<?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/>.

/**
 * Lists all the users within a given course.
 *
 * @copyright 1999 Martin Dougiamas  http://dougiamas.com
 * @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 * @package core_user
 */

require_once('../config.php');
require_once($CFG->dirroot.'/user/lib.php');
require_once($CFG->libdir.'/tablelib.php');
require_once($CFG->libdir.'/filelib.php');

define('USER_SMALL_CLASS', 20);   // Below this is considered small.
define('USER_LARGE_CLASS', 200);  // Above this is considered large.
define('DEFAULT_PAGE_SIZE', 20);
define('SHOW_ALL_PAGE_SIZE', 5000);
define('MODE_BRIEF', 0);
define('MODE_USERDETAILS', 1);

$page         = optional_param('page', 0, PARAM_INT); // Which page to show.
$perpage      = optional_param('perpage', DEFAULT_PAGE_SIZE, PARAM_INT); // How many per page.
$mode         = optional_param('mode', null, PARAM_INT); // Use the MODE_ constants.
$accesssince  = optional_param('accesssince', 0, PARAM_INT); // Filter by last access. -1 = never.
$search       = optional_param('search', '', PARAM_RAW); // Make sure it is processed with p() or s() when sending to output!
$roleid       = optional_param('roleid', 0, PARAM_INT); // Optional roleid, 0 means all enrolled users (or all on the frontpage).
$contextid    = optional_param('contextid', 0, PARAM_INT); // One of this or.
$courseid     = optional_param('id', 0, PARAM_INT); // This are required.
$selectall    = optional_param('selectall', false, PARAM_BOOL); // When rendering checkboxes against users mark them all checked.

$PAGE->set_url('/user/index.php', array(
        'page' => $page,
        'perpage' => $perpage,
        'mode' => $mode,
        'accesssince' => $accesssince,
        'search' => $search,
        'roleid' => $roleid,
        'contextid' => $contextid,
        'id' => $courseid));

if ($contextid) {
    $context = context::instance_by_id($contextid, MUST_EXIST);
    if ($context->contextlevel != CONTEXT_COURSE) {
        print_error('invalidcontext');
    }
    $course = $DB->get_record('course', array('id' => $context->instanceid), '*', MUST_EXIST);
} else {
    $course = $DB->get_record('course', array('id' => $courseid), '*', MUST_EXIST);
    $context = context_course::instance($course->id, MUST_EXIST);
}
// Not needed anymore.
unset($contextid);
unset($courseid);

require_login($course);

$systemcontext = context_system::instance();
$isfrontpage = ($course->id == SITEID);

$frontpagectx = context_course::instance(SITEID);

if ($isfrontpage) {
    $PAGE->set_pagelayout('admin');
    require_capability('moodle/site:viewparticipants', $systemcontext);
} else {
    $PAGE->set_pagelayout('incourse');
    require_capability('moodle/course:viewparticipants', $context);
}

$rolenamesurl = new moodle_url("$CFG->wwwroot/user/index.php?contextid=$context->id&sifirst=&silast=");

$rolenames = role_fix_names(get_profile_roles($context), $context, ROLENAME_ALIAS, true);
if ($isfrontpage) {
    $rolenames[0] = get_string('allsiteusers', 'role');
} else {
    $rolenames[0] = get_string('allparticipants');
}

// Make sure other roles may not be selected by any means.
if (empty($rolenames[$roleid])) {
    print_error('noparticipants');
}

// No roles to display yet?
// frontpage course is an exception, on the front page course we should display all users.
if (empty($rolenames) && !$isfrontpage) {
    if (has_capability('moodle/role:assign', $context)) {
        redirect($CFG->wwwroot.'/'.$CFG->admin.'/roles/assign.php?contextid='.$context->id);
    } else {
        print_error('noparticipants');
    }
}

// Trigger events.
user_list_view($course, $context);

$bulkoperations = has_capability('moodle/course:bulkmessaging', $context);

$countries = get_string_manager()->get_list_of_countries();

$strnever = get_string('never');

$datestring = new stdClass();
$datestring->year  = get_string('year');
$datestring->years = get_string('years');
$datestring->day   = get_string('day');
$datestring->days  = get_string('days');
$datestring->hour  = get_string('hour');
$datestring->hours = get_string('hours');
$datestring->min   = get_string('min');
$datestring->mins  = get_string('mins');
$datestring->sec   = get_string('sec');
$datestring->secs  = get_string('secs');

if ($mode !== null) {
    $mode = (int)$mode;
    $SESSION->userindexmode = $mode;
} else if (isset($SESSION->userindexmode)) {
    $mode = (int)$SESSION->userindexmode;
} else {
    $mode = MODE_BRIEF;
}

// Check to see if groups are being used in this course
// and if so, set $currentgroup to reflect the current group.

