use ratatui::{
    buffer::Buffer,
    layout::Rect,
    style::{Color, Modifier, Style},
    widgets::{Block, Borders, Clear, Widget},
};

/// A compact popup showing available key completions after a prefix key,
/// Emacs which-key style.
pub struct WhichKeyWidget<'a> {
    hints: &'a [(String, &'static str)],
}

impl<'a> WhichKeyWidget<'a> {
    pub fn new(hints: &'a [(String, &'static str)]) -> Self {
        Self { hints }
    }
}

impl Widget for WhichKeyWidget<'_> {
    fn render(self, area: Rect, buf: &mut Buffer) {
        if self.hints.is_empty() {
            return;
        }

        // Size: width fits the longest "key  command" line, height = hint count + border
        let content_width = self
            .hints
            .iter()
            .map(|(k, cmd)| k.len() + 2 + cmd.len())
            .max()
            .unwrap_or(10);
        let popup_w = (content_width as u16 + 4).min(area.width); // +4 for border + padding
        let popup_h = (self.hints.len() as u16 + 2).min(area.height); // +2 for border

        // Position: bottom-center, above the status bar
        let x = area.x + area.width.saturating_sub(popup_w) / 2;
        let y = area.y + area.height.saturating_sub(popup_h + 2); // 2 lines above bottom

        let popup_area = Rect::new(x, y, popup_w, popup_h);
        Clear.render(popup_area, buf);

        let block = Block::default()
            .borders(Borders::ALL)
            .border_style(Style::default().fg(Color::DarkGray))
            .title(" which-key ");
        let inner = block.inner(popup_area);
        block.render(popup_area, buf);

        let key_style = Style::default()
            .fg(Color::Cyan)
            .add_modifier(Modifier::BOLD);
        let cmd_style = Style::default().fg(Color::Gray);

        for (i, (key_label, cmd_name)) in self.hints.iter().enumerate() {
            if i >= inner.height as usize {
                break;
            }
            let y = inner.y + i as u16;
            buf.set_string(inner.x + 1, y, key_label, key_style);
            let cmd_x = inner.x + 4; // fixed column for command names
            if cmd_x < inner.x + inner.width {
                buf.set_string(cmd_x, y, cmd_name, cmd_style);
            }
        }
    }
}