/grade/lib.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/>.

/**
 * Functions used by gradebook plugins and reports.
 *
 * @package   core_grades
 * @copyright 2009 Petr Skoda and Nicolas Connault
 * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 */

require_once($CFG->libdir . '/gradelib.php');
require_once($CFG->dirroot . '/grade/export/lib.php');

/**
 * This class iterates over all users that are graded in a course.
 * Returns detailed info about users and their grades.
 *
 * @author Petr Skoda <skodak@moodle.org>
 * @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 */
class graded_users_iterator {

    /**
     * The couse whose users we are interested in
     */
    protected $course;

    /**
     * An array of grade items or null if only user data was requested
     */
    protected $grade_items;

    /**
     * The group ID we are interested in. 0 means all groups.
     */
    protected $groupid;

    /**
     * A recordset of graded users
     */
    protected $users_rs;

    /**
     * A recordset of user grades (grade_grade instances)
     */
    protected $grades_rs;

    /**
     * Array used when moving to next user while iterating through the grades recordset
     */
    protected $gradestack;

    /**
     * The first field of the users table by which the array of users will be sorted
     */
    protected $sortfield1;

    /**
     * Should sortfield1 be ASC or DESC
     */
    protected $sortorder1;

    /**
     * The second field of the users table by which the array of users will be sorted
     */
    protected $sortfield2;

    /**
     * Should sortfield2 be ASC or DESC
     */
    protected $sortorder2;

    /**
     * Should users whose enrolment has been suspended be ignored?
     */
    protected $onlyactive = false;

    /**
     * Enable user custom fields
     */
    protected $allowusercustomfields = false;

    /**
     * List of suspended users in course. This includes users whose enrolment status is suspended
     * or enrolment has expired or not started.
     */
    protected $suspendedusers = array();

    /**
     * Constructor
     *
     * @param object $course A course object
     * @param array  $grade_items array of grade items, if not specified only user info returned
     * @param int    $groupid iterate only group users if present
     * @param string $sortfield1 The first field of the users table by which the array of users will be sorted
     * @param string $sortorder1 The order in which the first sorting field will be sorted (ASC or DESC)
     * @param string $sortfield2 The second field of the users table by which the array of users will be sorted
     * @param string $sortorder2 The order in which the second sorting field will be sorted (ASC or DESC)
     */
    public function __construct($course, $grade_items=null, $groupid=0,
                                          $sortfield1='lastname', $sortorder1='ASC',
                                          $sortfield2='firstname', $sortorder2='ASC') {
        $this->course      = $course;
        $this->grade_items = $grade_items;
        $this->groupid     = $groupid;
        $this->sortfield1  = $sortfield1;
        $this->sortorder1  = $sortorder1;
        $this->sortfield2  = $sortfield2;
        $this->sortorder2  = $sortorder2;

        $this->gradestack  = array();
    }

    /**
     * Initialise the iterator
     *
     * @return boolean success
     */
    public function init() {
        global $CFG, $DB;

        $this->close();

        export_verify_grades($this->course->id);
        $course_item = grade_item::fetch_course_item($this->course->id);
        if ($course_item->needsupdate) {
            // Can not calculate all final grades - sorry.
            return false;
        }

        $coursecontext = context_course::instance($this->course->id);

        list($relatedctxsql, $relatedctxparams) = $DB->get_in_or_equal($coursecontext->get_parent_context_ids(true), SQL_PARAMS_NAMED, 'relatedctx');
        list($gradebookroles_sql, $params) = $DB->get_in_or_equal(explode(',', $CFG->gradebookroles), SQL_PARAMS_NAMED, 'grbr');
        list($enrolledsql, $enrolledparams) = get_enrolled_sql($coursecontext, '', 0, $this->onlyactive);

        $params = array_merge($params, $enrolledparams, $relatedctxparams);

        if ($this->groupid) {
            $groupsql = "INNER JOIN {groups_members} gm ON gm.userid = u.id";
            $groupwheresql = "AND gm.groupid = :groupid";
            // $params contents: gradebookroles
            $params['groupid'] = $this->groupid;
        } else {
            $groupsql = "";
            $groupwheresql = "";
        }

        if (empty($this->sortfield1)) {
            // We must do some sorting even if not specified.
            $ofields = ", u.id AS usrt";
            $order   = "usrt ASC";

        } else {
            $ofields = ", u.$this->sortfield1 AS usrt1";
            $order   = "usrt1 $this->sortorder1";
            if (!empty($this->sortfield2)) {
                $ofields .= ", u.$this->sortfield2 AS usrt2";
                $order   .= ", usrt2 $this->sortorder2";
            }
            if ($this->sortfield1 != 'id' and $this->sortfield2 != 'id') {
                // User order MUST be the same in both queries,
                // must include the only unique user->id if not already present.
                $ofields .= ", u.id AS usrt";
                $order   .= ", usrt ASC";
            }
        }

        $userfields = 'u.*';
        $customfieldssql = '';
        if ($this->allowusercustomfields && !empty($CFG->grade_export_customprofilefields)) {
            $customfieldscount = 0;
            $customfieldsarray = grade_helper::get_user_profile_fields($this->course->id, $this->allowusercustomfields);
            foreach ($customfieldsarray as $field) {
                if (!empty($field->customid)) {
                    $customfieldssql .= "
                            LEFT JOIN (SELECT * FROM {user_info_data}
                                WHERE fieldid = :cf$customfieldscount) cf$customfieldscount
                            ON u.id = cf$customfieldscount.userid";
                    $userfields .= ", cf$customfieldscount.data AS customfield_{$field->shortname}";
                    $params['cf'.$customfieldscount] = $field->customid;
                    $customfieldscount++;
                }
            }
        }

