<?PHP // $Id$

//  Lists all the users within a given course

    require_once('../config.php');
    require_once($CFG->libdir.'/tablelib.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);
    define('MODE_ENROLDETAILS', 2);

    $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);                             // use the MODE_ constants
    $accesssince  = optional_param('accesssince',0,PARAM_INT);               // filter by last access. -1 = never
    $search       = optional_param('search','',PARAM_CLEAN);
    $roleid       = optional_param('roleid', 0, PARAM_INT);                 // optional roleid

    $contextid    = optional_param('contextid', 0, PARAM_INT);                 // one of this or
    $courseid     = optional_param('id', 0, PARAM_INT);                        // this are required

    if ($contextid) {
        if (! $context = get_context_instance_by_id($contextid)) {
            error("Context ID is incorrect");
        }
        if (! $course = get_record('course', 'id', $context->instanceid)) {
            error("Course ID is incorrect");
        }
    } else {
        if (! $course = get_record('course', 'id', $courseid)) {
            error("Course ID is incorrect");
        }
        if (! $context = get_context_instance(CONTEXT_COURSE, $course->id)) {
            error("Context ID is incorrect");
        }
    }
    // not needed anymore
    unset($contextid);
    unset($courseid);

    require_login($course);

    $sitecontext = get_context_instance(CONTEXT_SYSTEM);
    $frontpagectx = get_context_instance(CONTEXT_COURSE, SITEID);

    if ($context->id != $frontpagectx->id) {
        require_capability('moodle/course:viewparticipants', $context);
    } else {
        require_capability('moodle/site:viewparticipants', $sitecontext);
    }

    /// front page course is different
    $rolenames = array();
    $avoidroles = array();

    if ($roles = get_roles_used_in_context($context, true)) {
        // We should ONLY allow roles with moodle/course:view because otherwise we get little niggly issues
        // like MDL-8093
        // We should further exclude "admin" users (those with "doanything" at site level) because
        // Otherwise they appear in every participant list

        $canviewroles    = get_roles_with_capability('moodle/course:view', CAP_ALLOW, $context);
        $doanythingroles = get_roles_with_capability('moodle/site:doanything', CAP_ALLOW, $sitecontext);

        foreach ($roles as $role) {
            if (!isset($canviewroles[$role->id])) {   // Avoid this role (eg course creator)
                $avoidroles[] = $role->id;
                unset($roles[$role->id]);
                continue;
            }
            if (isset($doanythingroles[$role->id])) {   // Avoid this role (ie admin)
                $avoidroles[] = $role->id;
                unset($roles[$role->id]);
                continue;
            }
            $rolenames[$role->id] = strip_tags(role_get_name($role, $context));   // Used in menus etc later on
        }
    }

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

    add_to_log($course->id, 'user', 'view all', 'index.php?id='.$course->id, '');

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

    $countries = get_list_of_countries();

    $strnever = get_string('never');

    $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 forum
/// 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 $course->groupmodeforce and
                         !has_capability('moodle/site:accessallgroups', $context));

    if ($isseparategroups and (!$currentgroup) ) {
        $navlinks = array();
        $navlinks[] = array('name' => get_string('participants'), 'link' => null, 'type' => 'misc');
        $navigation = build_navigation($navlinks);

        print_header("$course->shortname: ".get_string('participants'), $course->fullname, $navigation, "", "", true, "&nbsp;", navmenu($course));
        print_heading(get_string("notingroup", "forum"));
        print_footer($course);
        exit;
    }

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

/// Print headers

    $navlinks = array();
    $navlinks[] = array('name' => get_string('participants'), 'link' => null, 'type' => 'misc');
    $navigation = build_navigation($navlinks);

    print_header("$course->shortname: ".get_string('participants'), $course->fullname, $navigation, "", "", true, "&nbsp;", navmenu($course));

