vorto 0.10.1

//! Buffer viewport: gutter (diagnostic signs + line numbers),
//! per-character syntax highlighting layered with the visual selection,
//! and the terminal cursor placement that goes with it.

use ratatui::Frame;
use ratatui::layout::Rect;
use ratatui::style::{Color, Style};
use ratatui::text::{Line, Span};
use ratatui::widgets::Paragraph;

use crate::app::{App, JumpState, Selection};
use crate::config::{EditorConfig, IndentGuideStyle};
use crate::editor::{Buffer, IndentAnimState};
use crate::lsp::Severity;
use crate::syntax::{self, Capture};
use crate::text_width::{char_cell_width, visual_col_of};
use crate::vcs::LineStatus;

use std::collections::HashMap;

/// Color used to paint visually-selected text. Picked to read clearly on
/// both dark and light terminals.
const SEL_BG: Color = Color::Rgb(58, 78, 122);

/// Background used to highlight every visible match of the active
/// search pattern (vim's `hlsearch`). ANSI bright-black (the terminal's
/// dim gray) so it sits underneath text without competing with a
/// visual selection.
const SEARCH_HIT_BG: Color = Color::DarkGray;

/// Background used to render each extra-cursor cell. Distinct from
/// `SEL_BG` and `SEARCH_HIT_BG` so a stacked cursor remains visible
/// even when it sits inside a selection or a search match.
const EXTRA_CURSOR_BG: Color = Color::Rgb(160, 110, 60);

/// Foreground used to mark the bracket pair when the cursor sits on
/// one half of `()`, `[]`, or `{}`. Combined with `BOLD` rather than a
/// background fill so the highlight remains legible on top of any
/// other layer (search hit, selection, syntax bg) without competing
/// for the same channel.
const MATCH_BRACKET_FG: Color = Color::Yellow;

/// Foreground used for `gw` jump labels. Bright magenta on a near-black
/// background so the label always pops over surrounding syntax.
const JUMP_LABEL_FG: Color = Color::Rgb(255, 100, 200);
const JUMP_LABEL_BG: Color = Color::Rgb(40, 0, 40);

/// Foreground used for the whitespace marker glyphs (middle-dot and
/// tab arrow) when `show_whitespace` is enabled. Dim enough to fade
/// into the background but still legible.
const WHITESPACE_FG: Color = Color::DarkGray;

/// Foreground used for inactive indent-guide bars. Dim so the guides
/// stay readable as structural hints without competing with code.
const INDENT_GUIDE_FG: Color = Color::Rgb(60, 60, 70);

/// Default glyph for indent-guide cells. Light vertical box-drawing
/// line. Used as the per-cell glyph unless a specific guide
/// (`p10k` corners/arrow) carries its own.
const INDENT_GUIDE_CHAR: char = '│';

/// Width of the gutter prefix (severity sign + space). Kept in sync with
/// [`place_cursor`] so the cursor lands on the right column.
const GUTTER_SIGN_WIDTH: u16 = 1;

/// Width of the VCS-bar column rendered between the line number and the
/// buffer text. One cell wide regardless of status — the bar character
/// itself is single-width.
const GUTTER_VCS_WIDTH: u16 = 1;

/// Minimum rows kept above and below the cursor inside the viewport
/// (vim's `scrolloff`). Near the end of the file this lets scroll
/// advance past the last source row, leaving blank rows below — so the
/// cursor isn't pinned to the bottom edge when sitting on the last few
/// lines. Disabled automatically when the viewport is too small to
/// give the cursor room (height ≤ 2 * SCROLL_OFF + 1).
const SCROLL_OFF: usize = 5;

pub(super) fn draw_buffer(f: &mut Frame, app: &App, area: Rect) {
    let height = area.height as usize;
    let row_diag = build_row_diag_summary(app, app.buffer.cursor.row);
    let scroll = compute_scroll(app, height, &row_diag);