        $users_sql = "SELECT $userfields $ofields
                        FROM {user} u
                        JOIN ($enrolledsql) je ON je.id = u.id
                             $groupsql $customfieldssql
                        JOIN (
                                  SELECT DISTINCT ra.userid
                                    FROM {role_assignments} ra
                                   WHERE ra.roleid $gradebookroles_sql
                                     AND ra.contextid $relatedctxsql
                             ) rainner ON rainner.userid = u.id
                         WHERE u.deleted = 0
                             $groupwheresql
                    ORDER BY $order";
        $this->users_rs = $DB->get_recordset_sql($users_sql, $params);

        if (!$this->onlyactive) {
            $context = context_course::instance($this->course->id);
            $this->suspendedusers = get_suspended_userids($context);
        } else {
            $this->suspendedusers = array();
        }

        if (!empty($this->grade_items)) {
            $itemids = array_keys($this->grade_items);
            list($itemidsql, $grades_params) = $DB->get_in_or_equal($itemids, SQL_PARAMS_NAMED, 'items');
            $params = array_merge($params, $grades_params);

            $grades_sql = "SELECT g.* $ofields
                             FROM {grade_grades} g
                             JOIN {user} u ON g.userid = u.id
                             JOIN ($enrolledsql) je ON je.id = u.id
                                  $groupsql
                             JOIN (
                                      SELECT DISTINCT ra.userid
                                        FROM {role_assignments} ra
                                       WHERE ra.roleid $gradebookroles_sql
                                         AND ra.contextid $relatedctxsql
                                  ) rainner ON rainner.userid = u.id
                              WHERE u.deleted = 0
                              AND g.itemid $itemidsql
                              $groupwheresql
                         ORDER BY $order, g.itemid ASC";
            $this->grades_rs = $DB->get_recordset_sql($grades_sql, $params);
        } else {
            $this->grades_rs = false;
        }

        return true;
    }

    /**
     * Returns information about the next user
     * @return mixed array of user info, all grades and feedback or null when no more users found
     */
    public function next_user() {
        if (!$this->users_rs) {
            return false; // no users present
        }

        if (!$this->users_rs->valid()) {
            if ($current = $this->_pop()) {
                // this is not good - user or grades updated between the two reads above :-(
            }

            return false; // no more users
        } else {
            $user = $this->users_rs->current();
            $this->users_rs->next();
        }

        // find grades of this user
        $grade_records = array();
        while (true) {
            if (!$current = $this->_pop()) {
                break; // no more grades
            }

            if (empty($current->userid)) {
                break;
            }

            if ($current->userid != $user->id) {
                // grade of the next user, we have all for this user
                $this->_push($current);
                break;
            }

            $grade_records[$current->itemid] = $current;
        }

        $grades = array();
        $feedbacks = array();

        if (!empty($this->grade_items)) {
            foreach ($this->grade_items as $grade_item) {
                if (!isset($feedbacks[$grade_item->id])) {
                    $feedbacks[$grade_item->id] = new stdClass();
                }
                if (array_key_exists($grade_item->id, $grade_records)) {
                    $feedbacks[$grade_item->id]->feedback       = $grade_records[$grade_item->id]->feedback;
                    $feedbacks[$grade_item->id]->feedbackformat = $grade_records[$grade_item->id]->feedbackformat;
                    unset($grade_records[$grade_item->id]->feedback);
                    unset($grade_records[$grade_item->id]->feedbackformat);
                    $grades[$grade_item->id] = new grade_grade($grade_records[$grade_item->id], false);
                } else {
                    $feedbacks[$grade_item->id]->feedback       = '';
                    $feedbacks[$grade_item->id]->feedbackformat = FORMAT_MOODLE;
                    $grades[$grade_item->id] =
                        new grade_grade(array('userid'=>$user->id, 'itemid'=>$grade_item->id), false);
                }
            }
        }

        // Set user suspended status.
        $user->suspendedenrolment = isset($this->suspendedusers[$user->id]);
        $result = new stdClass();
        $result->user      = $user;
        $result->grades    = $grades;
        $result->feedbacks = $feedbacks;
        return $result;
    }

    /**
     * Close the iterator, do not forget to call this function
     */
    public function close() {
        if ($this->users_rs) {
            $this->users_rs->close();
            $this->users_rs = null;
        }
        if ($this->grades_rs) {
            $this->grades_rs->close();
            $this->grades_rs = null;
        }
        $this->gradestack = array();
    }

    /**
     * Should all enrolled users be exported or just those with an active enrolment?
     *
     * @param bool $onlyactive True to limit the export to users with an active enrolment
     */
    public function require_active_enrolment($onlyactive = true) {
        if (!empty($this->users_rs)) {
            debugging('Calling require_active_enrolment() has no effect unless you call init() again', DEBUG_DEVELOPER);
        }
        $this->onlyactive  = $onlyactive;
    }

    /**
     * Allow custom fields to be included
     *
     * @param bool $allow Whether to allow custom fields or not
     * @return void
     */
    public function allow_user_custom_fields($allow = true) {
        if ($allow) {
            $this->allowusercustomfields = true;
        } else {
            $this->allowusercustomfields = false;
        }
    }

    /**
     * Add a grade_grade instance to the grade stack
     *
     * @param grade_grade $grade Grade object
     *
     * @return void
     */
    private function _push($grade) {
        array_push($this->gradestack, $grade);
    }


