impl ServerState for PatchServerState {
    type Packet = PatchPacket;
    type PacketError = PatchError;

    fn on_connect(&mut self) -> Vec<OnConnect> {
        let mut rng = rand::thread_rng();
        let key_in: u32 = rng.gen();
        let key_out: u32 = rng.gen();

        vec![OnConnect::Packet(Box::new(PatchWelcome::new(key_out, key_in))),
             OnConnect::Cipher((Box::new(PSOPCCipher::new(key_in)), Box::new(PSOPCCipher::new(key_out))))
        ]
    }

    fn handle(&mut self, pkt: &PatchPacket) -> Box<dyn Iterator<Item = Box<dyn PSOPacket>>> {
        match pkt {
            PatchPacket::PatchWelcomeReply(_pkt) => {
                let p: Vec<Box<dyn PSOPacket>> = vec![Box::new(RequestLogin {})];
                Box::new(p.into_iter())
            },
            PatchPacket::LoginReply(_pkt) => {
                let mut p: Vec<Box<dyn PSOPacket>> = vec![Box::new(Message::new("hello player".to_string()))];
                p.append(&mut get_file_list_packets(&self.patch_file_tree));
                p.push(Box::new(PatchEndList {}));
                Box::new(p.into_iter())
            },
            PatchPacket::FileInfoReply(pkt) => {
                self.patch_file_info.push(pkt.clone());
                Box::new(None.into_iter())
            },
            PatchPacket::FileInfoListEnd(_pkt) => {
                let need_update = self.patch_file_info.iter()
                    .filter(|file_info| does_file_need_updating(file_info, &self.patch_file_lookup))
                    .collect::<Vec<_>>();

                let total_size = need_update.iter().fold(0, |a, file_info| a + file_info.size);
                let total_files = need_update.len() as u32;

                let p: Vec<Box<dyn PSOPacket>> = vec![Box::new(FilesToPatchMetadata::new(total_size, total_files)),
                                                      Box::new(PatchStartList {}),
                ];
                Box::new(p.into_iter().chain(SendFileIterator::new(&self)))
            }
        }
    }
}