/mod/assign/locallib.php

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<?php
// This file is part of Moodle - http://moodle.org/
//
// Moodle is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// Moodle 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 General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.

/**
 * This file contains the definition for the class assignment
 *
 * This class provides all the functionality for the new assign module.
 *
 * @package   mod_assign
 * @copyright 2012 NetSpot {@link http://www.netspot.com.au}
 * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 */

defined('MOODLE_INTERNAL') || die();

// Assignment submission statuses.
define('ASSIGN_SUBMISSION_STATUS_REOPENED', 'reopened');
define('ASSIGN_SUBMISSION_STATUS_DRAFT', 'draft');
define('ASSIGN_SUBMISSION_STATUS_SUBMITTED', 'submitted');

// Search filters for grading page.
define('ASSIGN_FILTER_SUBMITTED', 'submitted');
define('ASSIGN_FILTER_SINGLE_USER', 'singleuser');
define('ASSIGN_FILTER_REQUIRE_GRADING', 'require_grading');

// Reopen attempt methods.
define('ASSIGN_ATTEMPT_REOPEN_METHOD_NONE', 'none');
define('ASSIGN_ATTEMPT_REOPEN_METHOD_MANUAL', 'manual');
define('ASSIGN_ATTEMPT_REOPEN_METHOD_UNTILPASS', 'untilpass');

// Special value means allow unlimited attempts.
define('ASSIGN_UNLIMITED_ATTEMPTS', -1);

// Marking workflow states.
define('ASSIGN_MARKING_WORKFLOW_STATE_NOTMARKED', 'notmarked');
define('ASSIGN_MARKING_WORKFLOW_STATE_INMARKING', 'inmarking');
define('ASSIGN_MARKING_WORKFLOW_STATE_READYFORREVIEW', 'readyforreview');
define('ASSIGN_MARKING_WORKFLOW_STATE_INREVIEW', 'inreview');
define('ASSIGN_MARKING_WORKFLOW_STATE_READYFORRELEASE', 'readyforrelease');
define('ASSIGN_MARKING_WORKFLOW_STATE_RELEASED', 'released');

require_once($CFG->libdir . '/accesslib.php');
require_once($CFG->libdir . '/formslib.php');
require_once($CFG->dirroot . '/repository/lib.php');
require_once($CFG->dirroot . '/mod/assign/mod_form.php');
require_once($CFG->libdir . '/gradelib.php');
require_once($CFG->dirroot . '/grade/grading/lib.php');
require_once($CFG->dirroot . '/mod/assign/feedbackplugin.php');
require_once($CFG->dirroot . '/mod/assign/submissionplugin.php');
require_once($CFG->dirroot . '/mod/assign/renderable.php');
require_once($CFG->dirroot . '/mod/assign/gradingtable.php');
require_once($CFG->libdir . '/eventslib.php');
require_once($CFG->libdir . '/portfolio/caller.php');

/**
 * Standard base class for mod_assign (assignment types).
 *
 * @package   mod_assign
 * @copyright 2012 NetSpot {@link http://www.netspot.com.au}
 * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 */
class assign {

    /** @var stdClass the assignment record that contains the global settings for this assign instance */
    private $instance;

    /** @var stdClass the grade_item record for this assign instance's primary grade item. */
    private $gradeitem;

    /** @var context the context of the course module for this assign instance
     *               (or just the course if we are creating a new one)
     */
    private $context;

    /** @var stdClass the course this assign instance belongs to */
    private $course;

    /** @var stdClass the admin config for all assign instances  */
    private $adminconfig;

    /** @var assign_renderer the custom renderer for this module */
    private $output;

    /** @var stdClass the course module for this assign instance */
    private $coursemodule;

    /** @var array cache for things like the coursemodule name or the scale menu -
     *             only lives for a single request.
     */
    private $cache;

    /** @var array list of the installed submission plugins */
    private $submissionplugins;

    /** @var array list of the installed feedback plugins */
    private $feedbackplugins;

    /** @var string action to be used to return to this page
     *              (without repeating any form submissions etc).
     */
    private $returnaction = 'view';

    /** @var array params to be used to return to this page */
    private $returnparams = array();

    /** @var string modulename prevents excessive calls to get_string */
    private static $modulename = null;

    /** @var string modulenameplural prevents excessive calls to get_string */
    private static $modulenameplural = null;

    /** @var array of marking workflow states for the current user */
    private $markingworkflowstates = null;

    /** @var bool whether to exclude users with inactive enrolment */
    private $showonlyactiveenrol = null;

    /** @var array cached list of participants for this assignment. The cache key will be group, showactive and the context id */
    private $participants = array();

    /**
     * Constructor for the base assign class.
     *
     * @param mixed $coursemodulecontext context|null the course module context
     *                                   (or the course context if the coursemodule has not been
     *                                   created yet).
     * @param mixed $coursemodule the current course module if it was already loaded,
     *                            otherwise this class will load one from the context as required.
     * @param mixed $course the current course  if it was already loaded,
     *                      otherwise this class will load one from the context as required.
     */
    public function __construct($coursemodulecontext, $coursemodule, $course) {
        $this->context = $coursemodulecontext;
        $this->coursemodule = $coursemodule;
        $this->course = $course;

        // Temporary cache only lives for a single request - used to reduce db lookups.
        $this->cache = array();