    /**
     * Remove a grade_grade instance from the grade stack
     *
     * @return grade_grade current grade object
     */
    private function _pop() {
        global $DB;
        if (empty($this->gradestack)) {
            if (empty($this->grades_rs) || !$this->grades_rs->valid()) {
                return null; // no grades present
            }

            $current = $this->grades_rs->current();

            $this->grades_rs->next();

            return $current;
        } else {
            return array_pop($this->gradestack);
        }
    }
}

/**
 * Print a selection popup form of the graded users in a course.
 *
 * @deprecated since 2.0
 *
 * @param int    $course id of the course
 * @param string $actionpage The page receiving the data from the popoup form
 * @param int    $userid   id of the currently selected user (or 'all' if they are all selected)
 * @param int    $groupid id of requested group, 0 means all
 * @param int    $includeall bool include all option
 * @param bool   $return If true, will return the HTML, otherwise, will print directly
 * @return null
 */
function print_graded_users_selector($course, $actionpage, $userid=0, $groupid=0, $includeall=true, $return=false) {
    global $CFG, $USER, $OUTPUT;
    return $OUTPUT->render(grade_get_graded_users_select(substr($actionpage, 0, strpos($actionpage, '/')), $course, $userid, $groupid, $includeall));
}

function grade_get_graded_users_select($report, $course, $userid, $groupid, $includeall) {
    global $USER, $CFG;

    if (is_null($userid)) {
        $userid = $USER->id;
    }
    $coursecontext = context_course::instance($course->id);
    $defaultgradeshowactiveenrol = !empty($CFG->grade_report_showonlyactiveenrol);
    $showonlyactiveenrol = get_user_preferences('grade_report_showonlyactiveenrol', $defaultgradeshowactiveenrol);
    $showonlyactiveenrol = $showonlyactiveenrol || !has_capability('moodle/course:viewsuspendedusers', $coursecontext);
    $menu = array(); // Will be a list of userid => user name
    $menususpendedusers = array(); // Suspended users go to a separate optgroup.
    $gui = new graded_users_iterator($course, null, $groupid);
    $gui->require_active_enrolment($showonlyactiveenrol);
    $gui->init();
    $label = get_string('selectauser', 'grades');
    if ($includeall) {
        $menu[0] = get_string('allusers', 'grades');
        $label = get_string('selectalloroneuser', 'grades');
    }
    while ($userdata = $gui->next_user()) {
        $user = $userdata->user;
        $userfullname = fullname($user);
        if ($user->suspendedenrolment) {
            $menususpendedusers[$user->id] = $userfullname;
        } else {
            $menu[$user->id] = $userfullname;
        }
    }
    $gui->close();

    if ($includeall) {
        $menu[0] .= " (" . (count($menu) + count($menususpendedusers) - 1) . ")";
    }

    if (!empty($menususpendedusers)) {
        $menu[] = array(get_string('suspendedusers') => $menususpendedusers);
    }
    $select = new single_select(new moodle_url('/grade/report/'.$report.'/index.php', array('id'=>$course->id)), 'userid', $menu, $userid);
    $select->label = $label;
    $select->formid = 'choosegradeuser';
    return $select;
}

/**
 * Print grading plugin selection popup form.
 *
 * @param array   $plugin_info An array of plugins containing information for the selector
 * @param boolean $return return as string
 *
 * @return nothing or string if $return true
 */
function print_grade_plugin_selector($plugin_info, $active_type, $active_plugin, $return=false) {
    global $CFG, $OUTPUT, $PAGE;

    $menu = array();
    $count = 0;
    $active = '';

    foreach ($plugin_info as $plugin_type => $plugins) {
        if ($plugin_type == 'strings') {
            continue;
        }

        $first_plugin = reset($plugins);

        $sectionname = $plugin_info['strings'][$plugin_type];
        $section = array();

        foreach ($plugins as $plugin) {
            $link = $plugin->link->out(false);
            $section[$link] = $plugin->string;
            $count++;
            if ($plugin_type === $active_type and $plugin->id === $active_plugin) {
                $active = $link;
            }
        }

        if ($section) {
            $menu[] = array($sectionname=>$section);
        }
    }

    // finally print/return the popup form
    if ($count > 1) {
        $select = new url_select($menu, $active, null, 'choosepluginreport');
        $select->set_label(get_string('gradereport', 'grades'), array('class' => 'accesshide'));
        if ($return) {
            return $OUTPUT->render($select);
        } else {
            echo $OUTPUT->render($select);
        }
    } else {
        // only one option - no plugin selector needed
        return '';
    }
}

/**
 * Print grading plugin selection tab-based navigation.
 *
 * @param string  $active_type type of plugin on current page - import, export, report or edit
 * @param string  $active_plugin active plugin type - grader, user, cvs, ...
 * @param array   $plugin_info Array of plugins
 * @param boolean $return return as string
 *
 * @return nothing or string if $return true
 */
function grade_print_tabs($active_type, $active_plugin, $plugin_info, $return=false) {
    global $CFG, $COURSE;

    if (!isset($currenttab)) { //TODO: this is weird
        $currenttab = '';
    }

    $tabs = array();
    $top_row  = array();
    $bottom_row = array();
    $inactive = array($active_plugin);
    $activated = array();

    $count = 0;
    $active = '';

    foreach ($plugin_info as $plugin_type => $plugins) {
        if ($plugin_type == 'strings') {
            continue;
        }

        // If $plugins is actually the definition of a child-less parent link:
        if (!empty($plugins->id)) {
            $string = $plugins->string;
            if (!empty($plugin_info[$active_type]->parent)) {
                $string = $plugin_info[$active_type]->parent->string;
            }

