Initial commit.

Signed-off-by: Pavel Kirilin <win10@list.ru>

src/bot/handlers/fun/greeter.rs

@@ -0,0 +1,31 @@
+use async_trait::async_trait;
+use grammers_client::{Client, Update};
+use rand::seq::IteratorRandom;
+
+use crate::bot::handlers::base::Handler;
+
+#[derive(Clone)]
+pub struct Greeter;
+
+#[async_trait]
+impl Handler for Greeter {
+    async fn react(&self, client: &Client, update: &Update) -> anyhow::Result<()> {
+        let Update::NewMessage(message) = update else {return Ok(())};
+
+        // Check if chat has less than 100 participants.
+        let participants = client.iter_participants(message.chat()).total().await?;
+        if participants >= 100 {
+            return Ok(());
+        }
+
+        let reply_text = ["Привет!", "Добрый день!", "Здравствуйте.", "Приетствую"]
+            .into_iter()
+            .choose(&mut rand::thread_rng());
+
+        if let Some(text) = reply_text {
+            message.reply(text).await?;
+        }
+
+        Ok(())
+    }
+}