#[macro_use]
extern crate log;
use std::process;

use anyhow::{anyhow, Context, Result};
use event::{EventFlags, EventQueue};
use libredox::flag::{O_NONBLOCK, O_RDWR};
use libredox::Fd;

use redox_scheme::Socket;
use scheme::Smolnetd;
use smoltcp::wire::EthernetAddress;

mod buffer_pool;
mod error;
mod filter;
mod icmp_error;
mod link;
mod logger;
mod observer;
mod port_set;
mod router;
mod scheme;
mod slaac;

fn get_all_network_adapters() -> Result<Vec<String>> {
    use std::fs;

    let mut adapters = vec![];

    for entry_res in fs::read_dir("/scheme")? {
        let Ok(entry) = entry_res else { continue };
        let Ok(scheme) = entry.file_name().into_string() else { continue };
        if !scheme.starts_with("network") { continue; }
        adapters.push(scheme);
    }

    if adapters.is_empty() {
        // No NIC present is a normal state on a diskless/headless/bare machine,
        // or simply before an unsupported NIC's driver attaches. Report it as
        // info and let the caller exit cleanly instead of emitting a spurious
        // ERROR + non-zero exit on every boot of a NIC-less system.
        info!("no network adapter found; network stack idle");
        return Ok(adapters);
    }
    info!("Found {} network adapter(s): {:?}", adapters.len(), adapters);
    Ok(adapters)
}

fn run(daemon: daemon::Daemon) -> Result<()> {
    let adapters = get_all_network_adapters()?;
    if adapters.is_empty() {
        // Nothing to service; exit cleanly (see get_all_network_adapters).
        return Ok(());
    }
    trace!("found {} network adapter(s)", adapters.len());

    let mut network_fds = Vec::new();
    for name in &adapters {
        let fd = Fd::open(&format!("/scheme/{name}"), O_RDWR | O_NONBLOCK, 0)
            .map_err(|e| anyhow!("failed to open {name}: {e}"))?;
        let hw = std::fs::read(format!("/scheme/{name}/mac"))
            .map(|mac| EthernetAddress::from_bytes(&mac))
            .with_context(|| format!("failed to get mac for {name}"))?;
        network_fds.push((fd, hw, name.clone()));
    }

    trace!("opening ip scheme socket");
    let ip_fd = Socket::nonblock()
        .map_err(|e| anyhow!("failed to open create ip scheme socket: {:?}", e))?;

    trace!("opening udp scheme socket");
    let udp_fd =
        Socket::nonblock().map_err(|e| anyhow!("failed to open udp scheme socket: {:?}", e))?;

    trace!("opening tcp scheme socket");
    let tcp_fd =
        Socket::nonblock().map_err(|e| anyhow!("failed to open tcp scheme socket: {:?}", e))?;

    trace!("opening icmp scheme socket");
    let icmp_fd =
        Socket::nonblock().map_err(|e| anyhow!("failed to open icmp scheme socket: {:?}", e))?;

    trace!("opening netcfg scheme socket");
    let netcfg_fd =
        Socket::nonblock().map_err(|e| anyhow!("failed to open netcfg scheme socket {:?}", e))?;

    trace!("opening netfilter scheme socket");
    let netfilter_fd =
        Socket::nonblock().map_err(|e| anyhow!("failed to open netfilter scheme socket: {:?}", e))?;

    trace!("opening tun scheme socket");
    let tun_fd =
        Socket::nonblock().map_err(|e| anyhow!("failed to open tun scheme socket: {:?}", e))?;

    let time_path = format!("/scheme/time/{}", syscall::CLOCK_MONOTONIC);
    let time_fd = Fd::open(&time_path, O_RDWR, 0).context("failed to open /scheme/time")?;

    event::user_data! {
        enum EventSource {
            Network,
            Time,
            IpScheme,
            UdpScheme,
            TcpScheme,
            IcmpScheme,
            NetcfgScheme,
            NetfilterScheme,
            TunScheme,
        }
    }

    let event_queue = EventQueue::<EventSource>::new()
        .map_err(|e| anyhow!("failed to create event queue: {:?}", e))?;

    daemon.ready();