/// setting up tags
    if ($course->id == SITEID) {
        $filtertype = 'site';
    } else if ($course->id && !$currentgroup) {
        $filtertype = 'course';
        $filterselect = $course->id;
    } else {
        $filtertype = 'group';
        $filterselect = $currentgroup;
    }
    $currenttab = 'participants';
    $user = $USER;

    require_once($CFG->dirroot .'/user/tabs.php');


/// 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));
    }


/// Print settings and things in a table across the top

    echo '<table class="controls" cellspacing="0"><tr>';

/// Print my course menus
    if ($mycourses = get_my_courses($USER->id)) {
        echo '<td class="left">';
        $courselist = array();
        foreach ($mycourses as $mycourse) {
            $courselist[$mycourse->id] = format_string($mycourse->shortname);
        }
        popup_form($CFG->wwwroot.'/user/index.php?roleid='.$roleid.'&amp;sifirst=&amp;silast=&amp;id=',
                   $courselist, 'courseform', $course->id, '', '', '', false, 'self', get_string('mycourses'));
        echo '</td>';
    }

    echo '<td class="left">';
    groups_print_course_menu($course, $baseurl);
    echo '</td>';

    // get minimum lastaccess for this course and display a dropbox to filter by lastaccess going back this far.
    // this might not work anymore because you always going to get yourself as the most recent entry? added $USER!=$user ch
    $minlastaccess = get_field_sql('SELECT min(timeaccess) FROM '.$CFG->prefix.'user_lastaccess WHERE courseid = '.$course->id.' AND timeaccess != 0 AND userid!='.$USER->id);
    $lastaccess0exists = record_exists('user_lastaccess','courseid',$course->id,'timeaccess',0);
    $now = usergetmidnight(time());
    $timeaccess = array();

    // 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) {
        echo '<td class="left">';
        $baseurl = preg_replace('/&amp;accesssince='.$accesssince.'/','',$baseurl);
        popup_form($baseurl.'&amp;accesssince=',$timeoptions,'timeoptions',$accesssince, '', '', '', false, 'self', get_string('usersnoaccesssince'));
        echo '</td>';
    }

    // Decide wheteher we will fetch extra enrolment/groups data.
    //
    // MODE_ENROLDETAILS is expensive, and only suitable where the listing is small
    // (at or below DEFAULT_PAGE_SIZE) and $USER can enrol/unenrol
    // (will take 1 extra DB query - 2 on Oracle)
    //
    if ($course->id != SITEID && $perpage <= DEFAULT_PAGE_SIZE 
        && has_capability('moodle/role:assign',$context)) {
        $allowenroldetails=true;
    } else {
        $allowenroldetails=false;
    }
    if ($mode === MODE_ENROLDETAILS && !($allowenroldetails)) {
        // conditions haven't been met - reset
        $mode = MODE_BRIEF;
    }

    echo '<td class="right">';
    $formatmenu = array( '0' => get_string('brief'),
                         '1' => get_string('userdetails'));
    if ($allowenroldetails) {
        $formatmenu['2']= get_string('enroldetails');
    }
    popup_form($baseurl.'&amp;mode=', $formatmenu, 'formatmenu', $mode, '', '', '', false, 'self', get_string('userlist'));
    echo '</td></tr></table>';

    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))) {
                echo '<table class="groupinfobox"><tr><td class="left side picture">';
                print_group_picture($group, $course->id, true, false, false);
                echo '</td><td class="content">';
                echo '<h3>'.$group->name;
                if (has_capability('moodle/course:managegroups', $context)) {
                    echo '&nbsp;<a title="'.get_string('editgroupprofile').'" href="'.$CFG->wwwroot.'/group/group.php?id='.$group->id.'&amp;courseid='.$group->courseid.'">';
                    echo '<img src="'.$CFG->pixpath.'/t/edit.gif" alt="'.get_string('editgroupprofile').'" />';
                    echo '</a>';
                }
                echo '</h3>';
                echo format_text($group->description);
                echo '</td></tr></table>';
            }
        }
    }

