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<?php

/**
 * This file contains several functions for retrieving and manipulating calendar events, birthdays and holidays.
 *
 * Simple Machines Forum (SMF)
 *
 * @package SMF
 * @author Simple Machines https://www.simplemachines.org
 * @copyright 2020 Simple Machines and individual contributors
 * @license https://www.simplemachines.org/about/smf/license.php BSD
 *
 * @version 2.1 RC2
 */

if (!defined('SMF'))
    die('No direct access...');

/**
 * Get all birthdays within the given time range.
 * finds all the birthdays in the specified range of days.
 * works with birthdays set for no year, or any other year, and respects month and year boundaries.
 *
 * @param string $low_date The low end of the range, inclusive, in YYYY-MM-DD format
 * @param string $high_date The high end of the range, inclusive, in YYYY-MM-DD format
 * @return array An array of days, each of which is an array of birthday information for the context
 */
function getBirthdayRange($low_date, $high_date)
{
    global $smcFunc;

    // We need to search for any birthday in this range, and whatever year that birthday is on.
    $year_low = (int) substr($low_date, 0, 4);
    $year_high = (int) substr($high_date, 0, 4);

    if ($smcFunc['db_title'] !== POSTGRE_TITLE)
    {
        // Collect all of the birthdays for this month.  I know, it's a painful query.
        $result = $smcFunc['db_query']('birthday_array', '
            SELECT id_member, real_name, YEAR(birthdate) AS birth_year, birthdate
            FROM {db_prefix}members
            WHERE YEAR(birthdate) != {string:year_one}
                AND MONTH(birthdate) != {int:no_month}
                AND DAYOFMONTH(birthdate) != {int:no_day}
                AND YEAR(birthdate) <= {int:max_year}
                AND (
                    DATE_FORMAT(birthdate, {string:year_low}) BETWEEN {date:low_date} AND {date:high_date}' . ($year_low == $year_high ? '' : '
                    OR DATE_FORMAT(birthdate, {string:year_high}) BETWEEN {date:low_date} AND {date:high_date}') . '
                )
                AND is_activated = {int:is_activated}',
            array(
                'is_activated' => 1,
                'no_month' => 0,
                'no_day' => 0,
                'year_one' => '1004',
                'year_low' => $year_low . '-%m-%d',
                'year_high' => $year_high . '-%m-%d',
                'low_date' => $low_date,
                'high_date' => $high_date,
                'max_year' => $year_high,
            )
        );
    }
    else
    {
        $result = $smcFunc['db_query']('birthday_array', '
            SELECT id_member, real_name, YEAR(birthdate) AS birth_year, birthdate
            FROM {db_prefix}members
            WHERE YEAR(birthdate) != {string:year_one}
                AND MONTH(birthdate) != {int:no_month}
                AND DAYOFMONTH(birthdate) != {int:no_day}
                AND (
                    indexable_month_day(birthdate) BETWEEN indexable_month_day({date:year_low_low_date}) AND indexable_month_day({date:year_low_high_date})' . ($year_low == $year_high ? '' : '
                    OR  indexable_month_day(birthdate) BETWEEN indexable_month_day({date:year_high_low_date}) AND indexable_month_day({date:year_high_high_date})') . '
                )
                AND is_activated = {int:is_activated}',
            array(
                'is_activated' => 1,
                'no_month' => 0,
                'no_day' => 0,
                'year_one' => '1004',
                'year_low' => $year_low . '-%m-%d',
                'year_high' => $year_high . '-%m-%d',
                'year_low_low_date' => $low_date,
                'year_low_high_date' => ($year_low == $year_high ? $high_date : $year_low . '-12-31'),
                'year_high_low_date' => ($year_low == $year_high ? $low_date : $year_high . '-01-01'),
                'year_high_high_date' => $high_date,
            )
        );
    }
    $bday = array();
    while ($row = $smcFunc['db_fetch_assoc']($result))
    {
        if ($year_low != $year_high)
            $age_year = substr($row['birthdate'], 5) < substr($high_date, 5) ? $year_high : $year_low;
        else
            $age_year = $year_low;

        $bday[$age_year . substr($row['birthdate'], 4)][] = array(
            'id' => $row['id_member'],
            'name' => $row['real_name'],
            'age' => $row['birth_year'] > 1004 && $row['birth_year'] <= $age_year ? $age_year - $row['birth_year'] : null,
            'is_last' => false
        );
    }
    $smcFunc['db_free_result']($result);

    ksort($bday);

    // Set is_last, so the themes know when to stop placing separators.
    foreach ($bday as $mday => $array)
        $bday[$mday][count($array) - 1]['is_last'] = true;

    return $bday;
}

/**
 * Get all calendar events within the given time range.
 *
 * - finds all the posted calendar events within a date range.
 * - both the earliest_date and latest_date should be in the standard YYYY-MM-DD format.
 * - censors the posted event titles.
 * - uses the current user's permissions if use_permissions is true, otherwise it does nothing "permission specific"
 *
 * @param string $low_date The low end of the range, inclusive, in YYYY-MM-DD format
 * @param string $high_date The high end of the range, inclusive, in YYYY-MM-DD format
 * @param bool $use_permissions Whether to use permissions
 * @return array Contextual information if use_permissions is true, and an array of the data needed to build that otherwise
 */
function getEventRange($low_date, $high_date, $use_permissions = true)
{
    global $scripturl, $modSettings, $user_info, $smcFunc, $context, $sourcedir;
    static $timezone_array = array();
    require_once($sourcedir . '/Subs.php');

    if (empty($timezone_array['default']))
        $timezone_array['default'] = timezone_open(date_default_timezone_get());

    $low_object = date_create($low_date);
    $high_object = date_create($high_date);

    // Find all the calendar info...
    $result = $smcFunc['db_query']('calendar_get_events', '
        SELECT
            cal.id_event, cal.title, cal.id_member, cal.id_topic, cal.id_board,
            cal.start_date, cal.end_date, cal.start_time, cal.end_time, cal.timezone, cal.location,
            b.member_groups, t.id_first_msg, t.approved, b.id_board
        FROM {db_prefix}calendar AS cal
            LEFT JOIN {db_prefix}boards AS b ON (b.id_board = cal.id_board)
            LEFT JOIN {db_prefix}topics AS t ON (t.id_topic = cal.id_topic)
        WHERE cal.start_date <= {date:high_date}
            AND cal.end_date >= {date:low_date}' . ($use_permissions ? '
            AND (cal.id_board = {int:no_board_link} OR {query_wanna_see_board})' : ''),
        array(
            'high_date' => $high_date,
            'low_date' => $low_date,
            'no_board_link' => 0,
        )
    );
    $events = array();
    while ($row = $smcFunc['db_fetch_assoc']($result))
    {
        // If the attached topic is not approved then for the moment pretend it doesn't exist
        if (!empty($row['id_first_msg']) && $modSettings['postmod_active'] && !$row['approved'])
            continue;

        // Force a censor of the title - as often these are used by others.
        censorText($row['title'], $use_permissions ? false : true);

        // Get the various time and date properties for this event
        list($start, $end, $allday, $span, $tz, $tz_abbrev) = buildEventDatetimes($row);

        if (empty($timezone_array[$tz]))
            $timezone_array[$tz] = timezone_open($tz);

        // Sanity check
        if (!empty($start['error_count']) || !empty($start['warning_count']) || !empty($end['error_count']) || !empty($end['warning_count']))
            continue;

        // Get set up for the loop
        $start_object = date_create($row['start_date'] . (!$allday ? ' ' . $row['start_time'] : ''), $timezone_array[$tz]);
        $end_object = date_create($row['end_date'] . (!$allday ? ' ' . $row['end_time'] : ''), $timezone_array[$tz]);
        date_timezone_set($start_object, $timezone_array['default']);
        date_timezone_set($end_object, $timezone_array['default']);
        date_time_set($start_object, 0, 0, 0);
        date_time_set($end_object, 0, 0, 0);
        $start_date_string = date_format($start_object, 'Y-m-d');
        $end_date_string = date_format($end_object, 'Y-m-d');

        $cal_date = ($start_object >= $low_object) ? $start_object : $low_object;
        while ($cal_date <= $end_object && $cal_date <= $high_object)
        {
            $starts_today = (date_format($cal_date, 'Y-m-d') == $start_date_string);
            $ends_today = (date_format($cal_date, 'Y-m-d') == $end_date_string);

            $eventProperties = array(
                'id' => $row['id_event'],
                'title' => $row['title'],
                'year' => $start['year'],
                'month' => $start['month'],
                'day' => $start['day'],
                'hour' => !$allday ? $start['hour'] : null,
                'minute' => !$allday ? $start['minute'] : null,
                'second' => !$allday ? $start['second'] : null,
                'start_date' => $row['start_date'],
                'start_date_local' => $start['date_local'],
                'start_date_orig' => $start['date_orig'],
                'start_time' => !$allday ? $row['start_time'] : null,
                'start_time_local' => !$allday ? $start['time_local'] : null,
                'start_time_orig' => !$allday ? $start['time_orig'] : null,
                'start_timestamp' => $start['timestamp'],
                'start_datetime' => $start['datetime'],
                'start_iso_gmdate' => $start['iso_gmdate'],
                'end_year' => $end['year'],
                'end_month' => $end['month'],
                'end_day' => $end['day'],
                'end_hour' => !$allday ? $end['hour'] : null,
                'end_minute' => !$allday ? $end['minute'] : null,
                'end_second' => !$allday ? $end['second'] : null,
                'end_date' => $row['end_date'],
                'end_date_local' => $end['date_local'],
                'end_date_orig' => $end['date_orig'],
                'end_time' => !$allday ? $row['end_time'] : null,
                'end_time_local' => !$allday ? $end['time_local'] : null,
                'end_time_orig' => !$allday ? $end['time_orig'] : null,
                'end_timestamp' => $end['timestamp'],
                'end_datetime' => $end['datetime'],
                'end_iso_gmdate' => $end['iso_gmdate'],
                'allday' => $allday,
                'tz' => !$allday ? $tz : null,
                'tz_abbrev' => !$allday ? $tz_abbrev : null,
                'span' => $span,
                'is_last' => false,
                'id_board' => $row['id_board'],
                'is_selected' => !empty($context['selected_event']) && $context['selected_event'] == $row['id_event'],
                'starts_today' => $starts_today,
                'ends_today' => $ends_today,
                'location' => $row['location'],
            );

