Couchbase chat sync function

sync.js

function(doc, oldDoc) {
  
  if(doc._deleted) {
    if(oldDoc.type == "chatroom") {
      requireUser(oldDoc.user);
      var roomId = oldDoc._id;
      var roomMembers = oldDoc.members;
      var roomChannel = "room-" + roomId;
      channel(roomChannel);
      access(roomMembers, roomChannel);
    } else if (oldDoc.type == "message") {
      requireUser(oldDoc.user);
      var roomId = oldDoc.room;
      var messageChannel = "room-" + roomId;
      channel(messageChannel);
    }
    return;
  }
  
  if(doc.type == "chatroom") {
    var roomId = doc._id;
    var roomMembers = doc.members;
    var roomChannel = "room-" + roomId;
    channel(roomChannel);
    access(roomMembers, roomChannel);
  } else if(doc.type == "message") {
    // A user can only update its own messages
    if(oldDoc) {
      requireUser(oldDoc.user);
    }

    var roomId = doc.room;
    var messageChannel = "room-" + roomId;
    channel(messageChannel);
  }
}