use std::net::SocketAddrV4;

use anyhow::{Context, Result};
use igd::{aio::*, PortMappingProtocol};
use log::*;
use tokio::{
  select,
  sync::watch,
  time::{self, Duration},
};

use crate::messages;

pub struct IgdActor {
  last_ports: messages::PublicExposedPorts,
  rx_ports: watch::Receiver<messages::PublicExposedPorts>,
  gateway: Gateway,
  refresh: Duration,
  expire: Duration,
  private_ip: String,
}

impl IgdActor {
  pub async fn new(
    priv_ip: &str,
    refresh: Duration,
    expire: Duration,
    rxp: &watch::Receiver<messages::PublicExposedPorts>,
  ) -> Result<Self> {
    let gw = search_gateway(Default::default())
      .await
      .context("Failed to find IGD gateway")?;
    info!("IGD gateway: {}", gw);

    let ctx = Self {
      gateway: gw,
      rx_ports: rxp.clone(),
      private_ip: priv_ip.to_string(),
      refresh: refresh,
      expire: expire,
      last_ports: messages::PublicExposedPorts::new(),
    };

    return Ok(ctx)
  }

  pub async fn listen(&mut self) -> Result<()> {
    let mut interval = time::interval(self.refresh);
    loop {
      // 1. Wait for an event
      let new_ports = select! {
        Some(ports) = self.rx_ports.recv() => Some(ports),
        _ = interval.tick() => None,
        else => return Ok(()) // Sender dropped, terminate loop.
      };

      // 2. Update last ports if needed
      if let Some(p) = new_ports {
        self.last_ports = p;
      }

      // 3. Flush IGD requests
      match self.do_igd().await {
        Ok(()) => debug!("Successfully updated IGD"),
        Err(e) => error!("An error occured while updating IGD. {}", e),
      }
    }
  }

  pub async fn do_igd(&self) -> Result<()> {
    let actions = [
      (PortMappingProtocol::TCP, &self.last_ports.tcp_ports),
      (PortMappingProtocol::UDP, &self.last_ports.udp_ports),
    ];

    for (proto, list) in actions.iter() {
      for port in *list {
        let service_str = format!("{}:{}", self.private_ip, port);
        let service = service_str
          .parse::<SocketAddrV4>()
          .context("Invalid socket address")?;
        self
          .gateway
          .add_port(
            *proto,
            *port,
            service,
            self.expire.as_secs() as u32,
            "diplonat",
          )
          .await?;
        debug!("IGD request successful for {:#?} {}", proto, service);
      }
    }

    return Ok(())
  }
}