            // If we're using permissions (calendar pages?) then just ouput normal contextual style information.
            if ($use_permissions)
                $events[date_format($cal_date, 'Y-m-d')][] = array_merge($eventProperties, array(
                    'href' => $row['id_board'] == 0 ? '' : $scripturl . '?topic=' . $row['id_topic'] . '.0',
                    'link' => $row['id_board'] == 0 ? $row['title'] : '<a href="' . $scripturl . '?topic=' . $row['id_topic'] . '.0">' . $row['title'] . '</a>',
                    'can_edit' => allowedTo('calendar_edit_any') || ($row['id_member'] == $user_info['id'] && allowedTo('calendar_edit_own')),
                    'modify_href' => $scripturl . '?action=' . ($row['id_board'] == 0 ? 'calendar;sa=post;' : 'post;msg=' . $row['id_first_msg'] . ';topic=' . $row['id_topic'] . '.0;calendar;') . 'eventid=' . $row['id_event'] . ';' . $context['session_var'] . '=' . $context['session_id'],
                    'can_export' => !empty($modSettings['cal_export']) ? true : false,
                    'export_href' => $scripturl . '?action=calendar;sa=ical;eventid=' . $row['id_event'] . ';' . $context['session_var'] . '=' . $context['session_id'],
                ));
            // Otherwise, this is going to be cached and the VIEWER'S permissions should apply... just put together some info.
            else
                $events[date_format($cal_date, 'Y-m-d')][] = array_merge($eventProperties, array(
                    'href' => $row['id_topic'] == 0 ? '' : $scripturl . '?topic=' . $row['id_topic'] . '.0',
                    'link' => $row['id_topic'] == 0 ? $row['title'] : '<a href="' . $scripturl . '?topic=' . $row['id_topic'] . '.0">' . $row['title'] . '</a>',
                    'can_edit' => false,
                    'can_export' => !empty($modSettings['cal_export']) ? true : false,
                    'topic' => $row['id_topic'],
                    'msg' => $row['id_first_msg'],
                    'poster' => $row['id_member'],
                    'allowed_groups' => explode(',', $row['member_groups']),
                ));

            date_add($cal_date, date_interval_create_from_date_string('1 day'));
        }
    }
    $smcFunc['db_free_result']($result);

    // If we're doing normal contextual data, go through and make things clear to the templates ;).
    if ($use_permissions)
    {
        foreach ($events as $mday => $array)
            $events[$mday][count($array) - 1]['is_last'] = true;
    }

    ksort($events);

    return $events;
}

/**
 * Get all holidays within the given time range.
 *
 * @param string $low_date The low end of the range, inclusive, in YYYY-MM-DD format
 * @param string $high_date The high end of the range, inclusive, in YYYY-MM-DD format
 * @return array An array of days, which are all arrays of holiday names.
 */
function getHolidayRange($low_date, $high_date)
{
    global $smcFunc;

    // Get the lowest and highest dates for "all years".
    if (substr($low_date, 0, 4) != substr($high_date, 0, 4))
        $allyear_part = 'event_date BETWEEN {date:all_year_low} AND {date:all_year_dec}
            OR event_date BETWEEN {date:all_year_jan} AND {date:all_year_high}';
    else
        $allyear_part = 'event_date BETWEEN {date:all_year_low} AND {date:all_year_high}';

    // Find some holidays... ;).
    $result = $smcFunc['db_query']('', '
        SELECT event_date, YEAR(event_date) AS year, title
        FROM {db_prefix}calendar_holidays
        WHERE event_date BETWEEN {date:low_date} AND {date:high_date}
            OR ' . $allyear_part,
        array(
            'low_date' => $low_date,
            'high_date' => $high_date,
            'all_year_low' => '1004' . substr($low_date, 4),
            'all_year_high' => '1004' . substr($high_date, 4),
            'all_year_jan' => '1004-01-01',
            'all_year_dec' => '1004-12-31',
        )
    );
    $holidays = array();
    while ($row = $smcFunc['db_fetch_assoc']($result))
    {
        if (substr($low_date, 0, 4) != substr($high_date, 0, 4))
            $event_year = substr($row['event_date'], 5) < substr($high_date, 5) ? substr($high_date, 0, 4) : substr($low_date, 0, 4);
        else
            $event_year = substr($low_date, 0, 4);

        $holidays[$event_year . substr($row['event_date'], 4)][] = $row['title'];
    }
    $smcFunc['db_free_result']($result);

    ksort($holidays);

    return $holidays;
}

/**
 * Does permission checks to see if an event can be linked to a board/topic.
 * checks if the current user can link the current topic to the calendar, permissions et al.
 * this requires the calendar_post permission, a forum moderator, or a topic starter.
 * expects the $topic and $board variables to be set.
 * if the user doesn't have proper permissions, an error will be shown.
 */
function canLinkEvent()
{
    global $user_info, $topic, $board, $smcFunc;

    // If you can't post, you can't link.
    isAllowedTo('calendar_post');

    // No board?  No topic?!?
    if (empty($board))
        fatal_lang_error('missing_board_id', false);
    if (empty($topic))
        fatal_lang_error('missing_topic_id', false);

    // Administrator, Moderator, or owner.  Period.
    if (!allowedTo('admin_forum') && !allowedTo('moderate_board'))
    {
        // Not admin or a moderator of this board. You better be the owner - or else.
        $result = $smcFunc['db_query']('', '
            SELECT id_member_started
            FROM {db_prefix}topics
            WHERE id_topic = {int:current_topic}
            LIMIT 1',
            array(
                'current_topic' => $topic,
            )
        );
        if ($row = $smcFunc['db_fetch_assoc']($result))
        {
            // Not the owner of the topic.
            if ($row['id_member_started'] != $user_info['id'])
                fatal_lang_error('not_your_topic', 'user');
        }
        // Topic/Board doesn't exist.....
        else
            fatal_lang_error('calendar_no_topic', 'general');
        $smcFunc['db_free_result']($result);
    }
}

/**
 * Returns date information about 'today' relative to the users time offset.
 * returns an array with the current date, day, month, and year.
 * takes the users time offset into account.
 *
 * @return array An array of info about today, based on forum time. Has 'day', 'month', 'year' and 'date' (in YYYY-MM-DD format)
 */
function getTodayInfo()
{
    return array(
        'day' => (int) strftime('%d', forum_time()),
        'month' => (int) strftime('%m', forum_time()),
        'year' => (int) strftime('%Y', forum_time()),
        'date' => strftime('%Y-%m-%d', forum_time()),
    );
}

/**
 * Provides information (link, month, year) about the previous and next month.
 *
 * @param string $selected_date A date in YYYY-MM-DD format
 * @param array $calendarOptions An array of calendar options
 * @param bool $is_previous Whether this is the previous month
 * @return array A large array containing all the information needed to show a calendar grid for the given month
 */
function getCalendarGrid($selected_date, $calendarOptions, $is_previous = false)
{
    global $scripturl, $modSettings;

    $selected_object = date_create($selected_date);

    $next_object = date_create($selected_date);
    date_add($next_object, date_interval_create_from_date_string('1 month'));

    $prev_object = date_create($selected_date);
    date_sub($prev_object, date_interval_create_from_date_string('1 month'));

    // Eventually this is what we'll be returning.
    $calendarGrid = array(
        'week_days' => array(),
        'weeks' => array(),
        'short_day_titles' => !empty($calendarOptions['short_day_titles']),
        'short_month_titles' => !empty($calendarOptions['short_month_titles']),
        'current_month' => date_format($selected_object, 'n'),
        'current_year' => date_format($selected_object, 'Y'),
        'current_day' => date_format($selected_object, 'd'),
        'show_next_prev' => !empty($calendarOptions['show_next_prev']),
        'show_week_links' => isset($calendarOptions['show_week_links']) ? $calendarOptions['show_week_links'] : 0,
        'previous_calendar' => array(
            'year' => date_format($prev_object, 'Y'),
            'month' => date_format($prev_object, 'n'),
            'day' => date_format($prev_object, 'd'),
            'start_date' => date_format($prev_object, 'Y-m-d'),
            'disabled' => $modSettings['cal_minyear'] > date_format($prev_object, 'Y'),
        ),
        'next_calendar' => array(
            'year' => date_format($next_object, 'Y'),
            'month' => date_format($next_object, 'n'),
            'day' => date_format($next_object, 'd'),
            'start_date' => date_format($next_object, 'Y-m-d'),
            'disabled' => $modSettings['cal_maxyear'] < date_format($next_object, 'Y'),
        ),
        'start_date' => timeformat(date_format($selected_object, 'U'), get_date_or_time_format('date')),
    );

    // Get today's date.
    $today = getTodayInfo();

    $first_day_object = date_create(date_format($selected_object, 'Y-m-01'));
    $last_day_object = date_create(date_format($selected_object, 'Y-m-t'));

    // Get information about this month.
    $month_info = array(
        'first_day' => array(
            'day_of_week' => date_format($first_day_object, 'w'),
            'week_num' => date_format($first_day_object, 'W'),
            'date' => date_format($first_day_object, 'Y-m-d'),
        ),
        'last_day' => array(
            'day_of_month' => date_format($last_day_object, 't'),
            'date' => date_format($last_day_object, 'Y-m-d'),
        ),
        'first_day_of_year' => date_format(date_create(date_format($selected_object, 'Y-01-01')), 'w'),
        'first_day_of_next_year' => date_format(date_create((date_format($selected_object, 'Y') + 1) . '-01-01'), 'w'),
    );

    // The number of days the first row is shifted to the right for the starting day.
    $nShift = $month_info['first_day']['day_of_week'];

    $calendarOptions['start_day'] = empty($calendarOptions['start_day']) ? 0 : (int) $calendarOptions['start_day'];