    let sel = app.selection();
    let last_visible = scroll + height;
    let captures = app
        .buffer
        .highlighter
        .as_ref()
        .map(|h| h.captures_in_rows(scroll, last_visible))
        .unwrap_or_default();
    let row_severity = build_row_severity(app, scroll, last_visible);
    let vcs_statuses = app.buffer.vcs_statuses();
    let cursor_row = app.buffer.cursor.row;
    let cursor_col = app.buffer.cursor.col;
    let extras = &app.buffer.extra_cursors;
    let search_query = &app.search.query;
    let jump_overlay = build_jump_overlay(app.jump_state.as_ref());
    // Tree-sitter–driven matching-bracket highlight. Yields the two
    // cells to paint (cursor's bracket + its mate) only when the
    // cursor sits on a syntactic bracket token; brackets inside
    // strings/comments resolve to the containing literal node and
    // naturally don't match here.
    let bracket_pair: Vec<(usize, usize)> = app
        .buffer
        .highlighter
        .as_ref()
        .and_then(|h| h.matching_bracket(cursor_row, cursor_col))
        .map(|mate| vec![(cursor_row, cursor_col), mate])
        .unwrap_or_default();
    let eff = app.effective_editor();
    let tab_width = eff.tab_width.max(1);
    let show_whitespace = eff.show_whitespace;
    let indent_guides = if eff.indent_guides {
        compute_indent_guides(
            app,
            scroll,
            last_visible,
            tab_width,
            eff.indent_width,
            eff.indent_guides_skip_levels,
            eff.indent_guide_style,
            eff.indent_animation,
            eff.indent_animation_ms,
        )
    } else {
        GuideMap::new()
    };

    // Interleave one virtual diagnostic line below each source row that
    // has any diagnostics. Stop accumulating once we've consumed
    // `height` visual rows.
    let mut visible: Vec<Line> = Vec::with_capacity(height);
    let mut visual_y: u16 = 0;
    let mut cursor_visual_y: u16 = 0;
    let inner_text_width =
        area.width
            .saturating_sub(GUTTER_SIGN_WIDTH + 5 + GUTTER_VCS_WIDTH) as usize;
    let col_scroll = compute_col_scroll(app, inner_text_width, tab_width);
    for (i, line) in app.buffer.lines.iter().enumerate().skip(scroll) {
        if visual_y as usize >= height {
            break;
        }
        if i == cursor_row {
            cursor_visual_y = visual_y;
        }
        let mut spans = vec![sign_span(row_severity.get(&i).copied())];
        // Gutter layout: <sign><4-digit num><space><vcs-bar><buffer>.
        // The breathing-room space sits between the number and the
        // bar; cursor column math in `place_cursor` matches.
        let num = format!("{:>4} ", i + 1);
        // The cursor's row gets the terminal's default foreground
        // (`Color::Reset`) so the number stays in sync with whatever
        // color the terminal paints the cursor itself.
        let num_style = if i == cursor_row {
            Style::default().fg(Color::Reset)
        } else {
            Style::default().fg(Color::DarkGray)
        };
        spans.push(Span::styled(num, num_style));
        let vcs_status = vcs_statuses.get(i).copied().flatten();
        spans.push(vcs_bar_span(vcs_status));
        let extra_cols: Vec<usize> = extras
            .iter()
            .filter_map(|c| if c.row == i { Some(c.col) } else { None })
            .collect();
        let hits = find_matches_in_line(line, search_query);
        let row_jumps: Vec<(usize, char)> = jump_overlay
            .iter()
            .filter_map(|(pos, ch)| if pos.0 == i { Some((pos.1, *ch)) } else { None })
            .collect();
        let row_bracket_cols: Vec<usize> = bracket_pair
            .iter()
            .filter_map(|(r, c)| if *r == i { Some(*c) } else { None })
            .collect();
        let row_guides: &[IndentGuide] = indent_guides.get(&i).map(Vec::as_slice).unwrap_or(&[]);
        spans.extend(render_line(
            i,
            line,
            sel.as_ref(),
            &captures,
            &extra_cols,
            &hits,
            &row_jumps,
            &row_bracket_cols,
            row_guides,
            tab_width,
            col_scroll,
            inner_text_width,
            show_whitespace,
        ));
        // Inline suggestion (ghost text) — Phase 0 only paints
        // single-line suggestions at end of the cursor row. The stub
        // provider only fires when the cursor is at EOL, so appending
        // after the rendered line lands the ghost spans flush against
        // the cursor cell. Multi-line continuation and mid-line
        // overlay come later.
        if i == cursor_row
            && app.completion.is_none()
            && let Some(s) = app.inline_suggestion.showing()
            && s.is_anchored_at(app.buffer.cursor)
        {
            let style = Style::default()
                .fg(Color::DarkGray)
                .add_modifier(ratatui::style::Modifier::ITALIC);
            if let Some(first) = s.text.lines().next() {
                spans.push(Span::styled(first.to_string(), style));
            }
        }
        visible.push(Line::from(spans));
        visual_y += 1;
        if visual_y as usize >= height {
            break;
        }
        if let Some(summary) = row_diag.get(&i) {
            visible.push(diagnostic_line(summary, inner_text_width));
            visual_y += 1;
        }
    }

