/calendar/lib.php

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<?php // $Id: lib.php,v 1.206.2.16 2012/05/11 14:18:36 moodlerobot Exp $



/////////////////////////////////////////////////////////////////////////////

//                                                                         //

// NOTICE OF COPYRIGHT                                                     //

//                                                                         //

// Moodle - Calendar extension                                             //

//                                                                         //

// Copyright (C) 2003-2004  Greek School Network            www.sch.gr     //

//                                                                         //

// Designed by:                                                            //

//     Avgoustos Tsinakos (tsinakos@teikav.edu.gr)                         //

//     Jon Papaioannou (pj@moodle.org)                                     //

//                                                                         //

// Programming and development:                                            //

//     Jon Papaioannou (pj@moodle.org)                                     //

//                                                                         //

// For bugs, suggestions, etc contact:                                     //

//     Jon Papaioannou (pj@moodle.org)                                     //

//                                                                         //

// The current module was developed at the University of Macedonia         //

// (www.uom.gr) under the funding of the Greek School Network (www.sch.gr) //

// The aim of this project is to provide additional and improved           //

// functionality to the Asynchronous Distance Education service that the   //

// Greek School Network deploys.                                           //

//                                                                         //

// This program 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 2 of the License, or       //

// (at your option) any later version.                                     //

//                                                                         //

// This program 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:                            //

//                                                                         //

//          http://www.gnu.org/copyleft/gpl.html                           //

//                                                                         //

/////////////////////////////////////////////////////////////////////////////



// These are read by the administration component to provide default values

define('CALENDAR_DEFAULT_UPCOMING_LOOKAHEAD', 21);

define('CALENDAR_DEFAULT_UPCOMING_MAXEVENTS', 10);

define('CALENDAR_DEFAULT_STARTING_WEEKDAY',   1);

// This is a packed bitfield: day X is "weekend" if $field & (1 << X) is true

// Default value = 65 = 64 + 1 = 2^6 + 2^0 = Saturday & Sunday

define('CALENDAR_DEFAULT_WEEKEND',            65);



// Fetch the correct values from admin settings/lang pack

// If no such settings found, use the above defaults

$firstday = isset($CFG->calendar_startwday) ? $CFG->calendar_startwday : get_string('firstdayofweek');

if(!is_numeric($firstday)) {

    define ('CALENDAR_STARTING_WEEKDAY', CALENDAR_DEFAULT_STARTING_WEEKDAY);

}

else {

    define ('CALENDAR_STARTING_WEEKDAY', intval($firstday) % 7);

}

define ('CALENDAR_UPCOMING_DAYS', isset($CFG->calendar_lookahead) ? intval($CFG->calendar_lookahead) : CALENDAR_DEFAULT_UPCOMING_LOOKAHEAD);

define ('CALENDAR_UPCOMING_MAXEVENTS', isset($CFG->calendar_maxevents) ? intval($CFG->calendar_maxevents) : CALENDAR_DEFAULT_UPCOMING_MAXEVENTS);

define ('CALENDAR_WEEKEND', isset($CFG->calendar_weekend) ? intval($CFG->calendar_weekend) : CALENDAR_DEFAULT_WEEKEND);

define ('CALENDAR_URL', $CFG->wwwroot.'/calendar/');

define ('CALENDAR_TF_24', '%H:%M');

define ('CALENDAR_TF_12', '%I:%M %p');



$CALENDARDAYS = array('sunday','monday','tuesday','wednesday','thursday','friday','saturday');







function calendar_get_mini($courses, $groups, $users, $cal_month = false, $cal_year = false) {

    global $CFG, $USER;



    $display = new stdClass;

    $display->minwday = get_user_preferences('calendar_startwday', CALENDAR_STARTING_WEEKDAY);

    $display->maxwday = $display->minwday + 6;



    $content = '';



    if(!empty($cal_month) && !empty($cal_year)) {

        $thisdate = usergetdate(time()); // Date and time the user sees at his location

        if($cal_month == $thisdate['mon'] && $cal_year == $thisdate['year']) {

            // Navigated to this month

            $date = $thisdate;

            $display->thismonth = true;

        }

        else {

            // Navigated to other month, let's do a nice trick and save us a lot of work...

            if(!checkdate($cal_month, 1, $cal_year)) {

                $date = array('mday' => 1, 'mon' => $thisdate['mon'], 'year' => $thisdate['year']);

                $display->thismonth = true;

            }

            else {

                $date = array('mday' => 1, 'mon' => $cal_month, 'year' => $cal_year);

                $display->thismonth = false;

            }

        }

    }

    else {

        $date = usergetdate(time()); // Date and time the user sees at his location

        $display->thismonth = true;

    }



    // Fill in the variables we 're going to use, nice and tidy

    list($d, $m, $y) = array($date['mday'], $date['mon'], $date['year']); // This is what we want to display

    $display->maxdays = calendar_days_in_month($m, $y);



    if (get_user_timezone_offset() < 99) {

        // We 'll keep these values as GMT here, and offset them when the time comes to query the db

        $display->tstart = gmmktime(0, 0, 0, $m, 1, $y); // This is GMT

        $display->tend = gmmktime(23, 59, 59, $m, $display->maxdays, $y); // GMT

    } else {

        // no timezone info specified

        $display->tstart = mktime(0, 0, 0, $m, 1, $y);

        $display->tend = mktime(23, 59, 59, $m, $display->maxdays, $y);

    }



    $startwday = dayofweek(1, $m, $y);



    // Align the starting weekday to fall in our display range

    // This is simple, not foolproof.

    if($startwday < $display->minwday) {

        $startwday += 7;

    }



    // TODO: THIS IS TEMPORARY CODE!

