultnote.
 124              if (isset($note['clientnoteid'])) {
 125                  $resultnote['clientnoteid'] = $note['clientnoteid'];
 126              }
 127  
 128              if ($success) {
 129                  // Now we can create the note.
 130                  $dbnote = new stdClass;
 131                  $dbnote->courseid = $note['courseid'];
 132                  $dbnote->userid = $note['userid'];
 133                  // Need to support 'html' and 'text' format values for backward compatibility.
 134                  switch (strtolower($note['format'])) {
 135                      case 'html':
 136                          $textformat = FORMAT_HTML;
 137                          break;
 138                      case 'text':
 139                          $textformat = FORMAT_PLAIN;
 140                      default:
 141                          $textformat = external_validate_format($note['format']);
 142                          break;
 143                  }
 144                  $dbnote->content = $note['text'];
 145                  $dbnote->format = $textformat;
 146  
 147                  // Get the state ('personal', 'course', 'site').
 148                  switch ($note['publishstate']) {
 149                      case 'personal':
 150                          $dbnote->publishstate = NOTES_STATE_DRAFT;
 151                          break;
 152                      case 'course':
 153                          $dbnote->publishstate = NOTES_STATE_PUBLIC;
 154                          break;
 155                      case 'site':
 156                          $dbnote->publishstate = NOTES_STATE_SITE;
 157                          $dbnote->courseid = SITEID;
 158                          break;
 159                      default:
 160                          break;
 161                  }
 162  
 163                  // TODO MDL-31119 performance improvement - if possible create a bulk functions for saving multiple notes at once
 164                  if (note_save($dbnote)) { // Note_save attribut an id in case of success.
 165                      $success = $dbnote->id;
 166                  }
 167  
 168                  $resultnote['noteid'] = $success;
 169              } else {
 170                  // WARNINGS: for backward compatibility we return this errormessage.
 171                  //          We should have thrown exceptions as these errors prevent results to be returned.
 172                  // See http://docs.moodle.org/dev/Errors_handling_in_web_services#When_to_send_a_warning_on_the_server_side .
 173                  $resultnote['noteid'] = -1;
 174                  $resultnote['errormessage'] = $errormessage;
 175              }
 176  
 177              $resultnotes[] = $resultnote;
 178          }
 179  
 180          return $resultnotes;
 181      }
 182  
 183      /**
 184       * Returns description of method result value
 185       *
 186       * @return external_description
 187       * @since Moodle 2.2
 188       */
 189      public static function create_notes_returns() {
 190          return new external_multiple_structure(
 191              new external_single_structure(
 192                  array(
 193                      'clientnoteid' => new external_value(PARAM_ALPHANUMEXT, 'your own id for the note', VALUE_OPTIONAL),
 194                      'noteid' => new external_value(PARAM_INT, 'ID of the created note when successful, -1 when failed'),
 195                      'errormessage' => new external_value(PARAM_TEXT, 'error message - if failed', VALUE_OPTIONAL)
 196                  )
 197              )
 198          );
 199      }
 200  
 201      /**
 202       * Returns description of delete_notes parameters
 203       *
 204       * @return external_function_parameters
 205       * @since Moodle 2.5
 206       */
 207      public static function delete_notes_parameters() {
 208          return new external_function_parameters(
 209              array(
 210                  "notes"=> new external_multiple_structure(
 211                      new external_value(PARAM_INT, 'ID of the note to be deleted'), 'Array of Note Ids to be deleted.'
 212                  )
 213              )
 214          );
 215      }
 216  
 217      /**
 218       * Delete notes about users.
 219       * Note: code should be matching the /notes/delete.php checks.
 220       *
 221       * @param array $notes An array of ids for the notes to delete.
 222       * @return null
 223       * @since Moodle 2.5
 224       */
 225      public static function delete_notes($notes = array()) {
 226          global $CFG;
 227  
 228          $params = self::validate_parameters(self::delete_notes_parameters(), array('notes' => $notes));
 229  
 230          // Check if note system is enabled.
 231          if (!$CFG->enablenotes) {
 232              throw new moodle_exception('notesdisabled', 'notes');
 233          }
 234          $warnings = array();
 235          foreach ($params['notes'] as $noteid) {
 236              $note = note_load($noteid);
 237              if (isset($note->id)) {
 238                  // Ensure the current user is allowed to run this function.
