initial commit

src/main.rs

@@ -0,0 +1,183 @@
+use std::sync::Arc;
+
+use reqwest::{Client, Url};
+use serde::Deserialize;
+use tokio::signal::unix::{signal, SignalKind};
+
+const BOT_URL: &str = "https://api.telegram.org/bot";
+/// Command to search for in a message text
+const COMMAND: &str = "/xkcd";
+/// Long polling timeout in seconds
+const POLL_TIMEOUT: &str = "300";
+/// Update types to receive (filtered out on tg backend)
+const POLL_TYPES: &str = r#"["message"]"#;
+
+/// Shared mutable state object
+#[derive(Debug)]
+struct State {
+    offset: u32,
+}
+
+/// Shared config object
+#[derive(Debug, Clone)]
+struct Config {
+    client: Client,
+    upd_url: Arc<Url>,
+    send_url: Arc<Url>,
+}
+
+/// Telegram Bot API response:
+/// these idiots use `{ok:true,response:...}` schema
+/// for some reason
+#[derive(Debug, Deserialize)]
+struct TgResponse {
+    result: Vec<TgUpdate>,
+}
+
+/// Telegram Bot API update event schema
+#[derive(Debug, Deserialize)]
+struct TgUpdate {
+    update_id: u32,
+    message: Option<TgMessage>,
+}
+
+/// Telegram Bot API message object schema
+#[derive(Debug, Deserialize)]
+struct TgMessage {
+    #[serde(rename = "message_thread_id")]
+    thread: Option<i32>,
+    chat: TgChat,
+    text: Option<String>,
+}
+
+/// Telegram Bot API chat object schema
+#[derive(Debug, Deserialize)]
+struct TgChat {
+    id: i64,
+    // #[serde(default)]
+    // is_forum: bool,
+}
+
+/// XKCD.com API comic info schema
+#[derive(Debug, Deserialize)]
+struct XkcdInfo {
+    alt: String,
+    img: String,
+}
+
+#[tokio::main]
+async fn main() -> std::io::Result<()> {
+    let cfg = {
+        let token = std::env::var("BOT_TOKEN").expect("invalid BOT_TOKEN env var value");
+        Config {
+            client: Client::new(),
+            upd_url: Url::parse(&format!("{BOT_URL}{token}/getUpdates"))
+                .unwrap()
+                .into(),
+            send_url: Url::parse(&format!("{BOT_URL}{token}/sendPhoto"))
+                .unwrap()
+                .into(),
+        }
+    };
+
+    let mut s = State { offset: 0 };
+
+    let mut sigint = signal(SignalKind::interrupt())?;
+    let mut sigterm = signal(SignalKind::terminate())?;
+
+    loop {
+        tokio::select! {
+            _ = sigint.recv() => {
+                break;
+            }
+            _ = sigterm.recv() => {
+                break;
+            }
+            out = handler(&cfg, &mut s) => {
+                match out {
+                    Ok(_) => {}
+                    Err(e) => {
+                        eprintln!("[handler] {:?}", e);
+                    }
+                }
+            }
+        }
+    }
+
+    Ok(())
+}
+
+async fn handler(cfg: &Config, s: &mut State) -> Result<(), reqwest::Error> {
+    let mut updates = cfg
+        .client
+        .get((*cfg.upd_url).clone())
+        .query(&[
+            ("offset", s.offset.to_string().as_str()),
+            ("timeout", POLL_TIMEOUT),
+            ("allowed_updates", POLL_TYPES),
+        ])
+        .send()
+        .await?
+        .json::<TgResponse>()
+        .await?
+        .result;
+
+    for u in &mut updates {
+        let Some(mut msg) = u.message.take() else {
+            continue;
+        };
+
+        let Some(text) = msg.text.take() else {
+            continue;
+        };
+
+        if !text.starts_with(COMMAND) {
+            continue;
+        }
+
+        let Some(comic_id) = text
+            .split_whitespace()
+            .skip(1)
+            .next()
+            .and_then(|id| id.parse::<u16>().ok())
+        else {
+            continue;
+        };
+
+        tokio::spawn(send_comic(cfg.clone(), msg, comic_id));
+    }
+
+    if let Some(u) = updates.last() {
+        s.offset = u.update_id + 1;
+    }
+
+    Ok(())
+}
+
+async fn send_comic(cfg: Config, msg: TgMessage, comic_id: u16) -> Result<(), reqwest::Error> {
+    let info = cfg
+        .client
+        .get(format!("https://xkcd.com/{}/info.0.json", comic_id))
+        .send()
+        .await?
+        .json::<XkcdInfo>()
+        .await?;
+
+    cfg.client
+        .post((*cfg.send_url).clone())
+        .form(&[
+            ("chat_id", msg.chat.id.to_string()),
+            (
+                "message_thread_id",
+                msg.thread
+                    .map(|t| t.to_string())
+                    .unwrap_or("null".to_owned()),
+            ),
+            ("photo", info.img),
+            ("caption", info.alt),
+        ])
+        .send()
+        .await?;
+
+    Ok(())
+}