$groupmode    = groups_get_course_groupmode($course);   // Groups are being used.
$currentgroup = groups_get_course_group($course, true);

if (!$currentgroup) {      // To make some other functions work better later.
    $currentgroup  = null;
}

$isseparategroups = ($course->groupmode == SEPARATEGROUPS and !has_capability('moodle/site:accessallgroups', $context));

$PAGE->set_title("$course->shortname: ".get_string('participants'));
$PAGE->set_heading($course->fullname);
$PAGE->set_pagetype('course-view-' . $course->format);
$PAGE->add_body_class('path-user');                     // So we can style it independently.
$PAGE->set_other_editing_capability('moodle/course:manageactivities');

echo $OUTPUT->header();
echo $OUTPUT->heading(get_string('participants'));

echo '<div class="userlist">';

if ($isseparategroups and (!$currentgroup) ) {
    // The user is not in the group so show message and exit.
    echo $OUTPUT->heading(get_string("notingroup"));
    echo $OUTPUT->footer();
    exit;
}


// Should use this variable so that we don't break stuff every time a variable is added or changed.
$baseurl = new moodle_url('/user/index.php', array(
        'contextid' => $context->id,
        'roleid' => $roleid,
        'id' => $course->id,
        'perpage' => $perpage,
        'accesssince' => $accesssince,
        'search' => s($search)));

// Setting up tags.
if ($course->id == SITEID) {
    $filtertype = 'site';
} else if ($course->id && !$currentgroup) {
    $filtertype = 'course';
    $filterselect = $course->id;
} else {
    $filtertype = 'group';
    $filterselect = $currentgroup;
}



// Get the hidden field list.
if (has_capability('moodle/course:viewhiddenuserfields', $context)) {
    $hiddenfields = array();  // Teachers and admins are allowed to see everything.
} else {
    $hiddenfields = array_flip(explode(',', $CFG->hiddenuserfields));
}

if (isset($hiddenfields['lastaccess'])) {
    // Do not allow access since filtering.
    $accesssince = 0;
}

// Print settings and things in a table across the top.
$controlstable = new html_table();
$controlstable->attributes['class'] = 'controls';
$controlstable->cellspacing = 0;
$controlstable->data[] = new html_table_row();

// Print my course menus.
if ($mycourses = enrol_get_my_courses()) {
    $courselist = array();
    $popupurl = new moodle_url('/user/index.php?roleid='.$roleid.'&sifirst=&silast=');
    foreach ($mycourses as $mycourse) {
        $coursecontext = context_course::instance($mycourse->id);
        $courselist[$mycourse->id] = format_string($mycourse->shortname, true, array('context' => $coursecontext));
    }
    if (has_capability('moodle/site:viewparticipants', $systemcontext)) {
        unset($courselist[SITEID]);
        $courselist = array(SITEID => format_string($SITE->shortname, true, array('context' => $systemcontext))) + $courselist;
    }
    $select = new single_select($popupurl, 'id', $courselist, $course->id, null, 'courseform');
    $select->set_label(get_string('mycourses'));
    $controlstable->data[0]->cells[] = $OUTPUT->render($select);
}

if ($groupmenu = groups_print_course_menu($course, $baseurl->out(), true)) {
    $controlstable->data[0]->cells[] = $groupmenu;
}

if (!isset($hiddenfields['lastaccess'])) {
    // Get minimum lastaccess for this course and display a dropbox to filter by lastaccess going back this far.
    // We need to make it diferently for normal courses and site course.
    if (!$isfrontpage) {
        $minlastaccess = $DB->get_field_sql('SELECT min(timeaccess)
                                               FROM {user_lastaccess}
                                              WHERE courseid = ?
                                                    AND timeaccess != 0', array($course->id));
        $lastaccess0exists = $DB->record_exists('user_lastaccess', array('courseid' => $course->id, 'timeaccess' => 0));
    } else {
        $minlastaccess = $DB->get_field_sql('SELECT min(lastaccess)
                                               FROM {user}
                                              WHERE lastaccess != 0');
        $lastaccess0exists = $DB->record_exists('user', array('lastaccess' => 0));
    }

    $now = usergetmidnight(time());
    $timeaccess = array();
    $baseurl->remove_params('accesssince');

    // Makes sense for this to go first.
    $timeoptions[0] = get_string('selectperiod');