 239                  $context = context_course::instance($note->courseid);
 240                  self::validate_context($context);
 241                  require_capability('moodle/notes:manage', $context);
 242                  note_delete($note);
 243              } else {
 244                  $warnings[] = array('item'=>'note', 'itemid'=>$noteid, 'warningcode'=>'badid', 'message'=>'Note does not exist');
 245              }
 246          }
 247          return $warnings;
 248      }
 249  
 250      /**
 251       * Returns description of delete_notes result value.
 252       *
 253       * @return external_description
 254       * @since Moodle 2.5
 255       */
 256      public static function delete_notes_returns() {
 257          return  new external_warnings('item is always \'note\'',
 258                              'When errorcode is savedfailed the note could not be modified.' .
 259                              'When errorcode is badparam, an incorrect parameter was provided.' .
 260                              'When errorcode is badid, the note does not exist',
 261                              'errorcode can be badparam (incorrect parameter), savedfailed (could not be modified), or badid (note does not exist)');
 262  
 263      }
 264  
 265      /**
 266       * Returns description of get_notes parameters.
 267       *
 268       * @return external_function_parameters
 269       * @since Moodle 2.5
 270       */
 271      public static function get_notes_parameters() {
 272          return new external_function_parameters(
 273              array(
 274                  "notes"=> new external_multiple_structure(
 275                      new external_value(PARAM_INT, 'ID of the note to be retrieved'), 'Array of Note Ids to be retrieved.'
 276                  )
 277              )
 278          );
 279      }
 280  
 281      /**
 282       * Get notes about users.
 283       *
 284       * @param array $notes An array of ids for the notes to retrieve.
 285       * @return null
 286       * @since Moodle 2.5
 287       */
 288      public static function get_notes($notes) {
 289          global $CFG;
 290  
 291          $params = self::validate_parameters(self::get_notes_parameters(), array('notes' => $notes));
 292          // Check if note system is enabled.
 293          if (!$CFG->enablenotes) {
 294              throw new moodle_exception('notesdisabled', 'notes');
 295          }
 296          $resultnotes = array();
 297          foreach ($params['notes'] as $noteid) {
 298              $resultnote = array();
 299  
 300              $note = note_load($noteid);
 301              if (isset($note->id)) {
 302                  // Ensure the current user is allowed to run this function.
 303                  $context = context_course::instance($note->courseid);
 304                  self::validate_context($context);
 305                  require_capability('moodle/notes:view', $context);
 306                  list($gotnote['text'], $gotnote['format']) = external_format_text($note->content,
 307                                                                                    $note->format,
 308                                                                                    $context->id,
 309                                                                                    'notes',
 310                                                                                    '',
 311                                                                                    '');
 312                  $gotnote['noteid'] = $note->id;
 313                  $gotnote['userid'] = $note->userid;
 314                  $gotnote['publishstate'] = $note->publishstate;
 315                  $gotnote['courseid'] = $note->courseid;
 316                  $resultnotes["notes"][] = $gotnote;
 317              } else {
 318                  $resultnotes["warnings"][] = array('item' => 'note',
 319                                                     'itemid' => $noteid,
 320                                                     'warningcode' => 'badid',
 321                                                     'message' => 'Note does not exist');
 322              }
 323          }
 324          return $resultnotes;
 325      }
 326  
 327      /**
 328       * Returns description of get_notes result value.
 329       *
 330       * @return external_description
 331       * @since Moodle 2.5
 332       */
 333      public static function get_notes_returns() {
 334          return new external_single_structure(
 335              array(
 336                  'notes' => new external_multiple_structure(
 337                      new external_single_structure(
 338                          array(
 339                              'noteid' => new external_value(PARAM_INT, 'id of the note', VALUE_OPTIONAL),
 340                              'userid' => new external_value(PARAM_INT, 'id of the user the note is about', VALUE_OPTIONAL),
 341                              'publishstate' => new external_value(PARAM_ALPHA, '\'personal\', \'course\' or \'site\'', VALUE_OPTIONAL),
 342                              'courseid' => new external_value(PARAM_INT, 'course id of the note', VALUE_OPTIONAL),
 343                              'text' => new external_value(PARAM_RAW, 'the text of the message - text or HTML', VALUE_OPTIONAL),
 344                              'format' => new external_format_value('text', VALUE_OPTIONAL),
 345                          ), 'note'
 346                      )
 347                   ),
 348                   'warnings' => new external_warnings('item is always \'note\'',
 349                          'When errorcode is savedfailed the note could not be modified.' .
