use log::info;
use std::sync::Arc;
use crate::{daemon::Daemon, dbus::interface};

use dbus_crossroads::Crossroads;
use dbus_tokio::connection;
use dbus::{
    message::MatchRule,
    nonblock::SyncConnection,
    channel::{Sender, MatchingReceiver},
    Path,
};

pub struct Endpoint {
    connection: Arc<SyncConnection>,
    daemon: Arc<Daemon>,
}

impl Endpoint {
    pub fn new(daemon: Arc<Daemon>) -> Self {
        let (resource, connection) = connection::new_session_sync().unwrap();
        
        // The resource is a task that should be spawned onto a tokio compatible
        // reactor ASAP. If the resource ever finishes, you lost connection to D-Bus.
        //
        // To shut down the connection, both call _handle.abort() and drop the connection.
        let _handle = tokio::spawn(async {
            let err = resource.await;
            panic!("Lost connection to D-Bus: {}", err);
        });

        Self { connection, daemon }
    }

    pub async fn start(&self) {
        use crate::dbus::interface;

        self.connection
            .request_name(interface::NAME, false, true, false)
            .await
            .expect("Unable to acquire dbus name");

        let mut cr = Crossroads::new();

        // Enable async support for the crossroads instance. 
        // (Currently irrelevant since dbus generates sync code)
        cr.set_async_support(Some((
            self.connection.clone(),
            Box::new(|x| {
                tokio::spawn(x);
            }),
        )));

        // Register the daemon as a D-Bus object.
        let token = interface::register_net_buzzert_kordophone_server(&mut cr);
        cr.insert(interface::OBJECT_PATH, &[token], self.daemon.clone());

        // Start receiving messages.
        self.connection.start_receive(
            MatchRule::new_method_call(),
            Box::new(move |msg, conn| 
                cr.handle_message(msg, conn).is_ok()
            ),
        );

        info!(target: "dbus", "DBus server started");
    }

    pub fn send_signal<S>(&self, signal: S) -> Result<u32, ()>
    where
        S: dbus::message::SignalArgs + dbus::arg::AppendAll,
    {
        let message = signal.to_emit_message(&Path::new(interface::OBJECT_PATH).unwrap());
        self.connection.send(message)
    }
}