use async_trait::async_trait;

use bytes::BytesMut;
use log::warn;

use tokio::sync::mpsc::channel;

use crate::proxynat::udp::ProxyUdpHandler;

use crate::nat::handler::{NatHandler, NatHandlerContext, NatHandlerFactory};
use crate::nat::key::NatKeyProtocol;

use self::icmp::ProxyIcmpHandler;
use self::tcp::ProxyTcpHandler;

mod icmp;
mod tcp;
mod udp;

const RX_CHANNEL_QUEUE_LEN: usize = 1000;

pub struct ProxyNatHandlerFactory {}

impl Default for ProxyNatHandlerFactory {
    fn default() -> Self {
        Self::new()
    }
}

impl ProxyNatHandlerFactory {
    pub fn new() -> Self {
        Self {}
    }
}

#[async_trait]
impl NatHandlerFactory for ProxyNatHandlerFactory {
    async fn nat(&self, context: NatHandlerContext) -> Option<Box<dyn NatHandler>> {
        match context.key.protocol {
            NatKeyProtocol::Udp => {
                let (rx_sender, rx_receiver) = channel::<BytesMut>(RX_CHANNEL_QUEUE_LEN);
                let mut handler = ProxyUdpHandler::new(rx_sender);

                if let Err(error) = handler.spawn(context, rx_receiver).await {
                    warn!("unable to spawn udp proxy handler: {}", error);
                    None
                } else {
                    Some(Box::new(handler))
                }
            }

            NatKeyProtocol::Icmp => {
                let (rx_sender, rx_receiver) = channel::<BytesMut>(RX_CHANNEL_QUEUE_LEN);
                let mut handler = ProxyIcmpHandler::new(rx_sender);

                if let Err(error) = handler.spawn(context, rx_receiver).await {
                    warn!("unable to spawn icmp proxy handler: {}", error);
                    None
                } else {
                    Some(Box::new(handler))
                }
            }

            NatKeyProtocol::Tcp => {
                let (rx_sender, rx_receiver) = channel::<BytesMut>(RX_CHANNEL_QUEUE_LEN);
                let mut handler = ProxyTcpHandler::new(rx_sender);

                if let Err(error) = handler.spawn(context, rx_receiver).await {
                    warn!("unable to spawn tcp proxy handler: {}", error);
                    None
                } else {
                    Some(Box::new(handler))
                }
            }
        }
    }
}