    // Days.
    for ($i = 1; $i < 7; $i++) {
        if (strtotime('-'.$i.' days', $now) >= $minlastaccess) {
            $timeoptions[strtotime('-'.$i.' days', $now)] = get_string('numdays', 'moodle', $i);
        }
    }
    // Weeks.
    for ($i = 1; $i < 10; $i++) {
        if (strtotime('-'.$i.' weeks', $now) >= $minlastaccess) {
            $timeoptions[strtotime('-'.$i.' weeks', $now)] = get_string('numweeks', 'moodle', $i);
        }
    }
    // Months.
    for ($i = 2; $i < 12; $i++) {
        if (strtotime('-'.$i.' months', $now) >= $minlastaccess) {
            $timeoptions[strtotime('-'.$i.' months', $now)] = get_string('nummonths', 'moodle', $i);
        }
    }
    // Try a year.
    if (strtotime('-1 year', $now) >= $minlastaccess) {
        $timeoptions[strtotime('-1 year', $now)] = get_string('lastyear');
    }

    if (!empty($lastaccess0exists)) {
        $timeoptions[-1] = get_string('never');
    }

    if (count($timeoptions) > 1) {
        $select = new single_select($baseurl, 'accesssince', $timeoptions, $accesssince, null, 'timeoptions');
        $select->set_label(get_string('usersnoaccesssince'));
        $controlstable->data[0]->cells[] = $OUTPUT->render($select);
    }
}

$formatmenu = array( '0' => get_string('brief'),
                     '1' => get_string('userdetails'));
$select = new single_select($baseurl, 'mode', $formatmenu, $mode, null, 'formatmenu');
$select->set_label(get_string('userlist'));
$userlistcell = new html_table_cell();
$userlistcell->attributes['class'] = 'right';
$userlistcell->text = $OUTPUT->render($select);
$controlstable->data[0]->cells[] = $userlistcell;

echo html_writer::table($controlstable);

if ($currentgroup and (!$isseparategroups or has_capability('moodle/site:accessallgroups', $context))) {
    // Display info about the group.
    if ($group = groups_get_group($currentgroup)) {
        if (!empty($group->description) or (!empty($group->picture) and empty($group->hidepicture))) {
            $groupinfotable = new html_table();
            $groupinfotable->attributes['class'] = 'groupinfobox';
            $picturecell = new html_table_cell();
            $picturecell->attributes['class'] = 'left side picture';
            $picturecell->text = print_group_picture($group, $course->id, true, true, false);

            $contentcell = new html_table_cell();
            $contentcell->attributes['class'] = 'content';

            $contentheading = $group->name;
            if (has_capability('moodle/course:managegroups', $context)) {
                $aurl = new moodle_url('/group/group.php', array('id' => $group->id, 'courseid' => $group->courseid));
                $contentheading .= '&nbsp;' . $OUTPUT->action_icon($aurl, new pix_icon('t/edit', get_string('editgroupprofile')));
            }

            $group->description = file_rewrite_pluginfile_urls($group->description, 'pluginfile.php', $context->id, 'group',
                'description', $group->id);
            if (!isset($group->descriptionformat)) {
                $group->descriptionformat = FORMAT_MOODLE;
            }
            $options = array('overflowdiv' => true);
            $formatteddesc = format_text($group->description, $group->descriptionformat, $options);
            $contentcell->text = $OUTPUT->heading($contentheading, 3) . $formatteddesc;
            $groupinfotable->data[] = new html_table_row(array($picturecell, $contentcell));
            echo html_writer::table($groupinfotable);
        }
    }
}

// Define a table showing a list of users in the current role selection.
$tablecolumns = array();
$tableheaders = array();
if ($bulkoperations && $mode === MODE_BRIEF) {
    $tablecolumns[] = 'select';
    $tableheaders[] = get_string('select');
}
$tablecolumns[] = 'userpic';
$tablecolumns[] = 'fullname';

$extrafields = get_extra_user_fields($context);
$tableheaders[] = get_string('userpic');
$tableheaders[] = get_string('fullnameuser');

if ($mode === MODE_BRIEF) {
    foreach ($extrafields as $field) {
        $tablecolumns[] = $field;
        $tableheaders[] = get_user_field_name($field);
    }
}
if ($mode === MODE_BRIEF && !isset($hiddenfields['city'])) {
    $tablecolumns[] = 'city';
    $tableheaders[] = get_string('city');
}
if ($mode === MODE_BRIEF && !isset($hiddenfields['country'])) {
    $tablecolumns[] = 'country';
    $tableheaders[] = get_string('country');
}
if (!isset($hiddenfields['lastaccess'])) {
    $tablecolumns[] = 'lastaccess';
    if ($course->id == SITEID) {
        // Exception case for viewing participants on site home.
        $tableheaders[] = get_string('lastsiteaccess');
    } else {
        $tableheaders[] = get_string('lastcourseaccess');
    }
}

if ($bulkoperations && $mode === MODE_USERDETAILS) {
    $tablecolumns[] = 'select';
    $tableheaders[] = get_string('select');
}