        $this->submissionplugins = $this->load_plugins('assignsubmission');
        $this->feedbackplugins = $this->load_plugins('assignfeedback');
    }

    /**
     * Set the action and parameters that can be used to return to the current page.
     *
     * @param string $action The action for the current page
     * @param array $params An array of name value pairs which form the parameters
     *                      to return to the current page.
     * @return void
     */
    public function register_return_link($action, $params) {
        global $PAGE;
        $params['action'] = $action;
        $currenturl = $PAGE->url;

        $currenturl->params($params);
        $PAGE->set_url($currenturl);
    }

    /**
     * Return an action that can be used to get back to the current page.
     *
     * @return string action
     */
    public function get_return_action() {
        global $PAGE;

        $params = $PAGE->url->params();

        if (!empty($params['action'])) {
            return $params['action'];
        }
        return '';
    }

    /**
     * Based on the current assignment settings should we display the intro.
     *
     * @return bool showintro
     */
    protected function show_intro() {
        if ($this->get_instance()->alwaysshowdescription ||
                time() > $this->get_instance()->allowsubmissionsfromdate) {
            return true;
        }
        return false;
    }

    /**
     * Return a list of parameters that can be used to get back to the current page.
     *
     * @return array params
     */
    public function get_return_params() {
        global $PAGE;

        $params = $PAGE->url->params();
        unset($params['id']);
        unset($params['action']);
        return $params;
    }

    /**
     * Set the submitted form data.
     *
     * @param stdClass $data The form data (instance)
     */
    public function set_instance(stdClass $data) {
        $this->instance = $data;
    }

    /**
     * Set the context.
     *
     * @param context $context The new context
     */
    public function set_context(context $context) {
        $this->context = $context;
    }

    /**
     * Set the course data.
     *
     * @param stdClass $course The course data
     */
    public function set_course(stdClass $course) {
        $this->course = $course;
    }

    /**
     * Get list of feedback plugins installed.
     *
     * @return array
     */
    public function get_feedback_plugins() {
        return $this->feedbackplugins;
    }

    /**
     * Get list of submission plugins installed.
     *
     * @return array
     */
    public function get_submission_plugins() {
        return $this->submissionplugins;
    }

    /**
     * Is blind marking enabled and reveal identities not set yet?
     *
     * @return bool
     */
    public function is_blind_marking() {
        return $this->get_instance()->blindmarking && !$this->get_instance()->revealidentities;
    }

    /**
     * Does an assignment have submission(s) or grade(s) already?
     *
     * @return bool
     */
    public function has_submissions_or_grades() {
        $allgrades = $this->count_grades();
        $allsubmissions = $this->count_submissions();
        if (($allgrades == 0) && ($allsubmissions == 0)) {
            return false;
        }
        return true;
    }

    /**
     * Get a specific submission plugin by its type.
     *
     * @param string $subtype assignsubmission | assignfeedback
     * @param string $type
     * @return mixed assign_plugin|null
     */
    public function get_plugin_by_type($subtype, $type) {
        $shortsubtype = substr($subtype, strlen('assign'));
        $name = $shortsubtype . 'plugins';
        if ($name != 'feedbackplugins' && $name != 'submissionplugins') {
            return null;
        }
        $pluginlist = $this->$name;
        foreach ($pluginlist as $plugin) {
            if ($plugin->get_type() == $type) {
                return $plugin;
            }
        }
        return null;
    }

    /**
     * Get a feedback plugin by type.
     *
     * @param string $type - The type of plugin e.g comments
     * @return mixed assign_feedback_plugin|null
     */
    public function get_feedback_plugin_by_type($type) {
        return $this->get_plugin_by_type('assignfeedback', $type);
    }

    /**
     * Get a submission plugin by type.
     *
     * @param string $type - The type of plugin e.g comments
     * @return mixed assign_submission_plugin|null
     */
    public function get_submission_plugin_by_type($type) {
        return $this->get_plugin_by_type('assignsubmission', $type);
    }

    /**
     * Load the plugins from the sub folders under subtype.
     *
     * @param string $subtype - either submission or feedback
     * @return array - The sorted list of plugins
     */
    protected function load_plugins($subtype) {
        global $CFG;
        $result = array();

        $names = core_component::get_plugin_list($subtype);

        foreach ($names as $name => $path) {
            if (file_exists($path . '/locallib.php')) {
                require_once($path . '/locallib.php');

                $shortsubtype = substr($subtype, strlen('assign'));
                $pluginclass = 'assign_' . $shortsubtype . '_' . $name;

                $plugin = new $pluginclass($this, $name);

                if ($plugin instanceof assign_plugin) {
                    $idx = $plugin->get_sort_order();
                    while (array_key_exists($idx, $result)) {
                        $idx +=1;
                    }
                    $result[$idx] = $plugin;
                }
            }
        }
        ksort($result);
        return $result;
    }

    /**
     * Display the assignment, used by view.php
     *
     * The assignment is displayed differently depending on your role,
     * the settings for the assignment and the status of the assignment.
     *
     * @param string $action The current action if any.
     * @return string - The page output.
     */
    public function view($action='') {

        $o = '';
        $mform = null;
        $notices = array();
        $nextpageparams = array();

        if (!empty($this->get_course_module()->id)) {
            $nextpageparams['id'] = $this->get_course_module()->id;
        }