            $top_row[] = new tabobject($plugin_type, $plugins->link, $string);
            continue;
        }

        $first_plugin = reset($plugins);
        $url = $first_plugin->link;

        if ($plugin_type == 'report') {
            $url = $CFG->wwwroot.'/grade/report/index.php?id='.$COURSE->id;
        }

        $top_row[] = new tabobject($plugin_type, $url, $plugin_info['strings'][$plugin_type]);

        if ($active_type == $plugin_type) {
            foreach ($plugins as $plugin) {
                $bottom_row[] = new tabobject($plugin->id, $plugin->link, $plugin->string);
                if ($plugin->id == $active_plugin) {
                    $inactive = array($plugin->id);
                }
            }
        }
    }

    $tabs[] = $top_row;
    $tabs[] = $bottom_row;

    if ($return) {
        return print_tabs($tabs, $active_type, $inactive, $activated, true);
    } else {
        print_tabs($tabs, $active_type, $inactive, $activated);
    }
}

/**
 * grade_get_plugin_info
 *
 * @param int    $courseid The course id
 * @param string $active_type type of plugin on current page - import, export, report or edit
 * @param string $active_plugin active plugin type - grader, user, cvs, ...
 *
 * @return array
 */
function grade_get_plugin_info($courseid, $active_type, $active_plugin) {
    global $CFG, $SITE;

    $context = context_course::instance($courseid);

    $plugin_info = array();
    $count = 0;
    $active = '';
    $url_prefix = $CFG->wwwroot . '/grade/';

    // Language strings
    $plugin_info['strings'] = grade_helper::get_plugin_strings();

    if ($reports = grade_helper::get_plugins_reports($courseid)) {
        $plugin_info['report'] = $reports;
    }

    //showing grade categories and items make no sense if we're not within a course
    if ($courseid!=$SITE->id) {
        if ($edittree = grade_helper::get_info_edit_structure($courseid)) {
            $plugin_info['edittree'] = $edittree;
        }
    }

    if ($scale = grade_helper::get_info_scales($courseid)) {
        $plugin_info['scale'] = array('view'=>$scale);
    }

    if ($outcomes = grade_helper::get_info_outcomes($courseid)) {
        $plugin_info['outcome'] = $outcomes;
    }

    if ($letters = grade_helper::get_info_letters($courseid)) {
        $plugin_info['letter'] = $letters;
    }

    if ($imports = grade_helper::get_plugins_import($courseid)) {
        $plugin_info['import'] = $imports;
    }

    if ($exports = grade_helper::get_plugins_export($courseid)) {
        $plugin_info['export'] = $exports;
    }

    foreach ($plugin_info as $plugin_type => $plugins) {
        if (!empty($plugins->id) && $active_plugin == $plugins->id) {
            $plugin_info['strings']['active_plugin_str'] = $plugins->string;
            break;
        }
        foreach ($plugins as $plugin) {
            if (is_a($plugin, 'grade_plugin_info')) {
                if ($active_plugin == $plugin->id) {
                    $plugin_info['strings']['active_plugin_str'] = $plugin->string;
                }
            }
        }
    }

    //hide course settings if we're not in a course
    if ($courseid!=$SITE->id) {
        if ($setting = grade_helper::get_info_manage_settings($courseid)) {
            $plugin_info['settings'] = array('course'=>$setting);
        }
    }

    // Put preferences last
    if ($preferences = grade_helper::get_plugins_report_preferences($courseid)) {
        $plugin_info['preferences'] = $preferences;
    }

    foreach ($plugin_info as $plugin_type => $plugins) {
        if (!empty($plugins->id) && $active_plugin == $plugins->id) {
            $plugin_info['strings']['active_plugin_str'] = $plugins->string;
            break;
        }
        foreach ($plugins as $plugin) {
            if (is_a($plugin, 'grade_plugin_info')) {
                if ($active_plugin == $plugin->id) {
                    $plugin_info['strings']['active_plugin_str'] = $plugin->string;
                }
            }
        }
    }

    return $plugin_info;
}

/**
 * A simple class containing info about grade plugins.
 * Can be subclassed for special rules
 *
 * @package core_grades
 * @copyright 2009 Nicolas Connault
 * @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 */
class grade_plugin_info {
    /**
     * A unique id for this plugin
     *
     * @var mixed
     */
    public $id;
    /**
     * A URL to access this plugin
     *
     * @var mixed
     */
    public $link;
    /**
     * The name of this plugin
     *
     * @var mixed
     */
    public $string;
    /**
     * Another grade_plugin_info object, parent of the current one
     *
     * @var mixed
     */
    public $parent;

    /**
     * Constructor
     *
     * @param int $id A unique id for this plugin
     * @param string $link A URL to access this plugin
     * @param string $string The name of this plugin
     * @param object $parent Another grade_plugin_info object, parent of the current one
     *
     * @return void
     */
    public function __construct($id, $link, $string, $parent=null) {
        $this->id = $id;
        $this->link = $link;
        $this->string = $string;
        $this->parent = $parent;
    }
}