$table = new flexible_table('user-index-participants-'.$course->id);
$table->define_columns($tablecolumns);
$table->define_headers($tableheaders);
$table->define_baseurl($baseurl->out());

if (!isset($hiddenfields['lastaccess'])) {
    $table->sortable(true, 'lastaccess', SORT_DESC);
} else {
    $table->sortable(true, 'firstname', SORT_ASC);
}

$table->no_sorting('roles');
$table->no_sorting('groups');
$table->no_sorting('groupings');
$table->no_sorting('select');

$table->set_attribute('cellspacing', '0');
$table->set_attribute('id', 'participants');
$table->set_attribute('class', 'generaltable generalbox');

$table->set_control_variables(array(
            TABLE_VAR_SORT    => 'ssort',
            TABLE_VAR_HIDE    => 'shide',
            TABLE_VAR_SHOW    => 'sshow',
            TABLE_VAR_IFIRST  => 'sifirst',
            TABLE_VAR_ILAST   => 'silast',
            TABLE_VAR_PAGE    => 'spage'
            ));
$table->setup();

list($esql, $params) = get_enrolled_sql($context, null, $currentgroup, true);
$joins = array("FROM {user} u");
$wheres = array();

$userfields = array('username', 'email', 'city', 'country', 'lang', 'timezone', 'maildisplay');
$mainuserfields = user_picture::fields('u', $userfields);
$extrasql = get_extra_user_fields_sql($context, 'u', '', $userfields);

if ($isfrontpage) {
    $select = "SELECT $mainuserfields, u.lastaccess$extrasql";
    $joins[] = "JOIN ($esql) e ON e.id = u.id"; // Everybody on the frontpage usually.
    if ($accesssince) {
        $wheres[] = get_user_lastaccess_sql($accesssince);
    }

} else {
    $select = "SELECT $mainuserfields, COALESCE(ul.timeaccess, 0) AS lastaccess$extrasql";
    $joins[] = "JOIN ($esql) e ON e.id = u.id"; // Course enrolled users only.
    $joins[] = "LEFT JOIN {user_lastaccess} ul ON (ul.userid = u.id AND ul.courseid = :courseid)"; // Not everybody accessed course yet.
    $params['courseid'] = $course->id;
    if ($accesssince) {
        $wheres[] = get_course_lastaccess_sql($accesssince);
    }
}

// Performance hacks - we preload user contexts together with accounts.
$ccselect = ', ' . context_helper::get_preload_record_columns_sql('ctx');
$ccjoin = "LEFT JOIN {context} ctx ON (ctx.instanceid = u.id AND ctx.contextlevel = :contextlevel)";
$params['contextlevel'] = CONTEXT_USER;
$select .= $ccselect;
$joins[] = $ccjoin;


// Limit list to users with some role only.
if ($roleid) {
    // We want to query both the current context and parent contexts.
    list($relatedctxsql, $relatedctxparams) = $DB->get_in_or_equal($context->get_parent_context_ids(true), SQL_PARAMS_NAMED, 'relatedctx');

    $wheres[] = "u.id IN (SELECT userid FROM {role_assignments} WHERE roleid = :roleid AND contextid $relatedctxsql)";
    $params = array_merge($params, array('roleid' => $roleid), $relatedctxparams);
}

$from = implode("\n", $joins);
if ($wheres) {
    $where = "WHERE " . implode(" AND ", $wheres);
} else {
    $where = "";
}

$totalcount = $DB->count_records_sql("SELECT COUNT(u.id) $from $where", $params);

if (!empty($search)) {
    $fullname = $DB->sql_fullname('u.firstname', 'u.lastname');
    $wheres[] = "(". $DB->sql_like($fullname, ':search1', false, false) .
                " OR ". $DB->sql_like('email', ':search2', false, false) .
                " OR ". $DB->sql_like('idnumber', ':search3', false, false) .") ";
    $params['search1'] = "%$search%";
    $params['search2'] = "%$search%";
    $params['search3'] = "%$search%";
}

list($twhere, $tparams) = $table->get_sql_where();
if ($twhere) {
    $wheres[] = $twhere;
    $params = array_merge($params, $tparams);
}