    // Subscribe to the first adapter for I/O events; the router handles
    // packet dispatch across all adapters in the DeviceList.
    if let Some((first_fd, _, _)) = network_fds.first() {
        event_queue
            .subscribe(first_fd.raw(), EventSource::Network, EventFlags::READ)
            .map_err(|e| anyhow!("failed to listen to network events: {:?}", e))?;
    }

    event_queue
        .subscribe(time_fd.raw(), EventSource::Time, EventFlags::READ)
        .map_err(|e| anyhow!("failed to listen to timer events: {:?}", e))?;

    event_queue
        .subscribe(ip_fd.inner().raw(), EventSource::IpScheme, EventFlags::READ)
        .map_err(|e| anyhow!("failed to listen to ip scheme events: {:?}", e))?;

    event_queue
        .subscribe(
            udp_fd.inner().raw(),
            EventSource::UdpScheme,
            EventFlags::READ,
        )
        .map_err(|e| anyhow!("failed to listen to udp scheme events: {:?}", e))?;

    event_queue
        .subscribe(
            tcp_fd.inner().raw(),
            EventSource::TcpScheme,
            EventFlags::READ,
        )
        .map_err(|e| anyhow!("failed to listen to tcp scheme events: {:?}", e))?;

    event_queue
        .subscribe(
            icmp_fd.inner().raw(),
            EventSource::IcmpScheme,
            EventFlags::READ,
        )
        .map_err(|e| anyhow!("failed to listen to icmp scheme events: {:?}", e))?;

    event_queue
        .subscribe(
            netcfg_fd.inner().raw(),
            EventSource::NetcfgScheme,
            EventFlags::READ,
        )
        .map_err(|e| anyhow!("failed to listen to netcfg scheme events: {:?}", e))?;

    event_queue
        .subscribe(
            netfilter_fd.inner().raw(),
            EventSource::NetfilterScheme,
            EventFlags::READ,
        )
        .map_err(|e| anyhow!("failed to listen to netfilter scheme events: {:?}", e))?;

    event_queue
        .subscribe(
            tun_fd.inner().raw(),
            EventSource::TunScheme,
            EventFlags::READ,
        )
        .map_err(|e| anyhow!("failed to listen to tun scheme events: {:?}", e))?;

    let mut smolnetd = Smolnetd::new(
        network_fds,
        ip_fd,
        udp_fd,
        tcp_fd,
        icmp_fd,
        time_fd,
        netcfg_fd,
        netfilter_fd,
        tun_fd,
    )
    .context("smolnetd: failed to initialize smolnetd")?;

    libredox::call::setrens(0, 0).context("smolnetd: failed to enter null namespace")?;

    let all = {
        use EventSource::*;
        [Network, Time, IpScheme, UdpScheme, TcpScheme, IcmpScheme, NetcfgScheme, NetfilterScheme, TunScheme].map(Ok)
    };

    for event_res in all
        .into_iter()
        .chain(event_queue.map(|r| r.map(|e| e.user_data)))
    {
        match event_res.map_err(|e| anyhow!("event result is error: {:?}", e))? {
            EventSource::Network => smolnetd.on_network_scheme_event(),
            EventSource::Time => smolnetd.on_time_event(),
            EventSource::IpScheme => smolnetd.on_ip_scheme_event(),
            EventSource::UdpScheme => smolnetd.on_udp_scheme_event(),
            EventSource::TcpScheme => smolnetd.on_tcp_scheme_event(),
            EventSource::IcmpScheme => smolnetd.on_icmp_scheme_event(),
            EventSource::NetcfgScheme => smolnetd.on_netcfg_scheme_event(),
            EventSource::NetfilterScheme => smolnetd.on_netfilter_scheme_event(),
            EventSource::TunScheme => smolnetd.on_tun_scheme_event(),
        }
        .map_err(|e| error!("Received packet error: {:?}", e));
    }
    Ok(())
}

fn main() {
    daemon::Daemon::new(daemon_runner);
}

fn daemon_runner(daemon: daemon::Daemon) -> ! {
    logger::init_logger("smolnetd");

    if let Err(err) = run(daemon) {
        error!("smoltcpd: {}", err);
        process::exit(1);
    }
    process::exit(0);
}