    app.buffer.cursor_visual_y.set(cursor_visual_y);
    f.render_widget(Paragraph::new(visible), area);
}

pub(super) fn place_cursor(f: &mut Frame, app: &App, buf_area: Rect) {
    if app.prompt.is_open() {
        return;
    }
    let line_no_width: u16 = 5;
    let tab_width = app.effective_editor().tab_width.max(1);
    let line = &app.buffer.lines[app.buffer.cursor.row];
    let visual_col = visual_col_of(line, app.buffer.cursor.col, tab_width);
    let col_scroll = app.buffer.col_scroll.get();
    let on_screen_col = visual_col.saturating_sub(col_scroll);
    let x =
        buf_area.x + GUTTER_SIGN_WIDTH + line_no_width + GUTTER_VCS_WIDTH + on_screen_col as u16;
    // `draw_buffer` ran first this frame and published the cursor's
    // visual y, accounting for any virtual diagnostic lines pushing it
    // down. Use it directly so the terminal cursor stays glued to the
    // rendered cursor row.
    let y = buf_area.y + app.buffer.cursor_visual_y.get();
    f.set_cursor_position((x, y));
}

/// Visual column occupied by the first non-whitespace character of
/// `line`, with tabs expanded to `tab_width`-aligned stops. For a line
/// that is entirely whitespace (or empty), returns the visual width of
/// the whole line — callers treat that as "no content, defer to
/// neighbouring rows for guide layout".
fn leading_indent_visual(line: &str, tab_width: usize) -> Option<usize> {
    let mut v = 0usize;
    for ch in line.chars() {
        if ch == ' ' {
            v += 1;
        } else if ch == '\t' {
            v += tab_width - (v % tab_width);
        } else {
            return Some(v);
        }
    }
    None
}

/// One indent-guide cell to paint on a row: the visual column it
/// lives at, the glyph drawn there, and whether it belongs to the
/// active scope (→ distinct color/bold).
#[derive(Debug, Clone, Copy)]
struct IndentGuide {
    col: usize,
    glyph: char,
    active: bool,
}

/// Per-source-row guide list for the visible window. Keyed by row
/// index; rows with no guides are absent from the map.
type GuideMap = HashMap<usize, Vec<IndentGuide>>;

/// Compute indent guides for `[scroll, last_visible)`.
///
/// Drawing is tree-sitter–driven: every `@indent.begin` scope from
/// the language's `indents.scm` becomes one vertical bar, positioned
/// at the **header row's own indent column** (not the body indent).
/// That choice keeps the bar in the leading-whitespace area of every
/// body row instead of colliding with content at the body's indent
/// — which would otherwise force the guide to be skipped on the
/// rows that need it most.
///
/// Active marking is scoped to the innermost `@indent.begin` node
/// containing the cursor — its column lights up only on rows that
/// belong to that scope's body, so sibling scopes at the same column
/// stay quiet.
///
/// When no tree-sitter highlighter is loaded (plain-text buffer or a
/// language without `indents.scm`), drawing falls back to a uniform
/// leading-whitespace stair-step at multiples of `indent_width`.
#[allow(clippy::too_many_arguments)]
fn compute_indent_guides(
    app: &App,
    scroll: usize,
    last_visible: usize,
    tab_width: usize,
    indent_width: usize,
    skip_levels: usize,
    style: IndentGuideStyle,
    animation: bool,
    animation_ms: u64,
) -> GuideMap {
    let mut map: GuideMap = HashMap::new();
    if last_visible <= scroll || indent_width == 0 {
        return map;
    }
    let cursor_row = app.buffer.cursor.row;
    let lines = &app.buffer.lines;
    let line_count = lines.len();
    if line_count == 0 {
        return map;
    }

