/**
* Delete those messages from the database which corresponds to the given condition or to the given ids array
* Note: the delete cascade arrays are handled!
*
* @param string the name of this class
* Note: This is required until min phpversion will be 5.3. Since PHP 5.3 we can use static::function_name to achieve late static bindings
* @param string where condition
* @param array object ids
* @return mixed # of rows affected or false if error
*/
static function db_delete_where($class_name, $sql_where, $object_ids = NULL, $params = NULL)
{
global $DB;
$DB->begin();
if (!empty($sql_where)) {
$messages_to_delete = $DB->get_assoc('SELECT msg_ID, msg_thread_ID FROM T_messaging__message WHERE ' . $sql_where);
$object_ids = array_keys($messages_to_delete);
$thread_ids_to_delete = array_unique($messages_to_delete);
}
if (!$object_ids) {
// There is no comment to delete
$DB->commit();
return;
}
$message_ids_to_delete = implode(', ', $object_ids);
if (empty($thread_ids_to_delete)) {
// Make sure thread ids of the messages are collected
$thread_ids_to_delete = $DB->get_col('SELECT msg_thread_ID FROM T_messaging__message WHERE msg_ID IN ( ' . $message_ids_to_delete . ' )');
}
// Update thread statuses first unread message IDs
$result = $DB->query('UPDATE T_messaging__threadstatus
SET tsta_first_unread_msg_ID =
( SELECT message1.msg_ID
FROM T_messaging__message as message1
WHERE message1.msg_thread_ID = tsta_thread_ID
AND message1.msg_datetime > ( SELECT MAX( message2.msg_datetime)
FROM T_messaging__message as message2
WHERE message2.msg_ID IN ( ' . $message_ids_to_delete . ' )
AND message2.msg_thread_ID = tsta_thread_ID
)
ORDER BY message1.msg_datetime ASC
LIMIT 1
)
WHERE tsta_first_unread_msg_ID IN ( ' . $message_ids_to_delete . ')') !== false;
if ($result) {
// Remove messages with all of its delete cascade relations
$result = parent::db_delete_where($class_name, $sql_where, $object_ids);
}
if ($result !== false) {
// Delete those threads where all of the messages were deleted
load_class('messaging/model/_thread.class.php', 'Thread');
$orphan_thread_ids = $DB->get_col('
SELECT msg_thread_ID FROM T_messaging__message
WHERE msg_thread_ID IN ( ' . implode(', ', $thread_ids_to_delete) . ' )
GROUP BY msg_thread_ID
HAVING COUNT(*) < 1');
// Delete orphan threads if there are any
if (!empty($orphan_thread_ids) && Thread::db_delete_where('Thread', NULL, $orphan_thread_ids) === false) {
// Deleting threads was unsuccessful
$result = false;
}
}
// Commit or rollback the transaction
$result !== false ? $DB->commit() : $DB->rollback();
return $result;
}
/**
* Delete orphan threads
*
* @param integer or array of integers - one or multiple user ids - to delete those orphan threads where only the given user(s) was/were involved, leave it to NULL to delete all orphan threads
* @return boolean true on success
*/
function delete_orphan_threads($user_ids = NULL)
{
global $DB;
$DB->begin();
if (is_array($user_ids)) {
$users = implode(', ', $user_ids);
$in_users_condition = ' OR user_ID IN ( ' . $users . ' )';
$not_in_users_condition = ' AND user_ID NOT IN ( ' . $users . ' )';
} else {
$in_users_condition = is_number($user_ids) ? ' OR user_ID = ' . $user_ids : '';
$not_in_users_condition = is_number($user_ids) ? ' AND user_ID != ' . $user_ids : '';
}
// Get those thread ids which have already deleted participants or which participants will be deleted now
$affected_threads_ids = $DB->get_col('SELECT DISTINCT tsta_thread_ID
FROM T_messaging__threadstatus
LEFT JOIN T_users ON tsta_user_ID = user_ID
WHERE user_ID IS NULL' . $in_users_condition);
if (empty($affected_threads_ids)) {
// There are no affected thread ids, nothing to delete
$DB->commit();
return true;
}
// Filter previously collected thread ids to get those which have existing users outside of the deleted ones
$not_orphan_threads = $DB->get_col('SELECT DISTINCT tsta_thread_ID
FROM T_messaging__threadstatus
LEFT JOIN T_users ON tsta_user_ID = user_ID
WHERE tsta_thread_ID IN ( ' . implode(', ', $affected_threads_ids) . ' )
AND user_ID IS NOT NULL' . $not_in_users_condition);
// Orphan thread ids are the affected threads minus the ones with existing users
$orphan_thread_ids = array_diff($affected_threads_ids, $not_orphan_threads);
if (!empty($orphan_thread_ids)) {
// There are orphan threads ( or orphan thread targets )
load_class('messaging/model/_thread.class.php', 'Thread');
// Delete all orphan threads with all cascade relations
if (Thread::db_delete_where('Thread', NULL, $orphan_thread_ids, array('use_transaction' => false)) === false) {
// Deleting orphan threads failed
$DB->rollback();
return false;
}
}
$DB->commit();
return true;
}