    // Starting any day other than Sunday means a shift...
    if (!empty($calendarOptions['start_day']))
    {
        $nShift -= $calendarOptions['start_day'];
        if ($nShift < 0)
            $nShift = 7 + $nShift;
    }

    // Number of rows required to fit the month.
    $nRows = floor(($month_info['last_day']['day_of_month'] + $nShift) / 7);
    if (($month_info['last_day']['day_of_month'] + $nShift) % 7)
        $nRows++;

    // Fetch the arrays for birthdays, posted events, and holidays.
    $bday = $calendarOptions['show_birthdays'] ? getBirthdayRange($month_info['first_day']['date'], $month_info['last_day']['date']) : array();
    $events = $calendarOptions['show_events'] ? getEventRange($month_info['first_day']['date'], $month_info['last_day']['date']) : array();
    $holidays = $calendarOptions['show_holidays'] ? getHolidayRange($month_info['first_day']['date'], $month_info['last_day']['date']) : array();

    // Days of the week taking into consideration that they may want it to start on any day.
    $count = $calendarOptions['start_day'];
    for ($i = 0; $i < 7; $i++)
    {
        $calendarGrid['week_days'][] = $count;
        $count++;
        if ($count == 7)
            $count = 0;
    }

    // Iterate through each week.
    $calendarGrid['weeks'] = array();
    for ($nRow = 0; $nRow < $nRows; $nRow++)
    {
        // Start off the week - and don't let it go above 52, since that's the number of weeks in a year.
        $calendarGrid['weeks'][$nRow] = array(
            'days' => array(),
        );

        // And figure out all the days.
        for ($nCol = 0; $nCol < 7; $nCol++)
        {
            $nDay = ($nRow * 7) + $nCol - $nShift + 1;

            if ($nDay < 1 || $nDay > $month_info['last_day']['day_of_month'])
                $nDay = 0;

            $date = date_format($selected_object, 'Y-m-') . sprintf('%02d', $nDay);

            $calendarGrid['weeks'][$nRow]['days'][$nCol] = array(
                'day' => $nDay,
                'date' => $date,
                'is_today' => $date == $today['date'],
                'is_first_day' => !empty($calendarOptions['show_week_num']) && (($month_info['first_day']['day_of_week'] + $nDay - 1) % 7 == $calendarOptions['start_day']),
                'is_first_of_month' => $nDay === 1,
                'holidays' => !empty($holidays[$date]) ? $holidays[$date] : array(),
                'events' => !empty($events[$date]) ? $events[$date] : array(),
                'birthdays' => !empty($bday[$date]) ? $bday[$date] : array(),
            );
        }
    }

    // What is the last day of the month?
    if ($is_previous === true)
        $calendarGrid['last_of_month'] = $month_info['last_day']['day_of_month'];

    // We'll use the shift in the template.
    $calendarGrid['shift'] = $nShift;

    // Set the previous and the next month's links.
    $calendarGrid['previous_calendar']['href'] = $scripturl . '?action=calendar;viewmonth;year=' . $calendarGrid['previous_calendar']['year'] . ';month=' . $calendarGrid['previous_calendar']['month'] . ';day=' . $calendarGrid['previous_calendar']['day'];
    $calendarGrid['next_calendar']['href'] = $scripturl . '?action=calendar;viewmonth;year=' . $calendarGrid['next_calendar']['year'] . ';month=' . $calendarGrid['next_calendar']['month'] . ';day=' . $calendarGrid['previous_calendar']['day'];

    loadDatePicker('#calendar_navigation .date_input');
    loadDatePair('#calendar_navigation', 'date_input');

    return $calendarGrid;
}

/**
 * Returns the information needed to show a calendar for the given week.
 *
 * @param string $selected_date A date in YYYY-MM-DD format
 * @param array $calendarOptions An array of calendar options
 * @return array An array of information needed to display the grid for a single week on the calendar
 */
function getCalendarWeek($selected_date, $calendarOptions)
{
    global $scripturl, $modSettings, $txt;

    $selected_object = date_create($selected_date);

    // Get today's date.
    $today = getTodayInfo();

    // What is the actual "start date" for the passed day.
    $calendarOptions['start_day'] = empty($calendarOptions['start_day']) ? 0 : (int) $calendarOptions['start_day'];
    $day_of_week = date_format($selected_object, 'w');
    $first_day_object = date_create($selected_date);
    if ($day_of_week != $calendarOptions['start_day'])
    {
        // Here we offset accordingly to get things to the real start of a week.
        $date_diff = $day_of_week - $calendarOptions['start_day'];
        if ($date_diff < 0)
            $date_diff += 7;

        date_sub($first_day_object, date_interval_create_from_date_string($date_diff . ' days'));
    }

    $last_day_object = date_create(date_format($first_day_object, 'Y-m-d'));
    date_add($last_day_object, date_interval_create_from_date_string('1 week'));

    $month = date_format($first_day_object, 'n');
    $year = date_format($first_day_object, 'Y');
    $day = date_format($first_day_object, 'd');

    $next_object = date_create($selected_date);
    date_add($next_object, date_interval_create_from_date_string('1 week'));

    $prev_object = date_create($selected_date);
    date_sub($prev_object, date_interval_create_from_date_string('1 week'));

    // Now start filling in the calendar grid.
    $calendarGrid = array(
        'show_next_prev' => !empty($calendarOptions['show_next_prev']),
        'previous_week' => array(
            'year' => date_format($prev_object, 'Y'),
            'month' => date_format($prev_object, 'n'),
            'day' => date_format($prev_object, 'd'),
            'start_date' => date_format($prev_object, 'Y-m-d'),
            'disabled' => $modSettings['cal_minyear'] > date_format($prev_object, 'Y'),
        ),
        'next_week' => array(
            'year' => date_format($next_object, 'Y'),
            'month' => date_format($next_object, 'n'),
            'day' => date_format($next_object, 'd'),
            'start_date' => date_format($next_object, 'Y-m-d'),
            'disabled' => $modSettings['cal_maxyear'] < date_format($next_object, 'Y'),
        ),
        'start_date' => timeformat(date_format($selected_object, 'U'), get_date_or_time_format('date')),
    );

    // Fetch the arrays for birthdays, posted events, and holidays.
    $bday = $calendarOptions['show_birthdays'] ? getBirthdayRange(date_format($first_day_object, 'Y-m-d'), date_format($last_day_object, 'Y-m-d')) : array();
    $events = $calendarOptions['show_events'] ? getEventRange(date_format($first_day_object, 'Y-m-d'), date_format($last_day_object, 'Y-m-d')) : array();
    $holidays = $calendarOptions['show_holidays'] ? getHolidayRange(date_format($first_day_object, 'Y-m-d'), date_format($last_day_object, 'Y-m-d')) : array();

    $calendarGrid['week_title'] = sprintf($txt['calendar_week_beginning'], $txt['months_titles'][date_format($first_day_object, 'n')], date_format($first_day_object, 'j'), date_format($first_day_object, 'Y'));

    // This holds all the main data - there is at least one month!
    $calendarGrid['months'] = array();
    $current_day_object = date_create(date_format($first_day_object, 'Y-m-d'));
    for ($i = 0; $i < 7; $i++)
    {
        $current_month = date_format($current_day_object, 'n');
        $current_day = date_format($current_day_object, 'j');
        $current_date = date_format($current_day_object, 'Y-m-d');

        if (!isset($calendarGrid['months'][$current_month]))
            $calendarGrid['months'][$current_month] = array(
                'current_month' => $current_month,
                'current_year' => date_format($current_day_object, 'Y'),
                'days' => array(),
            );

        $calendarGrid['months'][$current_month]['days'][$current_day] = array(
            'day' => $current_day,
            'day_of_week' => (date_format($current_day_object, 'w') + 7 - $calendarOptions['start_day']) % 7,
            'date' => $current_date,
            'is_today' => $current_date == $today['date'],
            'holidays' => !empty($holidays[$current_date]) ? $holidays[$current_date] : array(),
            'events' => !empty($events[$current_date]) ? $events[$current_date] : array(),
            'birthdays' => !empty($bday[$current_date]) ? $bday[$current_date] : array()
        );

        date_add($current_day_object, date_interval_create_from_date_string('1 day'));
    }

    // Set the previous and the next week's links.
    $calendarGrid['previous_week']['href'] = $scripturl . '?action=calendar;viewweek;year=' . $calendarGrid['previous_week']['year'] . ';month=' . $calendarGrid['previous_week']['month'] . ';day=' . $calendarGrid['previous_week']['day'];
    $calendarGrid['next_week']['href'] = $scripturl . '?action=calendar;viewweek;year=' . $calendarGrid['next_week']['year'] . ';month=' . $calendarGrid['next_week']['month'] . ';day=' . $calendarGrid['next_week']['day'];

    loadDatePicker('#calendar_navigation .date_input');
    loadDatePair('#calendar_navigation', 'date_input', '');

    return $calendarGrid;
}

/**
 * Returns the information needed to show a list of upcoming events, birthdays, and holidays on the calendar.
 *
 * @param string $start_date The start of a date range in YYYY-MM-DD format
 * @param string $end_date The end of a date range in YYYY-MM-DD format
 * @param array $calendarOptions An array of calendar options
 * @return array An array of information needed to display a list of upcoming events, etc., on the calendar
 */
function getCalendarList($start_date, $end_date, $calendarOptions)
{
    global $modSettings, $user_info, $txt, $context, $sourcedir;
    require_once($sourcedir . '/Subs.php');

    // DateTime objects make life easier
    $start_object = date_create($start_date);
    $end_object = date_create($end_date);

    $calendarGrid = array(
        'start_date' => timeformat(date_format($start_object, 'U'), get_date_or_time_format('date')),
        'start_year' => date_format($start_object, 'Y'),
        'start_month' => date_format($start_object, 'm'),
        'start_day' => date_format($start_object, 'd'),
        'end_date' => timeformat(date_format($end_object, 'U'), get_date_or_time_format('date')),
        'end_year' => date_format($end_object, 'Y'),
        'end_month' => date_format($end_object, 'm'),
        'end_day' => date_format($end_object, 'd'),
    );