    // Stair-step at every multiple of `indent_width`. The step
    // comes from the effective per-language config so a 4-space
    // file doesn't get a guide every 2 cols just because the
    // global default is 2.
    let resolve_indent = |row: usize| -> usize {
        // Walk the leading whitespace ourselves so we can
        // distinguish "blank line, inherit from neighbours" from
        // "user typed indent but no content yet" — the latter
        // should use the typed-in width directly so guides show
        // up immediately while typing.
        let line = &lines[row];
        let mut ws = 0usize;
        let mut had_chars = false;
        for ch in line.chars() {
            had_chars = true;
            if ch == ' ' {
                ws += 1;
            } else if ch == '\t' {
                ws += tab_width - (ws % tab_width);
            } else {
                return ws;
            }
        }
        if had_chars {
            return ws;
        }
        // Truly empty: inherit from the shallower of the nearest
        // non-blank neighbours so bars stay continuous across
        // whitespace gaps.
        let above = (0..row)
            .rev()
            .find_map(|r| leading_indent_visual(&lines[r], tab_width))
            .unwrap_or(0);
        let below = (row + 1..line_count)
            .find_map(|r| leading_indent_visual(&lines[r], tab_width))
            .unwrap_or(0);
        above.min(below)
    };
    // With `skip_levels = 0` the stair-step also draws at col 0
    // (the buffer's left edge) so deeply indented rows show a `│`
    // running all the way to the left margin. The skip-levels
    // filter below handles other suppression — for `skip = 0`
    // nothing is dropped, so col 0 survives.
    let start_col = if skip_levels == 0 { 0 } else { indent_width };
    for row in scroll..last_visible.min(line_count) {
        let indent = resolve_indent(row);
        let mut col = start_col;
        while col < indent {
            push_unique_guide(
                &mut map,
                row,
                IndentGuide {
                    col,
                    glyph: INDENT_GUIDE_CHAR,
                    active: false,
                },
            );
            col += indent_width;
        }
    }

    // Suppress the first `skip_levels` indent positions
    // (`indent_width`, `2*indent_width`, …). Fixed by config —
    // not derived from what's visible — so a shallow file doesn't
    // lose its only guide just because the deeper levels weren't
    // present in the window.
    if skip_levels > 0 {
        let cutoff = skip_levels.saturating_mul(indent_width);
        for guides in map.values_mut() {
            guides.retain(|g| g.col > cutoff);
        }
    }

    // Active marking & (in p10k mode) bracket decoration.
    let active = active_scope_range(app, cursor_row, lines, tab_width, indent_width);
    if let Some((lo_active, hi_active, ac)) = active {
        // Envelope bounds use `s` (the scope's actual header row),
        // not `lo_active` (= s+1, the first body row), so the p10k
        // `╭─` corner can land on `s`. Line mode naturally clamps
        // away rows ≤ s when iterating, because no `│` exists at
        // the active col on the header row.
        let s = lo_active.saturating_sub(1);
        let (anim_top, anim_bot) = animation_envelope(
            &app.buffer.indent_anim,
            (s, hi_active, ac),
            cursor_row,
            animation,
            animation_ms,
        );
        // Both modes anchor at `ac` — same col as the inactive
        // stair-step guides on body rows. The p10k corner glyphs
        // (`╭`, `╰`, `>`) that land on header/last-row content
        // (e.g. the `i` of `if`, the closing `}`) are silently
        // dropped by `render_line`; only the `│` middles survive
        // — that's the trade-off for keeping the bracket aligned
        // with the rest of the indent guides instead of in its
        // own offset lane.
        let _ = indent_width;
        match style {
            IndentGuideStyle::Line => {
                // Mark the cursor scope's own col (`ac`) active
                // on its body rows. `ac == 0` for top-level
                // scopes, which lights up the leftmost stair-step
                // guide (col 0) — same logic as deeper scopes,
                // just at level 0.
                let s = lo_active.saturating_sub(1);
                let row_lo = s.max(anim_top).max(scroll);
                let row_hi = hi_active
                    .min(anim_bot)
                    .min(last_visible.saturating_sub(1))
                    .min(line_count.saturating_sub(1));
                if row_lo > row_hi {
                    return map;
                }
                for row in row_lo..=row_hi {
                    if let Some(guides) = map.get_mut(&row) {
                        for g in guides.iter_mut() {
                            if g.col == ac {
                                g.active = true;
                            }
                        }
                    }
                }
            }
            IndentGuideStyle::P10k => {
                // p10k bracket sits two cells left of `ac`. When
                // `ac < 2` (level-1 scope with `indent_width = 2`,
                // or any top-level scope) it lands at col 0 —
                // corner glyphs on the header / closing rows there
                // collide with content and silently drop, but the
                // `│` middles still animate visibly through body
                // rows where col 0 is in leading whitespace.
                let p10k_col = ac.saturating_sub(2);
                let anim_s = s.max(anim_top);
                let anim_e = hi_active.min(anim_bot);
                let row_lo = anim_s.max(scroll);
                let row_hi = anim_e
                    .min(last_visible.saturating_sub(1))
                    .min(line_count.saturating_sub(1));
                if row_lo > row_hi {
                    return map;
                }
                let top_reached = anim_s == s;
                let bot_reached = anim_e == hi_active;
                for row in row_lo..=row_hi {
                    let glyph = if top_reached && row == s {
                        '╭'
                    } else if bot_reached && row == hi_active {
                        '╰'
                    } else {
                        INDENT_GUIDE_CHAR
                    };
                    push_unique_guide(
                        &mut map,
                        row,
                        IndentGuide {
                            col: p10k_col,
                            glyph,
                            active: true,
                        },
                    );
                }
                // Horizontal extensions on the corner rows.
                // Gated by `top_reached`/`bot_reached` so the
                // bracket grows in two clean steps during the
                // animation rather than baring its cap mid-flight.
                let in_view = |row: usize| -> bool {
                    row >= scroll && row < last_visible && row < line_count
                };
                if top_reached && in_view(s) {
                    push_unique_guide(
                        &mut map,
                        s,
                        IndentGuide {
                            col: p10k_col + 1,
                            glyph: '─',
                            active: true,
                        },
                    );
                }
                // Skip the `>` only for top-level scopes (ac=0)
                // where the bracket has no scope header to point
                // at. For nested scopes (ac >= indent_width) the
                // `>` lands in leading whitespace of the close
                // row even when p10k_col is 0 (e.g. `ac=2` with
                // `indent_width=2`).
                if bot_reached && in_view(hi_active) && ac > 0 {
                    push_unique_guide(
                        &mut map,
                        hi_active,
                        IndentGuide {
                            col: p10k_col + 1,
                            glyph: '>',
                            active: true,
                        },
                    );
                }
            }
        }
    }
    map
}