    // [pj] I was just reading through this and realized that I when writing this code I was probably

    // asking for trouble, as all these time manipulations seem to be unnecessary and a simple

    // make_timestamp would accomplish the same thing. So here goes a test:

    //$test_start = make_timestamp($y, $m, 1);

    //$test_end   = make_timestamp($y, $m, $display->maxdays, 23, 59, 59);

    //if($test_start != usertime($display->tstart) - dst_offset_on($display->tstart)) {

        //notify('Failed assertion in calendar/lib.php line 126; display->tstart = '.$display->tstart.', dst_offset = '.dst_offset_on($display->tstart).', usertime = '.usertime($display->tstart).', make_t = '.$test_start);

    //}

    //if($test_end != usertime($display->tend) - dst_offset_on($display->tend)) {

        //notify('Failed assertion in calendar/lib.php line 130; display->tend = '.$display->tend.', dst_offset = '.dst_offset_on($display->tend).', usertime = '.usertime($display->tend).', make_t = '.$test_end);

    //}





    // Get the events matching our criteria. Don't forget to offset the timestamps for the user's TZ!

    $events = calendar_get_events(

        usertime($display->tstart) - dst_offset_on($display->tstart),

        usertime($display->tend) - dst_offset_on($display->tend),

        $users, $groups, $courses);



    // Set event course class for course events

    if (!empty($events)) {

        foreach ($events as $eventid => $event) {

            if (!empty($event->modulename)) {

                $cm = get_coursemodule_from_instance($event->modulename, $event->instance);

                if (!groups_course_module_visible($cm)) {

                    unset($events[$eventid]);

                }

            }

        }

    }



    // This is either a genius idea or an idiot idea: in order to not complicate things, we use this rule: if, after

    // possibly removing SITEID from $courses, there is only one course left, then clicking on a day in the month

    // will also set the $SESSION->cal_courses_shown variable to that one course. Otherwise, we 'd need to add extra

    // arguments to this function.



    $morehref = '';

    if(!empty($courses)) {

        $courses = array_diff($courses, array(SITEID));

        if(count($courses) == 1) {

            $morehref = '&amp;course='.reset($courses);

        }

    }



    // We want to have easy access by day, since the display is on a per-day basis.

    // Arguments passed by reference.

    //calendar_events_by_day($events, $display->tstart, $eventsbyday, $durationbyday, $typesbyday);

    calendar_events_by_day($events, $m, $y, $eventsbyday, $durationbyday, $typesbyday, $courses);



    //Accessibility: added summary and <abbr> elements.

    ///global $CALENDARDAYS; appears to be broken.

    $days_title = array('sunday','monday','tuesday','wednesday','thursday','friday','saturday');



    $summary = get_string('calendarheading', 'calendar', userdate(make_timestamp($y, $m), get_string('strftimemonthyear')));

    $summary = get_string('tabledata', 'access', $summary);

    $content .= '<table class="minicalendar" summary="'.$summary.'">'; // Begin table

    $content .= '<tr class="weekdays">'; // Header row: day names



    // Print out the names of the weekdays

    $days = array('sun', 'mon', 'tue', 'wed', 'thu', 'fri', 'sat');

    for($i = $display->minwday; $i <= $display->maxwday; ++$i) {

        // This uses the % operator to get the correct weekday no matter what shift we have

        // applied to the $display->minwday : $display->maxwday range from the default 0 : 6

        $content .= '<th scope="col"><abbr title="'. get_string($days_title[$i % 7], 'calendar') .'">'.

            get_string($days[$i % 7], 'calendar') ."</abbr></th>\n";

    }



    $content .= '</tr><tr>'; // End of day names; prepare for day numbers



    // For the table display. $week is the row; $dayweek is the column.

    $dayweek = $startwday;



    // Paddding (the first week may have blank days in the beginning)

    for($i = $display->minwday; $i < $startwday; ++$i) {

        $content .= '<td class="dayblank">&nbsp;</td>'."\n";

    }



    // Now display all the calendar

    for($day = 1; $day <= $display->maxdays; ++$day, ++$dayweek) {

        if($dayweek > $display->maxwday) {

            // We need to change week (table row)

            $content .= '</tr><tr>';

            $dayweek = $display->minwday;

        }



        // Reset vars

        $cell = '';

        if(CALENDAR_WEEKEND & (1 << ($dayweek % 7))) {

            // Weekend. This is true no matter what the exact range is.

            $class = 'weekend day';

        }

        else {

            // Normal working day.

            $class = 'day';

        }



        // Special visual fx if an event is defined

        if(isset($eventsbyday[$day])) {

            $dayhref = calendar_get_link_href(CALENDAR_URL.'view.php?view=day'.$morehref.'&amp;', $day, $m, $y);



            // OverLib popup

            $popupcontent = '';

            foreach($eventsbyday[$day] as $eventid) {

                if (!isset($events[$eventid])) {

                    continue;

                }

                $event = $events[$eventid];

                if(!empty($event->modulename)) {

                    $popupicon = $CFG->modpixpath.'/'.$event->modulename.'/icon.gif';

                    $popupalt  = $event->modulename;



                } else if ($event->courseid == SITEID) {                                // Site event

                    $popupicon = $CFG->pixpath.'/c/site.gif';

                    $popupalt  = '';

                } else if ($event->courseid != 0 && $event->courseid != SITEID && $event->groupid == 0) {      // Course event

                    $popupicon = $CFG->pixpath.'/c/course.gif';

                    $popupalt  = '';

                } else if ($event->groupid) {                                      // Group event

                    $popupicon = $CFG->pixpath.'/c/group.gif';

                    $popupalt  = '';

                } else if ($event->userid) {                                       // User event

                    $popupicon = $CFG->pixpath.'/c/user.gif';

                    $popupalt  = '';

                }

                $popupcontent .= '<div><img class="icon" src="'.$popupicon.'" alt="'.$popupalt.'" /><a href="'.$dayhref.'#event_'.$event->id.'">'.format_string($event->name, true).'</a></div>';

            }



            //Accessibility: functionality moved to calendar_get_popup.

            if($display->thismonth && $day == $d) {

                $popup = calendar_get_popup(true, $events[$eventid]->timestart, $popupcontent);

            } else {

                $popup = calendar_get_popup(false, $events[$eventid]->timestart, $popupcontent);

