use dbus::{
    channel::{MatchingReceiver, Token},
    message::MatchRule,
    nonblock::SyncConnection,
};
use dbus_crossroads::{Context, Crossroads, MethodErr};
use defguard_wireguard_rs::{key::Key, net::IpAddrMask, WireguardInterfaceApi};
use log::{debug, error, info, warn};
use rand::Rng;
use std::{
    collections::{hash_map::Entry, HashMap},
    marker::PhantomData,
    net::SocketAddr,
    ops::DerefMut,
    path::PathBuf,
    str::FromStr,
    sync::Arc,
    time::SystemTime,
};
use tokio::{net::TcpListener, sync::RwLock, task};

use crate::{daemon::*, daemon_config::*, daemon_network::*};

pub async fn start_dbus(
    state: Arc<RwLock<State>>,
    config_path: PathBuf,
) -> Result<(Arc<SyncConnection>, Token), DaemonError> {
    let mut cr = Crossroads::new();
    let if_token = cr.register("de.a.maesch", move |b| {
        //b.signal::<(String, String), _>("Proposal", ("network", "peer_data"));

        let state_rem_network = state.clone();
        let config_path_rem_network = config_path.clone();

        let state_add_peer = state.clone();
        let config_path_add_peer = config_path.clone();

        b.method_with_cr_async(
            "AddNetwork",
            ("name", "key", "ip", "listen_port", "maesch_port"),
            ("success",),
            move |ctx, _, args: (String, String, String, u16, u16)| {
                debug!("Received AddNetwork");
                handle_add_network(ctx, state.clone(), config_path.clone(), args)
            },
        );
        b.method_with_cr_async(
            "RemoveNetwork",
            ("name",),
            ("success",),
            move |ctx, _, args: (String,)| {
                debug!("Received RemoveNetwork");
                handle_remove_network(
                    ctx,
                    state_rem_network.clone(),
                    config_path_rem_network.clone(),
                    args,
                )
            },
        );
        b.method_with_cr_async(
            "AddPeer",
            (
                "network",
                "key",
                "psk",
                "use_hostnames",
                "endpoint",
                "maesch_endpoint",
                "ips",
            ),
            ("success",),
            move |ctx,
                  _,
                  args: (
                String,
                String,
                String,
                bool,
                String,
                String,
                Vec<(String, String)>,
            )| {
                debug!("Received AddPeer");
                handle_add_peer(
                    ctx,
                    state_add_peer.clone(),
                    config_path_add_peer.clone(),
                    args,
                )
            },
        );
    });
    cr.insert("/de/a/maesch", &[if_token], ());

    // drive dbus interface
    let (res, c) = dbus_tokio::connection::new_system_sync()?;
    cr.set_async_support(Some((
        c.clone(),
        Box::new(|x| {
            tokio::spawn(x);
        }),
    )));
    let _ = tokio::spawn(print_error(async {
        res.await;
        Result::<!, &'static str>::Err("lost connection to dbus!")
    }));
    let receive_token = c.start_receive(
        MatchRule::new_method_call(),
        Box::new(move |msg, conn| {
            cr.handle_message(msg, conn).unwrap();
            true
        }),
    );
    c.request_name("de.a.maesch", false, true, false).await?;

    Ok((c, receive_token))
}

async fn handle_add_peer(
    mut ctx: Context,
    state: Arc<RwLock<State>>,
    config_path: PathBuf,
    (nw_name, key, may_psk, use_hostnames, may_endpoint, may_mäsch_endpoint, allowed_ips): (
        String,
        String,
        String,
        bool,
        String,
        String,
        Vec<(String, String)>,
    ),
) -> PhantomData<(bool,)> {
    let key = match Key::from_str(&key) {
        Ok(k) => k,
        Err(e) => {
            warn!("AddPeer with bad key: {e}");
            return ctx.reply(Err(MethodErr::invalid_arg(&e)));
        }
    };

    let psk = match may_psk.as_str() {
        "" => None,
        _ => match Key::from_str(&may_psk) {
            Ok(k) => Some(k),
            Err(e) => {
                warn!("AddPeer with bad pre-shared key: {e}");
                return ctx.reply(Err(MethodErr::invalid_arg(&e)));
            }
        },
    };

    // use_hostnames is already a boolean, so i guess we require it to be set?