/// Animation envelope for the active scope's bracket/bar: the
/// (inclusive) row range that should currently be drawn as active.
///
/// When `enabled == false`, returns the scope's full span — the
/// bracket renders instantly.
///
/// When enabled, the envelope grows **top-to-bottom**: the `╭─`
/// corner appears immediately on the scope's start row and the
/// bar cascades downward to the `╰>` over `duration_ms`. Progress
/// `p = elapsed / duration_ms` is clamped to `[0, 1]`. At p = 0
/// only `scope.0` (the start row) is active; at p = 1 the full
/// `(scope.0, scope.1)` span is active and the cached state is
/// cleared so the loop can stop waking on the timer.
///
/// State is cached in the buffer's `indent_anim` `Cell` keyed by
/// the scope tuple. Any change to the key (cursor enters a
/// different scope) restarts the animation from the top.
fn animation_envelope(
    state: &std::cell::Cell<Option<IndentAnimState>>,
    scope: (usize, usize, usize),
    cursor_row: usize,
    enabled: bool,
    duration_ms: u64,
) -> (usize, usize) {
    if !enabled || duration_ms == 0 {
        state.set(None);
        return (scope.0, scope.1);
    }
    let now = std::time::Instant::now();
    let cached = state.get();
    // Three cases:
    // 1. Cached key matches current scope, in-flight (Some t): keep ticking.
    // 2. Cached key matches current scope, settled (None t): hold full extent.
    // 3. Key differs (or no cache): start a fresh animation.
    let started_at = match cached {
        Some((Some(t), k, _)) if k == scope => Some(t),
        Some((None, k, _)) if k == scope => None,
        _ => {
            state.set(Some((Some(now), scope, cursor_row)));
            Some(now)
        }
    };
    let p = match started_at {
        Some(t) => {
            let elapsed_ms = now.duration_since(t).as_millis() as u64;
            (elapsed_ms as f32 / duration_ms as f32).clamp(0.0, 1.0)
        }
        None => 1.0,
    };
    let length = scope.1.saturating_sub(scope.0) as f32;
    let bot = scope.0.saturating_add((length * p).round() as usize);
    if p >= 1.0 && started_at.is_some() {
        // Transition to settled — keep the key cached (so we detect
        // future scope changes) but drop the timer so the main loop
        // stops waking at 60fps.
        state.set(Some((None, scope, cursor_row)));
    }
    (scope.0, bot)
}