$from = implode("\n", $joins);
if ($wheres) {
    $where = "WHERE " . implode(" AND ", $wheres);
} else {
    $where = "";
}

if ($table->get_sql_sort()) {
    $sort = ' ORDER BY '.$table->get_sql_sort();
} else {
    $sort = '';
}

$matchcount = $DB->count_records_sql("SELECT COUNT(u.id) $from $where", $params);

$table->initialbars(true);
$table->pagesize($perpage, $matchcount);

// List of users at the current visible page - paging makes it relatively short.
$userlist = $DB->get_recordset_sql("$select $from $where $sort", $params, $table->get_page_start(), $table->get_page_size());

// If there are multiple Roles in the course, then show a drop down menu for switching.
if (count($rolenames) > 1) {
    echo '<div class="rolesform">';
    echo $OUTPUT->single_select($rolenamesurl, 'roleid', $rolenames, $roleid, null,
        'rolesform', array('label' => get_string('currentrole', 'role')));
    echo '</div>';

} else if (count($rolenames) == 1) {
    // When all users with the same role - print its name.
    echo '<div class="rolesform">';
    echo get_string('role').get_string('labelsep', 'langconfig');
    $rolename = reset($rolenames);
    echo $rolename;
    echo '</div>';
}

$editlink = '';
if ($course->id != SITEID && has_capability('moodle/course:enrolreview', $context)) {
    $editlink = new moodle_url('/enrol/users.php', array('id' => $course->id));
}

if ($roleid > 0) {
    $a = new stdClass();
    $a->number = $totalcount;
    $a->role = $rolenames[$roleid];
    $heading = format_string(get_string('xuserswiththerole', 'role', $a));

    if ($currentgroup and !empty($group)) {
        $a->group = $group->name;
        $heading .= ' ' . format_string(get_string('ingroup', 'role', $a));
    }

    if ($accesssince && !empty($timeoptions[$accesssince])) {
        $a->timeperiod = $timeoptions[$accesssince];
        $heading .= ' ' . format_string(get_string('inactiveformorethan', 'role', $a));
    }

    $heading .= ": $a->number";

    if (!empty($editlink)) {
        $editlink->param('role', $roleid);
        $heading .= $OUTPUT->action_icon($editlink, new pix_icon('t/edit', get_string('edit')));
    }
    echo $OUTPUT->heading($heading, 3);
} else {
    if ($course->id == SITEID and $roleid < 0) {
        $strallparticipants = get_string('allsiteusers', 'role');
    } else {
        $strallparticipants = get_string('allparticipants');
    }

    if (!empty($editlink)) {
        $editlink = $OUTPUT->action_icon($editlink, new pix_icon('t/edit', get_string('edit')));
    }

    if ($matchcount < $totalcount) {
        echo $OUTPUT->heading($strallparticipants.get_string('labelsep', 'langconfig').$matchcount.'/'.$totalcount . $editlink, 3);
    } else {
        echo $OUTPUT->heading($strallparticipants.get_string('labelsep', 'langconfig').$matchcount . $editlink, 3);
    }
}


if ($bulkoperations) {
    echo '<form action="action_redir.php" method="post" id="participantsform">';
    echo '<div>';
    echo '<input type="hidden" name="sesskey" value="'.sesskey().'" />';
    echo '<input type="hidden" name="returnto" value="'.s($PAGE->url->out(false)).'" />';
}

if ($mode === MODE_USERDETAILS) {    // Print simple listing.
    if ($totalcount < 1) {
        echo $OUTPUT->heading(get_string('nothingtodisplay'));
    } else {
        if ($totalcount > $perpage) {

            $firstinitial = $table->get_initial_first();
            $lastinitial  = $table->get_initial_last();
            $strall = get_string('all');
            $alpha  = explode(',', get_string('alphabet', 'langconfig'));

            // Bar of first initials.

            echo '<div class="initialbar firstinitial">'.get_string('firstname').' : ';
            if (!empty($firstinitial)) {
                echo '<a href="'.$baseurl->out().'&amp;sifirst=">'.$strall.'</a>';
            } else {
                echo '<strong>'.$strall.'</strong>';
            }
            foreach ($alpha as $letter) {
                if ($letter == $firstinitial) {
                    echo ' <strong>'.$letter.'</strong>';
                } else {
                    echo ' <a href="'.$baseurl->out().'&amp;sifirst='.$letter.'">'.$letter.'</a>';
                }
            }
            echo '</div>';