/**
 * Prints the page headers, breadcrumb trail, page heading, (optional) dropdown navigation menu and
 * (optional) navigation tabs for any gradebook page. All gradebook pages MUST use these functions
 * in favour of the usual print_header(), print_header_simple(), print_heading() etc.
 * !IMPORTANT! Use of tabs.php file in gradebook pages is forbidden unless tabs are switched off at
 * the site level for the gradebook ($CFG->grade_navmethod = GRADE_NAVMETHOD_DROPDOWN).
 *
 * @param int     $courseid Course id
 * @param string  $active_type The type of the current page (report, settings,
 *                             import, export, scales, outcomes, letters)
 * @param string  $active_plugin The plugin of the current page (grader, fullview etc...)
 * @param string  $heading The heading of the page. Tries to guess if none is given
 * @param boolean $return Whether to return (true) or echo (false) the HTML generated by this function
 * @param string  $bodytags Additional attributes that will be added to the <body> tag
 * @param string  $buttons Additional buttons to display on the page
 * @param boolean $shownavigation should the gradebook navigation drop down (or tabs) be shown?
 *
 * @return string HTML code or nothing if $return == false
 */
function print_grade_page_head($courseid, $active_type, $active_plugin=null,
                               $heading = false, $return=false,
                               $buttons=false, $shownavigation=true) {
    global $CFG, $OUTPUT, $PAGE;

    $plugin_info = grade_get_plugin_info($courseid, $active_type, $active_plugin);

    // Determine the string of the active plugin
    $stractive_plugin = ($active_plugin) ? $plugin_info['strings']['active_plugin_str'] : $heading;
    $stractive_type = $plugin_info['strings'][$active_type];

    if (empty($plugin_info[$active_type]->id) || !empty($plugin_info[$active_type]->parent)) {
        $title = $PAGE->course->fullname.': ' . $stractive_type . ': ' . $stractive_plugin;
    } else {
        $title = $PAGE->course->fullname.': ' . $stractive_plugin;
    }

    if ($active_type == 'report') {
        $PAGE->set_pagelayout('report');
    } else {
        $PAGE->set_pagelayout('admin');
    }
    $PAGE->set_title(get_string('grades') . ': ' . $stractive_type);
    $PAGE->set_heading($title);
    if ($buttons instanceof single_button) {
        $buttons = $OUTPUT->render($buttons);
    }
    $PAGE->set_button($buttons);
    grade_extend_settings($plugin_info, $courseid);

    $returnval = $OUTPUT->header();
    if (!$return) {
        echo $returnval;
    }

    // Guess heading if not given explicitly
    if (!$heading) {
        $heading = $stractive_plugin;
    }

    if ($shownavigation) {
        if ($CFG->grade_navmethod == GRADE_NAVMETHOD_COMBO || $CFG->grade_navmethod == GRADE_NAVMETHOD_DROPDOWN) {
            $returnval .= print_grade_plugin_selector($plugin_info, $active_type, $active_plugin, $return);
        }

        if ($return) {
            $returnval .= $OUTPUT->heading($heading);
        } else {
            echo $OUTPUT->heading($heading);
        }

        if ($CFG->grade_navmethod == GRADE_NAVMETHOD_COMBO || $CFG->grade_navmethod == GRADE_NAVMETHOD_TABS) {
            $returnval .= grade_print_tabs($active_type, $active_plugin, $plugin_info, $return);
        }
    }

    if ($return) {
        return $returnval;
    }
}

/**
 * Utility class used for return tracking when using edit and other forms in grade plugins
 *
 * @package core_grades
 * @copyright 2009 Nicolas Connault
 * @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 */
class grade_plugin_return {
    public $type;
    public $plugin;
    public $courseid;
    public $userid;
    public $page;

    /**
     * Constructor
     *
     * @param array $params - associative array with return parameters, if null parameter are taken from _GET or _POST
     */
    public function grade_plugin_return($params = null) {
        if (empty($params)) {
            $this->type     = optional_param('gpr_type', null, PARAM_SAFEDIR);
            $this->plugin   = optional_param('gpr_plugin', null, PARAM_PLUGIN);
            $this->courseid = optional_param('gpr_courseid', null, PARAM_INT);
            $this->userid   = optional_param('gpr_userid', null, PARAM_INT);
            $this->page     = optional_param('gpr_page', null, PARAM_INT);

        } else {
            foreach ($params as $key=>$value) {
                if (property_exists($this, $key)) {
                    $this->$key = $value;
                }
            }
        }
    }

    /**
     * Returns return parameters as options array suitable for buttons.
     * @return array options
     */
    public function get_options() {
        if (empty($this->type)) {
            return array();
        }

        $params = array();

        if (!empty($this->plugin)) {
            $params['plugin'] = $this->plugin;
        }

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

        if (!empty($this->userid)) {
            $params['userid'] = $this->userid;
        }

        if (!empty($this->page)) {
            $params['page'] = $this->page;
        }

        return $params;
    }

    /**
     * Returns return url
     *
     * @param string $default default url when params not set
     * @param array  $extras Extra URL parameters
     *
     * @return string url
     */
    public function get_return_url($default, $extras=null) {
        global $CFG;

        if (empty($this->type) or empty($this->plugin)) {
            return $default;
        }

        $url = $CFG->wwwroot.'/grade/'.$this->type.'/'.$this->plugin.'/index.php';
        $glue = '?';

        if (!empty($this->courseid)) {
            $url .= $glue.'id='.$this->courseid;
            $glue = '&amp;';
        }

        if (!empty($this->userid)) {
            $url .= $glue.'userid='.$this->userid;
            $glue = '&amp;';
        }

        if (!empty($this->page)) {
            $url .= $glue.'page='.$this->page;
            $glue = '&amp;';
        }

        if (!empty($extras)) {
            foreach ($extras as $key=>$value) {
                $url .= $glue.$key.'='.$value;
                $glue = '&amp;';
            }
        }

        return $url;
    }

    /**
     * Returns string with hidden return tracking form elements.
     * @return string
     */
    public function get_form_fields() {
        if (empty($this->type)) {
            return '';
        }

