/**
  * overridden constructor keeps a reference to the seplment class that is displaying this table
  *
  * @param sepl $seplment The seplment class
  * @param int $perpage how many per page
  * @param string $filter The current filter
  * @param int $rowoffset For showing a subsequent page of results
  * @param bool $quickgrading Is this table wrapped in a quickgrading form?
  * @param string $downloadfilename
  */
 public function __construct(sepl $seplment, $perpage, $filter, $rowoffset, $quickgrading, $downloadfilename = null)
 {
     global $CFG, $PAGE, $DB, $USER;
     parent::__construct('mod_sepl_grading');
     $this->is_persistent(true);
     $this->seplment = $seplment;
     // Check permissions up front.
     $this->hasgrantextension = has_capability('mod/sepl:grantextension', $this->seplment->get_context());
     $this->hasgrade = $this->seplment->can_grade();
     // Check if we have the elevated view capablities to see the blind details.
     $this->hasviewblind = has_capability('mod/sepl:viewblinddetails', $this->seplment->get_context());
     foreach ($seplment->get_feedback_plugins() as $plugin) {
         if ($plugin->is_visible() && $plugin->is_enabled()) {
             foreach ($plugin->get_grading_batch_operations() as $action => $description) {
                 if (empty($this->plugingradingbatchoperations)) {
                     $this->plugingradingbatchoperations[$plugin->get_type()] = array();
                 }
                 $this->plugingradingbatchoperations[$plugin->get_type()][$action] = $description;
             }
         }
     }
     $this->perpage = $perpage;
     $this->quickgrading = $quickgrading && $this->hasgrade;
     $this->output = $PAGE->get_renderer('mod_sepl');
     $urlparams = array('action' => 'grading', 'id' => $seplment->get_course_module()->id);
     $url = new moodle_url($CFG->wwwroot . '/mod/sepl/view.php', $urlparams);
     $this->define_baseurl($url);
     // Do some business - then set the sql.
     $currentgroup = groups_get_activity_group($seplment->get_course_module(), true);
     if ($rowoffset) {
         $this->rownum = $rowoffset - 1;
     }
     $users = array_keys($seplment->list_participants($currentgroup, true));
     if (count($users) == 0) {
         // Insert a record that will never match to the sql is still valid.
         $users[] = -1;
     }
     $params = array();
     $params['seplmentid1'] = (int) $this->seplment->get_instance()->id;
     $params['seplmentid2'] = (int) $this->seplment->get_instance()->id;
     $params['seplmentid3'] = (int) $this->seplment->get_instance()->id;
     $extrauserfields = get_extra_user_fields($this->seplment->get_context());
     $fields = user_picture::fields('u', $extrauserfields) . ', ';
     $fields .= 'u.id as userid, ';
     $fields .= 's.status as status, ';
     $fields .= 's.id as submissionid, ';
     $fields .= 's.timecreated as firstsubmission, ';
     $fields .= 's.timemodified as timesubmitted, ';
     $fields .= 's.attemptnumber as attemptnumber, ';
     $fields .= 'g.id as gradeid, ';
     $fields .= 'g.grade as grade, ';
     $fields .= 'g.timemodified as timemarked, ';
     $fields .= 'g.timecreated as firstmarked, ';
     $fields .= 'uf.mailed as mailed, ';
     $fields .= 'uf.locked as locked, ';
     $fields .= 'uf.extensionduedate as extensionduedate, ';
     $fields .= 'uf.workflowstate as workflowstate, ';
     $fields .= 'uf.allocatedmarker as allocatedmarker ';
     $from = '{user} u
                      LEFT JOIN {sepl_submission} s
                             ON u.id = s.userid
                            AND s.seplment = :seplmentid1
                            AND s.latest = 1
                      LEFT JOIN {sepl_grades} g
                             ON u.id = g.userid
                            AND g.seplment = :seplmentid2 ';
     // For group submissions we don't immediately create an entry in the sepl_submission table for each user,
     // instead the userid is set to 0. In this case we use a different query to retrieve the grade for the user.
     if ($this->seplment->get_instance()->teamsubmission) {
         $params['seplmentid4'] = (int) $this->seplment->get_instance()->id;
         $grademaxattempt = 'SELECT mxg.userid, MAX(mxg.attemptnumber) AS maxattempt
                               FROM {sepl_grades} mxg
                              WHERE mxg.seplment = :seplmentid4
                           GROUP BY mxg.userid';
         $from .= 'LEFT JOIN (' . $grademaxattempt . ') gmx
                          ON u.id = gmx.userid
                         AND g.attemptnumber = gmx.maxattempt ';
     } else {
         $from .= 'AND g.attemptnumber = s.attemptnumber ';
     }
     $from .= 'LEFT JOIN {sepl_user_flags} uf
                      ON u.id = uf.userid
                     AND uf.seplment = :seplmentid3';
     $userparams = array();
     $userindex = 0;
     list($userwhere, $userparams) = $DB->get_in_or_equal($users, SQL_PARAMS_NAMED, 'user');
     $where = 'u.id ' . $userwhere;
     $params = array_merge($params, $userparams);
     // The filters do not make sense when there are no submissions, so do not apply them.