    let endpoint = match may_endpoint.as_str() {
        "" => None,
        _ => match SocketAddr::from_str(&may_endpoint) {
            Ok(addr) => Some(Endpoint::Ip(addr)),
            Err(_) => {
                let mut parts_it = may_endpoint.split(':');
                match (parts_it.next(), parts_it.next(), parts_it.next()) {
                    (Some(domain), Some(port), None) if let Ok(port) = port.parse() => {
                        Some(Endpoint::Domain(domain.to_owned(), port))
                    }
                    _ => {
                        warn!("AddPeer with bad endpoint: {may_endpoint}");
                        return ctx.reply(Err(MethodErr::invalid_arg("Could not parse endpoint")));
                    }
                }
            }
        },
    };

    let mäsch_endpoint = match SocketAddr::from_str(&may_mäsch_endpoint) {
        Ok(addr) => addr,
        Err(e) => {
            warn!("AddPeer with bad mäsch endpoint: {e}");
            return ctx.reply(Err(MethodErr::invalid_arg(&e)));
        }
    };

    // let may_allowed_ips = mapM (\(addr, hostname) -> (, if hostname == "" then Nothing else Just hostname) <$> readMaybe addr) allowed_ips
    let may_allowed_ips: Result<Vec<(IpAddrMask, Option<String>)>, _> = allowed_ips
        .into_iter()
        .map(|(addr, hostname)| {
            addr.parse()
                .map(|ip_mask| (ip_mask, if hostname == "" { None } else { Some(hostname) }))
        })
        .collect();
    let allowed_ips = match may_allowed_ips {
        Ok(v) => v,
        Err(e) => {
            warn!("AddPeer with bad allowed ips: {e}");
            return ctx.reply(Err(MethodErr::invalid_arg(&e)));
        }
    };

    let mut state_rw_guard = state.write().await;
    if !state_rw_guard.conf.networks.contains_key(&nw_name) {
        warn!("AddPeer for non-existent network");
        return ctx.reply(Err(MethodErr::invalid_arg("bad network")));
    };

    let allowed_ips_without_domains = allowed_ips.iter().map(|(ip, _)| ip.clone()).collect();

    let wg_api = &state_rw_guard
        .nw_handles
        .get(&nw_name)
        .expect("state.conf.networks and state.nw_handles desynced")
        .0;
    match add_peer(
        wg_api,
        key.clone(),
        psk.clone(),
        endpoint.clone(),
        allowed_ips_without_domains,
    )
    .await
    {
        Ok(_) => info!("Added peer"),
        Err(e) => {
            warn!("AddPeer failed: {e}");
            return ctx.reply(Err(MethodErr::invalid_arg(&e)));
        }
    };

    match state_rw_guard
        .conf
        .networks
        .get_mut(&nw_name)
        .expect("state.conf.networks changed while lock was held")
        .peers
        .entry(key)
    {
        Entry::Vacant(e) => {
            e.insert(PeerConfig {
                psk,
                ips: allowed_ips,
                use_hostnames,
                endpoint,
                last_changed: SystemTime::now(),
                known_to: vec![],
                mäsch_endpoint,
            });
        }
        Entry::Occupied(e) => {
            let r = e.into_mut();
            r.psk = psk;
            r.ips = allowed_ips;
            r.use_hostnames = use_hostnames;
            r.endpoint = endpoint;
            r.last_changed = SystemTime::now();
            r.mäsch_endpoint = mäsch_endpoint;
        }
    };

    match write_config(&state_rw_guard.conf, &config_path) {
        Ok(_) => info!("Synced config"),
        Err(e) => {
            error!("Couldn't sync config: {e}");
            return ctx.reply(Err(MethodErr::failed(&e)));
        }
    };

    return ctx.reply(Ok((true,)));
}

async fn handle_remove_network(
    mut ctx: Context,
    state: Arc<RwLock<State>>,
    config_path: PathBuf,
    (name,): (String,),
) -> PhantomData<(bool,)> {
    let mut state_rw_guard = state.write().await;

    if let Some(_) = state_rw_guard.conf.networks.remove(&name) {
        let (wg_api, h) = state_rw_guard
            .nw_handles
            .remove(&name)
            .expect("state.conf.networks and state.nw_handles desynced");
        h.abort();

        let ri = wg_api.remove_interface();
        let _ = h.await;

        match write_config(&state_rw_guard.conf, &config_path) {
            Ok(_) => info!("Synced config"),
            Err(e) => {
                error!("Couldn't sync config: {e}");
                return ctx.reply(Err(MethodErr::failed(&e)));
            }
        };
        drop(state_rw_guard);