    $calendarGrid['birthdays'] = $calendarOptions['show_birthdays'] ? getBirthdayRange($start_date, $end_date) : array();
    $calendarGrid['holidays'] = $calendarOptions['show_holidays'] ? getHolidayRange($start_date, $end_date) : array();
    $calendarGrid['events'] = $calendarOptions['show_events'] ? getEventRange($start_date, $end_date) : array();

    // Get rid of duplicate events
    $temp = array();
    foreach ($calendarGrid['events'] as $date => $date_events)
    {
        foreach ($date_events as $event_key => $event_val)
        {
            if (in_array($event_val['id'], $temp))
                unset($calendarGrid['events'][$date][$event_key]);
            else
                $temp[] = $event_val['id'];
        }
    }

    // Give birthdays and holidays a friendly format, without the year
    $date_format = str_replace(array('%Y', '%y', '%G', '%g', '%C', '%c', '%D'), array('', '', '', '', '', '%b %d', '%m/%d'), get_date_or_time_format('date'));

    foreach (array('birthdays', 'holidays') as $type)
    {
        foreach ($calendarGrid[$type] as $date => $date_content)
        {
            $date_local = preg_replace('~(?<=\s)0+(\d)~', '$1', trim(timeformat(strtotime($date), $date_format), " \t\n\r\0\x0B,./;:<>()[]{}\\|-_=+"));

            $calendarGrid[$type][$date]['date_local'] = $date_local;
        }
    }

    loadDatePicker('#calendar_range .date_input');
    loadDatePair('#calendar_range', 'date_input', '');

    return $calendarGrid;
}

/**
 * Loads the necessary JavaScript and CSS to create a datepicker.
 *
 * @param string $selector A CSS selector for the input field(s) that the datepicker should be attached to.
 * @param string $date_format The date format to use, in strftime() format.
 */
function loadDatePicker($selector = 'input.date_input', $date_format = '')
{
    global $modSettings, $txt, $context, $user_info;

    if (empty($date_format))
        $date_format = get_date_or_time_format('date');

    // Convert to format used by datepicker
    $date_format = strtr($date_format, array(
        // Day
        '%a' => 'D', '%A' => 'DD', '%e' => 'd', '%d' => 'dd', '%j' => 'oo', '%u' => '', '%w' => '',
        // Week
        '%U' => '', '%V' => '', '%W' => '',
        // Month
        '%b' => 'M', '%B' => 'MM', '%h' => 'M', '%m' => 'mm',
        // Year
        '%C' => '', '%g' => 'y', '%G' => 'yy', '%y' => 'y', '%Y' => 'yy',
        // Time (we remove all of these)
        '%H' => '', '%k' => '', '%I' => '', '%l' => '', '%M' => '', '%p' => '', '%P' => '',
        '%r' => '', '%R' => '', '%S' => '', '%T' => '', '%X' => '', '%z' => '', '%Z' => '',
        // Time and Date Stamps
        '%c' => 'D, d M yy', '%D' => 'mm/dd/y', '%F' => 'yy-mm-dd', '%s' => '@', '%x' => 'D, d M yy',
        // Miscellaneous
        '%n' => ' ', '%t' => ' ', '%%' => '%',
    ));

    loadCSSFile('jquery-ui.datepicker.css', array(), 'smf_datepicker');
    loadJavaScriptFile('jquery-ui.datepicker.min.js', array('defer' => true), 'smf_datepicker');
    addInlineJavaScript('
    $("' . $selector . '").datepicker({
        dateFormat: "' . $date_format . '",
        autoSize: true,
        isRTL: ' . ($context['right_to_left'] ? 'true' : 'false') . ',
        constrainInput: true,
        showAnim: "",
        showButtonPanel: false,
        yearRange: "' . $modSettings['cal_minyear'] . ':' . $modSettings['cal_maxyear'] . '",
        hideIfNoPrevNext: true,
        monthNames: ["' . implode('", "', $txt['months_titles']) . '"],
        monthNamesShort: ["' . implode('", "', $txt['months_short']) . '"],
        dayNames: ["' . implode('", "', $txt['days']) . '"],
        dayNamesShort: ["' . implode('", "', $txt['days_short']) . '"],
        dayNamesMin: ["' . implode('", "', $txt['days_short']) . '"],
        prevText: "' . $txt['prev_month'] . '",
        nextText: "' . $txt['next_month'] . '",
    });', true);
}

/**
 * Loads the necessary JavaScript and CSS to create a timepicker.
 *
 * @param string $selector A CSS selector for the input field(s) that the timepicker should be attached to.
 * @param string $time_format A time format in strftime format
 */
function loadTimePicker($selector = 'input.time_input', $time_format = '')
{
    global $modSettings, $txt, $context;

    if (empty($time_format))
        $time_format = get_date_or_time_format('time');

    // Format used for timepicker
    $time_format = strtr($time_format, array(
        '%H' => 'H',
        '%k' => 'G',
        '%I' => 'h',
        '%l' => 'g',
        '%M' => 'i',
        '%p' => 'A',
        '%P' => 'a',
        '%r' => 'h:i:s A',
        '%R' => 'H:i',
        '%S' => 's',
        '%T' => 'H:i:s',
        '%X' => 'H:i:s',
    ));

    loadCSSFile('jquery.timepicker.css', array(), 'smf_timepicker');
    loadJavaScriptFile('jquery.timepicker.min.js', array('defer' => true), 'smf_timepicker');
    addInlineJavaScript('
    $("' . $selector . '").timepicker({
        timeFormat: "' . $time_format . '",
        showDuration: true,
        maxTime: "23:59:59",
    });', true);
}

/**
 * Loads the necessary JavaScript for Datepair.js.
 *
 * Datepair.js helps to keep date ranges sane in the UI.
 *
 * @param string $container CSS selector for the containing element of the date/time inputs to be paired.
 * @param string $date_class The CSS class of the date inputs to be paired.
 * @param string $time_class The CSS class of the time inputs to be paired.
 */
function loadDatePair($container, $date_class = '', $time_class = '')
{
    global $modSettings, $txt, $context;

    $container = (string) $container;
    $date_class = (string) $date_class;
    $time_class = (string) $time_class;

    if ($container == '')
        return;

    loadJavaScriptFile('jquery.datepair.min.js', array('defer' => true), 'smf_datepair');

    $datepair_options = '';

    // If we're not using a date input, we might as well disable these.
    if ($date_class == '')
    {
        $datepair_options .= '
        parseDate: function (el) {},
        updateDate: function (el, v) {},';
    }
    else
    {
        $datepair_options .= '
        dateClass: "' . $date_class . '",';

        // Customize Datepair to work with jQuery UI's datepicker.
        $datepair_options .= '
        parseDate: function (el) {
            var val = $(el).datepicker("getDate");
            if (!val) {
                return null;
            }
            var utc = new Date(val);
            return utc && new Date(utc.getTime() + (utc.getTimezoneOffset() * 60000));
        },
        updateDate: function (el, v) {
            $(el).datepicker("setDate", new Date(v.getTime() - (v.getTimezoneOffset() * 60000)));
        },';
    }

    // If not using a time input, disable time functions.
    if ($time_class == '')
    {
        $datepair_options .= '
        parseTime: function(input){},
        updateTime: function(input, dateObj){},
        setMinTime: function(input, dateObj){},';
    }
    else
    {
        $datepair_options .= '
        timeClass: "' . $time_class . '",';
    }

    addInlineJavaScript('
    $("' . $container . '").datepair({' . $datepair_options . "\n\t});", true);

}

/**
 * Retrieve all events for the given days, independently of the users offset.
 * cache callback function used to retrieve the birthdays, holidays, and events between now and now + days_to_index.
 * widens the search range by an extra 24 hours to support time offset shifts.
 * used by the cache_getRecentEvents function to get the information needed to calculate the events taking the users time offset into account.
 *
 * @param array $eventOptions With the keys 'num_days_shown', 'include_holidays', 'include_birthdays' and 'include_events'
 * @return array An array containing the data that was cached as well as an expression to calculate whether the data should be refreshed and when it expires
 */
function cache_getOffsetIndependentEvents($eventOptions)
{
    $days_to_index = $eventOptions['num_days_shown'];

    $low_date = strftime('%Y-%m-%d', forum_time(false) - 24 * 3600);
    $high_date = strftime('%Y-%m-%d', forum_time(false) + $days_to_index * 24 * 3600);

    return array(
        'data' => array(
            'holidays' => (!empty($eventOptions['include_holidays']) ? getHolidayRange($low_date, $high_date) : array()),
            'birthdays' => (!empty($eventOptions['include_birthdays']) ? getBirthdayRange($low_date, $high_date) : array()),
            'events' => (!empty($eventOptions['include_events']) ? getEventRange($low_date, $high_date, false) : array()),
        ),
        'refresh_eval' => 'return \'' . strftime('%Y%m%d', forum_time(false)) . '\' != strftime(\'%Y%m%d\', forum_time(false)) || (!empty($modSettings[\'calendar_updated\']) && ' . time() . ' < $modSettings[\'calendar_updated\']);',
        'expires' => time() + 3600,
    );
}

/**
 * cache callback function used to retrieve the upcoming birthdays, holidays, and events within the given period, taking into account the users time offset.
 * Called from the BoardIndex to display the current day's events on the board index
 * used by the board index and SSI to show the upcoming events.
 *
 * @param array $eventOptions An array of event options.
 * @return array An array containing the info that was cached as well as a few other relevant things
 */
function cache_getRecentEvents($eventOptions)
{
    // With the 'static' cached data we can calculate the user-specific data.
    $cached_data = cache_quick_get('calendar_index', 'Subs-Calendar.php', 'cache_getOffsetIndependentEvents', array($eventOptions));

    // Get the information about today (from user perspective).
    $today = getTodayInfo();

    $return_data = array(
        'calendar_holidays' => array(),
        'calendar_birthdays' => array(),
        'calendar_events' => array(),
    );

    // Set the event span to be shown in seconds.
    $days_for_index = $eventOptions['num_days_shown'] * 86400;

