Kigi-CLI/crates/codegen/kigi-pager-render/src/render/highlight.rs

//! Match-highlight overlay shared by the list pane and other search surfaces.

use ratatui::buffer::Buffer;
use ratatui::layout::Rect;

use crate::render::wrapping::{
    byte_offset_to_display_col, byte_range_to_row_cols, wrap_byte_ranges_matching,
};

/// Invert (REVERSED) the buffer cells covering every match of `re` in `text`.
///
/// Run as a post-pass after a line has been drawn, so matches are highlighted
/// regardless of the underlying colors.
///
/// - `area`: the pane area; `area.x` / `area.width` bound painting horizontally.
/// - `row_y`: buffer row of the line's first visible row.
/// - `viewport_bottom`: exclusive bottom row; wrapped rows at or below it stop.
/// - `skip`: leading wrapped rows of this line clipped above the viewport.
/// - `prefix_w`: display column where `text` begins (e.g. a line-number gutter).
/// - `text`: the plain text the regex runs against.
/// - `single_row`: the line occupies one buffer row (NoWrap, or any 1-row item).
#[allow(clippy::too_many_arguments)]
pub fn paint_match_highlights(
    buf: &mut Buffer,
    area: Rect,
    row_y: u16,
    viewport_bottom: u16,
    skip: u16,
    prefix_w: u16,
    text: &str,
    re: &regex::Regex,
    single_row: bool,
) {
    if text.is_empty() {
        return;
    }

    if single_row {
        for m in re.find_iter(text) {
            let col_start = prefix_w as usize + byte_offset_to_display_col(text, m.start());
            let col_end = prefix_w as usize + byte_offset_to_display_col(text, m.end());
            for col in col_start..col_end {
                let x = area.x + col as u16;
                if x < area.x + area.width {
                    invert_cell(&mut buf[(x, row_y)]);
                }
            }
        }
        return;
    }

    let text_w = area.width.saturating_sub(prefix_w) as usize;
    let ranges = wrap_byte_ranges_matching(text, text_w);
    for m in re.find_iter(text) {
        for seg in byte_range_to_row_cols(text, &ranges, m.start()..m.end()) {
            if seg.row < skip as usize {
                continue;
            }
            let y = row_y + (seg.row - skip as usize) as u16;
            if y >= viewport_bottom {
                break;
            }
            for col in seg.col_start..seg.col_end {
                let x = area.x + prefix_w + col as u16;
                if x < area.x + area.width {
                    invert_cell(&mut buf[(x, y)]);
                }
            }
        }
    }
}

/// Apply the terminal's REVERSED attribute so the fg/bg swap is native and
/// respects the user's theme.
fn invert_cell(cell: &mut ratatui::buffer::Cell) {
    cell.modifier.insert(ratatui::style::Modifier::REVERSED);
}