        // Handle form submissions first.
        if ($action == 'savesubmission') {
            $action = 'editsubmission';
            if ($this->process_save_submission($mform, $notices)) {
                $action = 'redirect';
                $nextpageparams['action'] = 'view';
            }
        } else if ($action == 'editprevioussubmission') {
            $action = 'editsubmission';
            if ($this->process_copy_previous_attempt($notices)) {
                $action = 'redirect';
                $nextpageparams['action'] = 'editsubmission';
            }
        } else if ($action == 'lock') {
            $this->process_lock_submission();
            $action = 'redirect';
            $nextpageparams['action'] = 'grading';
        } else if ($action == 'addattempt') {
            $this->process_add_attempt(required_param('userid', PARAM_INT));
            $action = 'redirect';
            $nextpageparams['action'] = 'grading';
        } else if ($action == 'reverttodraft') {
            $this->process_revert_to_draft();
            $action = 'redirect';
            $nextpageparams['action'] = 'grading';
        } else if ($action == 'unlock') {
            $this->process_unlock_submission();
            $action = 'redirect';
            $nextpageparams['action'] = 'grading';
        } else if ($action == 'setbatchmarkingworkflowstate') {
            $this->process_set_batch_marking_workflow_state();
            $action = 'redirect';
            $nextpageparams['action'] = 'grading';
        } else if ($action == 'setbatchmarkingallocation') {
            $this->process_set_batch_marking_allocation();
            $action = 'redirect';
            $nextpageparams['action'] = 'grading';
        } else if ($action == 'confirmsubmit') {
            $action = 'submit';
            if ($this->process_submit_for_grading($mform)) {
                $action = 'redirect';
                $nextpageparams['action'] = 'view';
            }
        } else if ($action == 'gradingbatchoperation') {
            $action = $this->process_grading_batch_operation($mform);
            if ($action == 'grading') {
                $action = 'redirect';
                $nextpageparams['action'] = 'grading';
            }
        } else if ($action == 'submitgrade') {
            if (optional_param('saveandshownext', null, PARAM_RAW)) {
                // Save and show next.
                $action = 'grade';
                if ($this->process_save_grade($mform)) {
                    $action = 'redirect';
                    $nextpageparams['action'] = 'grade';
                    $nextpageparams['rownum'] = optional_param('rownum', 0, PARAM_INT) + 1;
                    $nextpageparams['useridlistid'] = optional_param('useridlistid', time(), PARAM_INT);
                }
            } else if (optional_param('nosaveandprevious', null, PARAM_RAW)) {
                $action = 'redirect';
                $nextpageparams['action'] = 'grade';
                $nextpageparams['rownum'] = optional_param('rownum', 0, PARAM_INT) - 1;
                $nextpageparams['useridlistid'] = optional_param('useridlistid', time(), PARAM_INT);
            } else if (optional_param('nosaveandnext', null, PARAM_RAW)) {
                $action = 'redirect';
                $nextpageparams['action'] = 'grade';
                $nextpageparams['rownum'] = optional_param('rownum', 0, PARAM_INT) + 1;
                $nextpageparams['useridlistid'] = optional_param('useridlistid', time(), PARAM_INT);
            } else if (optional_param('savegrade', null, PARAM_RAW)) {
                // Save changes button.
                $action = 'grade';
                if ($this->process_save_grade($mform)) {
                    $action = 'redirect';
                    $nextpageparams['action'] = 'savegradingresult';
                }
            } else {
                // Cancel button.
                $action = 'redirect';
                $nextpageparams['action'] = 'grading';
            }
        } else if ($action == 'quickgrade') {
            $message = $this->process_save_quick_grades();
            $action = 'quickgradingresult';
        } else if ($action == 'saveoptions') {
            $this->process_save_grading_options();
            $action = 'redirect';
            $nextpageparams['action'] = 'grading';
        } else if ($action == 'saveextension') {
            $action = 'grantextension';
            if ($this->process_save_extension($mform)) {
                $action = 'redirect';
                $nextpageparams['action'] = 'grading';
            }
        } else if ($action == 'revealidentitiesconfirm') {
            $this->process_reveal_identities();
            $action = 'redirect';
            $nextpageparams['action'] = 'grading';
        }

        $returnparams = array('rownum'=>optional_param('rownum', 0, PARAM_INT),
                              'useridlistid'=>optional_param('useridlistid', 0, PARAM_INT));
        $this->register_return_link($action, $returnparams);