            }



            // Class and cell content

            if(isset($typesbyday[$day]['startglobal'])) {

                $class .= ' event_global';

            }

            else if(isset($typesbyday[$day]['startcourse'])) {

                $class .= ' event_course';

            }

            else if(isset($typesbyday[$day]['startgroup'])) {

                $class .= ' event_group';

            }

            else if(isset($typesbyday[$day]['startuser'])) {

                $class .= ' event_user';

            }

            $cell = '<a href="'.$dayhref.'" '.$popup.'>'.$day.'</a>';

        }

        else {

            $cell = $day;

        }



        if(isset($typesbyday[$day]['durationglobal'])) {

            $class .= ' duration_global';

        }

        else if(isset($typesbyday[$day]['durationcourse'])) {

            $class .= ' duration_course';

        }

        else if(isset($typesbyday[$day]['durationgroup'])) {

            $class .= ' duration_group';

        }

        else if(isset($typesbyday[$day]['durationuser'])) {

            $class .= ' duration_user';

        }



        // If event has a class set then add it to the table day <td> tag

        // Note: only one colour for minicalendar

        if(isset($eventsbyday[$day])) {

            foreach($eventsbyday[$day] as $eventid) {

                if (!isset($events[$eventid])) {

                    continue;

                }

                $event = $events[$eventid];

                if (!empty($event->class)) {

                    $class .= ' '.$event->class;

                }

                break;

            }

        }



        // Special visual fx for today

        //Accessibility: hidden text for today, and popup.

        if($display->thismonth && $day == $d) {

            $class .= ' today';

            $today = get_string('today', 'calendar').' '.userdate(time(), get_string('strftimedayshort'));



            if(! isset($eventsbyday[$day])) {

                $class .= ' eventnone';

                $popup = calendar_get_popup(true, false);

                $cell = '<a href="#" '.$popup.'>'.$day.'</a>';

            }

            $cell = get_accesshide($today.' ').$cell;

        }



        // Just display it

        if(!empty($class)) {

            $class = ' class="'.$class.'"';

        }

        $content .= '<td'.$class.'>'.$cell."</td>\n";

    }



    // Paddding (the last week may have blank days at the end)

    for($i = $dayweek; $i <= $display->maxwday; ++$i) {

        $content .= '<td class="dayblank">&nbsp;</td>';

    }

    $content .= '</tr>'; // Last row ends



    $content .= '</table>'; // Tabular display of days ends



    return $content;

}



/**

 * calendar_get_popup, called at multiple points in from calendar_get_mini.

 *        Copied and modified from calendar_get_mini.

 * @uses OverLib popup.

 * @param $is_today bool, false except when called on the current day.

 * @param $event_timestart mixed, $events[$eventid]->timestart, OR false if there are no events.

 * @param $popupcontent string.

 * @return $popup string, contains onmousover and onmouseout events.

 */

function calendar_get_popup($is_today, $event_timestart, $popupcontent='') {

    $popupcaption = '';

    if($is_today) {

        $popupcaption = get_string('today', 'calendar').' ';

    }

    if (false === $event_timestart) {

        $popupcaption .= userdate(time(), get_string('strftimedayshort'));

        $popupcontent = get_string('eventnone', 'calendar');



    } else {

        $popupcaption .= get_string('eventsfor', 'calendar', userdate($event_timestart, get_string('strftimedayshort')));

    }

    $popupcontent = str_replace("'", "\'", htmlspecialchars($popupcontent));

    $popupcaption = str_replace("'", "\'", htmlspecialchars($popupcaption));

    $popup = 'onmouseover="return overlib(\''.$popupcontent.'\', CAPTION, \''.$popupcaption.'\');" onmouseout="return nd();"';

    return $popup;

}



function calendar_get_upcoming($courses, $groups, $users, $daysinfuture, $maxevents, $fromtime=0) {

    global $CFG, $COURSE;



    $display = new stdClass;

    $display->range = $daysinfuture; // How many days in the future we 'll look

    $display->maxevents = $maxevents;



    $output = array();



    // Prepare "course caching", since it may save us a lot of queries

    $coursecache = array();



    $processed = 0;

    $now = time(); // We 'll need this later

    $usermidnighttoday = usergetmidnight($now);



    if ($fromtime) {

        $display->tstart = $fromtime;

    } else {

        $display->tstart = $usermidnighttoday;

    }



    // This works correctly with respect to the user's DST, but it is accurate

    // only because $fromtime is always the exact midnight of some day!

    $display->tend = usergetmidnight($display->tstart + DAYSECS * $display->range + 3 * HOURSECS) - 1;



    // Get the events matching our criteria

    $events = calendar_get_events($display->tstart, $display->tend, $users, $groups, $courses);



    // This is either a genius idea or an idiot idea: in order to not complicate things, we use this rule: if, after

    // possibly removing SITEID from $courses, there is only one course left, then clicking on a day in the month

    // will also set the $SESSION->cal_courses_shown variable to that one course. Otherwise, we 'd need to add extra

    // arguments to this function.



    $morehref = '';

    if(!empty($courses)) {

        $courses = array_diff($courses, array(SITEID));

        if(count($courses) == 1) {

            $morehref = '&amp;course='.reset($courses);

        }

    }



    if ($events !== false) {



        $modinfo =& get_fast_modinfo($COURSE);



        foreach($events as $event) {





            if (!empty($event->modulename)) {

                if ($event->courseid == $COURSE->id) {

                    if (isset($modinfo->instances[$event->modulename][$event->instance])) {

                        $cm = $modinfo->instances[$event->modulename][$event->instance];

                        if (!$cm->uservisible) {

                            continue;

                        }

                    }

                } else {

                    if (!$cm = get_coursemodule_from_instance($event->modulename, $event->instance)) {

                        continue;

                    }

                    if (!coursemodule_visible_for_user($cm)) {

                        continue;

