Help in PHP/Joomla Json function which is communicated in Mobile.

I have some functions that needs tuning and re-creation. such as the following example. function addsetting() { $erroe_message=""; $newdata=array(); $loginhtml = ''; $isnotification=""; $issound=""; $isnotification=JRequest::getVar('isnotification'); $user_id=JRequest::getVar('user_id'); $issound=JRequest::getVar('issound'); $isLanguage = false; if(JRequest::getVar('language')){ $language=JRequest::getVar('language'); } $db = JFactory::getDBO(); $object = new stdClass(); $object->user_id = $user_id; $object->isnotification = $isnotification; $object->issound = $issound; $object->language = $language; $success = "true"; $msg="Setting Updated Successfully"; $db = JFactory::getDBO(); $sql = 'SELECT [login to view URL] FROM #__users_devices as d WHERE d.user_id='.$user_id; $db->setQuery($sql); $deviceid=$db->loadresult(); if($deviceid>0){ $object->id = $deviceid; $db->updateObject('#__users_devices',$object,'id'); }else{ $db->insertObject('#__users_devices',$object,'id'); } $data=""; $loginhtml .= '{ "success": "'.$success.'","msg" : "'.json_encode([$msg]).'","error_message" : "'.$erroe_message.'","action":"addsetting" }'; $document = JFactory::getDocument(); $document->setMimeEncoding('application/json'); JResponse::setHeader('Content-Disposition','attachment;filename="[login to view URL]"'); JRequest::setVar('tmpl','component'); echo $loginhtml; exit; }