    // Get the current member time/date.
    $now = forum_time();

    if (!empty($eventOptions['include_holidays']))
    {
        // Holidays between now and now + days.
        for ($i = $now; $i < $now + $days_for_index; $i += 86400)
        {
            if (isset($cached_data['holidays'][strftime('%Y-%m-%d', $i)]))
                $return_data['calendar_holidays'] = array_merge($return_data['calendar_holidays'], $cached_data['holidays'][strftime('%Y-%m-%d', $i)]);
        }
    }

    if (!empty($eventOptions['include_birthdays']))
    {
        // Happy Birthday, guys and gals!
        for ($i = $now; $i < $now + $days_for_index; $i += 86400)
        {
            $loop_date = strftime('%Y-%m-%d', $i);
            if (isset($cached_data['birthdays'][$loop_date]))
            {
                foreach ($cached_data['birthdays'][$loop_date] as $index => $dummy)
                    $cached_data['birthdays'][strftime('%Y-%m-%d', $i)][$index]['is_today'] = $loop_date === $today['date'];
                $return_data['calendar_birthdays'] = array_merge($return_data['calendar_birthdays'], $cached_data['birthdays'][$loop_date]);
            }
        }
    }

    if (!empty($eventOptions['include_events']))
    {
        $duplicates = array();
        for ($i = $now; $i < $now + $days_for_index; $i += 86400)
        {
            // Determine the date of the current loop step.
            $loop_date = strftime('%Y-%m-%d', $i);

            // No events today? Check the next day.
            if (empty($cached_data['events'][$loop_date]))
                continue;

            // Loop through all events to add a few last-minute values.
            foreach ($cached_data['events'][$loop_date] as $ev => $event)
            {
                // Create a shortcut variable for easier access.
                $this_event = &$cached_data['events'][$loop_date][$ev];

                // Skip duplicates.
                if (isset($duplicates[$this_event['topic'] . $this_event['title']]))
                {
                    unset($cached_data['events'][$loop_date][$ev]);
                    continue;
                }
                else
                    $duplicates[$this_event['topic'] . $this_event['title']] = true;

                // Might be set to true afterwards, depending on the permissions.
                $this_event['can_edit'] = false;
                $this_event['is_today'] = $loop_date === $today['date'];
                $this_event['date'] = $loop_date;
            }

            if (!empty($cached_data['events'][$loop_date]))
                $return_data['calendar_events'] = array_merge($return_data['calendar_events'], $cached_data['events'][$loop_date]);
        }
    }

    // Mark the last item so that a list separator can be used in the template.
    for ($i = 0, $n = count($return_data['calendar_birthdays']); $i < $n; $i++)
        $return_data['calendar_birthdays'][$i]['is_last'] = !isset($return_data['calendar_birthdays'][$i + 1]);
    for ($i = 0, $n = count($return_data['calendar_events']); $i < $n; $i++)
        $return_data['calendar_events'][$i]['is_last'] = !isset($return_data['calendar_events'][$i + 1]);

    return array(
        'data' => $return_data,
        'expires' => time() + 3600,
        'refresh_eval' => 'return \'' . strftime('%Y%m%d', forum_time(false)) . '\' != strftime(\'%Y%m%d\', forum_time(false)) || (!empty($modSettings[\'calendar_updated\']) && ' . time() . ' < $modSettings[\'calendar_updated\']);',
        'post_retri_eval' => '
            global $context, $scripturl, $user_info;

            foreach ($cache_block[\'data\'][\'calendar_events\'] as $k => $event)
            {
                // Remove events that the user may not see or wants to ignore.
                if ((count(array_intersect($user_info[\'groups\'], $event[\'allowed_groups\'])) === 0 && !allowedTo(\'admin_forum\') && !empty($event[\'id_board\'])) || in_array($event[\'id_board\'], $user_info[\'ignoreboards\']))
                    unset($cache_block[\'data\'][\'calendar_events\'][$k]);
                else
                {
                    // Whether the event can be edited depends on the permissions.
                    $cache_block[\'data\'][\'calendar_events\'][$k][\'can_edit\'] = allowedTo(\'calendar_edit_any\') || ($event[\'poster\'] == $user_info[\'id\'] && allowedTo(\'calendar_edit_own\'));

                    // The added session code makes this URL not cachable.
                    $cache_block[\'data\'][\'calendar_events\'][$k][\'modify_href\'] = $scripturl . \'?action=\' . ($event[\'topic\'] == 0 ? \'calendar;sa=post;\' : \'post;msg=\' . $event[\'msg\'] . \';topic=\' . $event[\'topic\'] . \'.0;calendar;\') . \'eventid=\' . $event[\'id\'] . \';\' . $context[\'session_var\'] . \'=\' . $context[\'session_id\'];
                }
            }

            if (empty($params[0][\'include_holidays\']))
                $cache_block[\'data\'][\'calendar_holidays\'] = array();
            if (empty($params[0][\'include_birthdays\']))
                $cache_block[\'data\'][\'calendar_birthdays\'] = array();
            if (empty($params[0][\'include_events\']))
                $cache_block[\'data\'][\'calendar_events\'] = array();

            $cache_block[\'data\'][\'show_calendar\'] = !empty($cache_block[\'data\'][\'calendar_holidays\']) || !empty($cache_block[\'data\'][\'calendar_birthdays\']) || !empty($cache_block[\'data\'][\'calendar_events\']);',
    );
}

/**
 * Makes sure the calendar post is valid.
 */
function validateEventPost()
{
    global $modSettings, $smcFunc;

    if (!isset($_POST['deleteevent']))
    {
        // The 2.1 way
        if (isset($_POST['start_date']))
        {
            $d = date_parse($_POST['start_date']);
            if (!empty($d['error_count']) || !empty($d['warning_count']))
                fatal_lang_error('invalid_date', false);
            if (empty($d['year']))
                fatal_lang_error('event_year_missing', false);
            if (empty($d['month']))
                fatal_lang_error('event_month_missing', false);
        }
        elseif (isset($_POST['start_datetime']))
        {
            $d = date_parse($_POST['start_datetime']);
            if (!empty($d['error_count']) || !empty($d['warning_count']))
                fatal_lang_error('invalid_date', false);
            if (empty($d['year']))
                fatal_lang_error('event_year_missing', false);
            if (empty($d['month']))
                fatal_lang_error('event_month_missing', false);
        }
        // The 2.0 way
        else
        {
            // No month?  No year?
            if (!isset($_POST['month']))
                fatal_lang_error('event_month_missing', false);
            if (!isset($_POST['year']))
                fatal_lang_error('event_year_missing', false);

            // Check the month and year...
            if ($_POST['month'] < 1 || $_POST['month'] > 12)
                fatal_lang_error('invalid_month', false);
            if ($_POST['year'] < $modSettings['cal_minyear'] || $_POST['year'] > $modSettings['cal_maxyear'])
                fatal_lang_error('invalid_year', false);
        }
    }

    // Make sure they're allowed to post...
    isAllowedTo('calendar_post');

    // If they want to us to calculate an end date, make sure it will fit in an acceptable range.
    if (isset($_POST['span']))
    {
        if (($_POST['span'] < 1) || (!empty($modSettings['cal_maxspan']) && $_POST['span'] > $modSettings['cal_maxspan']))
            fatal_lang_error('invalid_days_numb', false);
    }

    // There is no need to validate the following values if we are just deleting the event.
    if (!isset($_POST['deleteevent']))
    {
        // If we're doing things the 2.0 way, check the day
        if (empty($_POST['start_date']) && empty($_POST['start_datetime']))
        {
            // No day?
            if (!isset($_POST['day']))
                fatal_lang_error('event_day_missing', false);

            // Bad day?
            if (!checkdate($_POST['month'], $_POST['day'], $_POST['year']))
                fatal_lang_error('invalid_date', false);
        }

        if (!isset($_POST['evtitle']) && !isset($_POST['subject']))
            fatal_lang_error('event_title_missing', false);
        elseif (!isset($_POST['evtitle']))
            $_POST['evtitle'] = $_POST['subject'];

        // No title?
        if ($smcFunc['htmltrim']($_POST['evtitle']) === '')
            fatal_lang_error('no_event_title', false);
        if ($smcFunc['strlen']($_POST['evtitle']) > 100)
            $_POST['evtitle'] = $smcFunc['substr']($_POST['evtitle'], 0, 100);
        $_POST['evtitle'] = str_replace(';', '', $_POST['evtitle']);
    }
}

/**
 * Get the event's poster.
 *
 * @param int $event_id The ID of the event
 * @return int|bool The ID of the poster or false if the event was not found
 */
function getEventPoster($event_id)
{
    global $smcFunc;

    // A simple database query, how hard can that be?
    $request = $smcFunc['db_query']('', '
        SELECT id_member
        FROM {db_prefix}calendar
        WHERE id_event = {int:id_event}
        LIMIT 1',
        array(
            'id_event' => $event_id,
        )
    );

    // No results, return false.
    if ($smcFunc['db_num_rows'] === 0)
        return false;

    // Grab the results and return.
    list ($poster) = $smcFunc['db_fetch_row']($request);
    $smcFunc['db_free_result']($request);
    return (int) $poster;
}

/**
 * Consolidating the various INSERT statements into this function.
 * Inserts the passed event information into the calendar table.
 * Allows to either set a time span (in days) or an end_date.
 * Does not check any permissions of any sort.
 *
 * @param array $eventOptions An array of event options ('title', 'span', 'start_date', 'end_date', etc.)
 */
function insertEvent(&$eventOptions)
{
    global $smcFunc, $context;

    // Add special chars to the title.
    $eventOptions['title'] = $smcFunc['htmlspecialchars']($eventOptions['title'], ENT_QUOTES);

    $eventOptions['location'] = isset($eventOptions['location']) ? $smcFunc['htmlspecialchars']($eventOptions['location'], ENT_QUOTES) : '';

    // Set the start and end dates and times
    list($start_date, $end_date, $start_time, $end_time, $tz) = setEventStartEnd($eventOptions);