        match ri {
            Ok(_) => info!("Removed network: {name}"),
            Err(e) => {
                error!("Removing network: {e}");
                return ctx.reply(Err(MethodErr::failed(&e)));
            }
        };
    } else {
        warn!("Tried to remove non-existent network: {name}");
        return ctx.reply(Err(MethodErr::invalid_arg("bad network")));
    }

    ctx.reply(Ok((true,)))
}

async fn handle_add_network(
    mut ctx: Context,
    state: Arc<RwLock<State>>,
    config_path: PathBuf,
    (name, may_key, may_ip, may_lp, may_mp): (String, String, String, u16, u16),
) -> PhantomData<(bool,)> {
    let mut state_rw_guard = state.write().await;
    let state_rw = state_rw_guard.deref_mut();

    // Scary!
    let prev_entry = state_rw.conf.networks.remove(&name);

    let key = if may_key.as_str() == "" {
        prev_entry
            .as_ref()
            .map(|nw| nw.privkey.clone())
            .unwrap_or_else(|| Key::new(rand::thread_rng().gen()).to_string())
    } else {
        may_key
    };

    // we store the ip as the original string, but should validate it regardless
    let (ip, ip_string) = match may_ip.as_str() {
        "" => match prev_entry.as_ref() {
            Some(e) => (
                IpAddrMask::from_str(&e.address)
                    .expect("Impossible: old config broken!")
                    .ip,
                e.address.clone(),
            ),
            None => {
                warn!("AddNetwork with no ip");
                prev_entry.map(|pe| state_rw.conf.networks.insert(name, pe));
                return ctx.reply(Err(MethodErr::invalid_arg("ip required")));
            }
        },
        _ => match IpAddrMask::from_str(&may_ip) {
            Ok(ip_mask) => (ip_mask.ip, may_ip),
            Err(_) => {
                warn!("AddNetwork with bad ip");
                prev_entry.map(|pe| state_rw.conf.networks.insert(name, pe));
                return ctx.reply(Err(MethodErr::invalid_arg("invalid ip")));
            }
        },
    };

    let lp = if may_lp == 0 {
        prev_entry
            .as_ref()
            .map(|nw| nw.listen_port)
            .unwrap_or(25565)
    } else {
        may_lp
    };
    let mp = if may_mp == 0 {
        prev_entry.as_ref().map(|nw| nw.mäsch_port).unwrap_or(51820)
    } else {
        may_mp
    };

    let (wg_api, hostnames) = match add_network(
        name.clone(),
        key.clone(),
        ip_string.clone(),
        lp,
        &HashMap::new(),
    )
    .await
    {
        Ok(v) => v,
        Err(e) => {
            warn!("AddNetwork couldn't add network: {e}");
            prev_entry.map(|pe| state_rw.conf.networks.insert(name, pe));
            return ctx.reply(Err(MethodErr::failed(&e)));
        }
    };

    let listener = match TcpListener::bind((ip, mp)).await {
        Ok(l) => l,
        Err(e) => {
            let _ = wg_api.remove_interface();
            warn!("AddNetwork couldn't start listener: {e}");
            prev_entry.map(|pe| state_rw.conf.networks.insert(name, pe));
            return ctx.reply(Err(MethodErr::failed(&e)));
        }
    };
    let h = task::spawn(print_error(run_network(
        state.clone(),
        listener,
        name.clone(),
    )));

    state_rw.nw_handles.insert(name.clone(), (wg_api, h));
    state_rw.conf.networks.insert(
        name,
        Network {
            privkey: key,
            address: ip_string,
            listen_port: lp,
            peers: prev_entry.map_or_else(|| HashMap::new(), |nw: Network| nw.peers),
            mäsch_port: mp,
        },
    );

    // NOTE this _is_ thread-safe, as we hold an exclusive write handle to the state.
    match write_config(&state_rw.conf, &config_path) {
        Ok(_) => info!("Synced config"),
        Err(e) => error!("Couldn't sync config: {e}"),
    }
    // similarly, this is still racy w.r.t. other processes running on the system, but at least
    // no other thread from this program should be able to concurrently call this
    match sync_hostnames(&hostnames) {
        Ok(_) => (),
        Err(e) => error!("Failed to sync hostnames to disk: {e}"),
    };

    ctx.reply(Ok((true,)))
}