        $result  = '<input type="hidden" name="gpr_type" value="'.$this->type.'" />';

        if (!empty($this->plugin)) {
            $result .= '<input type="hidden" name="gpr_plugin" value="'.$this->plugin.'" />';
        }

        if (!empty($this->courseid)) {
            $result .= '<input type="hidden" name="gpr_courseid" value="'.$this->courseid.'" />';
        }

        if (!empty($this->userid)) {
            $result .= '<input type="hidden" name="gpr_userid" value="'.$this->userid.'" />';
        }

        if (!empty($this->page)) {
            $result .= '<input type="hidden" name="gpr_page" value="'.$this->page.'" />';
        }
    }

    /**
     * Add hidden elements into mform
     *
     * @param object &$mform moodle form object
     *
     * @return void
     */
    public function add_mform_elements(&$mform) {
        if (empty($this->type)) {
            return;
        }

        $mform->addElement('hidden', 'gpr_type', $this->type);
        $mform->setType('gpr_type', PARAM_SAFEDIR);

        if (!empty($this->plugin)) {
            $mform->addElement('hidden', 'gpr_plugin', $this->plugin);
            $mform->setType('gpr_plugin', PARAM_PLUGIN);
        }

        if (!empty($this->courseid)) {
            $mform->addElement('hidden', 'gpr_courseid', $this->courseid);
            $mform->setType('gpr_courseid', PARAM_INT);
        }

        if (!empty($this->userid)) {
            $mform->addElement('hidden', 'gpr_userid', $this->userid);
            $mform->setType('gpr_userid', PARAM_INT);
        }

        if (!empty($this->page)) {
            $mform->addElement('hidden', 'gpr_page', $this->page);
            $mform->setType('gpr_page', PARAM_INT);
        }
    }

    /**
     * Add return tracking params into url
     *
     * @param moodle_url $url A URL
     *
     * @return string $url with return tracking params
     */
    public function add_url_params(moodle_url $url) {
        if (empty($this->type)) {
            return $url;
        }

        $url->param('gpr_type', $this->type);

        if (!empty($this->plugin)) {
            $url->param('gpr_plugin', $this->plugin);
        }

        if (!empty($this->courseid)) {
            $url->param('gpr_courseid' ,$this->courseid);
        }

        if (!empty($this->userid)) {
            $url->param('gpr_userid', $this->userid);
        }

        if (!empty($this->page)) {
            $url->param('gpr_page', $this->page);
        }

        return $url;
    }
}

/**
 * Function central to gradebook for building and printing the navigation (breadcrumb trail).
 *
 * @param string $path The path of the calling script (using __FILE__?)
 * @param string $pagename The language string to use as the last part of the navigation (non-link)
 * @param mixed  $id Either a plain integer (assuming the key is 'id') or
 *                   an array of keys and values (e.g courseid => $courseid, itemid...)
 *
 * @return string
 */
function grade_build_nav($path, $pagename=null, $id=null) {
    global $CFG, $COURSE, $PAGE;

    $strgrades = get_string('grades', 'grades');

    // Parse the path and build navlinks from its elements
    $dirroot_length = strlen($CFG->dirroot) + 1; // Add 1 for the first slash
    $path = substr($path, $dirroot_length);
    $path = str_replace('\\', '/', $path);

    $path_elements = explode('/', $path);

    $path_elements_count = count($path_elements);

    // First link is always 'grade'
    $PAGE->navbar->add($strgrades, new moodle_url('/grade/index.php', array('id'=>$COURSE->id)));

    $link = null;
    $numberofelements = 3;

    // Prepare URL params string
    $linkparams = array();
    if (!is_null($id)) {
        if (is_array($id)) {
            foreach ($id as $idkey => $idvalue) {
                $linkparams[$idkey] = $idvalue;
            }
        } else {
            $linkparams['id'] = $id;
        }
    }

    $navlink4 = null;

    // Remove file extensions from filenames
    foreach ($path_elements as $key => $filename) {
        $path_elements[$key] = str_replace('.php', '', $filename);
    }

    // Second level links
    switch ($path_elements[1]) {
        case 'edit': // No link
            if ($path_elements[3] != 'index.php') {
                $numberofelements = 4;
            }
            break;
        case 'import': // No link
            break;
        case 'export': // No link
            break;
        case 'report':
            // $id is required for this link. Do not print it if $id isn't given
            if (!is_null($id)) {
                $link = new moodle_url('/grade/report/index.php', $linkparams);
            }

            if ($path_elements[2] == 'grader') {
                $numberofelements = 4;
            }
            break;

        default:
            // If this element isn't among the ones already listed above, it isn't supported, throw an error.
            debugging("grade_build_nav() doesn't support ". $path_elements[1] .
                    " as the second path element after 'grade'.");
            return false;
    }
    $PAGE->navbar->add(get_string($path_elements[1], 'grades'), $link);

    // Third level links
    if (empty($pagename)) {
        $pagename = get_string($path_elements[2], 'grades');
    }

    switch ($numberofelements) {
        case 3:
            $PAGE->navbar->add($pagename, $link);
            break;
        case 4:
            if ($path_elements[2] == 'grader' AND $path_elements[3] != 'index.php') {
                $PAGE->navbar->add(get_string('pluginname', 'gradereport_grader'), new moodle_url('/grade/report/grader/index.php', $linkparams));
            }
            $PAGE->navbar->add($pagename);
            break;
    }

    return '';
}

/**
 * General structure representing grade items in course
 *
 * @package core_grades
 * @copyright 2009 Nicolas Connault
 * @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 */
class grade_structure {
    public $context;

    public $courseid;