    // If no topic and board are given, they are not linked to a topic.
    $eventOptions['board'] = isset($eventOptions['board']) ? (int) $eventOptions['board'] : 0;
    $eventOptions['topic'] = isset($eventOptions['topic']) ? (int) $eventOptions['topic'] : 0;

    $event_columns = array(
        'id_board' => 'int', 'id_topic' => 'int', 'title' => 'string-60', 'id_member' => 'int',
        'start_date' => 'date', 'end_date' => 'date', 'location' => 'string-255',
    );
    $event_parameters = array(
        $eventOptions['board'], $eventOptions['topic'], $eventOptions['title'], $eventOptions['member'],
        $start_date, $end_date, $eventOptions['location'],
    );
    if (!empty($start_time) && !empty($end_time) && !empty($tz) && in_array($tz, timezone_identifiers_list(DateTimeZone::ALL_WITH_BC)))
    {
        $event_columns['start_time'] = 'time';
        $event_parameters[] = $start_time;
        $event_columns['end_time'] = 'time';
        $event_parameters[] = $end_time;
        $event_columns['timezone'] = 'string';
        $event_parameters[] = $tz;
    }

    call_integration_hook('integrate_create_event', array(&$eventOptions, &$event_columns, &$event_parameters));

    // Insert the event!
    $eventOptions['id'] = $smcFunc['db_insert']('',
        '{db_prefix}calendar',
        $event_columns,
        $event_parameters,
        array('id_event'),
        1
    );

    // If this isn't tied to a topic, we need to notify people about it.
    if (empty($eventOptions['topic']))
    {
        $smcFunc['db_insert']('insert',
            '{db_prefix}background_tasks',
            array('task_file' => 'string', 'task_class' => 'string', 'task_data' => 'string', 'claimed_time' => 'int'),
            array('$sourcedir/tasks/EventNew-Notify.php', 'EventNew_Notify_Background', $smcFunc['json_encode'](array(
                'event_title' => $eventOptions['title'],
                'event_id' => $eventOptions['id'],
                'sender_id' => $eventOptions['member'],
                'sender_name' => $eventOptions['member'] == $context['user']['id'] ? $context['user']['name'] : '',
                'time' => time(),
            )), 0),
            array('id_task')
        );
    }

    // Update the settings to show something calendar-ish was updated.
    updateSettings(array(
        'calendar_updated' => time(),
    ));
}

/**
 * modifies an event.
 * allows to either set a time span (in days) or an end_date.
 * does not check any permissions of any sort.
 *
 * @param int $event_id The ID of the event
 * @param array $eventOptions An array of event information
 */
function modifyEvent($event_id, &$eventOptions)
{
    global $smcFunc;

    // Properly sanitize the title and location
    $eventOptions['title'] = $smcFunc['htmlspecialchars']($eventOptions['title'], ENT_QUOTES);
    $eventOptions['location'] = $smcFunc['htmlspecialchars']($eventOptions['location'], ENT_QUOTES);

    // Set the new start and end dates and times
    list($start_date, $end_date, $start_time, $end_time, $tz) = setEventStartEnd($eventOptions);

    $event_columns = array(
        'start_date' => '{date:start_date}',
        'end_date' => '{date:end_date}',
        'title' => 'SUBSTRING({string:title}, 1, 60)',
        'id_board' => '{int:id_board}',
        'id_topic' => '{int:id_topic}',
        'location' => 'SUBSTRING({string:location}, 1, 255)',
    );
    $event_parameters = array(
        'start_date' => $start_date,
        'end_date' => $end_date,
        'title' => $eventOptions['title'],
        'location' => $eventOptions['location'],
        'id_board' => isset($eventOptions['board']) ? (int) $eventOptions['board'] : 0,
        'id_topic' => isset($eventOptions['topic']) ? (int) $eventOptions['topic'] : 0,
    );
    if (!empty($start_time) && !empty($end_time) && !empty($tz) && in_array($tz, timezone_identifiers_list(DateTimeZone::ALL_WITH_BC)))
    {
        $event_columns['start_time'] = '{time:start_time}';
        $event_parameters['start_time'] = $start_time;
        $event_columns['end_time'] = '{time:end_time}';
        $event_parameters['end_time'] = $end_time;
        $event_columns['timezone'] = '{string:timezone}';
        $event_parameters['timezone'] = $tz;
    }

    // This is to prevent hooks to modify the id of the event
    $real_event_id = $event_id;
    call_integration_hook('integrate_modify_event', array($event_id, &$eventOptions, &$event_columns, &$event_parameters));

    $column_clauses = array();
    foreach ($event_columns as $col => $crit)
        $column_clauses[] = $col . ' = ' . $crit;

    $smcFunc['db_query']('', '
        UPDATE {db_prefix}calendar
        SET
            ' . implode(', ', $column_clauses) . '
        WHERE id_event = {int:id_event}',
        array_merge(
            $event_parameters,
            array(
                'id_event' => $real_event_id
            )
        )
    );

    if (empty($start_time) || empty($end_time) || empty($tz) || !in_array($tz, timezone_identifiers_list(DateTimeZone::ALL_WITH_BC)))
    {
        $smcFunc['db_query']('', '
            UPDATE {db_prefix}calendar
            SET start_time = NULL, end_time = NULL, timezone = NULL
            WHERE id_event = {int:id_event}',
            array(
                'id_event' => $real_event_id
            )
        );
    }

    updateSettings(array(
        'calendar_updated' => time(),
    ));
}

/**
 * Remove an event
 * removes an event.
 * does no permission checks.
 *
 * @param int $event_id The ID of the event to remove
 */
function removeEvent($event_id)
{
    global $smcFunc;

    $smcFunc['db_query']('', '
        DELETE FROM {db_prefix}calendar
        WHERE id_event = {int:id_event}',
        array(
            'id_event' => $event_id,
        )
    );

    call_integration_hook('integrate_remove_event', array($event_id));

    updateSettings(array(
        'calendar_updated' => time(),
    ));
}

/**
 * Gets all the events properties
 *
 * @param int $event_id The ID of the event
 * @return array An array of event information
 */
function getEventProperties($event_id)
{
    global $smcFunc;

    $request = $smcFunc['db_query']('', '
        SELECT
            c.id_event, c.id_board, c.id_topic, c.id_member, c.title,
            c.start_date, c.end_date, c.start_time, c.end_time, c.timezone, c.location,
            t.id_first_msg, t.id_member_started,
            mb.real_name, m.modified_time
        FROM {db_prefix}calendar AS c
            LEFT JOIN {db_prefix}topics AS t ON (t.id_topic = c.id_topic)
            LEFT JOIN {db_prefix}members AS mb ON (mb.id_member = t.id_member_started)
            LEFT JOIN {db_prefix}messages AS m ON (m.id_msg  = t.id_first_msg)
        WHERE c.id_event = {int:id_event}',
        array(
            'id_event' => $event_id,
        )
    );

    // If nothing returned, we are in poo, poo.
    if ($smcFunc['db_num_rows']($request) === 0)
        return false;

    $row = $smcFunc['db_fetch_assoc']($request);
    $smcFunc['db_free_result']($request);

    list($start, $end, $allday, $span, $tz, $tz_abbrev) = buildEventDatetimes($row);

    // Sanity check
    if (!empty($start['error_count']) || !empty($start['warning_count']) || !empty($end['error_count']) || !empty($end['warning_count']))
        return false;

    $return_value = array(
        'boards' => array(),
        'board' => $row['id_board'],
        'new' => 0,
        'eventid' => $event_id,
        'year' => $start['year'],
        'month' => $start['month'],
        'day' => $start['day'],
        'hour' => !$allday ? $start['hour'] : null,
        'minute' => !$allday ? $start['minute'] : null,
        'second' => !$allday ? $start['second'] : null,
        'start_date' => $row['start_date'],
        'start_date_local' => $start['date_local'],
        'start_date_orig' => $start['date_orig'],
        'start_time' => !$allday ? $row['start_time'] : null,
        'start_time_local' => !$allday ? $start['time_local'] : null,
        'start_time_orig' => !$allday ? $start['time_orig'] : null,
        'start_timestamp' => $start['timestamp'],
        'start_datetime' => $start['datetime'],
        'start_iso_gmdate' => $start['iso_gmdate'],
        'end_year' => $end['year'],
        'end_month' => $end['month'],
        'end_day' => $end['day'],
        'end_hour' => !$allday ? $end['hour'] : null,
        'end_minute' => !$allday ? $end['minute'] : null,
        'end_second' => !$allday ? $end['second'] : null,
        'end_date' => $row['end_date'],
        'end_date_local' => $end['date_local'],
        'end_date_orig' => $end['date_orig'],
        'end_time' => !$allday ? $row['end_time'] : null,
        'end_time_local' => !$allday ? $end['time_local'] : null,
        'end_time_orig' => !$allday ? $end['time_orig'] : null,
        'end_timestamp' => $end['timestamp'],
        'end_datetime' => $end['datetime'],
        'end_iso_gmdate' => $end['iso_gmdate'],
        'allday' => $allday,
        'tz' => !$allday ? $tz : null,
        'tz_abbrev' => !$allday ? $tz_abbrev : null,
        'span' => $span,
        'title' => $row['title'],
        'location' => $row['location'],
        'member' => $row['id_member'],
        'realname' => $row['real_name'],
        'sequence' => $row['modified_time'],
        'topic' => array(
            'id' => $row['id_topic'],
            'member_started' => $row['id_member_started'],
            'first_msg' => $row['id_first_msg'],
        ),
    );

    $return_value['last_day'] = (int) strftime('%d', mktime(0, 0, 0, $return_value['month'] == 12 ? 1 : $return_value['month'] + 1, 0, $return_value['month'] == 12 ? $return_value['year'] + 1 : $return_value['year']));

    return $return_value;
}

/**
 * Gets an initial set of date and time values for creating a new event.
 *
 * @return array An array containing an initial set of date and time values for an event.
 */
function getNewEventDatetimes()
{
    // Ensure setEventStartEnd() has something to work with
    $now = date_create();
    $_POST['year'] = !empty($_POST['year']) ? $_POST['year'] : date_format($now, 'Y');
    $_POST['month'] = !empty($_POST['month']) ? $_POST['month'] : date_format($now, 'm');
    $_POST['day'] = !empty($_POST['day']) ? $_POST['day'] : date_format($now, 'd');
    $_POST['hour'] = !empty($_POST['hour']) ? $_POST['hour'] : date_format($now, 'H');
    $_POST['minute'] = !empty($_POST['minute']) ? $_POST['minute'] : date_format($now, 'i');
    $_POST['second'] = !empty($_POST['second']) ? $_POST['second'] : date_format($now, 's');

