kiln/kiln-tui/src/speech.rs

use ratatui::buffer::Buffer;
use ratatui::layout::Rect;
use ratatui::prelude::{Color, Line, Style, Widget};
use ratatui::widgets::{Block, Fill, Paragraph};
use kiln_core::Board;
use kiln_core::game::SpeechBubble;
use crate::render::BoardWidget;
use crate::utils::rects_overlap;

/// A ratatui widget that draws speech bubbles for all active [`SpeechBubble`]s over the board.
///
/// Each bubble appears as a box-drawing frame with a tail pointing down at the speaker's cell.
/// Bubbles that would collide (same horizontal range, adjacent vertically) are shifted upward
/// one at a time until there is no overlap.
pub struct SpeechBubblesWidget<'a> {
    /// The board, used to look up object positions and viewport layout.
    pub board: &'a Board,
    /// The active speech bubbles to render.
    pub bubbles: &'a [SpeechBubble],
}

impl<'a> SpeechBubblesWidget<'a> {
    /// Creates a widget for the given board and bubble slice.
    pub fn new(board: &'a Board, bubbles: &'a [SpeechBubble]) -> Self {
        Self { board, bubbles }
    }

    /// Finds a non-overlapping screen position for a bubble and records it in `placed`.
    ///
    /// Sizes the bubble from `lines`, centers it horizontally over `(obj_sx, obj_sy)`,
    /// then shifts upward until it clears all already-placed rects (or runs out of room).
    /// Returns the full bubble rect (including the tail row) on success, or `None` if
    /// the bubble can't fit within `area`. Appends to `placed` on success.
    fn place_bubble(
        area: Rect,
        obj_sx: u16,
        obj_sy: u16,
        lines: &[&str],
        placed: &mut Vec<Rect>,
    ) -> Option<Rect> {
        let text_w = lines.iter().map(|l| l.chars().count()).max().unwrap_or(0) as u16;
        let box_w = text_w + 4;
        let box_h = lines.len() as u16 + 3;

        // Center horizontally over the speaker, clamped inside the viewport.
        let left = obj_sx.saturating_sub(box_w / 2)
            .min(area.right().saturating_sub(box_w))
            .max(area.left());

        // Start directly above the speaker and shift upward until no overlap.
        let mut top = obj_sy.saturating_sub(box_h);
        let mut iterations = 0u16;
        'place: loop {
            if iterations > 20 || top < area.top() { return None; }
            let candidate = Rect { x: left, y: top, width: box_w, height: box_h };
            for p in placed.iter() {
                if rects_overlap(candidate, *p) {
                    top = top.saturating_sub(1);
                    iterations += 1;
                    continue 'place;
                }
            }
            break;
        }

        let rect = Rect { x: left, y: top, width: box_w, height: box_h };
        placed.push(rect);
        Some(rect)
    }
}

impl Widget for SpeechBubblesWidget<'_> {
    fn render(self, area: Rect, buf: &mut Buffer) {
        // Determine the screen position of each visible bubble's speaker.
        let mut items: Vec<(u16, u16, &SpeechBubble)> = self.bubbles
            .iter()
            .filter_map(|b| {
                let obj = self.board.objects.get(&b.object_id)?;
                let (sx, sy) = board_screen_pos(area, self.board, obj.x, obj.y)?;
                Some((sx, sy, b))
            })
            .collect();

        // Process bubbles lowest on screen first so upward-shift doesn't interfere
        // with already-placed higher bubbles.
        items.sort_by_key(|&(_, sy, _)| std::cmp::Reverse(sy));

        // Track the rects of already-placed bubbles to detect collisions.
        let mut placed: Vec<Rect> = Vec::new();

        let bubble_style = Style::default()
            .fg(Color::White)
            .bg(Color::Rgb(20, 20, 40));
        let border_style = Style::default()
            .fg(Color::Rgb(160, 160, 220))
            .bg(Color::Rgb(20, 20, 40));

        for (obj_sx, obj_sy, bubble) in items {
            let lines: Vec<&str> = bubble.text.split('\n').collect();
            let Some(r) = Self::place_bubble(area, obj_sx, obj_sy, &lines, &mut placed) else { continue };

            // Render the bordered box (top border + one row per line + bottom border).
            let box_rect = Rect { height: r.height - 1, ..r };
            let block = Block::bordered()
                .border_style(border_style)
                .style(bubble_style);
            let text_rect = block.inner(box_rect);
            block.render(box_rect, buf);

            Fill::new(" ").style(bubble_style).render(text_rect, buf);

            let para_lines: Vec<Line> = lines.iter()
                .map(|l| Line::styled(format!(" {l}"), bubble_style))
                .collect();
            Paragraph::new(para_lines).render(text_rect, buf);

            // Overwrite the tail-join cell on the bottom border, then draw the tail itself.
            // These are the only two cells that ratatui's Block can't produce for us.
            let tail_col = obj_sx.clamp(r.x + 1, r.x + r.width - 2);
            let border_bottom = r.y + r.height - 2;
            if let Some(cell) = buf.cell_mut((tail_col, border_bottom)) {
                cell.set_char('┬').set_style(border_style);
            }
            if let Some(cell) = buf.cell_mut((tail_col, border_bottom + 1)) {
                cell.set_char('│').set_style(border_style);
            }
        }
    }
}

/// Converts a board cell coordinate to terminal screen coordinates within `area`,
/// accounting for centering/scrolling. Returns `None` if the cell is off-screen.
fn board_screen_pos(area: Rect, board: &Board, bx: usize, by: usize) -> Option<(u16, u16)> {
    let (off_x, pad_x, cols) = BoardWidget::axis(board.width, area.width as usize, board.player.x);
    let (off_y, pad_y, rows) = BoardWidget::axis(board.height, area.height as usize, board.player.y);
    if bx < off_x || bx >= off_x + cols { return None; }
    if by < off_y || by >= off_y + rows { return None; }
    let sx = area.x + pad_x + (bx - off_x) as u16;
    let sy = area.y + pad_y + (by - off_y) as u16;
    Some((sx, sy))
}