            // Bar of last initials.

            echo '<div class="initialbar lastinitial">'.get_string('lastname').' : ';
            if (!empty($lastinitial)) {
                echo '<a href="'.$baseurl->out().'&amp;silast=">'.$strall.'</a>';
            } else {
                echo '<strong>'.$strall.'</strong>';
            }
            foreach ($alpha as $letter) {
                if ($letter == $lastinitial) {
                    echo ' <strong>'.$letter.'</strong>';
                } else {
                    echo ' <a href="'.$baseurl->out().'&amp;silast='.$letter.'">'.$letter.'</a>';
                }
            }
            echo '</div>';

            $pagingbar = new paging_bar($matchcount, intval($table->get_page_start() / $perpage), $perpage, $baseurl);
            $pagingbar->pagevar = 'spage';
            echo $OUTPUT->render($pagingbar);
        }

        if ($matchcount > 0) {
            $usersprinted = array();
            foreach ($userlist as $user) {
                if (in_array($user->id, $usersprinted)) { // Prevent duplicates by r.hidden - MDL-13935.
                    continue;
                }
                $usersprinted[] = $user->id; // Add new user to the array of users printed.

                context_helper::preload_from_record($user);

                $context = context_course::instance($course->id);
                $usercontext = context_user::instance($user->id);

                $countries = get_string_manager()->get_list_of_countries();

                // Get the hidden field list.
                if (has_capability('moodle/course:viewhiddenuserfields', $context)) {
                    $hiddenfields = array();
                } else {
                    $hiddenfields = array_flip(explode(',', $CFG->hiddenuserfields));
                }
                $table = new html_table();
                $table->attributes['class'] = 'userinfobox';

                $row = new html_table_row();
                $row->cells[0] = new html_table_cell();
                $row->cells[0]->attributes['class'] = 'left side';

                $row->cells[0]->text = $OUTPUT->user_picture($user, array('size' => 100, 'courseid' => $course->id));
                $row->cells[1] = new html_table_cell();
                $row->cells[1]->attributes['class'] = 'content';

                $row->cells[1]->text = $OUTPUT->container(fullname($user, has_capability('moodle/site:viewfullnames', $context)), 'username');
                $row->cells[1]->text .= $OUTPUT->container_start('info');

                if (!empty($user->role)) {
                    $row->cells[1]->text .= get_string('role').get_string('labelsep', 'langconfig').$user->role.'<br />';
                }
                if ($user->maildisplay == 1 or ($user->maildisplay == 2 and ($course->id != SITEID) and !isguestuser()) or
                            in_array('email', $extrafields) or ($user->id == $USER->id)) {
                    $row->cells[1]->text .= get_string('email').get_string('labelsep', 'langconfig').html_writer::link("mailto:$user->email", $user->email) . '<br />';
                }
                foreach ($extrafields as $field) {
                    if ($field === 'email') {
                        // Skip email because it was displayed with different logic above
                        // because this page is intended for students too.
                        continue;
                    }
                    $row->cells[1]->text .= get_user_field_name($field) .
                            get_string('labelsep', 'langconfig') . s($user->{$field}) . '<br />';
                }
                if (($user->city or $user->country) and (!isset($hiddenfields['city']) or !isset($hiddenfields['country']))) {
                    $row->cells[1]->text .= get_string('city').get_string('labelsep', 'langconfig');
                    if ($user->city && !isset($hiddenfields['city'])) {
                        $row->cells[1]->text .= $user->city;
                    }
                    if (!empty($countries[$user->country]) && !isset($hiddenfields['country'])) {
                        if ($user->city && !isset($hiddenfields['city'])) {
                            $row->cells[1]->text .= ', ';
                        }
                        $row->cells[1]->text .= $countries[$user->country];
                    }
                    $row->cells[1]->text .= '<br />';
                }

                if (!isset($hiddenfields['lastaccess'])) {
                    if ($user->lastaccess) {
                        $row->cells[1]->text .= get_string('lastaccess').get_string('labelsep', 'langconfig').userdate($user->lastaccess);
                        $row->cells[1]->text .= '&nbsp; ('. format_time(time() - $user->lastaccess, $datestring) .')';
                    } else {
                        $row->cells[1]->text .= get_string('lastaccess').get_string('labelsep', 'langconfig').get_string('never');
                    }
                }

                $row->cells[1]->text .= $OUTPUT->container_end();

                $row->cells[2] = new html_table_cell();
                $row->cells[2]->attributes['class'] = 'links';
                $row->cells[2]->text = '';