/// Active scope range as `(first_body_row, last_body_row,
/// active_col)`. Tree-sitter innermost scope containing the cursor
/// when available; synthetic indent-run otherwise.
fn active_scope_range(
    app: &App,
    cursor_row: usize,
    lines: &[String],
    tab_width: usize,
    indent_width: usize,
) -> Option<(usize, usize, usize)> {
    if let Some(h) = app.buffer.highlighter.as_ref() {
        let scopes = h.indent_scopes_in_rows(cursor_row, cursor_row);
        // Innermost = smallest span containing the cursor.
        // Header (start) row counts as inside so moving from
        // `if y:` into its body doesn't reassign which level is
        // active. Top-level scopes (header indent 0) are kept
        // — their `ac` of 0 lights up col 0 in the stair-step,
        // which makes the leftmost guide participate in the
        // active highlight (and its animation) just like deeper
        // levels.
        let mut best: Option<(usize, usize)> = None;
        for (s, e) in scopes {
            if cursor_row >= s && cursor_row <= e {
                match best {
                    None => best = Some((s, e)),
                    Some((bs, be)) if (e - s) < (be - bs) => best = Some((s, e)),
                    _ => {}
                }
            }
        }
        if let Some((s, e)) = best {
            let col = leading_indent_visual(&lines[s], tab_width).unwrap_or(0);
            return Some((s + 1, e, col));
        }
    }

    // Synthetic fallback: contiguous run of rows at or below the
    // cursor's indent level. Used for plain-text buffers and for
    // tree-sitter buffers whose innermost containing scope is at
    // column 0 (top-level).
    let cursor_indent = match leading_indent_visual(&lines[cursor_row], tab_width) {
        Some(v) => v,
        None => {
            let above = (0..cursor_row)
                .rev()
                .find_map(|r| leading_indent_visual(&lines[r], tab_width))
                .unwrap_or(0);
            let below = (cursor_row + 1..lines.len())
                .find_map(|r| leading_indent_visual(&lines[r], tab_width))
                .unwrap_or(0);
            above.min(below)
        }
    };
    if cursor_indent < indent_width {
        return None;
    }
    let active_col = ((cursor_indent - 1) / indent_width) * indent_width;
    if active_col == 0 {
        return None;
    }
    let threshold = active_col + indent_width;
    let n = lines.len();
    let mut s = cursor_row;
    while s > 0 {
        match leading_indent_visual(&lines[s - 1], tab_width) {
            Some(i) if i >= threshold => s -= 1,
            None => s -= 1,
            _ => break,
        }
    }
    let mut e = cursor_row;
    while e + 1 < n {
        match leading_indent_visual(&lines[e + 1], tab_width) {
            Some(i) if i >= threshold => e += 1,
            None => e += 1,
            _ => break,
        }
    }
    Some((s, e, active_col))
}

fn push_unique_guide(map: &mut GuideMap, row: usize, guide: IndentGuide) {
    let entry = map.entry(row).or_default();
    // When two scopes report the same column the later one wins on
    // active flag and on glyph — the p10k decorator passes through
    // here to upgrade plain `│` cells into corner/arrow glyphs.
    if let Some(existing) = entry.iter_mut().find(|g| g.col == guide.col) {
        if guide.active {
            existing.active = true;
        }
        if guide.glyph != INDENT_GUIDE_CHAR {
            existing.glyph = guide.glyph;
        }
        return;
    }
    entry.push(guide);
}

/// Build a `row → highest severity` lookup for the visible window. Rows
/// outside `[scroll, last)` are skipped, multi-line diagnostics fill all
/// rows they span, and the most severe diagnostic wins per row.
fn build_row_severity(
    app: &App,
    scroll: usize,
    last: usize,
) -> std::collections::HashMap<usize, Severity> {
    let mut map: std::collections::HashMap<usize, Severity> = std::collections::HashMap::new();
    let diags = match app.current_diagnostics() {
        Some(d) => d,
        None => return map,
    };
    for d in diags {
        let lo = d.range.start.line as usize;
        let hi = d.range.end.line as usize;
        for row in lo.max(scroll)..=hi.min(last.saturating_sub(1)) {
            map.entry(row)
                .and_modify(|s| {
                    if (d.severity as u8) < (*s as u8) {
                        *s = d.severity;
                    }
                })
                .or_insert(d.severity);
        }
    }
    map
}

/// Gutter cell rendered between the line number and the buffer text.
/// A thin vertical bar colored per VCS status, or a plain space when
/// the row has no status (and the trailing-space slot is preserved).
fn vcs_bar_span(status: Option<LineStatus>) -> Span<'static> {
    match status {
        Some(LineStatus::Added) => Span::styled("▎", Style::default().fg(Color::Green)),
        Some(LineStatus::Modified) => Span::styled("▎", Style::default().fg(Color::Yellow)),
        Some(LineStatus::DeletedAbove) => Span::styled("▁", Style::default().fg(Color::Red)),
        None => Span::raw(" "),
    }
}

fn sign_span(sev: Option<Severity>) -> Span<'static> {
    match sev {
        Some(Severity::Error) => Span::styled("E", Style::default().fg(Color::Red)),
        Some(Severity::Warning) => Span::styled("W", Style::default().fg(Color::Yellow)),
        Some(Severity::Info) => Span::styled("I", Style::default().fg(Color::LightBlue)),
        Some(Severity::Hint) => Span::styled("H", Style::default().fg(Color::DarkGray)),
        None => Span::raw(" "),
    }
}