                    }

                }

                if ($event->modulename == 'assignment'){

                    // TODO: rewrite this hack somehow

                    if (!calendar_edit_event_allowed($event)){ // cannot manage entries, eg. student  

                        if(!$assignment = get_record('assignment','id',$event->instance)){

                            // error("assignment ID was incorrect");

                            continue;

                        }

                        // assign assignment to assignment object to use hidden_is_hidden method

                        require_once($CFG->dirroot.'/mod/assignment/lib.php');



                        if (!file_exists($CFG->dirroot.'/mod/assignment/type/'.$assignment->assignmenttype.'/assignment.class.php')) {

                            continue;

                        }

                        require_once ($CFG->dirroot.'/mod/assignment/type/'.$assignment->assignmenttype.'/assignment.class.php');



                        $assignmentclass = 'assignment_'.$assignment->assignmenttype;

                        $assignmentinstance = new $assignmentclass($cm->id, $assignment, $cm);



                        if ($assignmentinstance->description_is_hidden()){//force not to show description before availability

                            $event->description = get_string('notavailableyet', 'assignment');

                        }

                    }

                }

            }



            if ($processed >= $display->maxevents) {

                break;

            }



            $event->time = calendar_format_event_time($event, $now, $morehref);

            $output[] = $event;

            ++$processed;

        }

    }

    return $output;

}



function calendar_add_event_metadata($event) {

    global $CFG;



    //Support multilang in event->name

    $event->name = format_string($event->name,true);



    if(!empty($event->modulename)) {                                // Activity event

        // The module name is set. I will assume that it has to be displayed, and

        // also that it is an automatically-generated event. And of course that the

        // fields for get_coursemodule_from_instance are set correctly.

        $module = calendar_get_module_cached($coursecache, $event->modulename, $event->instance);



        if ($module === false) {

            return;

        }



        $modulename = get_string('modulename', $event->modulename);

        $eventtype = get_string($event->eventtype, $event->modulename);

        $icon = $CFG->modpixpath.'/'.$event->modulename.'/icon.gif';



        $event->icon = '<img height="16" width="16" src="'.$icon.'" alt="'.$eventtype.'" title="'.$modulename.'" style="vertical-align: middle;" />';

        $event->referer = '<a href="'.$CFG->wwwroot.'/mod/'.$event->modulename.'/view.php?id='.$module->id.'">'.$event->name.'</a>';

        $event->courselink = '<a href="'.$CFG->wwwroot.'/course/view.php?id='.$module->course.'">'.$coursecache[$module->course]->fullname.'</a>';

        $event->cmid = $module->id;





    } else if($event->courseid == SITEID) {                              // Site event

        $event->icon = '<img height="16" width="16" src="'.$CFG->pixpath.'/c/site.gif" alt="'.get_string('globalevent', 'calendar').'" style="vertical-align: middle;" />';

        $event->cssclass = 'event_global';

    } else if($event->courseid != 0 && $event->courseid != SITEID && $event->groupid == 0) {          // Course event

        calendar_get_course_cached($coursecache, $event->courseid);

        $event->icon = '<img height="16" width="16" src="'.$CFG->pixpath.'/c/course.gif" alt="'.get_string('courseevent', 'calendar').'" style="vertical-align: middle;" />';

        $event->courselink = '<a href="'.$CFG->wwwroot.'/course/view.php?id='.$event->courseid.'">'.$coursecache[$event->courseid]->fullname.'</a>';

        $event->cssclass = 'event_course';

    } else if ($event->groupid) {                                    // Group event

        $event->icon = '<img height="16" width="16" src="'.$CFG->pixpath.'/c/group.gif" alt="'.get_string('groupevent', 'calendar').'" style="vertical-align: middle;" />';

        $event->cssclass = 'event_group';

    } else if($event->userid) {                                      // User event

        $event->icon = '<img height="16" width="16" src="'.$CFG->pixpath.'/c/user.gif" alt="'.get_string('userevent', 'calendar').'" style="vertical-align: middle;" />';

        $event->cssclass = 'event_user';

    }

    return $event;

}



function calendar_print_event($event) {

    global $CFG, $USER;



    static $strftimetime;



    $event = calendar_add_event_metadata($event);

    echo '<a name="event_'.$event->id.'"></a><table class="event" cellspacing="0">';

    echo '<tr><td class="picture">';

    if (!empty($event->icon)) {

        echo $event->icon;

    } else {

        print_spacer(16,16);

    }

    echo '</td>';

    echo '<td class="topic">';



    if (!empty($event->referer)) {

        echo '<div class="referer">'.$event->referer.'</div>';

    } else {

        echo '<div class="name">'.$event->name."</div>";

    }

    if (!empty($event->courselink)) {

        echo '<div class="course">'.$event->courselink.' </div>';

    }

    if (!empty($event->time)) {

        echo '<span class="date">'.$event->time.'</span>';

    } else {

        echo '<span class="date">'.calendar_time_representation($event->timestart).'</span>';

    }



    echo '</td></tr>';

    echo '<tr><td class="side">&nbsp;</td>';

    if (isset($event->cssclass)) {

        echo '<td class="description '.$event->cssclass.'">';

    } else {

        echo '<td class="description">'; 

    }

    echo format_text($event->description, FORMAT_HTML);

    if (calendar_edit_event_allowed($event)) {

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

        $calendarcourseid = '';

        if (!empty($event->calendarcourseid)) {

            $calendarcourseid = '&amp;course='.$event->calendarcourseid;

        }

        if (empty($event->cmid)) {

            $editlink   = CALENDAR_URL.'event.php?action=edit&amp;id='.$event->id.$calendarcourseid;

            $deletelink = CALENDAR_URL.'event.php?action=delete&amp;id='.$event->id.$calendarcourseid;

        } else {

            $editlink   = $CFG->wwwroot.'/course/mod.php?update='.$event->cmid.'&amp;return=true&amp;sesskey='.$USER->sesskey;

            $deletelink = ''; // deleting activities directly from calendar is dangerous/confusing - see MDL-11843