        // Now show the right view page.
        if ($action == 'redirect') {
            $nextpageurl = new moodle_url('/mod/assign/view.php', $nextpageparams);
            redirect($nextpageurl);
            return;
        } else if ($action == 'savegradingresult') {
            $message = get_string('gradingchangessaved', 'assign');
            $o .= $this->view_savegrading_result($message);
        } else if ($action == 'quickgradingresult') {
            $mform = null;
            $o .= $this->view_quickgrading_result($message);
        } else if ($action == 'grade') {
            $o .= $this->view_single_grade_page($mform);
        } else if ($action == 'viewpluginassignfeedback') {
            $o .= $this->view_plugin_content('assignfeedback');
        } else if ($action == 'viewpluginassignsubmission') {
            $o .= $this->view_plugin_content('assignsubmission');
        } else if ($action == 'editsubmission') {
            $o .= $this->view_edit_submission_page($mform, $notices);
        } else if ($action == 'grading') {
            $o .= $this->view_grading_page();
        } else if ($action == 'downloadall') {
            $o .= $this->download_submissions();
        } else if ($action == 'submit') {
            $o .= $this->check_submit_for_grading($mform);
        } else if ($action == 'grantextension') {
            $o .= $this->view_grant_extension($mform);
        } else if ($action == 'revealidentities') {
            $o .= $this->view_reveal_identities_confirm($mform);
        } else if ($action == 'plugingradingbatchoperation') {
            $o .= $this->view_plugin_grading_batch_operation($mform);
        } else if ($action == 'viewpluginpage') {
             $o .= $this->view_plugin_page();
        } else if ($action == 'viewcourseindex') {
             $o .= $this->view_course_index();
        } else if ($action == 'viewbatchsetmarkingworkflowstate') {
             $o .= $this->view_batch_set_workflow_state($mform);
        } else if ($action == 'viewbatchmarkingallocation') {
            $o .= $this->view_batch_markingallocation($mform);
        } else {
            $o .= $this->view_submission_page();
        }

        return $o;
    }

    /**
     * Add this instance to the database.
     *
     * @param stdClass $formdata The data submitted from the form
     * @param bool $callplugins This is used to skip the plugin code
     *             when upgrading an old assignment to a new one (the plugins get called manually)
     * @return mixed false if an error occurs or the int id of the new instance
     */
    public function add_instance(stdClass $formdata, $callplugins) {
        global $DB;

        $err = '';

        // Add the database record.
        $update = new stdClass();
        $update->name = $formdata->name;
        $update->timemodified = time();
        $update->timecreated = time();
        $update->course = $formdata->course;
        $update->courseid = $formdata->course;
        $update->intro = $formdata->intro;
        $update->introformat = $formdata->introformat;
        $update->alwaysshowdescription = !empty($formdata->alwaysshowdescription);
        $update->submissiondrafts = $formdata->submissiondrafts;
        $update->requiresubmissionstatement = $formdata->requiresubmissionstatement;
        $update->sendnotifications = $formdata->sendnotifications;
        $update->sendlatenotifications = $formdata->sendlatenotifications;
        $update->duedate = $formdata->duedate;
        $update->cutoffdate = $formdata->cutoffdate;
        $update->allowsubmissionsfromdate = $formdata->allowsubmissionsfromdate;
        $update->grade = $formdata->grade;
        $update->completionsubmit = !empty($formdata->completionsubmit);
        $update->teamsubmission = $formdata->teamsubmission;
        $update->requireallteammemberssubmit = $formdata->requireallteammemberssubmit;
        if (isset($formdata->teamsubmissiongroupingid)) {
            $update->teamsubmissiongroupingid = $formdata->teamsubmissiongroupingid;
        }
        $update->blindmarking = $formdata->blindmarking;
        $update->attemptreopenmethod = ASSIGN_ATTEMPT_REOPEN_METHOD_NONE;
        if (!empty($formdata->attemptreopenmethod)) {
            $update->attemptreopenmethod = $formdata->attemptreopenmethod;
        }
        if (!empty($formdata->maxattempts)) {
            $update->maxattempts = $formdata->maxattempts;
        }
        $update->markingworkflow = $formdata->markingworkflow;
        $update->markingallocation = $formdata->markingallocation;
        if (empty($update->markingworkflow)) { // If marking workflow is disabled, make sure allocation is disabled.
            $update->markingallocation = 0;
        }

        $returnid = $DB->insert_record('assign', $update);
        $this->instance = $DB->get_record('assign', array('id'=>$returnid), '*', MUST_EXIST);
        // Cache the course record.
        $this->course = $DB->get_record('course', array('id'=>$formdata->course), '*', MUST_EXIST);

        if ($callplugins) {
            // Call save_settings hook for submission plugins.
            foreach ($this->submissionplugins as $plugin) {
                if (!$this->update_plugin_instance($plugin, $formdata)) {
                    print_error($plugin->get_error());
                    return false;
                }
            }
            foreach ($this->feedbackplugins as $plugin) {
                if (!$this->update_plugin_instance($plugin, $formdata)) {
                    print_error($plugin->get_error());
                    return false;
                }
            }

            // In the case of upgrades the coursemodule has not been set,
            // so we need to wait before calling these two.
            $this->update_calendar($formdata->coursemodule);
            $this->update_gradebook(false, $formdata->coursemodule);

        }

        $update = new stdClass();
        $update->id = $this->get_instance()->id;
        $update->nosubmissions = (!$this->is_any_submission_plugin_enabled()) ? 1: 0;
        $DB->update_record('assign', $update);

        return $returnid;
    }

    /**
     * Delete all grades from the gradebook for this assignment.
     *
     * @return bool
     */
    protected function delete_grades() {
        global $CFG;

        $result = grade_update('mod/assign',
                               $this->get_course()->id,
                               'mod',
                               'assign',
                               $this->get_instance()->id,
                               0,
                               null,
                               array('deleted'=>1));
        return $result == GRADE_UPDATE_OK;
    }

    /**
     * Delete this instance from the database.
     *
     * @return bool false if an error occurs
     */
    public function delete_instance() {
        global $DB;
        $result = true;

        foreach ($this->submissionplugins as $plugin) {
            if (!$plugin->delete_instance()) {
                print_error($plugin->get_error());
                $result = false;
            }
        }
        foreach ($this->feedbackplugins as $plugin) {
            if (!$plugin->delete_instance()) {
                print_error($plugin->get_error());
                $result = false;
            }
        }

