feat: add event handler.

this is basically a 1:1 copy of the event handler used in the old
codebase but without all the database stuff or the unnecessary event
monitoring.

Cargo.toml

@@ -20,10 +20,15 @@ humantime           = "2.1.0"
 itertools           = "0.10.3"
 lastfm-rs           = "0.5.0"
 poise               = "0.6.1"
+serenity            = "0.12.2"
 serde               = { version = "1.0.203", features = ["derive"] }
 serde_json          = "1.0.117"
 tokio               = { version = "1.38.0", features = ["full"] }
 toml                = "0.5.8"
+tracing             = "0.1.40"
+tracing-futures     = "0.2.5"
+tracing-log         = "0.2.0"
+tracing-subscriber  = { version = "0.3.16", features = ["env-filter"] }
 
 [dependencies.reqwest]
 version             = "0.11.12"

src/listeners/handler.rs

@@ -0,0 +1,30 @@
+use serenity::{all::{ActivityData, Context, EventHandler, OnlineStatus, Ready}, async_trait};
+use tracing::info;
+
+pub struct Handler;
+
+#[async_trait]
+impl EventHandler for Handler {
+    async fn ready(&self, context: Context, ready: Ready) {
+        let http = &context.http;
+
+        let api_version = ready.version;
+        let bot_gateway = http.get_bot_gateway().await.unwrap();
+        let bot_owner = http.get_current_application_info().await.unwrap().owner.expect("Could not get owner!");
+        let t_sessions = bot_gateway.session_start_limit.total;
+        let r_sessions = bot_gateway.session_start_limit.remaining;
+
+        info!("Successfully logged into Discord as the following user:");
+        info!("Bot username: {}", ready.user.tag());
+        info!("Bot user ID: {}", ready.user.id);
+        info!("Bot owner: {}", bot_owner.tag());
+
+        let guild_count = ready.guilds.len();
+
+        info!("Connected to the Discord API (version {api_version}) with {r_sessions}/{t_sessions} sessions remaining.");
+        info!("Connected to and serving a total of {guild_count} guild(s).");
+
+        let presence = format!("on {guild_count} guilds | e.help");
+        context.set_presence(Some(ActivityData::playing(presence)), OnlineStatus::Online);
+    }
+}

src/listeners/mod.rs

@@ -0,0 +1 @@
+pub mod handler;

src/main.rs

@@ -1,9 +1,14 @@
 use crate::serenity::GatewayIntents;
+use listeners::handler::Handler;
 use poise::serenity_prelude as serenity;
 use poise::{builtins::register_application_commands_buttons, Framework, FrameworkOptions, PrefixFrameworkOptions};
+use tracing::{info, Level};
+use tracing_log::LogTracer;
+use tracing_subscriber::{EnvFilter, FmtSubscriber};
 use utils::read_config;
 
 mod config;
+mod listeners;
 mod utils;
 
 type Error = Box<dyn std::error::Error + Send + Sync>;
@@ -20,6 +25,28 @@ async fn register(ctx: Context<'_>) -> Result<(), Error> {
 #[tokio::main(worker_threads = 16)]
 async fn main() -> Result<(), Error> {
     let configuration = read_config("config.toml");
+    if configuration.bot.logging.enabled {
+        LogTracer::init()?;
+
+        let level = match configuration.bot.logging.level.as_str() {
+            "error" => Level::ERROR,
+            "warn" => Level::WARN,
+            "info" => Level::INFO,
+            "debug" => Level::DEBUG,
+            _ => Level::TRACE,
+        };
+
+        let subscriber = FmtSubscriber::builder()
+            .with_target(false)
+            .with_max_level(level)
+            .with_env_filter(EnvFilter::from_default_env())
+            .finish();
+
+        tracing::subscriber::set_global_default(subscriber)?;
+
+        info!("Tracing initialized with logging level set to {}.", level);
+    }
+
     let token = configuration.bot.discord.token;
     let framework = Framework::builder()
         .options(FrameworkOptions {
@@ -33,7 +60,7 @@ async fn main() -> Result<(), Error> {
         .setup(move |_ctx, _ready, _framework| Box::pin(async move { Ok(Data {}) }))
         .build();
 
-    let client = serenity::Client::builder(token, GatewayIntents::all()).framework(framework).await;
+    let client = serenity::Client::builder(token, GatewayIntents::all()).event_handler(Handler).framework(framework).await;
     client.unwrap().start().await.unwrap();
 
     Ok(())