    /// Define a table showing a list of users in the current role selection

    $tablecolumns = array('userpic', 'fullname');
    $tableheaders = array(get_string('userpic'), get_string('fullname'));
    if ($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';
        $tableheaders[] = get_string('lastaccess');
    }

    if ($course->enrolperiod) {
        $tablecolumns[] = 'timeend';
        $tableheaders[] = get_string('enrolmentend');
    }

    if ($mode === MODE_ENROLDETAILS) {
        $tablecolumns[] = 'roles';
        $tableheaders[] = get_string('roles');
        if ($groupmode != 0) {
            $tablecolumns[] = 'groups';
            $tableheaders[] = get_string('groups');
            if (!empty($CFG->enablegroupings)) {
                $tablecolumns[] = 'groupings';
                $tableheaders[] = get_string('groupings', 'group');
            }
        }
    }

    if ($bulkoperations) {
        $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);

    $table->sortable(true, 'lastaccess', SORT_DESC);
    $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();


    // we are looking for all users with this role assigned in this context or higher
    if ($usercontexts = get_parent_contexts($context)) {
        $listofcontexts = '('.implode(',', $usercontexts).')';
    } else {
        $listofcontexts = '('.$sitecontext->id.')'; // must be site
    }
    if ($roleid) {
        $selectrole = " AND r.roleid = $roleid ";
    } else {
        $selectrole = " ";
    }
    
    if ($context->id != $frontpagectx->id) {
        $select = 'SELECT DISTINCT u.id, u.username, u.firstname, u.lastname,
                      u.email, u.city, u.country, u.picture,
                      u.lang, u.timezone, u.emailstop, u.maildisplay, u.imagealt,
                      COALESCE(ul.timeaccess, 0) AS lastaccess,
                      r.hidden,
                      ctx.id AS ctxid, ctx.path AS ctxpath,
                      ctx.depth AS ctxdepth, ctx.contextlevel AS ctxlevel ';    
        $select .= $course->enrolperiod?', r.timeend ':'';
    } else {
        $select = 'SELECT u.id, u.username, u.firstname, u.lastname,
                      u.email, u.city, u.country, u.picture,
                      u.lang, u.timezone, u.emailstop, u.maildisplay, u.imagealt,
                      u.lastaccess,
                      ctx.id AS ctxid, ctx.path AS ctxpath,
                      ctx.depth AS ctxdepth, ctx.contextlevel AS ctxlevel ';
    }

    if ($context->id != $frontpagectx->id) {
        $from   = "FROM {$CFG->prefix}user u
                LEFT OUTER JOIN {$CFG->prefix}context ctx
                    ON (u.id=ctx.instanceid AND ctx.contextlevel = ".CONTEXT_USER.")
                JOIN {$CFG->prefix}role_assignments r
                    ON u.id=r.userid
                LEFT OUTER JOIN {$CFG->prefix}user_lastaccess ul
                    ON (r.userid=ul.userid and ul.courseid = $course->id) ";
    } else {
        $from = "FROM {$CFG->prefix}user u
                LEFT OUTER JOIN {$CFG->prefix}context ctx
                    ON (u.id=ctx.instanceid AND ctx.contextlevel = ".CONTEXT_USER.") ";               
     
    }
    
    $hiddensql = has_capability('moodle/role:viewhiddenassigns', $context)? '':' AND r.hidden = 0 ';

    // exclude users with roles we are avoiding
    if ($avoidroles) {
        $adminroles = 'AND r.roleid NOT IN (';
        $adminroles .= implode(',', $avoidroles);
        $adminroles .= ')';
    } else {
        $adminroles = '';
    }

    // join on 2 conditions
    // otherwise we run into the problem of having records in ul table, but not relevant course
    // and user record is not pulled out
    
    if ($context->id != $frontpagectx->id) {
        $where  = "WHERE (r.contextid = $context->id OR r.contextid in $listofcontexts)
            AND u.deleted = 0 $selectrole
            AND (ul.courseid = $course->id OR ul.courseid IS NULL)
            AND u.username != 'guest'
            $adminroles
            $hiddensql ";
            $where .= get_lastaccess_sql($accesssince);
    } else {
        $where = "WHERE u.deleted = 0
            AND u.username != 'guest'";
            $where .= get_lastaccess_sql($accesssince); 
    }
    $wheresearch = '';

    if (!empty($search)) {
        $LIKE = sql_ilike();
        $fullname  = sql_fullname('u.firstname','u.lastname');
        $wheresearch .= ' AND ('. $fullname .' '. $LIKE .'\'%'. $search .'%\' OR email '. $LIKE .'\'%'. $search .'%\' OR idnumber '.$LIKE.' \'%'.$search.'%\') ';