        // Delete files associated with this assignment.
        $fs = get_file_storage();
        if (! $fs->delete_area_files($this->context->id) ) {
            $result = false;
        }

        // Delete_records will throw an exception if it fails - so no need for error checking here.
        $DB->delete_records('assign_submission', array('assignment'=>$this->get_instance()->id));
        $DB->delete_records('assign_grades', array('assignment'=>$this->get_instance()->id));
        $DB->delete_records('assign_plugin_config', array('assignment'=>$this->get_instance()->id));

        // Delete items from the gradebook.
        if (! $this->delete_grades()) {
            $result = false;
        }

        // Delete the instance.
        $DB->delete_records('assign', array('id'=>$this->get_instance()->id));

        return $result;
    }

    /**
     * Actual implementation of the reset course functionality, delete all the
     * assignment submissions for course $data->courseid.
     *
     * @param stdClass $data the data submitted from the reset course.
     * @return array status array
     */
    public function reset_userdata($data) {
        global $CFG, $DB;

        $componentstr = get_string('modulenameplural', 'assign');
        $status = array();

        $fs = get_file_storage();
        if (!empty($data->reset_assign_submissions)) {
            // Delete files associated with this assignment.
            foreach ($this->submissionplugins as $plugin) {
                $fileareas = array();
                $plugincomponent = $plugin->get_subtype() . '_' . $plugin->get_type();
                $fileareas = $plugin->get_file_areas();
                foreach ($fileareas as $filearea) {
                    $fs->delete_area_files($this->context->id, $plugincomponent, $filearea);
                }

                if (!$plugin->delete_instance()) {
                    $status[] = array('component'=>$componentstr,
                                      'item'=>get_string('deleteallsubmissions', 'assign'),
                                      'error'=>$plugin->get_error());
                }
            }

            foreach ($this->feedbackplugins as $plugin) {
                $fileareas = array();
                $plugincomponent = $plugin->get_subtype() . '_' . $plugin->get_type();
                $fileareas = $plugin->get_file_areas();
                foreach ($fileareas as $filearea) {
                    $fs->delete_area_files($this->context->id, $plugincomponent, $filearea);
                }

                if (!$plugin->delete_instance()) {
                    $status[] = array('component'=>$componentstr,
                                      'item'=>get_string('deleteallsubmissions', 'assign'),
                                      'error'=>$plugin->get_error());
                }
            }

            $assignssql = 'SELECT a.id
                             FROM {assign} a
                           WHERE a.course=:course';
            $params = array('course'=>$data->courseid);

            $DB->delete_records_select('assign_submission', "assignment IN ($assignssql)", $params);

            $status[] = array('component'=>$componentstr,
                              'item'=>get_string('deleteallsubmissions', 'assign'),
                              'error'=>false);

            if (!empty($data->reset_gradebook_grades)) {
                $DB->delete_records_select('assign_grades', "assignment IN ($assignssql)", $params);
                // Remove all grades from gradebook.
                require_once($CFG->dirroot.'/mod/assign/lib.php');
                assign_reset_gradebook($data->courseid);
            }
        }
        // Updating dates - shift may be negative too.
        if ($data->timeshift) {
            shift_course_mod_dates('assign',
                                    array('duedate', 'allowsubmissionsfromdate', 'cutoffdate'),
                                    $data->timeshift,
                                    $data->courseid, $this->get_instance()->id);
            $status[] = array('component'=>$componentstr,
                              'item'=>get_string('datechanged'),
                              'error'=>false);
        }

        return $status;
    }

    /**
     * Update the settings for a single plugin.
     *
     * @param assign_plugin $plugin The plugin to update
     * @param stdClass $formdata The form data
     * @return bool false if an error occurs
     */
    protected function update_plugin_instance(assign_plugin $plugin, stdClass $formdata) {
        if ($plugin->is_visible()) {
            $enabledname = $plugin->get_subtype() . '_' . $plugin->get_type() . '_enabled';
            if (!empty($formdata->$enabledname)) {
                $plugin->enable();
                if (!$plugin->save_settings($formdata)) {
                    print_error($plugin->get_error());
                    return false;
                }
            } else {
                $plugin->disable();
            }
        }
        return true;
    }

    /**
     * Update the gradebook information for this assignment.
     *
     * @param bool $reset If true, will reset all grades in the gradbook for this assignment
     * @param int $coursemoduleid This is required because it might not exist in the database yet
     * @return bool
     */
    public function update_gradebook($reset, $coursemoduleid) {
        global $CFG;

        require_once($CFG->dirroot.'/mod/assign/lib.php');
        $assign = clone $this->get_instance();
        $assign->cmidnumber = $coursemoduleid;
        $param = null;
        if ($reset) {
            $param = 'reset';
        }

        return assign_grade_item_update($assign, $param);
    }

    /**
     * Load and cache the admin config for this module.
     *
     * @return stdClass the plugin config
     */
    public function get_admin_config() {
        if ($this->adminconfig) {
            return $this->adminconfig;
        }
        $this->adminconfig = get_config('assign');
        return $this->adminconfig;
    }

