Show vertical scrollbar only if height is lower than total monitors

src/ui/app.rs

@@ -18,7 +18,7 @@ use ratatui::{
     layout::{Alignment, Constraint, Direction, Layout, Rect},
     style::{Color, Modifier, Style},
     text::{Line, Span, Text},
-    widgets::{Block, Borders, Padding, Paragraph},
+    widgets::{Block, Borders, Padding, Paragraph, Scrollbar, ScrollbarOrientation},
 };
 
 use std::{
@@ -128,14 +128,26 @@ impl App {
 
             render_header(frame, chunks[0], &self.state);
 
+            let mut main_constraint = Vec::with_capacity(2);
+            main_constraint.push(Constraint::Min(1));
+
+            if self.state.show_vertical_scrollbar(chunks[1].height) {
+                main_constraint.push(Constraint::Length(1));
+            }
+
+            let main_chunks = Layout::default()
+                .direction(Direction::Horizontal)
+                .constraints(main_constraint)
+                .split(chunks[1]);
+
             if self.state.is_loading {
-                Self::render_loading(frame, chunks[1]);
+                Self::render_loading(frame, main_chunks[0]);
             } else if let Some(error) = &self.state.error_message {
-                Self::render_error(frame, chunks[1], error);
+                Self::render_error(frame, main_chunks[0], error);
             } else if self.state.groups.is_empty() || self.state.get_all_monitors().is_empty() {
-                Self::render_no_data(frame, chunks[1]);
+                Self::render_no_data(frame, main_chunks[0]);
             } else {
-                render_monitor_list(frame, chunks[1], &self.state);
+                Self::render_main(frame, main_chunks.to_vec(), &mut self.state);
             }
 
             let seconds_until_update = self
@@ -148,6 +160,22 @@ impl App {
         });
     }
 
+    fn render_main(frame: &mut Frame, area: Vec<Rect>, state: &mut DashboardViewState) {
+        render_monitor_list(frame, area[0], state);
+
+        let total_monitors = state.get_all_monitors().len();
+
+        if area[0].height > total_monitors as u16 {
+            return;
+        }
+
+        let scrollbar = Scrollbar::new(ScrollbarOrientation::VerticalRight)
+            .begin_symbol(Some("↑"))
+            .end_symbol(Some("↓"));
+
+        frame.render_stateful_widget(scrollbar, area[1], &mut state.scroll_state);
+    }
+
     fn handle_events(&mut self) -> io::Result<()> {
         let timeout = Duration::from_secs(1);
 
@@ -159,6 +187,12 @@ impl App {
 
                 match key.code {
                     KeyCode::Char('q') | KeyCode::Esc => self.should_quit = true,
+                    KeyCode::Up | KeyCode::Char('k') => {
+                        self.state.scroll_state.prev();
+                    }
+                    KeyCode::Down | KeyCode::Char('j') => {
+                        self.state.scroll_state.next();
+                    }
                     _ => {}
                 }
             }