 350                          'When errorcode is badparam, an incorrect parameter was provided.' .
 351                          'When errorcode is badid, the note does not exist',
 352                          'errorcode can be badparam (incorrect parameter), savedfailed (could not be modified), or badid (note does not exist)')
 353              )
 354          );
 355      }
 356  
 357      /**
 358       * Returns description of update_notes parameters.
 359       *
 360       * @return external_function_parameters
 361       * @since Moodle 2.5
 362       */
 363      public static function update_notes_parameters() {
 364          return new external_function_parameters(
 365              array(
 366                  'notes' => new external_multiple_structure(
 367                      new external_single_structure(
 368                          array(
 369                              'id' => new external_value(PARAM_INT, 'id of the note'),
 370                              'publishstate' => new external_value(PARAM_ALPHA, '\'personal\', \'course\' or \'site\''),
 371                              'text' => new external_value(PARAM_RAW, 'the text of the message - text or HTML'),
 372                              'format' => new external_format_value('text', VALUE_DEFAULT),
 373                          )
 374                      ), "Array of Notes", VALUE_DEFAULT, array()
 375                  )
 376              )
 377          );
 378      }
 379  
 380      /**
 381       * Update notes about users.
 382       *
 383       * @param array $notes An array of ids for the notes to update.
 384       * @return array fail infos.
 385       * @since Moodle 2.2
 386       */
 387      public static function update_notes($notes = array()) {
 388          global $CFG, $DB;
 389  
 390          $params = self::validate_parameters(self::update_notes_parameters(), array('notes' => $notes));
 391  
 392          // Check if note system is enabled.
 393          if (!$CFG->enablenotes) {
 394              throw new moodle_exception('notesdisabled', 'notes');
 395          }
 396  
 397          $warnings = array();
 398          foreach ($params['notes'] as $note) {
 399              $notedetails = note_load($note['id']);
 400              if (isset($notedetails->id)) {
 401                  // Ensure the current user is allowed to run this function.
 402                  $context = context_course::instance($notedetails->courseid);
 403                  self::validate_context($context);
 404                  require_capability('moodle/notes:manage', $context);
 405  
 406                  $dbnote = new stdClass;
 407                  $dbnote->id = $note['id'];
 408                  $dbnote->content = $note['text'];
 409                  $dbnote->format = external_validate_format($note['format']);
 410                  // Get the state ('personal', 'course', 'site').
 411                  switch ($note['publishstate']) {
 412                      case 'personal':
 413                          $dbnote->publishstate = NOTES_STATE_DRAFT;
 414                          break;
 415                      case 'course':
 416                          $dbnote->publishstate = NOTES_STATE_PUBLIC;
 417                          break;
 418                      case 'site':
 419                          $dbnote->publishstate = NOTES_STATE_SITE;
 420                          $dbnote->courseid = SITEID;
 421                          break;
 422                      default:
 423                          $warnings[] = array('item' => 'note',
 424                                              'itemid' => $note["id"],
 425                                              'warningcode' => 'badparam',
 426                                              'message' => 'Provided publishstate incorrect');
 427                          break;
 428                  }
 429                  if (!note_save($dbnote)) {
 430                      $warnings[] = array('item' => 'note',
 431                                          'itemid' => $note["id"],
 432                                          'warningcode' => 'savedfailed',
 433                                          'message' => 'Note could not be modified');
 434                  }
 435              } else {
 436                  $warnings[] = array('item' => 'note',
 437                                      'itemid' => $note["id"],
 438                                      'warningcode' => 'badid',
 439                                      'message' => 'Note does not exist');
 440              }
 441          }
 442          return $warnings;
 443      }
 444  
 445      /**
 446       * Returns description of update_notes result value.
 447       *
 448       * @return external_description
 449       * @since Moodle 2.5
 450       */
 451      public static function update_notes_returns() {
 452          return new external_warnings('item is always \'note\'',
 453                              'When errorcode is savedfailed the note could not be modified.' .
 454                              'When errorcode is badparam, an incorrect parameter was provided.' .