/// Render one buffer line, layering syntax-highlight captures
/// (foreground) underneath the visual-selection background. Spans
/// group consecutive characters that share the same resolved style so
/// the terminal sees as few escape changes as possible.
///
/// `captures` is the row-range slice produced by the highlighter for
/// the visible window; we filter per row internally rather than
/// re-extracting per call.
#[allow(clippy::too_many_arguments)]
fn render_line(
    row: usize,
    line: &str,
    sel: Option<&Selection>,
    captures: &[Capture],
    extra_cols: &[usize],
    search_hits: &[(usize, usize)],
    jump_labels: &[(usize, char)],
    bracket_cols: &[usize],
    indent_guides: &[IndentGuide],
    tab_width: usize,
    col_scroll: usize,
    viewport_width: usize,
    show_whitespace: bool,
) -> Vec<Span<'static>> {
    // Look up a guide at visual column `vc`; cached by closure so the
    // tight per-cell loop stays branch-light.
    let guide_at =
        |vc: usize| -> Option<IndentGuide> { indent_guides.iter().find(|g| g.col == vc).copied() };
    let guide_style = |g: IndentGuide| -> Style {
        if g.active {
            // Active uses the terminal's default foreground + bold so
            // the bar is the same hue as code (no extra palette
            // assumption) but visibly stands out from inactive guides.
            Style::default().add_modifier(ratatui::style::Modifier::BOLD)
        } else {
            Style::default().fg(INDENT_GUIDE_FG)
        }
    };
    let is_extra_cursor = |col: usize| -> bool { extra_cols.contains(&col) };
    let is_search_hit =
        |col: usize| -> bool { search_hits.iter().any(|(lo, hi)| col >= *lo && col < *hi) };
    let is_match_bracket = |col: usize| -> bool { bracket_cols.contains(&col) };
    let jump_label_at = |col: usize| -> Option<char> {
        jump_labels
            .iter()
            .find_map(|(c, ch)| if *c == col { Some(*ch) } else { None })
    };
    let is_selected = |col: usize| -> bool {
        let Some(sel) = sel else { return false };
        match *sel {
            Selection::Char { from, to } => {
                if row < from.row || row > to.row {
                    return false;
                }
                let lo = if row == from.row { from.col } else { 0 };
                if row < to.row {
                    col >= lo
                } else {
                    col >= lo && col <= to.col
                }
            }
            Selection::Line { from_row, to_row } => row >= from_row && row <= to_row,
            Selection::Block { r0, c0, r1, c1 } => row >= r0 && row <= r1 && col >= c0 && col <= c1,
        }
    };

    let chars: Vec<char> = line.chars().collect();
    let viewport_right = col_scroll.saturating_add(viewport_width);
    // Max guide visual column — used to pad past EOL when guides need
    // to extend beyond the line content (blank lines inside a scope,
    // or lines shorter than the deepest scope's column).
    let max_guide_col = indent_guides.iter().map(|g| g.col).max();
    if chars.is_empty() {
        let cursor_cell_style = {
            let mut style = Style::default();
            if is_selected(0) {
                style = style.bg(SEL_BG);
            }
            if is_extra_cursor(0) {
                style = extra_cursor_style(style);
            }
            style
        };
        let emit_until = max_guide_col.map(|m| m + 1).unwrap_or(0).max(
            if cursor_cell_style != Style::default() {
                1
            } else {
                0
            },
        );
        if emit_until == 0 || col_scroll >= emit_until {
            return Vec::new();
        }
        let mut spans: Vec<Span<'static>> = Vec::new();
        let mut buf = String::new();
        let mut buf_style = Style::default();
        let mut started = false;
        for vc in col_scroll..emit_until {
            if viewport_width > 0 && vc >= viewport_right {
                break;
            }
            let (ch, style) = if let Some(g) = guide_at(vc) {
                (g.glyph, guide_style(g))
            } else if vc == 0 {
                (' ', cursor_cell_style)
            } else {
                (' ', Style::default())
            };
            if !started {
                buf_style = style;
                started = true;
            } else if style != buf_style {
                if !buf.is_empty() {
                    spans.push(Span::styled(std::mem::take(&mut buf), buf_style));
                }
                buf_style = style;
            }
            buf.push(ch);
        }
        if !buf.is_empty() {
            spans.push(Span::styled(buf, buf_style));
        }
        return spans;
    }

