feat(m1): journald watcher — streams journalctl JSON to event channel

src-tauri/src/watcher/journald.rs

@@ -1,6 +1,71 @@
-use super::SystemEvent;
+use super::{EventSource, SystemEvent, now_unix};
+use tokio::io::{AsyncBufReadExt, BufReader};
+use tokio::process::Command;
 use tokio::sync::mpsc;
 
-pub async fn watch(_tx: mpsc::Sender<SystemEvent>) {
-    // implemented in Task 6
+pub async fn watch(tx: mpsc::Sender<SystemEvent>) {
+    let mut child = match Command::new("journalctl")
+        .args(["--follow", "--output=json", "--lines=0"])
+        .stdout(std::process::Stdio::piped())
+        .spawn()
+    {
+        Ok(c) => c,
+        Err(e) => {
+            log::error!("journald watcher: failed to spawn journalctl: {e}");
+            return;
+        }
+    };
+
+    let stdout = match child.stdout.take() {
+        Some(s) => s,
+        None => return,
+    };
+
+    let mut lines = BufReader::new(stdout).lines();
+    while let Ok(Some(line)) = lines.next_line().await {
+        if let Some(msg) = extract_message(&line) {
+            let _ = tx
+                .send(SystemEvent {
+                    source: EventSource::Journald,
+                    raw_line: msg,
+                    timestamp: now_unix(),
+                })
+                .await;
+        }
+    }
+}
+
+fn extract_message(line: &str) -> Option<String> {
+    let json: serde_json::Value = serde_json::from_str(line).ok()?;
+    let msg = json.get("MESSAGE")?.as_str()?;
+    if msg.is_empty() {
+        return None;
+    }
+    Some(msg.to_string())
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn extract_message_from_journald_json() {
+        let line = r#"{"MESSAGE":"AUR build failed for foo","PRIORITY":"3","_COMM":"makepkg"}"#;
+        assert_eq!(
+            extract_message(line),
+            Some("AUR build failed for foo".to_string())
+        );
+    }
+
+    #[test]
+    fn extract_message_missing_returns_none() {
+        let line = r#"{"PRIORITY":"6","_COMM":"systemd"}"#;
+        assert_eq!(extract_message(line), None);
+    }
+
+    #[test]
+    fn extract_message_empty_skipped() {
+        let line = r#"{"MESSAGE":"","PRIORITY":"6"}"#;
+        assert_eq!(extract_message(line), None);
+    }
 }