        }

        echo ' <a href="'.$editlink.'"><img

                  src="'.$CFG->pixpath.'/t/edit.gif" alt="'.get_string('tt_editevent', 'calendar').'"

                  title="'.get_string('tt_editevent', 'calendar').'" /></a>';

        if ($deletelink) {

            echo ' <a href="'.$deletelink.'"><img

                      src="'.$CFG->pixpath.'/t/delete.gif" alt="'.get_string('tt_deleteevent', 'calendar').'"

                      title="'.get_string('tt_deleteevent', 'calendar').'" /></a>';

        }

        echo '</div>';

    }

    echo '</td></tr></table>';



}



/**

 * Get calendar events

 * @param int $tstart Start time of time range for events

 * @param int $tend   End time of time range for events

 * @param array/int/boolean $users array of users, user id or boolean for all/no user events

 * @param array/int/boolean $groups array of groups, group id or boolean for all/no group events

 * @param array/int/boolean $courses array of courses, course id or boolean for all/no course events

 * @param boolean $withduration whether only events starting within time range selected

 *                              or events in progress/already started selected as well

 * @param boolean $ignorehidden whether to select only visible events or all events

 * @return array of selected events or an empty array if there aren't any (or there was an error)

 */

function calendar_get_events($tstart, $tend, $users, $groups, $courses, $withduration=true, $ignorehidden=true) {

    $whereclause = '';

    // Quick test

    if(is_bool($users) && is_bool($groups) && is_bool($courses)) {

        return array();

    }



    if(is_array($users) && !empty($users)) {

        // Events from a number of users

        if(!empty($whereclause)) $whereclause .= ' OR';

        $whereclause .= ' (userid IN ('.implode(',', $users).') AND courseid = 0 AND groupid = 0)';

    }

    else if(is_numeric($users)) {

        // Events from one user

        if(!empty($whereclause)) $whereclause .= ' OR';

        $whereclause .= ' (userid = '.$users.' AND courseid = 0 AND groupid = 0)';

    }

    else if($users === true) {

        // Events from ALL users

        if(!empty($whereclause)) $whereclause .= ' OR';

        $whereclause .= ' (userid != 0 AND courseid = 0 AND groupid = 0)';

    }

    else if($users === false) {

        // No user at all, do nothing

    }



    if(is_array($groups) && !empty($groups)) {

        // Events from a number of groups

        if(!empty($whereclause)) $whereclause .= ' OR';

        $whereclause .= ' groupid IN ('.implode(',', $groups).')';

    }

    else if(is_numeric($groups)) {

        // Events from one group

        if(!empty($whereclause)) $whereclause .= ' OR ';

        $whereclause .= ' groupid = '.$groups;

    }

    else if($groups === true) {

        // Events from ALL groups

        if(!empty($whereclause)) $whereclause .= ' OR ';

        $whereclause .= ' groupid != 0';

    }

    // boolean false (no groups at all): we don't need to do anything



    if(is_array($courses)) {

        // A number of courses (maybe none at all!)

        if(!empty($courses)) {

            if(!empty($whereclause)) {

                $whereclause .= ' OR';

            }

            $whereclause .= ' (groupid = 0 AND courseid IN ('.implode(',', $courses).'))';

        }

        else {

            // This means NO courses, not that we don't care!

            // No need to do anything

        }

    }

    else if(is_numeric($courses)) {

        // One course

        if(!empty($whereclause)) $whereclause .= ' OR';

        $whereclause .= ' (groupid = 0 AND courseid = '.$courses.')';

    }

    else if($courses === true) {

        // Events from ALL courses

        if(!empty($whereclause)) $whereclause .= ' OR';

        $whereclause .= ' (groupid = 0 AND courseid != 0)';

    }



    // Security check: if, by now, we have NOTHING in $whereclause, then it means

    // that NO event-selecting clauses were defined. Thus, we won't be returning ANY

    // events no matter what. Allowing the code to proceed might return a completely

    // valid query with only time constraints, thus selecting ALL events in that time frame!

    if(empty($whereclause)) {

        return array();

    }



    if($withduration) {

        $timeclause = '(timestart >= '.$tstart.' OR timestart + timeduration > '.$tstart.') AND timestart <= '.$tend;

    }

    else {

        $timeclause = 'timestart >= '.$tstart.' AND timestart <= '.$tend;

    }

    if(!empty($whereclause)) {

        // We have additional constraints

        $whereclause = $timeclause.' AND ('.$whereclause.')';

    }

    else {

        // Just basic time filtering

        $whereclause = $timeclause;

    }



    if ($ignorehidden) {

        $whereclause .= ' AND visible = 1';

    }



    $events = get_records_select('event', $whereclause, 'timestart');

    if ($events === false) {

        $events = array();

    }

    return $events;

}



function calendar_top_controls($type, $data) {

    global $CFG, $CALENDARDAYS, $THEME;

    $content = '';

    if(!isset($data['d'])) {

        $data['d'] = 1;

    }



    // Ensure course id passed if relevant

    // Required due to changes in view/lib.php mainly (calendar_session_vars())

    $courseid = '';

    if (!empty($data['id'])) {

        $courseid = '&amp;course='.$data['id'];

    }



    if(!checkdate($data['m'], $data['d'], $data['y'])) {

        $time = time();

    }

    else {

        $time = make_timestamp($data['y'], $data['m'], $data['d']);

    }

    $date = usergetdate($time);



    $data['m'] = $date['mon'];

    $data['y'] = $date['year'];



    //Accessibility: calendar block controls, replaced <table> with <div>.