    }

    if ($currentgroup) {    // Displaying a group by choice
        // FIX: TODO: This will not work if $currentgroup == 0, i.e. "those not in a group"
        $from  .= 'LEFT JOIN '.$CFG->prefix.'groups_members gm ON u.id = gm.userid ';
        $where .= ' AND gm.groupid = '.$currentgroup;
    }

    $totalcount = count_records_sql('SELECT COUNT(distinct u.id) '.$from.$where);   // Each user could have > 1 role

    if ($table->get_sql_where()) {
        $where .= ' AND '.$table->get_sql_where();
    }

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

    $matchcount = count_records_sql('SELECT COUNT(distinct u.id) '.$from.$where.$wheresearch);

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

    $userlist = get_recordset_sql($select.$from.$where.$wheresearch.$sort,
            $table->get_page_start(),  $table->get_page_size());

    //
    // The SELECT behind get_participants_extra() is cheaper if we pass an array
    // if IDs. We could pass the SELECT we did before (with the limit bits - tricky!)
    // but this is much cheaper. And in any case, it is only doable with limited numbers
    // of rows anyway. On a large course it will explode badly...
    //
    if ($mode===MODE_ENROLDETAILS) {
        $userids = array();

        while ($user = rs_fetch_next_record($userlist)) {
            $userids[] = $user->id;
        }
        $userlist_extra = get_participants_extra($userids, $avoidroles, $course, $context);

        // Only Oracle cannot seek backwards
        // and must re-query...
        if ($userlist->canSeek === true) {
            $userlist->MoveFirst();
        } else {
            $userlist = get_recordset_sql($select.$from.$where.$wheresearch.$sort,
                                          $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 get_string('currentrole', 'role').': ';
        $rolenames = array(0 => get_string('all')) + $rolenames;
        popup_form("$CFG->wwwroot/user/index.php?contextid=$context->id&amp;sifirst=&amp;silast=&amp;roleid=", $rolenames,
                   'rolesform', $roleid, '');
        echo '</div>';
    }

    if ($roleid) {
        if (!$currentrole = get_record('role','id',$roleid)) {
            error('That role does not exist');
        }
        $a->number = $totalcount;
        // MDL-12217, use course specific rolename
        if (isset($rolenames[$currentrole->id])){
            $a->role = $rolenames[$currentrole->id];
        }else{                
            $a->role = $currentrole->name;//safety net
        }
        $heading = format_string(get_string('xuserswiththerole', 'role', $a));
        if (user_can_assign($context, $roleid)) {
            $heading .= ' <a href="'.$CFG->wwwroot.'/'.$CFG->admin.'/roles/assign.php?roleid='.$roleid.'&amp;contextid='.$context->id.'">';
            $heading .= '<img src="'.$CFG->pixpath.'/i/edit.gif" class="icon" alt="" /></a>';
        }
        print_heading($heading, 'center', 3);
    } else {
        if ($matchcount < $totalcount) {
            print_heading(get_string('allparticipants').': '.$matchcount.'/'.$totalcount, '', 3);
        } else {
            print_heading(get_string('allparticipants').': '.$matchcount, '', 3);
        }
    }


    if ($bulkoperations) {
        echo '
        <script type="text/javascript">
        //<![CDATA[
        function checksubmit(form) {
            var destination = form.formaction.options[form.formaction.selectedIndex].value;
            if (destination == "" || !checkchecked(form)) {
                form.formaction.selectedIndex = 0;
                return false;
            } else {
                return true;
            }
        }

