Add discord bot framework

Cargo.toml

@@ -6,12 +6,17 @@ edition = "2021"
 [dependencies]
 bytes = "1.1.0"
 futures = "0.3.21"
+rand = "0.8.5"
 rsip = "0.4.0"
 rtp = "0.6.5"
 sdp-rs = "0.2.1"
+songbird = { version = "0.2.2", features = ["builtin-queue"]}
 tokio = { version = "1.19.2", features = ["full"] }
 tokio-stream = "0.1.9"
 tokio-util = { version = "0.7.3", features = ["net", "codec"] }
 tracing = "0.1.35"
 tracing-subscriber = "0.3.14"
+twilight-gateway = "0.11.1"
+twilight-http = "0.11.1"
+twilight-model = "0.11.3"
 webrtc-util = "0.5.4"

flake.nix

@@ -31,6 +31,7 @@
       packages.default = naersk-lib.buildPackage {
         pname = "discosip";
         root = ./.;
+        buildInputs = with pkgs; [libopus pkgconfig];
       };
 
       apps.default = utils.lib.mkApp {drv = packages.default;};
@@ -43,11 +44,22 @@
         };
       in
         pkgs.devshell.mkShell {
-          packages = with pkgs; [
+          devshell.packages = with pkgs; [
             (rust.override {extensions = ["rls"];})
             ffmpeg
             (callPackage ./pjsip {inherit (darwin.apple_sdk.frameworks) AppKit;})
             opusTools
+            libopus
+            pkgconfig
+          ];
+          # Devshell doesn't do any of the automagic that pkgs.mkshell (thanks to
+          # mkderivation) does. So we need to manually tell pkg-config where to find
+          # libopus so that we can `cargo build` in our devshell.
+          env = [
+            {
+              name = "PKG_CONFIG_PATH";
+              value = "${pkgs.libopus.dev}/lib/pkgconfig";
+            }
           ];
         };
       formatter = pkgs.alejandra;

src/discord.rs

@@ -0,0 +1,65 @@
+use crate::StdErr;
+use futures::stream::StreamExt;
+use rand::seq::SliceRandom;
+use rand::{prelude::ThreadRng, thread_rng};
+use std::cell::RefCell;
+use std::sync::Arc;
+use tracing::{event, instrument, Level};
+use twilight_gateway::{Cluster, Event};
+use twilight_http::Client;
+use twilight_model::{
+    channel::message::Message,
+    gateway::Intents,
+    id::{marker::UserMarker, Id},
+};
+
+thread_local!(static RNG: RefCell<ThreadRng> = RefCell::new(thread_rng()));
+
+const GREETINGS: &'static [&'static str] =
+    &["You rung?", "Hello there", "Right back atcha", "Yes?"];
+
+pub async fn run_discord(token: &str) -> StdErr<()> {
+    event!(Level::INFO, "Starting...");
+    let (cluster, mut events) = Cluster::new(
+        token.to_owned(),
+        Intents::GUILD_MESSAGES | Intents::MESSAGE_CONTENT,
+    )
+    .await?;
+    tokio::spawn(async move {
+        cluster.up().await;
+    });
+    let client = Arc::new(Client::new(token.to_owned()));
+    while let Some((shard_id, ev)) = events.next().await {
+        let client = client.clone();
+        tokio::spawn(async move {
+            if let Err(e) = handle_event(ev, shard_id, client).await {
+                event!(Level::ERROR, err=?e, "Error handling discord event");
+            }
+        });
+    }
+    Ok(())
+}
+
+fn mentions(msg: &Message, us: Id<UserMarker>) -> bool {
+    msg.mentions.iter().filter(|m| m.id == us).next().is_some()
+}
+
+#[instrument(skip(client))]
+async fn handle_event(ev: Event, shard_id: u64, client: Arc<Client>) -> StdErr<()> {
+    let me = client.current_user().exec().await?.model().await?;
+    match ev {
+        Event::MessageCreate(msg) => {
+            if mentions(&msg.0, me.id) {
+                let greet = RNG.with(|rng| GREETINGS.choose(&mut *rng.borrow_mut()).unwrap());
+                client
+                    .create_message(msg.channel_id)
+                    .content(greet)?
+                    .exec()
+                    .await?;
+            }
+        }
+        Event::ShardConnected(_) => event!(Level::INFO, "Shard connected"),
+        _ => {}
+    }
+    Ok(())
+}

src/main.rs

@@ -7,6 +7,7 @@ use sdp_rs::lines::{attribute::Rtpmap, Attribute, Media};
 use sdp_rs::{MediaDescription, SessionDescription};
 use std::net::SocketAddr;
 use std::str;
+use std::env;
 use std::net::IpAddr;
 use std::time::Duration;
 use tokio::net::UdpSocket;
@@ -18,10 +19,13 @@ use tokio_util::{
     udp::UdpFramed,
 };
 use tracing::{event, instrument, Level};
+use songbird::driver::Driver;
 
 mod codecs;
 use codecs::{SipCodec, RtpCodec};
 
+mod discord;
+
 const SIP_PORT: u16 = 5060;
 const BIND_ADDR: &str = "0.0.0.0"; // for now
 
@@ -312,5 +316,9 @@ impl Server {
 #[tokio::main]
 async fn main() -> Result<(), Box<dyn std::error::Error>> {
     tracing_subscriber::fmt::init();
+    let discord_token = env::var("DISCORD_TOKEN")?;
+    tokio::spawn(async move {
+        discord::run_discord(&discord_token).await;
+    });
     Server::run_sip().await
 }