/**
* Resolves an alias into a Version.
*
* IMPROVE: this method has an NPath complexity of 400. The configured NPath complexity threshold is 200.
*
* @SuppressWarnings(PHPMD.NPathComplexity)
*
* @param string $alias
* @param Collection $collection
*
* @return \Baleen\Migrations\Version\VersionInterface|null|string
*/
protected function doResolve($alias, Collection $collection)
{
if (!$collection instanceof Sortable) {
return null;
}
// parse alias
$matches = [];
if (!preg_match(self::PATTERN, $alias, $matches)) {
return null;
}
list(, $newAlias, $operator) = $matches;
// resolve the new alias (this will allow to resolve e.g. HEAD-1)
$absoluteVersion = $collection->get($newAlias);
if (null === $absoluteVersion) {
return null;
}
// calculate the offset
$count = !isset($matches[3]) ? strlen($operator) : (int) $matches[3];
if (strlen($operator) > 1) {
$operator = substr($operator, 0, 1);
}
$multiplier = $operator === '+' ? 1 : -1;
$offset = $count * $multiplier;
// find version by absolute position + offset
$absolutePos = $collection->indexOf($absoluteVersion);
return $collection->get($absolutePos + $offset);
}
