use moka::future::Cache;
use std::net::SocketAddr;
use std::sync::Arc;
use std::time::Duration;
use tokio::task::JoinHandle;
use tracing::{error, info};

use crate::config::Config;
use crate::packet::question::DnsQuestion;
use crate::packet::{Result, Packet};

use super::binding::Binding;
use super::resolver::Resolver;

pub struct Server {
    addr: SocketAddr,
    config: Arc<Config>,
    cache: Cache<DnsQuestion, (Packet, u64)>,
}

impl Server {
    pub async fn new(config: Config) -> Result<Self> {
        let addr = format!("[::]:{}", config.get_port()).parse::<SocketAddr>()?;
        let cache = Cache::builder()
            .time_to_live(Duration::from_secs(60 * 60))
            .max_capacity(1_000)
            .build();
        Ok(Self {
            addr,
            config: Arc::new(config),
            cache,
        })
    }

    pub async fn run(&self) -> Result<()> {
        let tcp = Binding::tcp(self.addr).await?;
        let tcp_handle = self.listen(tcp);

        let udp = Binding::udp(self.addr).await?;
        let udp_handle = self.listen(udp);

        info!("Fallback DNS Server is set to: {:?}", self.config.get_fallback_ns());
        info!("Listening for TCP and UDP traffic on [::]:{}", self.config.get_port());

        tokio::join!(tcp_handle)
            .0
            .expect("Failed to join tcp thread");
        tokio::join!(udp_handle)
            .0
            .expect("Failed to join udp thread");
        Ok(())
    }

    fn listen(&self, mut binding: Binding) -> JoinHandle<()> {
        let config = self.config.clone();
        let cache = self.cache.clone();
        tokio::spawn(async move {
            let mut id = 0;
            loop {
                let Ok(connection) = binding.connect().await else { continue };
                info!("Received request on {}", binding.name());

                let resolver = Resolver::new(id, connection, config.clone(), cache.clone());

                if let Err(err) = resolver.handle_query().await {
                    error!("{} request {} failed: {:?}", binding.name(), id, err);
                };

                id += 1;
            }
        })
    }
}