added matrix support, added matrix-sdk dependency

src/matrix.rs

@@ -0,0 +1,114 @@
+use std::env;
+
+use matrix_sdk::{
+    Client, Room, RoomState,
+    config::SyncSettings,
+    ruma::events::room::{
+        member::{MembershipState, StrippedRoomMemberEvent},
+        message::{
+            AddMentions, ForwardThread, MessageType, OriginalSyncRoomMessageEvent,
+            RoomMessageEventContent,
+        },
+    },
+};
+
+use crate::commands;
+
+async fn on_room_message(event: OriginalSyncRoomMessageEvent, room: Room) {
+    if room.state() != RoomState::Joined {
+        return;
+    }
+
+    let MessageType::Text(text_content) = event.content.msgtype.to_owned() else {
+        return;
+    };
+
+    let body = text_content.body.trim();
+    if !body.starts_with('!') {
+        return;
+    }
+
+    let mut parts = body.splitn(3, ' ');
+    let command = parts.next().unwrap_or("");
+    let arg = parts.next();
+
+    let response = match command {
+        "!roll" => commands::roll::run_core(arg),
+        "!random" => commands::random::run_core(arg),
+        "!about" => commands::about::run_core(),
+        _ => return,
+    };
+
+    let reply = RoomMessageEventContent::text_plain(response).make_reply_to(
+        &event.into_full_event(room.room_id().to_owned()),
+        ForwardThread::No,
+        AddMentions::Yes,
+    );
+
+    match room.send(reply).await {
+        Ok(_) => (),
+        Err(e) => {
+            println!("Failed to send message: {e}");
+        }
+    }
+}
+
+async fn on_stripped_member(event: StrippedRoomMemberEvent, client: Client, room: Room) {
+    let user_id = match client.user_id() {
+        Some(u) => u,
+        None => {
+            println!("Irregular Matrix ID");
+            return;
+        }
+    };
+
+    if event.state_key != user_id {
+        return;
+    }
+
+    if event.content.membership != MembershipState::Invite {
+        return;
+    }
+
+    if let Err(e) = room.join().await {
+        println!("Failed to join room: {e}");
+    }
+}
+
+pub async fn run() {
+    let homeserver =
+        env::var("MATRIX_HOMESERVER").expect("Expected MATRIX_HOMESERVER in environment");
+    let username = env::var("MATRIX_USERNAME").expect("Expected MATRIX_USERNAME in environment");
+    let password = env::var("MATRIX_PASSWORD").expect("Expected MATRIX_PASSWORD in environment");
+
+    let client = Client::builder()
+        .homeserver_url(&homeserver)
+        .build()
+        .await
+        .expect("Failed to build Matrix client");
+
+    client
+        .matrix_auth()
+        .login_username(&username, &password)
+        .initial_device_display_name("caitsith")
+        .send()
+        .await
+        .expect("Failed to log in to Matrix");
+
+    println!("Logged in to Matrix as {username}");
+
+    // Advance past existing messages before registering handlers so the bot
+    // doesn't reply to messages that ever existed in a given room.
+    let sync_response = client
+        .sync_once(SyncSettings::default())
+        .await
+        .expect("Matrix initial sync error");
+
+    client.add_event_handler(on_room_message);
+    client.add_event_handler(on_stripped_member);
+
+    client
+        .sync(SyncSettings::default().token(sync_response.next_batch))
+        .await
+        .expect("Matrix sync error");
+}