    /**
     * Update the calendar entries for this assignment.
     *
     * @param int $coursemoduleid - Required to pass this in because it might
     *                              not exist in the database yet.
     * @return bool
     */
    public function update_calendar($coursemoduleid) {
        global $DB, $CFG;
        require_once($CFG->dirroot.'/calendar/lib.php');

        // Special case for add_instance as the coursemodule has not been set yet.
        $instance = $this->get_instance();

        if ($instance->duedate) {
            $event = new stdClass();

            $params = array('modulename'=>'assign', 'instance'=>$instance->id);
            $event->id = $DB->get_field('event', 'id', $params);
            $event->name = $instance->name;
            $event->timestart = $instance->duedate;

            // Convert the links to pluginfile. It is a bit hacky but at this stage the files
            // might not have been saved in the module area yet.
            $intro = $instance->intro;
            if ($draftid = file_get_submitted_draft_itemid('introeditor')) {
                $intro = file_rewrite_urls_to_pluginfile($intro, $draftid);
            }

            // We need to remove the links to files as the calendar is not ready
            // to support module events with file areas.
            $intro = strip_pluginfile_content($intro);
            if ($this->show_intro()) {
                $event->description = array(
                    'text' => $intro,
                    'format' => $instance->introformat
                );
            } else {
                $event->description = array(
                    'text' => '',
                    'format' => $instance->introformat
                );
            }

            if ($event->id) {
                $calendarevent = calendar_event::load($event->id);
                $calendarevent->update($event);
            } else {
                unset($event->id);
                $event->courseid    = $instance->course;
                $event->groupid     = 0;
                $event->userid      = 0;
                $event->modulename  = 'assign';
                $event->instance    = $instance->id;
                $event->eventtype   = 'due';
                $event->timeduration = 0;
                calendar_event::create($event);
            }
        } else {
            $DB->delete_records('event', array('modulename'=>'assign', 'instance'=>$instance->id));
        }
    }


    /**
     * Update this instance in the database.
     *
     * @param stdClass $formdata - the data submitted from the form
     * @return bool false if an error occurs
     */
    public function update_instance($formdata) {
        global $DB;

        $update = new stdClass();
        $update->id = $formdata->instance;
        $update->name = $formdata->name;
        $update->timemodified = time();
        $update->course = $formdata->course;
        $update->intro = $formdata->intro;
        $update->introformat = $formdata->introformat;
        $update->alwaysshowdescription = !empty($formdata->alwaysshowdescription);
        $update->submissiondrafts = $formdata->submissiondrafts;
        $update->requiresubmissionstatement = $formdata->requiresubmissionstatement;
        $update->sendnotifications = $formdata->sendnotifications;
        $update->sendlatenotifications = $formdata->sendlatenotifications;
        $update->duedate = $formdata->duedate;
        $update->cutoffdate = $formdata->cutoffdate;
        $update->allowsubmissionsfromdate = $formdata->allowsubmissionsfromdate;
        $update->grade = $formdata->grade;
        if (!empty($formdata->completionunlocked)) {
            $update->completionsubmit = !empty($formdata->completionsubmit);
        }
        $update->teamsubmission = $formdata->teamsubmission;
        $update->requireallteammemberssubmit = $formdata->requireallteammemberssubmit;
        if (isset($formdata->teamsubmissiongroupingid)) {
            $update->teamsubmissiongroupingid = $formdata->teamsubmissiongroupingid;
        }
        $update->blindmarking = $formdata->blindmarking;
        $update->attemptreopenmethod = ASSIGN_ATTEMPT_REOPEN_METHOD_NONE;
        if (!empty($formdata->attemptreopenmethod)) {
            $update->attemptreopenmethod = $formdata->attemptreopenmethod;
        }
        if (!empty($formdata->maxattempts)) {
            $update->maxattempts = $formdata->maxattempts;
        }
        $update->markingworkflow = $formdata->markingworkflow;
        $update->markingallocation = $formdata->markingallocation;
        if (empty($update->markingworkflow)) { // If marking workflow is disabled, make sure allocation is disabled.
            $update->markingallocation = 0;
        }

        $result = $DB->update_record('assign', $update);
        $this->instance = $DB->get_record('assign', array('id'=>$update->id), '*', MUST_EXIST);

        // Load the assignment so the plugins have access to it.

        // Call save_settings hook for submission plugins.
        foreach ($this->submissionplugins as $plugin) {
            if (!$this->update_plugin_instance($plugin, $formdata)) {
                print_error($plugin->get_error());
                return false;
            }
        }
        foreach ($this->feedbackplugins as $plugin) {
            if (!$this->update_plugin_instance($plugin, $formdata)) {
                print_error($plugin->get_error());
                return false;
            }
        }

        $this->update_calendar($this->get_course_module()->id);
        $this->update_gradebook(false, $this->get_course_module()->id);

        $update = new stdClass();
        $update->id = $this->get_instance()->id;
        $update->nosubmissions = (!$this->is_any_submission_plugin_enabled()) ? 1: 0;
        $DB->update_record('assign', $update);

        return $result;
    }

    /**
     * Add elements in grading plugin form.
     *
     * @param mixed $grade stdClass|null
     * @param MoodleQuickForm $mform
     * @param stdClass $data
     * @param int $userid - The userid we are grading
     * @return void
     */
    protected function add_plugin_grade_elements($grade, MoodleQuickForm $mform, stdClass $data, $userid) {
        foreach ($this->feedbackplugins as $plugin) {
            if ($plugin->is_enabled() && $plugin->is_visible()) {
                $mform->addElement('header', 'header_' . $plugin->get_type(), $plugin->get_name());
                $mform->setExpanded('header_' . $plugin->get_type());
                if (!$plugin->get_form_elements_for_user($grade, $mform, $data, $userid)) {
                    $mform->removeElement('header_' . $plugin->get_type());
                }
            }
        }
    }



