/**
* Parses extension from file path.
* It returns [[self::$extension]] is the last is set.
* Otherwise the method tries to detect file mime type.
* If mime type was not detected the method tries to parse file extension.
* @param string $readFilePath path to file which extension must be parsed.
* @return string|null parsed extension in local file system charset or null if extension is unknown.
*/
protected function parseFileExtension($readFilePath)
{
if ($this->extension !== null) {
return $this->extension;
}
// try to determine mime type
$mimeType = FileSystemHelper::getMimeType($readFilePath, null, true);
if ($mimeType !== null) {
$extensions = FileSystemHelper::getExtensionsByMimeType($mimeType, $this->mimeMagicFile);
if (is_array($extensions) && count($extensions)) {
return reset($extensions);
}
}
// try to parse extension
$decodedReadFilePath = FileSystemHelper::decodeFilename($readFilePath);
if ($decodedReadFilePath === false) {
return null;
}
$extension = FileSystemHelper::extension($decodedReadFilePath);
if ($extension === null || $extension === '') {
return $extension;
}
$fsExtension = FileSystemHelper::encodeFilename($extension);
return $fsExtension === false ? null : $fsExtension;
}