                $links = array();

                if ($CFG->enableblogs && ($CFG->bloglevel != BLOG_USER_LEVEL || $USER->id == $user->id)) {
                    $links[] = html_writer::link(new moodle_url('/blog/index.php?userid='.$user->id), get_string('blogs', 'blog'));
                }

                if (!empty($CFG->enablenotes) and (has_capability('moodle/notes:manage', $context) || has_capability('moodle/notes:view', $context))) {
                    $links[] = html_writer::link(new moodle_url('/notes/index.php?course=' . $course->id. '&user='.$user->id), get_string('notes', 'notes'));
                }

                if (has_capability('moodle/site:viewreports', $context) or has_capability('moodle/user:viewuseractivitiesreport', $usercontext)) {
                    $links[] = html_writer::link(new moodle_url('/course/user.php?id='. $course->id .'&user='. $user->id), get_string('activity'));
                }

                if ($USER->id != $user->id && !\core\session\manager::is_loggedinas() && has_capability('moodle/user:loginas', $context) && !is_siteadmin($user->id)) {
                    $links[] = html_writer::link(new moodle_url('/course/loginas.php?id='. $course->id .'&user='. $user->id .'&sesskey='. sesskey()), get_string('loginas'));
                }

                $links[] = html_writer::link(new moodle_url('/user/view.php?id='. $user->id .'&course='. $course->id), get_string('fullprofile') . '...');

                $row->cells[2]->text .= implode('', $links);

                if ($bulkoperations) {
                    if ($selectall) {
                        $checked = 'checked="true"';
                    } else {
                        $checked = '';
                    }
                    $row->cells[2]->text .= '<br /><input type="checkbox" class="usercheckbox" name="user'.$user->id.'" ' .$checked .'/> ';
                }
                $table->data = array($row);
                echo html_writer::table($table);
            }

        } else {
            echo $OUTPUT->heading(get_string('nothingtodisplay'));
        }
    }

} else {
    $countrysort = (strpos($sort, 'country') !== false);
    $timeformat = get_string('strftimedate');


    if ($userlist) {

        $usersprinted = array();
        foreach ($userlist as $user) {
            if (in_array($user->id, $usersprinted)) { // Prevent duplicates by r.hidden - MDL-13935.
                continue;
            }
            $usersprinted[] = $user->id; // Add new user to the array of users printed.

            context_helper::preload_from_record($user);

            if ($user->lastaccess) {
                $lastaccess = format_time(time() - $user->lastaccess, $datestring);
            } else {
                $lastaccess = $strnever;
            }

            if (empty($user->country)) {
                $country = '';

            } else {
                if ($countrysort) {
                    $country = '('.$user->country.') '.$countries[$user->country];
                } else {
                    $country = $countries[$user->country];
                }
            }

            $usercontext = context_user::instance($user->id);

            if ($piclink = ($USER->id == $user->id || has_capability('moodle/user:viewdetails', $context) || has_capability('moodle/user:viewdetails', $usercontext))) {
                $profilelink = '<strong><a href="'.$CFG->wwwroot.'/user/view.php?id='.$user->id.'&amp;course='.$course->id.'">'.fullname($user).'</a></strong>';
            } else {
                $profilelink = '<strong>'.fullname($user).'</strong>';
            }

            $data = array();
            if ($bulkoperations) {
                if ($selectall) {
                    $checked = 'checked="true"';
                } else {
                    $checked = '';
                }
                $data[] = '<input type="checkbox" class="usercheckbox" name="user'.$user->id.'" ' . $checked .'/>';
            }
            $data[] = $OUTPUT->user_picture($user, array('size' => 35, 'courseid' => $course->id));
            $data[] = $profilelink;

            if ($mode === MODE_BRIEF) {
                foreach ($extrafields as $field) {
                    $data[] = $user->{$field};
                }
            }
            if ($mode === MODE_BRIEF && !isset($hiddenfields['city'])) {
                $data[] = $user->city;
            }
            if ($mode === MODE_BRIEF && !isset($hiddenfields['country'])) {
                $data[] = $country;
            }
            if (!isset($hiddenfields['lastaccess'])) {
                $data[] = $lastaccess;
            }

            $table->add_data($data);
        }
    }

    $table->print_html();

}

$perpageurl = clone($baseurl);
$perpageurl->remove_params('perpage');
if ($perpage == SHOW_ALL_PAGE_SIZE) {
    $perpageurl->param('perpage', DEFAULT_PAGE_SIZE);
    echo $OUTPUT->container(html_writer::link($perpageurl, get_string('showperpage', '', DEFAULT_PAGE_SIZE)), array(), 'showall');