    /**
     * Add one plugins settings to edit plugin form.
     *
     * @param assign_plugin $plugin The plugin to add the settings from
     * @param MoodleQuickForm $mform The form to add the configuration settings to.
     *                               This form is modified directly (not returned).
     * @param array $pluginsenabled A list of form elements to be added to a group.
     *                              The new element is added to this array by this function.
     * @return void
     */
    protected function add_plugin_settings(assign_plugin $plugin, MoodleQuickForm $mform, & $pluginsenabled) {
        global $CFG;
        if ($plugin->is_visible() && !$plugin->is_configurable() && $plugin->is_enabled()) {
            $name = $plugin->get_subtype() . '_' . $plugin->get_type() . '_enabled';
            $pluginsenabled[] = $mform->createElement('hidden', $name, 1);
            $mform->setType($name, PARAM_BOOL);
            $plugin->get_settings($mform);
        } else if ($plugin->is_visible() && $plugin->is_configurable()) {
            $name = $plugin->get_subtype() . '_' . $plugin->get_type() . '_enabled';
            $label = $plugin->get_name();
            $label .= ' ' . $this->get_renderer()->help_icon('enabled', $plugin->get_subtype() . '_' . $plugin->get_type());
            $pluginsenabled[] = $mform->createElement('checkbox', $name, '', $label);

            $default = get_config($plugin->get_subtype() . '_' . $plugin->get_type(), 'default');
            if ($plugin->get_config('enabled') !== false) {
                $default = $plugin->is_enabled();
            }
            $mform->setDefault($plugin->get_subtype() . '_' . $plugin->get_type() . '_enabled', $default);

            $plugin->get_settings($mform);

        }
    }

    /**
     * Add settings to edit plugin form.
     *
     * @param MoodleQuickForm $mform The form to add the configuration settings to.
     *                               This form is modified directly (not returned).
     * @return void
     */
    public function add_all_plugin_settings(MoodleQuickForm $mform) {
        $mform->addElement('header', 'submissiontypes', get_string('submissiontypes', 'assign'));

        $submissionpluginsenabled = array();
        $group = $mform->addGroup(array(), 'submissionplugins', get_string('submissiontypes', 'assign'), array(' '), false);
        foreach ($this->submissionplugins as $plugin) {
            $this->add_plugin_settings($plugin, $mform, $submissionpluginsenabled);
        }
        $group->setElements($submissionpluginsenabled);

        $mform->addElement('header', 'feedbacktypes', get_string('feedbacktypes', 'assign'));
        $feedbackpluginsenabled = array();
        $group = $mform->addGroup(array(), 'feedbackplugins', get_string('feedbacktypes', 'assign'), array(' '), false);
        foreach ($this->feedbackplugins as $plugin) {
            $this->add_plugin_settings($plugin, $mform, $feedbackpluginsenabled);
        }
        $group->setElements($feedbackpluginsenabled);
        $mform->setExpanded('submissiontypes');
    }

    /**
     * Allow each plugin an opportunity to update the defaultvalues
     * passed in to the settings form (needed to set up draft areas for
     * editor and filemanager elements)
     *
     * @param array $defaultvalues
     */
    public function plugin_data_preprocessing(&$defaultvalues) {
        foreach ($this->submissionplugins as $plugin) {
            if ($plugin->is_visible()) {
                $plugin->data_preprocessing($defaultvalues);
            }
        }
        foreach ($this->feedbackplugins as $plugin) {
            if ($plugin->is_visible()) {
                $plugin->data_preprocessing($defaultvalues);
            }
        }
    }

    /**
     * Get the name of the current module.
     *
     * @return string the module name (Assignment)
     */
    protected function get_module_name() {
        if (isset(self::$modulename)) {
            return self::$modulename;
        }
        self::$modulename = get_string('modulename', 'assign');
        return self::$modulename;
    }

    /**
     * Get the plural name of the current module.
     *
     * @return string the module name plural (Assignments)
     */
    protected function get_module_name_plural() {
        if (isset(self::$modulenameplural)) {
            return self::$modulenameplural;
        }
        self::$modulenameplural = get_string('modulenameplural', 'assign');
        return self::$modulenameplural;
    }

    /**
     * Has this assignment been constructed from an instance?
     *
     * @return bool
     */
    public function has_instance() {
        return $this->instance || $this->get_course_module();
    }

    /**
     * Get the settings for the current instance of this assignment
     *
     * @return stdClass The settings
     */
    public function get_instance() {
        global $DB;
        if ($this->instance) {
            return $this->instance;
        }
        if ($this->get_course_module()) {
            $params = array('id' => $this->get_course_module()->instance);
            $this->instance = $DB->get_record('assign', $params, '*', MUST_EXIST);
        }
        if (!$this->instance) {
            throw new coding_exception('Improper use of the assignment class. ' .
                                       'Cannot load the assignment record.');
        }
        return $this->instance;
    }