    /**
    * Reference to modinfo for current course (for performance, to save
    * retrieving it from courseid every time). Not actually set except for
    * the grade_tree type.
    * @var course_modinfo
    */
    public $modinfo;

    /**
     * 1D array of grade items only
     */
    public $items;

    /**
     * Returns icon of element
     *
     * @param array &$element An array representing an element in the grade_tree
     * @param bool  $spacerifnone return spacer if no icon found
     *
     * @return string icon or spacer
     */
    public function get_element_icon(&$element, $spacerifnone=false) {
        global $CFG, $OUTPUT;
        require_once $CFG->libdir.'/filelib.php';

        switch ($element['type']) {
            case 'item':
            case 'courseitem':
            case 'categoryitem':
                $is_course   = $element['object']->is_course_item();
                $is_category = $element['object']->is_category_item();
                $is_scale    = $element['object']->gradetype == GRADE_TYPE_SCALE;
                $is_value    = $element['object']->gradetype == GRADE_TYPE_VALUE;
                $is_outcome  = !empty($element['object']->outcomeid);

                if ($element['object']->is_calculated()) {
                    $strcalc = get_string('calculatedgrade', 'grades');
                    return '<img src="'.$OUTPUT->pix_url('i/calc') . '" class="icon itemicon" title="'.
                            s($strcalc).'" alt="'.s($strcalc).'"/>';

                } else if (($is_course or $is_category) and ($is_scale or $is_value)) {
                    if ($category = $element['object']->get_item_category()) {
                        switch ($category->aggregation) {
                            case GRADE_AGGREGATE_MEAN:
                            case GRADE_AGGREGATE_MEDIAN:
                            case GRADE_AGGREGATE_WEIGHTED_MEAN:
                            case GRADE_AGGREGATE_WEIGHTED_MEAN2:
                            case GRADE_AGGREGATE_EXTRACREDIT_MEAN:
                                $stragg = get_string('aggregation', 'grades');
                                return '<img src="'.$OUTPUT->pix_url('i/agg_mean') . '" ' .
                                        'class="icon itemicon" title="'.s($stragg).'" alt="'.s($stragg).'"/>';
                            case GRADE_AGGREGATE_SUM:
                                $stragg = get_string('aggregation', 'grades');
                                return '<img src="'.$OUTPUT->pix_url('i/agg_sum') . '" ' .
                                        'class="icon itemicon" title="'.s($stragg).'" alt="'.s($stragg).'"/>';
                        }
                    }

                } else if ($element['object']->itemtype == 'mod') {
                    //prevent outcomes being displaying the same icon as the activity they are attached to
                    if ($is_outcome) {
                        $stroutcome = s(get_string('outcome', 'grades'));
                        return '<img src="'.$OUTPUT->pix_url('i/outcomes') . '" ' .
                            'class="icon itemicon" title="'.$stroutcome.
                            '" alt="'.$stroutcome.'"/>';
                    } else {
                        $strmodname = get_string('modulename', $element['object']->itemmodule);
                        return '<img src="'.$OUTPUT->pix_url('icon',
                            $element['object']->itemmodule) . '" ' .
                            'class="icon itemicon" title="' .s($strmodname).
                            '" alt="' .s($strmodname).'"/>';
                    }
                } else if ($element['object']->itemtype == 'manual') {
                    if ($element['object']->is_outcome_item()) {
                        $stroutcome = get_string('outcome', 'grades');
                        return '<img src="'.$OUTPUT->pix_url('i/outcomes') . '" ' .
                                'class="icon itemicon" title="'.s($stroutcome).
                                '" alt="'.s($stroutcome).'"/>';
                    } else {
                        $strmanual = get_string('manualitem', 'grades');
                        return '<img src="'.$OUTPUT->pix_url('i/manual_item') . '" '.
                                'class="icon itemicon" title="'.s($strmanual).
                                '" alt="'.s($strmanual).'"/>';
                    }
                }
                break;

            case 'category':
                $strcat = get_string('category', 'grades');
                return '<img src="'.$OUTPUT->pix_url('i/folder') . '" class="icon itemicon" ' .
                        'title="'.s($strcat).'" alt="'.s($strcat).'" />';
        }

        if ($spacerifnone) {
            return $OUTPUT->spacer().' ';
        } else {
            return '';
        }
    }

    /**
     * Returns name of element optionally with icon and link
     *
     * @param array &$element An array representing an element in the grade_tree
     * @param bool  $withlink Whether or not this header has a link
     * @param bool  $icon Whether or not to display an icon with this header
     * @param bool  $spacerifnone return spacer if no icon found
     *
     * @return string header
     */
    public function get_element_header(&$element, $withlink=false, $icon=true, $spacerifnone=false) {
        $header = '';

        if ($icon) {
            $header .= $this->get_element_icon($element, $spacerifnone);
        }

        $header .= $element['object']->get_name();

        if ($element['type'] != 'item' and $element['type'] != 'categoryitem' and
            $element['type'] != 'courseitem') {
            return $header;
        }

        if ($withlink) {
            $url = $this->get_activity_link($element);
            if ($url) {
                $a = new stdClass();
                $a->name = get_string('modulename', $element['object']->itemmodule);
                $title = get_string('linktoactivity', 'grades', $a);

                $header = html_writer::link($url, $header, array('title' => $title));
            }
        }

        return $header;
    }

    private function get_activity_link($element) {
        global $CFG;
        /** @var array static cache of the grade.php file existence flags */
        static $hasgradephp = array();

        $itemtype = $element['object']->itemtype;
        $itemmodule = $element['object']->itemmodule;
        $iteminstance = $element['object']->iteminstance;
        $itemnumber = $element['object']->itemnumber;

