/**
* this methode calculate the next date
*/
function calculate_recurrence($recurrence_row)
{
// get the recurrence information
$recurrence_number = $recurrence_row['recurrence_number'];
$recurrence_type = $recurrence_row['recurrence_type'];
$day_time = 86400;
// 60 sec. * 60 min. * 24 h
$week_time = 604800;
// $day_time * 7days
$date_array = ELHelper::generate_date($recurrence_row['dates'], $recurrence_row['enddates']);
switch ($recurrence_type) {
case "1":
// +1 hour for the Summer to Winter clock change
$start_day = mktime(1, 0, 0, $date_array["month"], $date_array["day"], $date_array["year"]);
$start_day = $start_day + $recurrence_number * $day_time;
break;
case "2":
// +1 hour for the Summer to Winter clock change
$start_day = mktime(1, 0, 0, $date_array["month"], $date_array["day"], $date_array["year"]);
$start_day = $start_day + $recurrence_number * $week_time;
break;
case "3":
// month recurrence
/*
* warning here, we have to make sure the date exists: 31 of october + 1 month = 31 of november, which doesn't exists => skip the date!
*/
$start_day = mktime(1, 0, 0, $date_array["month"] + $recurrence_number, $date_array["day"], $date_array["year"]);
$interval = $recurrence_number;
while ((date('m', $start_day) + 12 - $date_array["month"]) % 12 != $interval) {
$interval += $recurrence_number;
$start_day = mktime(1, 0, 0, $date_array["month"] + $interval, $date_array["day"], $date_array["year"]);
}
break;
case "4":
$selected = ELHelper::convert2CharsDaysToInt(explode(',', $recurrence_row['recurrence_byday']), $recurrence_row['weekstart']);
// the selected weekdays
$current_weekday = (int) $date_array["weekday"];
if ($recurrence_row['weekstart'] == 1) {
// O for monday, not sunday
$current_weekday = ($current_weekday + 6) % 7;
}
if (count($selected) == 0) {
// this shouldn't happen, but if it does, to prevent problem use the current weekday for the repetition.
JError::raiseWarning(500, JText::_('Empty weekday recurrence'));
$selected = array($current_weekday);
}
sort($selected);
if ($recurrence_number < 5) {
// 1. - 4. week in a month
// look for the position of current start date in 'selected' days.
if ($current_weekday >= max($selected)) {
// last selected day of the week => next occurence is first selected day of next (interval) week
$start_day = $date_array["unixtime"] - ($current_weekday - $selected[0]) * $day_time + $week_time * $recurrence_number;
} else {
// next weekday
foreach ($selected as $k => $day) {
if ($current_weekday < $day) {
$next_weekday = $day;
break;
}
}
$start_day = $date_array["unixtime"] + ($next_weekday - $current_weekday) * $day_time;
}
} else {
if ($current_weekday >= max($selected)) {
// next occurence is next month
// the last or the before last week in a month
// the last day in the new month
$start_day = mktime(1, 0, 0, $date_array["month"] + 2, 1, $date_array["year"]) - $day_time;
$weekday_is = date("w", $start_day);
// first selected day of the week
$weekday_must = $selected[0];
// calculate the day difference between these days
if ($weekday_is >= $weekday_must) {
$day_diff = $weekday_is - $weekday_must;
} else {
$day_diff = $weekday_is - $weekday_must + 7;
}
$start_day = $start_day - $day_diff * $day_time;
if ($recurrence_number == 6) {
// before last?
$start_day = $start_day - $week_time;
}
} else {
// next weekday
foreach ($selected as $k => $day) {
if ($current_weekday < $day) {
$next_weekday = $day;
break;
}
}
// next occurence is next selected weekday
$start_day = $date_array["unixtime"] + ($next_weekday - $current_weekday) * $day_time;
}
}
break;
}
$recurrence_row['dates'] = date("Y-m-d", $start_day);
if ($recurrence_row['enddates']) {
$recurrence_row['enddates'] = date("Y-m-d", $start_day + $date_array["day_diff"]);
}
if ($start_day < $date_array["unixtime"]) {
JError::raiseError(500, JText::_('Recurrence date generation error'));
}
return $recurrence_row;
}