 455                              'When errorcode is badid, the note does not exist',
 456                              'errorcode can be badparam (incorrect parameter), savedfailed (could not be modified), or badid (note does not exist)');
 457      }
 458  
 459      /**
 460       * Returns description of method parameters
 461       *
 462       * @return external_function_parameters
 463       * @since Moodle 2.9
 464       */
 465      public static function get_course_notes_parameters() {
 466          return new external_function_parameters(
 467              array(
 468                  'courseid' => new external_value(PARAM_INT, 'course id, 0 for SITE'),
 469                  'userid'   => new external_value(PARAM_INT, 'user id', VALUE_DEFAULT, 0),
 470              )
 471          );
 472      }
 473  
 474      /**
 475       * Create a notes list
 476       *
 477       * @param int $courseid ID of the Course
 478       * @param stdClass $context context object
 479       * @param int $userid ID of the User
 480       * @param int $state
 481       * @param int $author
 482       * @return array of notes
 483       * @since Moodle 2.9
 484       */
 485      protected static function create_note_list($courseid, $context, $userid, $state, $author = 0) {
 486          $results = array();
 487          $notes = note_list($courseid, $userid, $state, $author);
 488          foreach ($notes as $key => $note) {
 489              $note = (array)$note;
 490              list($note['content'], $note['format']) = external_format_text($note['content'],
 491                                                                             $note['format'],
 492                                                                             $context->id,
 493                                                                             '',
 494                                                                             '',
 495                                                                             0);
 496              $results[$key] = $note;
 497          }
 498          return $results;
 499      }
 500  
 501      /**
 502       * Get a list of course notes
 503       *
 504       * @param int $courseid ID of the Course
 505       * @param int $userid ID of the User
 506       * @return array of site, course and personal notes and warnings
 507       * @since Moodle 2.9
 508       * @throws moodle_exception
 509       */
 510      public static function get_course_notes($courseid, $userid = 0) {
 511          global $CFG, $USER;
 512  
 513          if (empty($CFG->enablenotes)) {
 514              throw new moodle_exception('notesdisabled', 'notes');
 515          }
 516  
 517          $warnings = array();
 518          $arrayparams = array(
 519              'courseid' => $courseid,
 520              'userid'   => $userid,
 521          );
 522          $params = self::validate_parameters(self::get_course_notes_parameters(), $arrayparams);
 523  
 524          if (empty($params['courseid'])) {
 525              $params['courseid'] = SITEID;
 526          }
 527          $user = null;
 528          if (!empty($params['userid'])) {
 529              $user = core_user::get_user($params['userid'], '*', MUST_EXIST);
 530              core_user::require_active_user($user);
 531          }
 532  
 533          $course = get_course($params['courseid']);
 534  
 535          if ($course->id == SITEID) {
 536              $context = context_system::instance();
 537          } else {
 538              $context = context_course::instance($course->id);
 539          }
 540          self::validate_context($context);
 541  
 542          $sitenotes = array();
 543          $coursenotes = array();
 544          $personalnotes = array();
 545  
 546          if ($course->id != SITEID) {
 547  
 548              require_capability('moodle/notes:view', $context);
 549              $sitenotes = self::create_note_list(0, context_system::instance(), $params['userid'], NOTES_STATE_SITE);
 550              $coursenotes = self::create_note_list($course->id, $context, $params['userid'], NOTES_STATE_PUBLIC);
 551              $personalnotes = self::create_note_list($course->id, $context, $params['userid'], NOTES_STATE_DRAFT,
 552                                                          $USER->id);
 553          } else {
 554              if (has_capability('moodle/notes:view', $context)) {
 555                  $sitenotes = self::create_note_list(0, $context, $params['userid'], NOTES_STATE_SITE);
 556              }
 557              // It returns notes only for a specific user!
 558              if (!empty($user)) {
 559                  $usercourses = enrol_get_users_courses($user->id, true);
 560                  foreach ($usercourses as $c) {
 561                      // All notes at course level, only if we have capability on every course.