    //$nexttext = link_arrow_right(get_string('monthnext', 'access'), $url='', $accesshide=true);

    //$prevtext = link_arrow_left(get_string('monthprev', 'access'), $url='', $accesshide=true);



    switch($type) {

        case 'frontpage':

            list($prevmonth, $prevyear) = calendar_sub_month($data['m'], $data['y']);

            list($nextmonth, $nextyear) = calendar_add_month($data['m'], $data['y']);

            $nextlink = calendar_get_link_next(get_string('monthnext', 'access'), 'index.php?', 0, $nextmonth, $nextyear, $accesshide=true);

            $prevlink = calendar_get_link_previous(get_string('monthprev', 'access'), 'index.php?', 0, $prevmonth, $prevyear, true);

            $content .= "\n".'<div class="calendar-controls">'. $prevlink;

            $content .= '<span class="hide"> | </span><span class="current"><a href="'.calendar_get_link_href(CALENDAR_URL.'view.php?view=month'.$courseid.'&amp;', 1, $data['m'], $data['y']).'">'.userdate($time, get_string('strftimemonthyear')).'</a></span>';

            $content .= '<span class="hide"> | </span>'. $nextlink ."\n";

            $content .= "<span class=\"clearer\"><!-- --></span></div>\n";

        break;

        case 'course':

            list($prevmonth, $prevyear) = calendar_sub_month($data['m'], $data['y']);

            list($nextmonth, $nextyear) = calendar_add_month($data['m'], $data['y']);

            $nextlink = calendar_get_link_next(get_string('monthnext', 'access'), 'view.php?id='.$data['id'].'&amp;', 0, $nextmonth, $nextyear, $accesshide=true);

            $prevlink = calendar_get_link_previous(get_string('monthprev', 'access'), 'view.php?id='.$data['id'].'&amp;', 0, $prevmonth, $prevyear, true);

            $content .= "\n".'<div class="calendar-controls">'. $prevlink;

            $content .= '<span class="hide"> | </span><span class="current"><a href="'.calendar_get_link_href(CALENDAR_URL.'view.php?view=month'.$courseid.'&amp;', 1, $data['m'], $data['y']).'">'.userdate($time, get_string('strftimemonthyear')).'</a></span>';

            $content .= '<span class="hide"> | </span>'. $nextlink ."\n";

            $content .= "<span class=\"clearer\"><!-- --></span></div>\n";

        break;

        case 'upcoming':

            $content .= '<div style="text-align: center;"><a href="'.CALENDAR_URL.'view.php?view=upcoming"'.$courseid.'>'.userdate($time, get_string('strftimemonthyear'))."</a></div>\n";

        break;

        case 'display':

            $content .= '<div style="text-align: center;"><a href="'.calendar_get_link_href(CALENDAR_URL.'view.php?view=month'.$courseid.'&amp;', 1, $data['m'], $data['y']).'">'.userdate($time, get_string('strftimemonthyear'))."</a></div>\n";

        break;

        case 'month':

            list($prevmonth, $prevyear) = calendar_sub_month($data['m'], $data['y']);

            list($nextmonth, $nextyear) = calendar_add_month($data['m'], $data['y']);

            $prevdate = make_timestamp($prevyear, $prevmonth, 1);

            $nextdate = make_timestamp($nextyear, $nextmonth, 1);

            $content .= "\n".'<div class="calendar-controls">';

            $content .= calendar_get_link_previous(userdate($prevdate, get_string('strftimemonthyear')), 'view.php?view=month'.$courseid.'&amp;', 1, $prevmonth, $prevyear);

            $content .= '<span class="hide"> | </span><span class="current">'.userdate($time, get_string('strftimemonthyear'))."</span>\n";

            $content .= '<span class="hide"> | </span>'.calendar_get_link_next(userdate($nextdate, get_string('strftimemonthyear')), 'view.php?view=month'.$courseid.'&amp;', 1, $nextmonth, $nextyear);

            $content .= "<span class=\"clearer\"><!-- --></span></div>\n";

        break;

        case 'day':

            $data['d'] = $date['mday']; // Just for convenience

            $prevdate = usergetdate(make_timestamp($data['y'], $data['m'], $data['d'] - 1));

            $nextdate = usergetdate(make_timestamp($data['y'], $data['m'], $data['d'] + 1));

            $prevname = calendar_wday_name($CALENDARDAYS[$prevdate['wday']]);

            $nextname = calendar_wday_name($CALENDARDAYS[$nextdate['wday']]);

            $content .= "\n".'<div class="calendar-controls">';

            $content .= calendar_get_link_previous($prevname, 'view.php?view=day'.$courseid.'&amp;', $prevdate['mday'], $prevdate['mon'], $prevdate['year']);



            // Get the format string

            $text = get_string('strftimedaydate');

            /*

            // Regexp hackery to make a link out of the month/year part

            $text = ereg_replace('(%B.+%Y|%Y.+%B|%Y.+%m[^ ]+)', '<a href="'.calendar_get_link_href('view.php?view=month&amp;', 1, $data['m'], $data['y']).'">\\1</a>', $text);

            $text = ereg_replace('(F.+Y|Y.+F|Y.+m[^ ]+)', '<a href="'.calendar_get_link_href('view.php?view=month&amp;', 1, $data['m'], $data['y']).'">\\1</a>', $text);

            */

            // Replace with actual values and lose any day leading zero

            $text = userdate($time, $text);

            // Print the actual thing

            $content .= '<span class="hide"> | </span><span class="current">'.$text.'</span>';



            $content .= '<span class="hide"> | </span>'. calendar_get_link_next($nextname, 'view.php?view=day'.$courseid.'&amp;', $nextdate['mday'], $nextdate['mon'], $nextdate['year']);

            $content .= "<span class=\"clearer\"><!-- --></span></div>\n";

        break;

    }

    return $content;

}



function calendar_filter_controls($type, $vars = NULL, $course = NULL, $courses = NULL) {

    global $CFG, $SESSION, $USER;



    $groupevents = true;

    $getvars = '';



    $id = optional_param( 'id',0,PARAM_INT );



    switch($type) {

        case 'event':

        case 'upcoming':

        case 'day':

        case 'month':

            $getvars = '&amp;from='.$type;

        break;

        case 'course':

            if ($id > 0) {

                $getvars = '&amp;from=course&amp;id='.$id;

            } else {

                $getvars = '&amp;from=course';

            }

            if (isset($course->groupmode) and $course->groupmode == NOGROUPS and $course->groupmodeforce) {

                $groupevents = false;