        function checkchecked(form) {
            var inputs = document.getElementsByTagName(\'INPUT\');
            var checked = false;
            inputs = filterByParent(inputs, function() {return form;});
            for(var i = 0; i < inputs.length; ++i) {
                if (inputs[i].type == \'checkbox\' && inputs[i].checked) {
                    checked = true;
                }
            }
            return checked;
        }
        //]]>
        </script>
            ';
        echo '<form action="action_redir.php" method="post" id="participantsform" onsubmit="return checksubmit(this);">';
        echo '<div>';
        echo '<input type="hidden" name="sesskey" value="'.$USER->sesskey.'" />';
        echo '<input type="hidden" name="returnto" value="'.s($_SERVER['REQUEST_URI']).'" />';
    }

    if ($CFG->longtimenosee > 0 && $CFG->longtimenosee < 1000 && $totalcount > 0) {
        echo '<p id="longtimenosee">('.get_string('unusedaccounts', '', $CFG->longtimenosee).')</p>';
    }

    if ($mode===MODE_USERDETAILS) {    // Print simple listing
        if ($totalcount < 1) {
            print_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'));

                // Bar of first initials

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

                // Bar of last initials

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

                print_paging_bar($matchcount, intval($table->get_page_start() / $perpage), $perpage, $baseurl.'&amp;', 'spage');
            }

            if ($matchcount > 0) {
                while ($user = rs_fetch_next_record($userlist)) {
                    $user = make_context_subobj($user);
                    print_user($user, $course, $bulkoperations);
                }

            } else {
                print_heading(get_string('nothingtodisplay'));
            }
        }

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


        if ($userlist)  {

            // only show the plugin if multiple enrolment plugins
            // are enabled...
            if (strpos($CFG->enrol_plugins_enabled, ',')=== false) {
                $showenrolplugin = true;
            } else {
                $showenrolplugin = false;
            }
            
            while ($user = rs_fetch_next_record($userlist)) {
                $user = make_context_subobj($user);
                if ( !empty($user->hidden) ) {
                // if the assignment is hidden, display icon
                    $hidden = " <img src=\"{$CFG->pixpath}/t/hide.gif\" alt=\"".get_string('hiddenassign')."\" class=\"hide-show-image\"/>";
                } else {
                    $hidden = '';
                }

                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];
                    }
                }

                if (!isset($user->context)) {
                    $usercontext = get_context_instance(CONTEXT_USER, $user->id);
                } else {
                    $usercontext = $user->context;
                }

                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>';
                }

                $data = array (
                        print_user_picture($user, $course->id, $user->picture, false, true, $piclink),
                        $profilelink . $hidden);

                if ($mode === MODE_BRIEF && !isset($hiddenfields['city'])) {
                    $data[] = $user->city;
                }
                if ($mode === MODE_BRIEF && !isset($hiddenfields['country'])) {
                    $data[] = $country;
                }
                if (!isset($hiddenfields['lastaccess'])) {
                    $data[] = $lastaccess;
                }
                if ($course->enrolperiod) {
                    if ($user->timeend) {
                        $data[] = userdate($user->timeend, $timeformat);
                    } else {
                        $data[] = get_string('unlimited');
                    }
                }

                if (isset($userlist_extra) && isset($userlist_extra[$user->id])) {
                    $ras = $userlist_extra[$user->id]['ra'];
                    $rastring = '';
                    foreach ($ras AS $key=>$ra) {
                        $rolename = $rolenames [ $ra['roleid'] ] ;
                        if ($ra['ctxlevel'] == CONTEXT_COURSECAT) {
                            $rastring .= $rolename. ' @ ' . '<a href="'.$CFG->wwwroot.'/course/category.php?id='.$ra['ctxinstanceid'].'">'.s($ra['ccname']).'</a>';
                        } elseif ($ra['ctxlevel'] == CONTEXT_SYSTEM) {
                            $rastring .= $rolename. ' - ' . get_string('globalrole','role');
                        } else {
                            $rastring .= $rolename;
                        }
                        if ($showenrolplugin) {
                            $rastring .= '<br />';
                        } else {
                            $rastring .= ' ('. $ra['enrolplugin'] .')<br />';
                        }
                    }
                    $data[] = $rastring; 
                    if ($groupmode != 0) {
                        // htmlescape with s() and implode the array
                        $data[] = implode(', ', array_map('s',$userlist_extra[$user->id]['group']));
                        if (!empty($CFG->enablegroupings)) {
                            $data[] = implode(', ', array_map('s', $userlist_extra[$user->id]['gping']));
                        }
                    }
                }