     if ($this->seplment->is_any_submission_plugin_enabled()) {
         if ($filter == ASSIGN_FILTER_SUBMITTED) {
             $where .= ' AND (s.timemodified IS NOT NULL AND
                              s.status = :submitted) ';
             $params['submitted'] = ASSIGN_SUBMISSION_STATUS_SUBMITTED;
         } else {
             if ($filter == ASSIGN_FILTER_NOT_SUBMITTED) {
                 $where .= ' AND (s.timemodified IS NULL OR s.status != :submitted) ';
                 $params['submitted'] = ASSIGN_SUBMISSION_STATUS_SUBMITTED;
             } else {
                 if ($filter == ASSIGN_FILTER_REQUIRE_GRADING) {
                     $where .= ' AND (s.timemodified IS NOT NULL AND
                              s.status = :submitted AND
                              (s.timemodified >= g.timemodified OR g.timemodified IS NULL OR g.grade IS NULL))';
                     $params['submitted'] = ASSIGN_SUBMISSION_STATUS_SUBMITTED;
                 } else {
                     if (strpos($filter, ASSIGN_FILTER_SINGLE_USER) === 0) {
                         $userfilter = (int) array_pop(explode('=', $filter));
                         $where .= ' AND (u.id = :userid)';
                         $params['userid'] = $userfilter;
                     }
                 }
             }
         }
     }
     if ($this->seplment->get_instance()->markingworkflow && $this->seplment->get_instance()->markingallocation) {
         if (has_capability('mod/sepl:manageallocations', $this->seplment->get_context())) {
             // Check to see if marker filter is set.
             $markerfilter = (int) get_user_preferences('sepl_markerfilter', '');
             if (!empty($markerfilter)) {
                 if ($markerfilter == ASSIGN_MARKER_FILTER_NO_MARKER) {
                     $where .= ' AND (uf.allocatedmarker IS NULL OR uf.allocatedmarker = 0)';
                 } else {
                     $where .= ' AND uf.allocatedmarker = :markerid';
                     $params['markerid'] = $markerfilter;
                 }
             }
         } else {
             // Only show users allocated to this marker.
             $where .= ' AND uf.allocatedmarker = :markerid';
             $params['markerid'] = $USER->id;
         }
     }
     if ($this->seplment->get_instance()->markingworkflow) {
         $workflowstates = $this->seplment->get_marking_workflow_states_for_current_user();
         if (!empty($workflowstates)) {
             $workflowfilter = get_user_preferences('sepl_workflowfilter', '');
             if ($workflowfilter == ASSIGN_MARKING_WORKFLOW_STATE_NOTMARKED) {
                 $where .= ' AND (uf.workflowstate = :workflowstate OR uf.workflowstate IS NULL OR ' . $DB->sql_isempty('sepl_user_flags', 'workflowstate', true, true) . ')';
                 $params['workflowstate'] = $workflowfilter;
             } else {
                 if (array_key_exists($workflowfilter, $workflowstates)) {
                     $where .= ' AND uf.workflowstate = :workflowstate';
                     $params['workflowstate'] = $workflowfilter;
                 }
             }
         }
     }
     $this->set_sql($fields, $from, $where, $params);
     if ($downloadfilename) {
         $this->is_downloading('csv', $downloadfilename);
     }
     $columns = array();
     $headers = array();
     // Select.
     if (!$this->is_downloading() && $this->hasgrade) {
         $columns[] = 'select';
         $headers[] = get_string('select') . '<div class="selectall"><label class="accesshide" for="selectall">' . get_string('selectall') . '</label>
                 <input type="checkbox" id="selectall" name="selectall" title="' . get_string('selectall') . '"/></div>';
     }
     // User picture.
     if ($this->hasviewblind || !$this->seplment->is_blind_marking()) {
         if (!$this->is_downloading()) {
             $columns[] = 'picture';
             $headers[] = get_string('pictureofuser');
         } else {
             $columns[] = 'recordid';
             $headers[] = get_string('recordid', 'sepl');
         }
         // Fullname.
         $columns[] = 'fullname';
         $headers[] = get_string('fullname');
         foreach ($extrauserfields as $extrafield) {
             $columns[] = $extrafield;
             $headers[] = get_user_field_name($extrafield);
         }
     } else {
         // Record ID.
         $columns[] = 'recordid';
         $headers[] = get_string('recordid', 'sepl');
     }
     // Submission status.
     $columns[] = 'status';
     $headers[] = get_string('status', 'sepl');
     // Team submission columns.
     if ($seplment->get_instance()->teamsubmission) {
         $columns[] = 'team';
         $headers[] = get_string('submissionteam', 'sepl');
     }
     // Allocated marker.
     if ($this->seplment->get_instance()->markingworkflow && $this->seplment->get_instance()->markingallocation && has_capability('mod/sepl:manageallocations', $this->seplment->get_context())) {
         // Add a column for the allocated marker.