    /**
     * Get the primary grade item for this assign instance.
     *
     * @return stdClass The grade_item record
     */
    public function get_grade_item() {
        if ($this->gradeitem) {
            return $this->gradeitem;
        }
        $instance = $this->get_instance();
        $params = array('itemtype' => 'mod',
                        'itemmodule' => 'assign',
                        'iteminstance' => $instance->id,
                        'courseid' => $instance->course,
                        'itemnumber' => 0);
        $this->gradeitem = grade_item::fetch($params);
        if (!$this->gradeitem) {
            throw new coding_exception('Improper use of the assignment class. ' .
                                       'Cannot load the grade item.');
        }
        return $this->gradeitem;
    }

    /**
     * Get the context of the current course.
     *
     * @return mixed context|null The course context
     */
    public function get_course_context() {
        if (!$this->context && !$this->course) {
            throw new coding_exception('Improper use of the assignment class. ' .
                                       'Cannot load the course context.');
        }
        if ($this->context) {
            return $this->context->get_course_context();
        } else {
            return context_course::instance($this->course->id);
        }
    }


    /**
     * Get the current course module.
     *
     * @return mixed stdClass|null The course module
     */
    public function get_course_module() {
        if ($this->coursemodule) {
            return $this->coursemodule;
        }
        if (!$this->context) {
            return null;
        }

        if ($this->context->contextlevel == CONTEXT_MODULE) {
            $this->coursemodule = get_coursemodule_from_id('assign',
                                                           $this->context->instanceid,
                                                           0,
                                                           false,
                                                           MUST_EXIST);
            return $this->coursemodule;
        }
        return null;
    }

    /**
     * Get context module.
     *
     * @return context
     */
    public function get_context() {
        return $this->context;
    }

    /**
     * Get the current course.
     *
     * @return mixed stdClass|null The course
     */
    public function get_course() {
        global $DB;

        if ($this->course) {
            return $this->course;
        }

        if (!$this->context) {
            return null;
        }
        $params = array('id' => $this->get_course_context()->instanceid);
        $this->course = $DB->get_record('course', $params, '*', MUST_EXIST);

        return $this->course;
    }

    /**
     * Return a grade in user-friendly form, whether it's a scale or not.
     *
     * @param mixed $grade int|null
     * @param boolean $editing Are we allowing changes to this grade?
     * @param int $userid The user id the grade belongs to
     * @param int $modified Timestamp from when the grade was last modified
     * @return string User-friendly representation of grade
     */
    public function display_grade($grade, $editing, $userid=0, $modified=0) {
        global $DB;

        static $scalegrades = array();

        $o = '';

        if ($this->get_instance()->grade >= 0) {
            // Normal number.
            if ($editing && $this->get_instance()->grade > 0) {
                if ($grade < 0) {
                    $displaygrade = '';
                } else {
                    $displaygrade = format_float($grade, 2);
                }
                $o .= '<label class="accesshide" for="quickgrade_' . $userid . '">' .
                       get_string('usergrade', 'assign') .
                       '</label>';
                $o .= '<input type="text"
                              id="quickgrade_' . $userid . '"
                              name="quickgrade_' . $userid . '"
                              value="' .  $displaygrade . '"
                              size="6"
                              maxlength="10"
                              class="quickgrade"/>';
                $o .= '&nbsp;/&nbsp;' . format_float($this->get_instance()->grade, 2);
                return $o;
            } else {
                if ($grade == -1 || $grade === null) {
                    $o .= '-';
                } else {
                    $item = $this->get_grade_item();
                    $o .= grade_format_gradevalue($grade, $item);
                    if ($item->get_displaytype() == GRADE_DISPLAY_TYPE_REAL) {
                        // If displaying the raw grade, also display the total value.
                        $o .= '&nbsp;/&nbsp;' . format_float($this->get_instance()->grade, 2);
                    }
                }
                return $o;
            }

        } else {
            // Scale.
            if (empty($this->cache['scale'])) {
                if ($scale = $DB->get_record('scale', array('id'=>-($this->get_instance()->grade)))) {
                    $this->cache['scale'] = make_menu_from_list($scale->scale);
                } else {
                    $o .= '-';
                    return $o;
                }
            }
            if ($editing) {
                $o .= '<label class="accesshide"
                              for="quickgrade_' . $userid . '">' .
                      get_string('usergrade', 'assign') .
                      '</label>';
                $o .= '<select name="quickgrade_' . $userid . '" class="quickgrade">';
                $o .= '<option value="-1">' . get_string('nograde') . '</option>';
                foreach ($this->cache['scale'] as $optionid => $option) {
                    $selected = '';
                    if ($grade == $optionid) {
                        $selected = 'selected="selected"';
                    }
                    $o .= '<option value="' . $optionid . '" ' . $selected . '>' . $option . '</option>';
                }
                $o .= '</select>';
                return $o;
            } else {
                $scaleid = (int)$grade;
                if (isset($this->cache['scale'][$scaleid])) {
                    $o .= $this->cache['scale'][$scaleid];
                    return $o;
                }
                $o .= '-';
                return $o;
            }
        }
    }

    /**
     * Load a list of users enrolled in the current course with the specified permission and group.
     * 0 for no group.
     *
     * @param int $currentgroup
     * @param bool $idsonly
     * @return array List of user records
     */
    public function list_participants($currentgroup, $idsonly) {
        $key = $this->context->id…