Add last_seen to peer info (#1688)

* add last_seen to peer and update on ping/pong
expose last_seen in tui

* rustfmt

* chrono serde features

src/bin/tui/peers.rs

@@ -18,6 +18,8 @@ use std::cmp::Ordering;
 
 use servers::{PeerStats, ServerStats};
 
+use chrono::prelude::*;
+
 use cursive::direction::Orientation;
 use cursive::traits::{Boxable, Identifiable};
 use cursive::view::View;
@@ -54,9 +56,12 @@ impl TableViewItem<PeerColumn> for PeerStats {
 		match column {
 			PeerColumn::Address => self.addr.clone(),
 			PeerColumn::State => self.state.clone(),
-			PeerColumn::TotalDifficulty => {
-				format!("{} D @ {} H", self.total_difficulty, self.height).to_string()
-			}
+			PeerColumn::TotalDifficulty => format!(
+				"{} D @ {} H ({}s)",
+				self.total_difficulty,
+				self.height,
+				(Utc::now() - self.last_seen).num_seconds(),
+			).to_string(),
 			PeerColumn::Direction => self.direction.clone(),
 			PeerColumn::Version => self.version.to_string(),
 		}