        // Links only for module items that have valid instance, module and are
        // called from grade_tree with valid modinfo
        if ($itemtype != 'mod' || !$iteminstance || !$itemmodule || !$this->modinfo) {
            return null;
        }

        // Get $cm efficiently and with visibility information using modinfo
        $instances = $this->modinfo->get_instances();
        if (empty($instances[$itemmodule][$iteminstance])) {
            return null;
        }
        $cm = $instances[$itemmodule][$iteminstance];

        // Do not add link if activity is not visible to the current user
        if (!$cm->uservisible) {
            return null;
        }

        if (!array_key_exists($itemmodule, $hasgradephp)) {
            if (file_exists($CFG->dirroot . '/mod/' . $itemmodule . '/grade.php')) {
                $hasgradephp[$itemmodule] = true;
            } else {
                $hasgradephp[$itemmodule] = false;
            }
        }

        // If module has grade.php, link to that, otherwise view.php
        if ($hasgradephp[$itemmodule]) {
            $args = array('id' => $cm->id, 'itemnumber' => $itemnumber);
            if (isset($element['userid'])) {
                $args['userid'] = $element['userid'];
            }
            return new moodle_url('/mod/' . $itemmodule . '/grade.php', $args);
        } else {
            return new moodle_url('/mod/' . $itemmodule . '/view.php', array('id' => $cm->id));
        }
    }

    /**
     * Returns URL of a page that is supposed to contain detailed grade analysis
     *
     * At the moment, only activity modules are supported. The method generates link
     * to the module's file grade.php with the parameters id (cmid), itemid, itemnumber,
     * gradeid and userid. If the grade.php does not exist, null is returned.
     *
     * @return moodle_url|null URL or null if unable to construct it
     */
    public function get_grade_analysis_url(grade_grade $grade) {
        global $CFG;
        /** @var array static cache of the grade.php file existence flags */
        static $hasgradephp = array();

        if (empty($grade->grade_item) or !($grade->grade_item instanceof grade_item)) {
            throw new coding_exception('Passed grade without the associated grade item');
        }
        $item = $grade->grade_item;

        if (!$item->is_external_item()) {
            // at the moment, only activity modules are supported
            return null;
        }
        if ($item->itemtype !== 'mod') {
            throw new coding_exception('Unknown external itemtype: '.$item->itemtype);
        }
        if (empty($item->iteminstance) or empty($item->itemmodule) or empty($this->modinfo)) {
            return null;
        }

        if (!array_key_exists($item->itemmodule, $hasgradephp)) {
            if (file_exists($CFG->dirroot . '/mod/' . $item->itemmodule . '/grade.php')) {
                $hasgradephp[$item->itemmodule] = true;
            } else {
                $hasgradephp[$item->itemmodule] = false;
            }
        }

        if (!$hasgradephp[$item->itemmodule]) {
            return null;
        }

        $instances = $this->modinfo->get_instances();
        if (empty($instances[$item->itemmodule][$item->iteminstance])) {
            return null;
        }
        $cm = $instances[$item->itemmodule][$item->iteminstance];
        if (!$cm->uservisible) {
            return null;
        }

        $url = new moodle_url('/mod/'.$item->itemmodule.'/grade.php', array(
            'id'         => $cm->id,
            'itemid'     => $item->id,
            'itemnumber' => $item->itemnumber,
            'gradeid'    => $grade->id,
            'userid'     => $grade->userid,
        ));

        return $url;
    }

    /**
     * Returns an action icon leading to the grade analysis page
     *
     * @param grade_grade $grade
     * @return string
     */
    public function get_grade_analysis_icon(grade_grade $grade) {
        global $OUTPUT;

        $url = $this->get_grade_analysis_url($grade);
        if (is_null($url)) {
            return '';
        }

        return $OUTPUT->action_icon($url, new pix_icon('t/preview',
            get_string('gradeanalysis', 'core_grades')));
    }

    /**
     * Returns the grade eid - the grade may not exist yet.
     *
     * @param grade_grade $grade_grade A grade_grade object
     *
     * @return string eid
     */
    public function get_grade_eid($grade_grade) {
        if (empty($grade_grade->id)) {
            return 'n'.$grade_grade->itemid.'u'.$grade_grade->userid;
        } else {
            return 'g'.$grade_grade->id;
        }
    }

    /**
     * Returns the grade_item eid
     * @param grade_item $grade_item A grade_item object
     * @return string eid
     */
    public function get_item_eid($grade_item) {
        return 'i'.$grade_item->id;
    }

    /**
     * Given a grade_tree element, returns an array of parameters
     * used to build an icon for that element.
     *
     * @param array $element An array representing an element in the grade_tree
     *
     * @return array
     */
    public function get_params_for_iconstr($element) {
        $strparams = new stdClass();
        $strparams->category = '';
        $strparams->itemname = '';
        $strparams->itemmodule = '';

        if (!method_exists($element['object'], 'get_name')) {
            return $strparams;
        }

        $strparams->itemname = html_to_text($element['object']->get_name());

        // If element name is categorytotal, get the name of the parent category
        if ($strparams->itemname == get_string('categorytotal', 'grades')) {
            $parent = $element['object']->get_parent_category();
            $strparams->category = $parent->get_name() . ' ';
        } else {
            $strparams->category = '';
        }

        $strparams->itemmodule = null;
        if (isset($element['object']->itemmodule)) {
            $strparams->itemmodule = $element['object']->itemmodule;
        }
        return $strparams;
    }

    /**
     * Return edit icon for give element
     *
     * @param array  $element An array represen…