private function getRecurrenceRule()
{
$rule = '';
switch ($this->frequency_id) {
case FREQUENCY_WEEKLY:
$rule = 'FREQ=WEEKLY;';
break;
case FREQUENCY_TWO_WEEKS:
$rule = 'FREQ=WEEKLY;INTERVAL=2;';
break;
case FREQUENCY_FOUR_WEEKS:
$rule = 'FREQ=WEEKLY;INTERVAL=4;';
break;
case FREQUENCY_MONTHLY:
$rule = 'FREQ=MONTHLY;';
break;
case FREQUENCY_THREE_MONTHS:
$rule = 'FREQ=MONTHLY;INTERVAL=3;';
break;
case FREQUENCY_SIX_MONTHS:
$rule = 'FREQ=MONTHLY;INTERVAL=6;';
break;
case FREQUENCY_ANNUALLY:
$rule = 'FREQ=YEARLY;';
break;
}
if ($this->end_date) {
$rule .= 'UNTIL=' . $this->getOriginal('end_date');
}
return $rule;
}