            }

        break;

    }



    if (!empty($vars)) {

        $getvars .= '&amp;'.$vars;

    }



    $content = '<table>';



    $content .= '<tr>';

    if($SESSION->cal_show_global) {

        $content .= '<td class="eventskey event_global" style="width: 11px;"><img src="'.$CFG->pixpath.'/t/hide.gif" class="iconsmall" alt="'.get_string('hide').'" title="'.get_string('tt_hideglobal', 'calendar').'" style="cursor:pointer" onclick="location.href='."'".CALENDAR_URL.'set.php?var=showglobal'.$getvars."'".'" /></td>';

        $content .= '<td><a href="'.CALENDAR_URL.'set.php?var=showglobal'.$getvars.'" title="'.get_string('tt_hideglobal', 'calendar').'">'.get_string('global', 'calendar').'</a></td>'."\n";

    } else {

        $content .= '<td style="width: 11px;"><img src="'.$CFG->pixpath.'/t/show.gif" class="iconsmall" alt="'.get_string('show').'" title="'.get_string('tt_showglobal', 'calendar').'" style="cursor:pointer" onclick="location.href='."'".CALENDAR_URL.'set.php?var=showglobal'.$getvars."'".'" /></td>';

        $content .= '<td><a href="'.CALENDAR_URL.'set.php?var=showglobal'.$getvars.'" title="'.get_string('tt_showglobal', 'calendar').'">'.get_string('global', 'calendar').'</a></td>'."\n";

    }

    if($SESSION->cal_show_course) {

        $content .= '<td class="eventskey event_course" style="width: 11px;"><img src="'.$CFG->pixpath.'/t/hide.gif" class="iconsmall" alt="'.get_string('hide').'" title="'.get_string('tt_hidecourse', 'calendar').'" style="cursor:pointer" onclick="location.href='."'".CALENDAR_URL.'set.php?var=showcourses'.$getvars."'".'" /></td>';

        $content .= '<td><a href="'.CALENDAR_URL.'set.php?var=showcourses'.$getvars.'" title="'.get_string('tt_hidecourse', 'calendar').'">'.get_string('course', 'calendar').'</a></td>'."\n";

    } else {

        $content .= '<td style="width: 11px;"><img src="'.$CFG->pixpath.'/t/show.gif" class="iconsmall" alt="'.get_string('hide').'" title="'.get_string('tt_showcourse', 'calendar').'" style="cursor:pointer" onclick="location.href='."'".CALENDAR_URL.'set.php?var=showcourses'.$getvars."'".'" /></td>';

        $content .= '<td><a href="'.CALENDAR_URL.'set.php?var=showcourses'.$getvars.'" title="'.get_string('tt_showcourse', 'calendar').'">'.get_string('course', 'calendar').'</a></td>'."\n";

    

    }





    if(!empty($USER->id) && !isguest()) {

        $content .= "</tr>\n<tr>";



        if($groupevents) {

            // This course MIGHT have group events defined, so show the filter

            if($SESSION->cal_show_groups) {

                $content .= '<td class="eventskey event_group" style="width: 11px;"><img src="'.$CFG->pixpath.'/t/hide.gif" class="iconsmall" alt="'.get_string('hide').'" title="'.get_string('tt_hidegroups', 'calendar').'" style="cursor:pointer" onclick="location.href='."'".CALENDAR_URL.'set.php?var=showgroups'.$getvars."'".'" /></td>';

                $content .= '<td><a href="'.CALENDAR_URL.'set.php?var=showgroups'.$getvars.'" title="'.get_string('tt_hidegroups', 'calendar').'">'.get_string('group', 'calendar').'</a></td>'."\n";

            } else {

                $content .= '<td style="width: 11px;"><img src="'.$CFG->pixpath.'/t/show.gif" class="iconsmall" alt="'.get_string('show').'" title="'.get_string('tt_showgroups', 'calendar').'" style="cursor:pointer" onclick="location.href='."'".CALENDAR_URL.'set.php?var=showgroups'.$getvars."'".'" /></td>';

                $content .= '<td><a href="'.CALENDAR_URL.'set.php?var=showgroups'.$getvars.'" title="'.get_string('tt_showgroups', 'calendar').'">'.get_string('group', 'calendar').'</a></td>'."\n";

            }

        } else {

            // This course CANNOT have group events, so lose the filter

            $content .= '<td style="width: 11px;"></td><td>&nbsp;</td>'."\n";

        }

        if($SESSION->cal_show_user) {

            $content .= '<td class="eventskey event_user" style="width: 11px;"><img src="'.$CFG->pixpath.'/t/hide.gif" class="iconsmall" alt="'.get_string('hide').'" title="'.get_string('tt_hideuser', 'calendar').'" style="cursor:pointer" onclick="location.href='."'".CALENDAR_URL.'set.php?var=showuser'.$getvars."'".'" /></td>';

            $content .= '<td><a href="'.CALENDAR_URL.'set.php?var=showuser'.$getvars.'" title="'.get_string('tt_hideuser', 'calendar').'">'.get_string('user', 'calendar').'</a></td>'."\n";

        } else {

            $content .= '<td style="width: 11px;"><img src="'.$CFG->pixpath.'/t/show.gif" class="iconsmall" alt="'.get_string('show').'" title="'.get_string('tt_showuser', 'calendar').'" style="cursor:pointer" onclick="location.href='."'".CALENDAR_URL.'set.php?var=showuser'.$getvars."'".'" /></td>';

            $content .= '<td><a href="'.CALENDAR_URL.'set.php?var=showuser'.$getvars.'" title="'.get_string('tt_showuser', 'calendar').'">'.get_string('user', 'calendar').'</a></td>'."\n";

        }

    }

    $content .= "</tr>\n</table>\n";



    return $content;

}



function calendar_day_representation($tstamp, $now = false, $usecommonwords = true) {



    static $shortformat;

    if(empty($shortformat)) {

        $shortformat = get_string('strftimedayshort');

    }



    if($now === false) {

        $now = time();