} else if ($matchcount > 0 && $perpage < $matchcount) {
    $perpageurl->param('perpage', SHOW_ALL_PAGE_SIZE);
    echo $OUTPUT->container(html_writer::link($perpageurl, get_string('showall', '', $matchcount)), array(), 'showall');
}

if ($bulkoperations) {
    echo '<br /><div class="buttons">';

    if ($matchcount > 0 && $perpage < $matchcount) {
        $perpageurl = clone($baseurl);
        $perpageurl->remove_params('perpage');
        $perpageurl->param('perpage', SHOW_ALL_PAGE_SIZE);
        $perpageurl->param('selectall', true);
        $showalllink = $perpageurl;
    } else {
        $showalllink = false;
    }

    echo html_writer::start_tag('div', array('class' => 'btn-group'));
    if ($perpage < $matchcount) {
        // Select all users, refresh page showing all users and mark them all selected.
        $label = get_string('selectalluserswithcount', 'moodle', $matchcount);
        echo html_writer::tag('input', "", array('type' => 'button', 'id' => 'checkall', 'class' => 'btn btn-secondary',
                'value' => $label, 'data-showallink' => $showalllink));
        // Select all users, mark all users on page as selected.
        echo html_writer::tag('input', "", array('type' => 'button', 'id' => 'checkallonpage', 'class' => 'btn btn-secondary',
        'value' => get_string('selectallusersonpage')));
    } else {
        echo html_writer::tag('input', "", array('type' => 'button', 'id' => 'checkallonpage', 'class' => 'btn btn-secondary',
        'value' => get_string('selectall')));
    }

    echo html_writer::tag('input', "", array('type' => 'button', 'id' => 'checknone', 'class' => 'btn btn-secondary',
        'value' => get_string('deselectall')));
    echo html_writer::end_tag('div');
    $displaylist = array();
    $displaylist['messageselect.php'] = get_string('messageselectadd');
    if (!empty($CFG->enablenotes) && has_capability('moodle/notes:manage', $context) && $context->id != $frontpagectx->id) {
        $displaylist['addnote.php'] = get_string('addnewnote', 'notes');
        $displaylist['groupaddnote.php'] = get_string('groupaddnewnote', 'notes');
    }

    echo $OUTPUT->help_icon('withselectedusers');
    echo html_writer::tag('label', get_string("withselectedusers"), array('for' => 'formactionid'));
    echo html_writer::select($displaylist, 'formaction', '', array('' => 'choosedots'), array('id' => 'formactionid'));

    echo '<input type="hidden" name="id" value="'.$course->id.'" />';
    echo '<noscript style="display:inline">';
    echo '<div><input type="submit" value="'.get_string('ok').'" /></div>';
    echo '</noscript>';
    echo '</div></div>';
    echo '</form>';

    $module = array('name' => 'core_user', 'fullpath' => '/user/module.js');
    $PAGE->requires->js_init_call('M.core_user.init_participation', null, false, $module);
}

// Show a search box if all participants don't fit on a single screen.
if ($totalcount > $perpage) {
    echo '<form action="index.php" class="searchform"><div><input type="hidden" name="id" value="'.$course->id.'" />';
    echo '<label for="search">' . get_string('search', 'search') . ' </label>';
    echo '<input type="text" id="search" name="search" value="'.s($search).'" />&nbsp;<input type="submit" value="'.get_string('search').'" /></div></form>'."\n";
}

echo '</div>';  // Userlist.

echo $OUTPUT->footer();

if ($userlist) {
    $userlist->close();
}

/**
 * Returns SQL that can be used to limit a query to a period where the user last accessed a course..
 *
 * @param string $accesssince
 * @return string
 */
function get_course_lastaccess_sql($accesssince='') {
    if (empty($accesssince)) {
        return '';
    }
    if ($accesssince == -1) { // Never.
        return 'ul.timeaccess = 0';
    } else {
        return 'ul.timeaccess != 0 AND ul.timeaccess < '.$accesssince;
    }
}

/**
 * Returns SQL that can be used to limit a query to a period where the user last accessed the system.
 *
 * @param string $accesssince
 * @return string
 */
function get_user_lastaccess_sql($accesssince='') {
    if (empty($accesssince)) {
        return '';
    }
    if ($accesssince == -1) { // Never.
        return 'u.lastaccess = 0';
    } else {
        return 'u.lastaccess != 0 AND u.lastaccess < '.$accesssince;
    }
}