    // Set the basic values for the new event
    $row_keys = array('start_date', 'end_date', 'start_time', 'end_time', 'timezone');
    $row = array_combine($row_keys, setEventStartEnd());

    // And now set the full suite of values
    list($start, $end, $allday, $span, $tz, $tz_abbrev) = buildEventDatetimes($row);

    // Default theme only uses some of this info, but others might want it all
    $eventProperties = array(
        'year' => $start['year'],
        'month' => $start['month'],
        'day' => $start['day'],
        'hour' => !$allday ? $start['hour'] : null,
        'minute' => !$allday ? $start['minute'] : null,
        'second' => !$allday ? $start['second'] : null,
        'start_date' => $row['start_date'],
        'start_date_local' => $start['date_local'],
        'start_date_orig' => $start['date_orig'],
        'start_time' => !$allday ? $row['start_time'] : null,
        'start_time_local' => !$allday ? $start['time_local'] : null,
        'start_time_orig' => !$allday ? $start['time_orig'] : null,
        'start_timestamp' => $start['timestamp'],
        'start_datetime' => $start['datetime'],
        'start_iso_gmdate' => $start['iso_gmdate'],
        'end_year' => $end['year'],
        'end_month' => $end['month'],
        'end_day' => $end['day'],
        'end_hour' => !$allday ? $end['hour'] : null,
        'end_minute' => !$allday ? $end['minute'] : null,
        'end_second' => !$allday ? $end['second'] : null,
        'end_date' => $row['end_date'],
        'end_date_local' => $end['date_local'],
        'end_date_orig' => $end['date_orig'],
        'end_time' => !$allday ? $row['end_time'] : null,
        'end_time_local' => !$allday ? $end['time_local'] : null,
        'end_time_orig' => !$allday ? $end['time_orig'] : null,
        'end_timestamp' => $end['timestamp'],
        'end_datetime' => $end['datetime'],
        'end_iso_gmdate' => $end['iso_gmdate'],
        'allday' => $allday,
        'tz' => !$allday ? $tz : null,
        'tz_abbrev' => !$allday ? $tz_abbrev : null,
        'span' => $span,
    );

    return $eventProperties;
}

/**
 * Set the start and end dates and times for a posted event for insertion into the database.
 * Validates all date and times given to it.
 * Makes sure events do not exceed the maximum allowed duration (if any).
 * If passed an array that defines any time or date parameters, they will be used. Otherwise, gets the values from $_POST.
 *
 * @param array $eventOptions An array of optional time and date parameters (span, start_year, end_month, etc., etc.)
 * @return array An array containing $start_date, $end_date, $start_time, $end_time
 */
function setEventStartEnd($eventOptions = array())
{
    global $modSettings;

    // Set $span, in case we need it
    $span = isset($eventOptions['span']) ? $eventOptions['span'] : (isset($_POST['span']) ? $_POST['span'] : 0);
    if ($span > 0)
        $span = !empty($modSettings['cal_maxspan']) ? min($modSettings['cal_maxspan'], $span - 1) : $span - 1;

    // Define the timezone for this event, falling back to the default if not provided
    if (!empty($eventOptions['tz']) && in_array($eventOptions['tz'], timezone_identifiers_list(DateTimeZone::ALL_WITH_BC)))
        $tz = $eventOptions['tz'];
    elseif (!empty($_POST['tz']) && in_array($_POST['tz'], timezone_identifiers_list(DateTimeZone::ALL_WITH_BC)))
        $tz = $_POST['tz'];
    else
        $tz = getUserTimezone();

    // Is this supposed to be an all day event, or should it have specific start and end times?
    if (isset($eventOptions['allday']))
        $allday = $eventOptions['allday'];
    elseif (empty($_POST['allday']))
        $allday = false;
    else
        $allday = true;

    // Input might come as individual parameters...
    $start_year = isset($eventOptions['year']) ? $eventOptions['year'] : (isset($_POST['year']) ? $_POST['year'] : null);
    $start_month = isset($eventOptions['month']) ? $eventOptions['month'] : (isset($_POST['month']) ? $_POST['month'] : null);
    $start_day = isset($eventOptions['day']) ? $eventOptions['day'] : (isset($_POST['day']) ? $_POST['day'] : null);
    $start_hour = isset($eventOptions['hour']) ? $eventOptions['hour'] : (isset($_POST['hour']) ? $_POST['hour'] : null);
    $start_minute = isset($eventOptions['minute']) ? $eventOptions['minute'] : (isset($_POST['minute']) ? $_POST['minute'] : null);
    $start_second = isset($eventOptions['second']) ? $eventOptions['second'] : (isset($_POST['second']) ? $_POST['second'] : null);
    $end_year = isset($eventOptions['end_year']) ? $eventOptions['end_year'] : (isset($_POST['end_year']) ? $_POST['end_year'] : null);
    $end_month = isset($eventOptions['end_month']) ? $eventOptions['end_month'] : (isset($_POST['end_month']) ? $_POST['end_month'] : null);
    $end_day = isset($eventOptions['end_day']) ? $eventOptions['end_day'] : (isset($_POST['end_day']) ? $_POST['end_day'] : null);
    $end_hour = isset($eventOptions['end_hour']) ? $eventOptions['end_hour'] : (isset($_POST['end_hour']) ? $_POST['end_hour'] : null);
    $end_minute = isset($eventOptions['end_minute']) ? $eventOptions['end_minute'] : (isset($_POST['end_minute']) ? $_POST['end_minute'] : null);
    $end_second = isset($eventOptions['end_second']) ? $eventOptions['end_second'] : (isset($_POST['end_second']) ? $_POST['end_second'] : null);

    // ... or as datetime strings ...
    $start_string = isset($eventOptions['start_datetime']) ? $eventOptions['start_datetime'] : (isset($_POST['start_datetime']) ? $_POST['start_datetime'] : null);
    $end_string = isset($eventOptions['end_datetime']) ? $eventOptions['end_datetime'] : (isset($_POST['end_datetime']) ? $_POST['end_datetime'] : null);

    // ... or as date strings and time strings.
    $start_date_string = isset($eventOptions['start_date']) ? $eventOptions['start_date'] : (isset($_POST['start_date']) ? $_POST['start_date'] : null);
    $start_time_string = isset($eventOptions['start_time']) ? $eventOptions['start_time'] : (isset($_POST['start_time']) ? $_POST['start_time'] : null);
    $end_date_string = isset($eventOptions['end_date']) ? $eventOptions['end_date'] : (isset($_POST['end_date']) ? $_POST['end_date'] : null);
    $end_time_string = isset($eventOptions['end_time']) ? $eventOptions['end_time'] : (isset($_POST['end_time']) ? $_POST['end_time'] : null);

    // If the date and time were given in separate strings, combine them
    if (empty($start_string) && isset($start_date_string))
        $start_string = $start_date_string . (isset($start_time_string) ? ' ' . $start_time_string : '');
    if (empty($end_string) && isset($end_date_string))
        $end_string = $end_date_string . (isset($end_time_string) ? ' ' . $end_time_string : '');

    // If some form of string input was given, override individually defined options with it
    if (isset($start_string))
    {
        $start_string_parsed = date_parse($start_string);
        if (empty($start_string_parsed['error_count']) && empty($start_string_parsed['warning_count']))
        {
            if ($start_string_parsed['year'] != false)
            {
                $start_year = $start_string_parsed['year'];
                $start_month = $start_string_parsed['month'];
                $start_day = $start_string_parsed['day'];
            }
            if ($start_string_parsed['hour'] != false)
            {
                $start_hour = $start_string_parsed['hour'];
                $start_minute = $start_string_parsed['minute'];
                $start_second = $start_string_parsed['second'];
            }
        }
    }
    if (isset($end_string))
    {
        $end_string_parsed = date_parse($end_string);
        if (empty($end_string_parsed['error_count']) && empty($end_string_parsed['warning_count']))
        {
            if ($end_string_parsed['year'] != false)
            {
                $end_year = $end_string_parsed['year'];
                $end_month = $end_string_parsed['month'];
                $end_day = $end_string_parsed['day'];
            }
            if ($end_string_parsed['hour'] != false)
            {
                $end_hour = $end_string_parsed['hour'];
                $end_minute = $end_string_parsed['minute'];
                $end_second = $end_string_parsed['second'];
            }
        }
    }

    // Validate input
    $start_date_isvalid = checkdate($start_month, $start_day, $start_year);
    $end_date_isvalid = checkdate($end_month, $end_day, $end_year);

    $start_time_isset = (isset($start_hour) && isset($start_minute) && isset($start_second));
    $d = date_parse(sprintf('%02d:%02d:%02d', $start_hour, $start_minute, $start_second));
    $start_time_isvalid = ($d['error_count'] == 0 && $d['warning_count'] == 0) ? true : false;

    $end_time_isset = (isset($end_hour) && isset($end_minute) && isset($end_second));
    $d = date_parse(sprintf('%02d:%02d:%02d', $end_hour, $end_minute, $end_second));
    $end_time_isvalid = ($d['error_count'] == 0 && $d['warning_count'] == 0) ? true : false;

    // Uh-oh...
    if ($start_date_isvalid === false)
    {
        fatal_lang_error('invalid_date', false);
    }

    // Make sure we use valid values for everything
    if ($end_date_isvalid === false)
    {
        $end_year = $start_year;
        $end_month = $start_month;
        $end_day = $start_day;
    }

    if ($allday === true || $start_time_isset === false || $start_time_isvalid === false)
    {
        $allday = true;
        $start_hour = 0;
        $start_minute = 0;
        $start_second = 0;
    }

    if ($allday === true || $end_time_isvalid === false || $end_time_isset === false)
    {
        $end_hour = $start_hour;
        $end_minute = $start_minute;
        $end_second = $start_second;
    }