                if ($bulkoperations) {
                    $data[] = '<input type="checkbox" name="user'.$user->id.'" />';
                }
                $table->add_data($data);

            }
        }

        $table->print_html();

    }

    if ($bulkoperations) {
        echo '<br /><div class="buttons">';
        echo '<input type="button" onclick="checkall()" value="'.get_string('selectall').'" /> ';
        echo '<input type="button" onclick="checknone()" value="'.get_string('deselectall').'" /> ';
        $displaylist = array();
        $displaylist['messageselect.php'] = get_string('messageselectadd');
        if (has_capability('moodle/notes:manage', $context) && $context->id != $frontpagectx->id) {
            $displaylist['addnote.php'] = get_string('addnewnote', 'notes');
            $displaylist['groupaddnote.php'] = get_string('groupaddnewnote', 'notes');
        }

        if ($context->id != $frontpagectx->id) {
            $displaylist['extendenrol.php'] = get_string('extendenrol');
            $displaylist['groupextendenrol.php'] = get_string('groupextendenrol');
        }

        helpbutton("participantswithselectedusers", get_string("withselectedusers"));
        choose_from_menu ($displaylist, "formaction", "", get_string("withselectedusers"), "if(checksubmit(this.form))this.form.submit();", "");
        echo '<input type="hidden" name="id" value="'.$course->id.'" />';
        echo '<input type="submit" value="' . get_string('ok') . '" />';
        echo '</div>';
        echo '</div>';
        echo '</form>';

    }

    if ($bulkoperations && $totalcount > ($perpage*3)) {
        echo '<form action="index.php"><div><input type="hidden" name="id" value="'.$course->id.'" />'.get_string('search').':&nbsp;'."\n";
        echo '<input type="text" name="search" value="'.s($search).'" />&nbsp;<input type="submit" value="'.get_string('search').'" /></div></form>'."\n";
    }

    $perpageurl = preg_replace('/&amp;perpage=\d*/','', $baseurl);
    if ($perpage == SHOW_ALL_PAGE_SIZE) {
        echo '<div id="showall"><a href="'.$perpageurl.'&amp;perpage='.DEFAULT_PAGE_SIZE.'">'.get_string('showperpage', '', DEFAULT_PAGE_SIZE).'</a></div>';

    } else if ($matchcount > 0 && $perpage < $matchcount) {
        echo '<div id="showall"><a href="'.$perpageurl.'&amp;perpage='.SHOW_ALL_PAGE_SIZE.'">'.get_string('showall', '', $matchcount).'</a></div>';
    }

    print_footer($course);

    if ($userlist) {
        rs_close($userlist);
    }


function get_lastaccess_sql($accesssince='') {
    if (empty($accesssince)) {
        return '';
    }
    if ($accesssince == -1) { // never
        return ' AND ul.timeaccess = 0';
    } else {
        return ' AND ul.timeaccess != 0 AND timeaccess < '.$accesssince;
    }
}

function get_participants_extra ($userids, $avoidroles, $course, $context) {

    global $CFG;

    if (count($userids) === 0 || count($avoidroles) === 0) {
        return array();
    }

    $userids = implode(',', $userids);

