top + report + log --follow (issues #37 #38) - top 10 par lancements, digest markdown hebdo/mensuel, suivi du journal en direct

src/commands/log_cmd.rs

@@ -35,6 +35,34 @@ pub fn filter_events(
     Ok(events)
 }
 
+/// Live view: print matching events as they arrive (issue #38).
+fn follow_loop(app: &App, agent: Option<&str>, kinds: Option<&str>, since: Option<&str>) -> Result<i32> {
+    app.log.info("following the journal (Ctrl-C to stop)");
+    let mut seen: usize = 0;
+    loop {
+        let events = filter_events(app, agent, kinds, since, 200)?;
+        let mut rendered = String::new();
+        for e in events.iter().rev() {
+            rendered.push_str(&e.ts);
+            rendered.push(' ');
+            rendered.push_str(e.kind.as_str());
+            if let Some(a) = &e.agent {
+                rendered.push(' ');
+                rendered.push_str(a);
+            }
+            rendered.push('\n');
+        }
+        let bytes = rendered.as_bytes();
+        if bytes.len() > seen {
+            print!("{}", text_after(&rendered, seen));
+            use std::io::Write;
+            let _ = std::io::stdout().flush();
+        }
+        seen = bytes.len();
+        std::thread::sleep(std::time::Duration::from_secs(1));
+    }
+}
+
 pub fn parse_since(s: &str) -> Result<chrono::DateTime<chrono::FixedOffset>> {
     if let Ok(t) = chrono::DateTime::parse_from_rfc3339(s) {
         return Ok(t);
@@ -71,13 +99,25 @@ impl From<&Event> for LogRow {
     }
 }
 
+/// Chars of text after byte offset seen (UTF-8 safe).
+pub fn text_after(text: &str, seen: usize) -> String {
+    text.char_indices()
+        .filter(|(i, _)| *i >= seen)
+        .map(|(_, c)| c)
+        .collect()
+}
+
 pub fn run(
     app: &App,
     agent: Option<&str>,
     kinds: Option<&str>,
     since: Option<&str>,
     limit: usize,
+    follow: bool,
 ) -> Result<i32> {
+    if follow {
+        return follow_loop(app, agent, kinds, since);
+    }
     let events = filter_events(app, agent, kinds, since, limit)?;
     if app.json() {
         let rows: Vec<LogRow> = events.iter().map(LogRow::from).collect();