    }



    // To have it in one place, if a change is needed

    $formal = userdate($tstamp, $shortformat);



    $datestamp = usergetdate($tstamp);

    $datenow   = usergetdate($now);



    if($usecommonwords == false) {

        // We don't want words, just a date

        return $formal;

    }

    else if($datestamp['year'] == $datenow['year'] && $datestamp['yday'] == $datenow['yday']) {

        // Today

        return get_string('today', 'calendar');

    }

    else if(

        ($datestamp['year'] == $datenow['year'] && $datestamp['yday'] == $datenow['yday'] - 1 ) ||

        ($datestamp['year'] == $datenow['year'] - 1 && $datestamp['mday'] == 31 && $datestamp['mon'] == 12 && $datenow['yday'] == 1)

        ) {

        // Yesterday

        return get_string('yesterday', 'calendar');

    }

    else if(

        ($datestamp['year'] == $datenow['year'] && $datestamp['yday'] == $datenow['yday'] + 1 ) ||

        ($datestamp['year'] == $datenow['year'] + 1 && $datenow['mday'] == 31 && $datenow['mon'] == 12 && $datestamp['yday'] == 1)

        ) {

        // Tomorrow

        return get_string('tomorrow', 'calendar');

    }

    else {

        return $formal;

    }

}



function calendar_time_representation($time) {

    static $langtimeformat = NULL;

    if($langtimeformat === NULL) {

        $langtimeformat = get_string('strftimetime');

    }

    $timeformat = get_user_preferences('calendar_timeformat');

    if(empty($timeformat)){

        $timeformat = get_config(NULL,'calendar_site_timeformat');

    }

    // The ? is needed because the preference might be present, but empty

    return userdate($time, empty($timeformat) ? $langtimeformat : $timeformat);

}



/**

 * TODO document

 */

function calendar_get_link_href($linkbase, $d, $m, $y) {

    if(empty($linkbase)) return '';

    $paramstr = '';

    if(!empty($d)) $paramstr .= '&amp;cal_d='.$d;

    if(!empty($m)) $paramstr .= '&amp;cal_m='.$m;

    if(!empty($y)) $paramstr .= '&amp;cal_y='.$y;

    if(!empty($paramstr)) $paramstr = substr($paramstr, 5);

    return $linkbase.$paramstr;

}



/**

 * TODO document

 */

function calendar_get_link_tag($text, $linkbase, $d, $m, $y) {

    $href = calendar_get_link_href($linkbase, $d, $m, $y);

    if(empty($href)) return $text;

    return '<a href="'.$href.'">'.$text.'</a>';

}



/**

 * Build and return a previous month HTML link, with an arrow.

 * @param string $text The text label.

 * @param string $linkbase The URL stub.

 * @param int $d $m $y Day of month, month and year numbers.

 * @param bool $accesshide Default visible, or hide from all except screenreaders.

 * @return string HTML string.

 */

function calendar_get_link_previous($text, $linkbase, $d, $m, $y, $accesshide=false) {

    $href = calendar_get_link_href($linkbase, $d, $m, $y);

    if(empty($href)) return $text;

    return link_arrow_left($text, $href, $accesshide, 'previous');

}



/**

 * Build and return a next month HTML link, with an arrow.

 * @param string $text The text label.

 * @param string $linkbase The URL stub.

 * @param int $d $m $y Day of month, month and year numbers.

 * @param bool $accesshide Default visible, or hide from all except screenreaders.

 * @return string HTML string.

 */

function calendar_get_link_next($text, $linkbase, $d, $m, $y, $accesshide=false) {

    $href = calendar_get_link_href($linkbase, $d, $m, $y);

    if(empty($href)) return $text;

    return link_arrow_right($text, $href, $accesshide, 'next');

}



function calendar_wday_name($englishname) {

    return get_string(strtolower($englishname), 'calendar');

}



function calendar_days_in_month($month, $year) {

   return intval(date('t', mktime(0, 0, 0, $month, 1, $year)));

}



function calendar_get_sideblock_upcoming($events, $linkhref = NULL) {

    $content = '';

    $lines = count($events);

    if (!$lines) {

        return $content;

    }



    for ($i = 0; $i < $lines; ++$i) {

        if (!isset($events[$i]->time)) {   // Just for robustness

            continue;

        }

        $events[$i] = calendar_add_event_metadata($events[$i]);

        $content .= '<div class="event"><span class="icon c0">'.$events[$i]->icon.'</span> ';

        if (!empty($events[$i]->referer)) {

            // That's an activity event, so let's provide the hyperlink

            $content .= $events[$i]->referer;

        } else {

            if(!empty($linkhref)) {

                $ed = usergetdate($events[$i]->timestart);

                $href = calendar_get_link_href(CALENDAR_URL.$linkhref, $ed['mday'], $ed['mon'], $ed['year']);

                $content .= '<a href="'.$href.'#event_'.$events[$i]->id.'">'.$events[$i]->name.'</a>';

            }

            else {

                $content .= $events[$i]->name;

            }

        }

        $events[$i]->time = str_replace('&raquo;', '<br />&raquo;', $events[$i]->time);

        $content .= '<div class="date">'.$events[$i]->time.'</div></div>';

        if ($i < $lines - 1) $content .= '<hr />';

    }



    return $content;

}



function calendar_add_month($month, $year) {

    if($month == 12) {

        return array(1, $year + 1);

    }

    else {

        return array($month + 1, $year);

    }

}



function calendar_sub_month($month, $year) {

    if($month == 1) {

        return array(12, $year - 1);

    }

    else {

        return array($month - 1, $year);

    }

}



function calendar_events_by_day($events, $month, $year, &$eventsbyday, &$durationbyday, &$typesbyday, &$courses) {

    $eventsbyday = array();

    $typesbyday = array();

    $durationbyday = array();



    if($events === false) {

        return;

    }



    foreach($events as $event) {



        $startdate = usergetdate($event->timestart);

        // Set end date = start date if no duration

        if ($event->timedura…