    // turn the path into a list of context ids
    $contextids = substr($context->path, 1); // kill leading slash
    $contextids = str_replace('/', ',', $contextids);;

    if (count($avoidroles) > 0) {
        $avoidroles = implode(',', $avoidroles);
        $avoidrolescond = " AND ra.roleid NOT IN ($avoidroles) ";
    } else {
        $avoidrolescond = '';
    }

    if (!empty($CFG->enablegroupings)) {
        $gpjoin = "LEFT OUTER JOIN {$CFG->prefix}groupings_groups gpg
                     ON gpg.groupid=g.id
                   LEFT OUTER JOIN {$CFG->prefix}groupings gp
                     ON (gp.courseid={$course->id} AND gp.id=gpg.groupingid)";
        $gpselect = ',gp.id AS gpid, gp.name AS gpname ';
    } else {
        $gpjoin   = '';
        $gpselect = '';
    }

    // Note: this returns strange redundant rows, perhaps
    // due to the multiple OUTER JOINs. If we can tweak the
    // JOINs to avoid it ot
    $sql = "SELECT DISTINCT ra.userid, 
                   ctx.id AS ctxid, ctx.path AS ctxpath, ctx.depth AS ctxdepth, 
                   ctx.contextlevel AS ctxlevel, ctx.instanceid AS ctxinstanceid,
                   cc.name  AS ccname, 
                   ra.roleid AS roleid,
                   ra.enrol AS enrolplugin,
                   g.id     AS gid, g.name AS gname
                   $gpselect
            FROM {$CFG->prefix}role_assignments ra
            JOIN {$CFG->prefix}context ctx
              ON (ra.contextid=ctx.id)
            LEFT OUTER JOIN {$CFG->prefix}course_categories cc
              ON (ctx.contextlevel=40 AND ctx.instanceid=cc.id)

            /* only if groups active */
            LEFT OUTER JOIN {$CFG->prefix}groups_members gm
              ON (ra.userid=gm.userid)
            LEFT OUTER JOIN {$CFG->prefix}groups g
              ON (gm.groupid=g.id AND g.courseid={$course->id})
            /* and if groupings is enabled... */
            $gpjoin

            WHERE ra.userid IN ( $userids ) 
                  AND ra.contextid in ( $contextids ) 
                  $avoidrolescond

            ORDER BY ra.userid, ctx.depth DESC";

    $rs = get_recordset_sql($sql);
    $extra = array();

    // Data structure -
    // $extra [ $userid ] [ 'group' ] [ $groupid => 'group name']
    //                    [ 'gping' ] [ $gpingid => 'gping name']
    //                    [ 'ra' ] [  [ "$ctxid:$roleid" => [ctxid => $ctxid
    //                                                       ctxdepth =>  $ctxdepth, 
    //                                                       ctxpath => $ctxpath,
    //                                                       ctxname => 'name' (categories only)
    //                                                       ctxinstid => 
    //                                                       roleid => $roleid
    //                                                       enrol => $pluginname
    //
    // Might be interesting to add to RA timestart, timeend, timemodified,
    // and modifierid (with an outer join to mdl_user!
    //

    while ($rec = rs_fetch_next_record($rs)) {
        $userid = $rec->userid;

        // Prime an initial user rec...
        if (!isset($extra[$userid])) {
            $extra[$userid] = array( 'group' => array(),
                                     'gping' => array(),
                                     'ra'    => array() );
        }

        if (!empty($rec->gid)) {
            $extra[$userid]['group'][$rec->gid]= $rec->gname;
        }
        if (!empty($rec->gpid)) {
            $extra[$userid]['gping'][$rec->gpid]= $rec->gpname;
        }
        $rakey = $rec->ctxid . ':' . $rec->roleid;
        if (!isset($extra[$userid]['ra'][$rakey])) {
            $extra[$userid]['ra'][$rakey] = array('ctxid'         => $rec->ctxid,
                                                  'ctxlevel'       => $rec->ctxlevel,
                                                  'ctxinstanceid' => $rec->ctxinstanceid,
                                                  'ccname'        => $rec->ccname,
                                                  'roleid'        => $rec->roleid,
                                                  'enrolplugin'   => $rec->enrolplugin);

        }
    }
    return $extra;

}

?>