codex/codex-rs/tui/src/bottom_pane/live_ring_widget.rs

use ratatui::buffer::Buffer;
use ratatui::layout::Rect;
use ratatui::text::Line;
use ratatui::widgets::Paragraph;
use ratatui::widgets::WidgetRef;

/// Minimal rendering-only widget for the transient ring rows.
pub(crate) struct LiveRingWidget {
    max_rows: u16,
    rows: Vec<Line<'static>>, // newest at the end
}

impl LiveRingWidget {
    pub fn new() -> Self {
        Self {
            max_rows: 3,
            rows: Vec::new(),
        }
    }

    pub fn set_max_rows(&mut self, n: u16) {
        self.max_rows = n.max(1);
    }

    pub fn set_rows(&mut self, rows: Vec<Line<'static>>) {
        self.rows = rows;
    }

    pub fn desired_height(&self, _width: u16) -> u16 {
        let len = self.rows.len() as u16;
        len.min(self.max_rows)
    }
}

impl WidgetRef for LiveRingWidget {
    fn render_ref(&self, area: Rect, buf: &mut Buffer) {
        if area.height == 0 {
            return;
        }
        let visible = self.rows.len().saturating_sub(self.max_rows as usize);
        let slice = &self.rows[visible..];
        let para = Paragraph::new(slice.to_vec());
        para.render_ref(area, buf);
    }
}