src: main: Do not send a matrix message on duplicate status updates

Keep track of the last status update and post to the matrix room only if
it changes.

src/main.rs

@@ -32,9 +32,15 @@ use crate::{
     mqtt::{MQTT, StatusMessage},
 };
 
-use std::sync::Arc;
+use std::sync::{ Arc, Mutex };
 use tracing::{ info, debug };
 
+#[derive(PartialEq)]
+enum LolOpenerStatus {
+    Open,
+    Closed,
+}
+
 #[tokio::main]
 async fn main() -> anyhow::Result<()> {
     tracing_subscriber::fmt::init();
@@ -59,15 +65,23 @@ async fn main() -> anyhow::Result<()> {
             matrix_ready.notified().await;
             info!("Matrix is ready");
 
+            let current_status = Arc::new(Mutex::new(None));
+            let current_status = Arc::clone(&current_status);
+
             let mut mqtt = MQTT::new(config.mqtt.clone()).await;
-            mqtt.subscribe(|status: StatusMessage| {
-                let msg = match status {
-                    StatusMessage { contact: true, .. } => "🔴 Le LOL est fermé :(",
-                    StatusMessage { contact: false, .. } => "🟢 Le LOL est ouvert :)",
+            mqtt.subscribe(move |status: StatusMessage| {
+                let (new_status, msg) = match status {
+                    StatusMessage { contact: true, .. } => (Some(LolOpenerStatus::Closed), "🔴 Le LOL est fermé :("),
+                    StatusMessage { contact: false, .. } => (Some(LolOpenerStatus::Open), "🟢 Le LOL est ouvert :)"),
                 };
-                debug!("Sending msg {}", msg);
-                //XXX: Panic if the matrix module can't get the message
-                bcast_tx.send((msg.into(), config.rooms.clone())).unwrap();
+
+                let mut current_status = current_status.lock().unwrap();
+                if new_status != *current_status {
+                    debug!("Sending msg {}", msg);
+                    //XXX: Panic if the matrix module can't get the message
+                    bcast_tx.send((msg.into(), config.rooms.clone())).unwrap();
+                    *current_status = new_status;
+                }
             }).await.unwrap(); //XXX: Panic if the mqtt broker fails
         })
     };