use std::net::SocketAddrV4;

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

use crate::config::RuntimeConfigIgd;
use crate::messages;

pub struct IgdActor {
  expire: Duration,
  gateway: Gateway,
  last_ports: messages::PublicExposedPorts,
  private_ip: String,
  refresh: Duration,

  rx_ports: watch::Receiver<messages::PublicExposedPorts>,
}

impl IgdActor {
  pub async fn new(config: Option<RuntimeConfigIgd>, rxp: &watch::Receiver<messages::PublicExposedPorts>) -> Result<Option<Self>> {
    if config.is_none() {
      return Ok(None);
    }
    let config = config.unwrap();

    let gw = search_gateway(Default::default())
              .await
              .context("Failed to find IGD gateway")?;
    info!("IGD gateway: {}", gw);

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

    return Ok(Some(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(());
  }
}