         $columns[] = 'allocatedmarker';
         $headers[] = get_string('marker', 'sepl');
     }
     // Grade.
     $columns[] = 'grade';
     $headers[] = get_string('grade');
     if ($this->is_downloading()) {
         if ($this->seplment->get_instance()->grade >= 0) {
             $columns[] = 'grademax';
             $headers[] = get_string('maxgrade', 'sepl');
         } else {
             // This is a custom scale.
             $columns[] = 'scale';
             $headers[] = get_string('scale', 'sepl');
         }
         if ($this->seplment->get_instance()->markingworkflow) {
             // Add a column for the marking workflow state.
             $columns[] = 'workflowstate';
             $headers[] = get_string('markingworkflowstate', 'sepl');
         }
         // Add a column for the list of valid marking workflow states.
         $columns[] = 'gradecanbechanged';
         $headers[] = get_string('gradecanbechanged', 'sepl');
     }
     if (!$this->is_downloading() && $this->hasgrade) {
         // We have to call this column userid so we can use userid as a default sortable column.
         $columns[] = 'userid';
         $headers[] = get_string('edit');
     }
     // Submission plugins.
     if ($seplment->is_any_submission_plugin_enabled()) {
         $columns[] = 'timesubmitted';
         $headers[] = get_string('lastmodifiedsubmission', 'sepl');
         foreach ($this->seplment->get_submission_plugins() as $plugin) {
             if ($this->is_downloading()) {
                 if ($plugin->is_visible() && $plugin->is_enabled()) {
                     foreach ($plugin->get_editor_fields() as $field => $description) {
                         $index = 'plugin' . count($this->plugincache);
                         $this->plugincache[$index] = array($plugin, $field);
                         $columns[] = $index;
                         $headers[] = $plugin->get_name();
                     }
                 }
             } else {
                 if ($plugin->is_visible() && $plugin->is_enabled() && $plugin->has_user_summary()) {
                     $index = 'plugin' . count($this->plugincache);
                     $this->plugincache[$index] = array($plugin);
                     $columns[] = $index;
                     $headers[] = $plugin->get_name();
                 }
             }
         }
     }
     // Time marked.
     $columns[] = 'timemarked';
     $headers[] = get_string('lastmodifiedgrade', 'sepl');
     // Feedback plugins.
     foreach ($this->seplment->get_feedback_plugins() as $plugin) {
         if ($this->is_downloading()) {
             if ($plugin->is_visible() && $plugin->is_enabled()) {
                 foreach ($plugin->get_editor_fields() as $field => $description) {
                     $index = 'plugin' . count($this->plugincache);
                     $this->plugincache[$index] = array($plugin, $field);
                     $columns[] = $index;
                     $headers[] = $description;
                 }
             }
         } else {
             if ($plugin->is_visible() && $plugin->is_enabled() && $plugin->has_user_summary()) {
                 $index = 'plugin' . count($this->plugincache);
                 $this->plugincache[$index] = array($plugin);
                 $columns[] = $index;
                 $headers[] = $plugin->get_name();
             }
         }
     }
     // Exclude 'Final grade' column in downloaded grading worksheets.
     if (!$this->is_downloading()) {
         // Final grade.
         $columns[] = 'finalgrade';
         $headers[] = get_string('finalgrade', 'grades');
     }
     // Load the grading info for all users.
     $this->gradinginfo = grade_get_grades($this->seplment->get_course()->id, 'mod', 'sepl', $this->seplment->get_instance()->id, $users);
     if (!empty($CFG->enableoutcomes) && !empty($this->gradinginfo->outcomes)) {
         $columns[] = 'outcomes';
         $headers[] = get_string('outcomes', 'grades');
     }
     // Set the columns.
     $this->define_columns($columns);
     $this->define_headers($headers);
     foreach ($extrauserfields as $extrafield) {
         $this->column_class($extrafield, $extrafield);
     }
     // We require at least one unique column for the sort.
     $this->sortable(true, 'userid');
     $this->no_sorting('recordid');
     $this->no_sorting('finalgrade');
     $this->no_sorting('userid');
     $this->no_sorting('select');
     $this->no_sorting('outcomes');
     if ($seplment->get_instance()->teamsubmission) {
         $this->no_sorting('team');
     }
     $plugincolumnindex = 0;
     foreach ($this->seplment->get_submission_plugins() as $plugin) {
         if ($plugin->is_visible() && $plugin->is_enabled() && $plugin->has_user_summary()) {
             $submissionpluginindex = 'plugin' . $plugincolumnindex++;
             $this->no_sorting($submissionpluginindex);
         }
     }
     foreach ($this->seplment->get_feedback_plugins() as $plugin) {
         if ($plugin->is_visible() && $plugin->is_enabled() && $plugin->has_user_summary()) {
             $feedbackpluginindex = 'plugin' . $plugincolumnindex++;
             $this->no_sorting($feedbackpluginindex);
         }
     }
     // When there is no data we still want the column headers printed in the csv file.
     if ($this->is_downloading()) {
         $this->start_output();
     }
 }