 562                      if (has_capability('moodle/notes:view', context_course::instance($c->id))) {
 563                          $coursenotes += self::create_note_list($c->id, $context, $params['userid'], NOTES_STATE_PUBLIC);
 564                      }
 565                  }
 566              }
 567          }
 568  
 569          $results = array(
 570              'sitenotes'     => $sitenotes,
 571              'coursenotes'   => $coursenotes,
 572              'personalnotes' => $personalnotes,
 573              'warnings'      => $warnings
 574          );
 575          return $results;
 576  
 577      }
 578  
 579      /**
 580       * Returns array of note structure
 581       *
 582       * @return external_description
 583       * @since Moodle 2.9
 584       */
 585      protected static function get_note_structure() {
 586          return array(
 587                       'id'           => new external_value(PARAM_INT, 'id of this note'),
 588                       'courseid'     => new external_value(PARAM_INT, 'id of the course'),
 589                       'userid'       => new external_value(PARAM_INT, 'user id'),
 590                       'content'      => new external_value(PARAM_RAW, 'the content text formated'),
 591                       'format'       => new external_format_value('content'),
 592                       'created'      => new external_value(PARAM_INT, 'time created (timestamp)'),
 593                       'lastmodified' => new external_value(PARAM_INT, 'time of last modification (timestamp)'),
 594                       'usermodified' => new external_value(PARAM_INT, 'user id of the creator of this note'),
 595                       'publishstate' => new external_value(PARAM_ALPHA, "state of the note (i.e. draft, public, site) ")
 596          );
 597      }
 598  
 599      /**
 600       * Returns description of method result value
 601       *
 602       * @return external_description
 603       * @since Moodle 2.9
 604       */
 605      public static function get_course_notes_returns() {
 606          return new external_single_structure(
 607              array(
 608                    'sitenotes' => new external_multiple_structure(
 609                        new external_single_structure(
 610                            self::get_note_structure() , ''
 611                        ), 'site notes', VALUE_OPTIONAL
 612                     ),
 613                     'coursenotes' => new external_multiple_structure(
 614                        new external_single_structure(
 615                            self::get_note_structure() , ''
 616                        ), 'couse notes', VALUE_OPTIONAL
 617                     ),
 618                     'personalnotes' => new external_multiple_structure(
 619                        new external_single_structure(
 620                            self::get_note_structure() , ''
 621                        ), 'personal notes', VALUE_OPTIONAL
 622                     ),
 623                   'warnings' => new external_warnings()
 624              ), 'notes'
 625          );
 626      }
 627  
 628      /**
 629       * Returns description of method parameters
 630       *
 631       * @return external_function_parameters
 632       * @since Moodle 2.9
 633       */
 634      public static function view_notes_parameters() {
 635          return new external_function_parameters(
 636              array(
 637                  'courseid' => new external_value(PARAM_INT, 'course id, 0 for notes at system level'),
 638                  'userid' => new external_value(PARAM_INT, 'user id, 0 means view all the user notes', VALUE_DEFAULT, 0)
 639              )
 640          );
 641      }
 642  
 643      /**
 644       * Simulates the web interface view of notes/index.php: trigger events
 645       *
 646       * @param int $courseid id of the course
 647       * @param int $userid id of the user
 648       * @return array of warnings and status result
 649       * @since Moodle 2.9
 650       * @throws moodle_exception
 651       */
 652      public static function view_notes($courseid, $userid = 0) {
 653          global $CFG;
 654          require_once($CFG->dirroot . "/notes/lib.php");
 655  
 656          if (empty($CFG->enablenotes)) {
 657              throw new moodle_exception('notesdisabled', 'notes');
 658          }
 659  
 660          $warnings = array();
 661          $arrayparams = array(
 662              'courseid' => $courseid,
 663              'userid' => $userid
 664          );
 665          $params = self::validate_parameters(self::view_notes_parameters(), $arrayparams);
 666  
 667          if (empty($params['courseid'])) {
 668              $params['courseid'] = SITEID;
 669          }
 670  
 671          $course = get_course($params['courseid']);
 672  
 673          if ($course->id == SITEID) {
 674              $context = context_system::instance();
 675          } else {
 676              $context = context_course::instance($course->id);
 677          }
 678  
 679          // First of all, validate the context before do further permission checks.
 680          self::validate_context($context);
 681          require_capability('moodle/notes:view', $context);
 682  
 683          if (!empty($params['userid'])) {
 684              $user = core_user::get_user($params['userid'], '*', MUST_EXIST);
 685              core_user::require_active_user($user);
 686  
 687              if ($course->id != SITEID and !can_access_course($course, $user, '', true)) {
 688                  throw new moodle_exception('notenrolledprofile');
 689              }
 690          }
 691  
 692          note_view($context, $params['userid']);
 693  
 694          $result = array();
 695          $result['status'] = true;
 696          $result['warnings'] = $warnings;
 697          return $result;
 698  
 699      }
 700  
 701      /**
 702       * Returns description of method result value
 703       *
 704       * @return external_description
 705       * @since Moodle 2.9
 706       */
 707      public static function view_notes_returns() {
 708          return new external_single_structure(
 709              array(
 710                  'status' => new external_value(PARAM_BOOL, 'status: true if success'),
 711                  'warnings' => new external_warnings()
 712              )
 713          );
 714      }
 715  
 716  }