    // Now create our datetime objects
    $start_object = date_create(sprintf('%04d-%02d-%02d %02d:%02d:%02d', $start_year, $start_month, $start_day, $start_hour, $start_minute, $start_second) . ' ' . $tz);
    $end_object = date_create(sprintf('%04d-%02d-%02d %02d:%02d:%02d', $end_year, $end_month, $end_day, $end_hour, $end_minute, $end_second) . ' ' . $tz);

    // Is $end_object too early?
    if ($start_object >= $end_object)
    {
        $end_object = date_create(sprintf('%04d-%02d-%02d %02d:%02d:%02d', $start_year, $start_month, $start_day, $start_hour, $start_minute, $start_second) . ' ' . $tz);
        if ($span > 0)
            date_add($end_object, date_interval_create_from_date_string($span . ' days'));
        else
            date_add($end_object, date_interval_create_from_date_string('1 hour'));
    }

    // Is $end_object too late?
    if (!empty($modSettings['cal_maxspan']))
    {
        $date_diff = date_diff($start_object, $end_object);
        if ($date_diff->days > $modSettings['cal_maxspan'])
        {
            if ($modSettings['cal_maxspan'] > 1)
            {
                $end_object = date_create(sprintf('%04d-%02d-%02d %02d:%02d:%02d', $start_year, $start_month, $start_day, $start_hour, $start_minute, $start_second) . ' ' . $tz);
                date_add($end_object, date_interval_create_from_date_string($modSettings['cal_maxspan'] . ' days'));
            }
            else
                $end_object = date_create(sprintf('%04d-%02d-%02d %02d:%02d:%02d', $start_year, $start_month, $start_day, '11', '59', '59') . ' ' . $tz);
        }
    }

    // Finally, make our strings
    $start_date = date_format($start_object, 'Y-m-d');
    $end_date = date_format($end_object, 'Y-m-d');

    if ($allday == true)
    {
        $start_time = null;
        $end_time = null;
        $tz = null;
    }
    else
    {
        $start_time = date_format($start_object, 'H:i:s');
        $end_time = date_format($end_object, 'H:i:s');
    }

    return array($start_date, $end_date, $start_time, $end_time, $tz);
}

/**
 * Helper function for getEventRange, getEventProperties, getNewEventDatetimes, etc.
 *
 * @param array $row A database row representing an event from the calendar table
 * @return array An array containing the start and end date and time properties for the event
 */
function buildEventDatetimes($row)
{
    global $sourcedir, $user_info, $txt;
    static $date_format = '', $time_format = '';

    require_once($sourcedir . '/Subs.php');
    static $timezone_array = array();

    loadLanguage('Timezones');

    // First, try to create a better date format, ignoring the "time" elements.
    if (empty($date_format))
        $date_format = get_date_or_time_format('date');

    // We want a fairly compact version of the time, but as close as possible to the user's settings.
    if (empty($time_format))
        $time_format = strtr(get_date_or_time_format('time'), array(
            '%I' => '%l',
            '%H' => '%k',
            '%S' => '',
            '%r' => '%l:%M %p',
            '%R' => '%k:%M',
            '%T' => '%l:%M',
        ));

    // Should this be an all day event?
    $allday = (empty($row['start_time']) || empty($row['end_time']) || empty($row['timezone']) || !in_array($row['timezone'], timezone_identifiers_list(DateTimeZone::ALL_WITH_BC))) ? true : false;

    // How many days does this event span?
    $span = 1 + date_interval_format(date_diff(date_create($row['start_date']), date_create($row['end_date'])), '%d');

    // We need to have a defined timezone in the steps below
    if (empty($row['timezone']))
        $row['timezone'] = getUserTimezone();

    if (empty($timezone_array[$row['timezone']]))
        $timezone_array[$row['timezone']] = timezone_open($row['timezone']);

    // Get most of the standard date information for the start and end datetimes
    $start = date_parse($row['start_date'] . (!$allday ? ' ' . $row['start_time'] : ''));
    $end = date_parse($row['end_date'] . (!$allday ? ' ' . $row['end_time'] : ''));

    // But we also want more info, so make some DateTime objects we can use
    $start_object = date_create($row['start_date'] . (!$allday ? ' ' . $row['start_time'] : ''), $timezone_array[$row['timezone']]);
    $end_object = date_create($row['end_date'] . (!$allday ? ' ' . $row['end_time'] : ''), $timezone_array[$row['timezone']]);

    // Unix timestamps are good
    $start['timestamp'] = date_format($start_object, 'U');
    $end['timestamp'] = date_format($end_object, 'U');

    // Datetime string without timezone  (e.g. '2016-12-28 22:45:30')
    $start['datetime'] = date_format($start_object, 'Y-m-d H:i:s');
    $end['datetime'] = date_format($start_object, 'Y-m-d H:i:s');

    // ISO formatted datetime string, relative to UTC (e.g. '2016-12-29T05:45:30+00:00')
    $start['iso_gmdate'] = gmdate('c', $start['timestamp']);
    $end['iso_gmdate'] = gmdate('c', $end['timestamp']);

    // Strings showing the datetimes in the user's preferred format, relative to the user's time zone
    list($start['date_local'], $start['time_local']) = explode(' § ', timeformat($start['timestamp'], $date_format . ' § ' . $time_format));
    list($end['date_local'], $end['time_local']) = explode(' § ', timeformat($end['timestamp'], $date_format . ' § ' . $time_format));

    // Strings showing the datetimes in the user's preferred format, relative to the event's time zone
    list($start['date_orig'], $start['time_orig']) = explode(' § ', timeformat(strtotime(date_format($start_object, 'Y-m-d H:i:s')), $date_format . ' § ' . $time_format, 'none'));
    list($end['date_orig'], $end['time_orig']) = explode(' § ', timeformat(strtotime(date_format($end_object, 'Y-m-d H:i:s')), $date_format . ' § ' . $time_format, 'none'));

    // The time zone identifier (e.g. 'Europe/London') and abbreviation (e.g. 'GMT')
    $tz = date_format($start_object, 'e');
    $tz_abbrev = date_format($start_object, 'T');

    // If the abbreviation is just a numerical offset from UTC, make that clear.
    if (strspn($tz_abbrev, '+-') > 0)
        $tz_abbrev = 'UTC' . $tz_abbrev;

    return array($start, $end, $allday, $span, $tz, $tz_abbrev);
}

/**
 * Gets a member's selected timezone identifier directly from the database
 *
 * @param int $id_member The member id to look up. If not provided, the current user's id will be used.
 * @return string The timezone identifier string for the user's timezone.
 */
function getUserTimezone($id_member = null)
{
    global $smcFunc, $context, $user_info, $modSettings, $user_settings;
    static $member_cache = array();

    if (is_null($id_member) && $user_info['is_guest'] == false)
        $id_member = $context['user']['id'];

    //check if the cache got the data
    if (isset($id_member) && isset($member_cache[$id_member]))
    {
        return $member_cache[$id_member];
    }

    //maybe the current user is the one
    if (isset($user_settings['id_member']) && $user_settings['id_member'] == $id_member && !empty($user_settings['timezone']))
    {
        $member_cache[$id_member] = $user_settings['timezone'];
        return $user_settings['timezone'];
    }

    if (isset($id_member))
    {
        $request = $smcFunc['db_query']('', '
            SELECT timezone
            FROM {db_prefix}members
            WHERE id_member = {int:id_member}',
            array(
                'id_member' => $id_member,
            )
        );
        list($timezone) = $smcFunc['db_fetch_row']($request);
        $smcFunc['db_free_result']($request);
    }

    if (empty($timezone) || !in_array($timezone, timezone_identifiers_list(DateTimeZone::ALL_WITH_BC)))
        $timezone = isset($modSettings['default_timezone']) ? $modSettings['default_timezone'] : date_default_timezone_get();

    if (isset($id_member))
        $member_cache[$id_member] = $timezone;

    return $timezone;
}

/**
 * Gets all of the holidays for the listing
 *
 * @param int $start The item to start with (for pagination purposes)
 * @param int $items_per_page How many items to show on each page
 * @param string $sort A string indicating how to sort the results
 * @return array An array of holidays, each of which is an array containing the id, year, month, day and title of the holiday
 */
function list_getHolidays($start, $items_per_page, $sort)
{
    global $smcFunc;

    $request = $smcFunc['db_query']('', '
        SELECT id_holiday, YEAR(event_date) AS year, MONTH(event_date) AS month, DAYOFMONTH(event_date) AS day, title
        FROM {db_prefix}calendar_holidays
        ORDER BY {raw:sort}
        LIMIT {int:start}, {int:max}',
        array(
            'sort' => $sort,
            'start' => $start,
            'max' => $items_per_page,
        )
    );
    $holidays = array();
    while ($row = $smcFunc['db_fetch_assoc']($request))
        $holidays[] = $row;
    $smcFunc['db_free_result']($request);

    return $holidays;
}

/**
 * Helper function to get the total number of holidays
 *
 * @return int The total number of holidays
 */
function list_getNumHolidays()
{
    global $smcFunc;

    $request = $smcFunc['db_query']('', '
        SELECT COUNT(*)
        FROM {db_prefix}calendar_holidays',
        array(
        )
    );
    list($num_items) = $smcFunc['db_fetch_row']($request);
    $smcFunc['db_free_result']($request);

    return (int) $num_items;
}

/**
 * Remove a holiday from the calendar
 *
 * @param array $holiday_ids An array of IDs of holidays to delete
 */
function removeHolidays($holiday_ids)
{
    global $smcFunc;

    $smcFunc['db_query']('', '
        DELETE FROM {db_prefix}calendar_holidays
        WHERE id_holiday IN ({array_int:id_holiday})',
        array(
            'id_holiday' => $holiday_ids,
        )
    );

    updateSettings(array(
        'calendar_updated' => time(),
    ));
}

?>