    // Build the per-character base (highlight) style. Captures are
    // sorted in document order; later-arriving captures overwrite
    // earlier ones for the same character, matching the convention
    // that more-specific rules appear later in `highlights.scm`.
    let mut base: Vec<Style> = vec![Style::default(); chars.len()];
    for cap in captures {
        if cap.end_row < row || cap.start_row > row {
            continue;
        }
        let lo = if cap.start_row == row {
            cap.start_col
        } else {
            0
        };
        let hi = if cap.end_row == row {
            cap.end_col.min(chars.len())
        } else {
            chars.len()
        };
        if lo >= hi {
            continue;
        }
        let style = syntax::style_for(&cap.name);
        for slot in base.iter_mut().take(hi).skip(lo) {
            *slot = style;
        }
    }

    // Backgrounds layered from least to most specific: search hit →
    // visual selection → extra cursor (which uses an outline modifier
    // rather than a fill, so it sits on top of any underlying bg).
    // Matching-bracket is a fg/bold overlay applied last so the pair
    // remains identifiable even when sitting inside a selection or
    // search match.
    let style_at = |col: usize| -> Style {
        let mut s = base[col];
        if is_search_hit(col) {
            s = s.bg(SEARCH_HIT_BG);
        }
        if is_selected(col) {
            s = s.bg(SEL_BG);
        }
        if is_extra_cursor(col) {
            s = extra_cursor_style(s);
        }
        if is_match_bracket(col) {
            s = s
                .fg(MATCH_BRACKET_FG)
                .add_modifier(ratatui::style::Modifier::BOLD);
        }
        s
    };

    // Per-col character + style. A `gw` jump label overlays its char on
    // top of the underlying buffer char with `JUMP_LABEL_*` styling.
    // When `show_whitespace` is on, plain spaces become `·` and the
    // leading cell of a tab becomes `→`, both painted in `WHITESPACE_FG`
    // so they sit visibly above (but quietly with) the surrounding text.
    let cell_at = |col: usize| -> (char, Style) {
        if let Some(label) = jump_label_at(col) {
            return (
                label,
                Style::default()
                    .fg(JUMP_LABEL_FG)
                    .bg(JUMP_LABEL_BG)
                    .add_modifier(ratatui::style::Modifier::BOLD),
            );
        }
        let original = chars[col];
        let style = style_at(col);
        if show_whitespace {
            match original {
                ' ' => return ('·', style.fg(WHITESPACE_FG)),
                '\t' => return ('→', style.fg(WHITESPACE_FG)),
                _ => {}
            }
        }
        (original, style)
    };

    // Each char takes one visible cell except `\t`, which jumps to the
    // next `tab_width`-aligned stop. The expanded tab is filled with
    // spaces so its background style (selection / search hit / extra
    // cursor) covers the entire run, and `visual_col` tracks the running
    // cell position so each tab measures from where it actually sits.
    let mut spans: Vec<Span<'static>> = Vec::new();
    let mut buf = String::new();
    let mut buf_style = Style::default();
    let mut visual_col = 0usize;
    let mut started = false;
    let push_cell = |spans: &mut Vec<Span<'static>>,
                     buf: &mut String,
                     buf_style: &mut Style,
                     started: &mut bool,
                     ch: char,
                     style: Style| {
        if !*started {
            *buf_style = style;
            *started = true;
        } else if style != *buf_style {
            if !buf.is_empty() {
                spans.push(Span::styled(std::mem::take(buf), *buf_style));
            }
            *buf_style = style;
        }
        buf.push(ch);
    };
    for (col, &original) in chars.iter().enumerate() {
        let (ch, style) = cell_at(col);
        let width = if original == '\t' {
            tab_width - (visual_col % tab_width)
        } else {
            char_cell_width(original)
        };
        let cell_start = visual_col;
        let cell_end = visual_col + width;
        visual_col = cell_end;

        // Stop once we've passed the right edge: ratatui's Paragraph
        // would truncate anyway, but bailing early keeps very long
        // lines from materializing megabytes of spans per draw.
        if viewport_width > 0 && cell_start >= viewport_right {
            break;
        }
        // Skip cells entirely to the left of the horizontal scroll.
        if cell_end <= col_scroll {
            continue;
        }
        let is_ws = original == ' ' || original == '\t';
        // Per-cell emission so a tab spanning multiple cells can have
        // any subset overridden by an indent-guide glyph at that
        // exact visual column.
        for k in 0..width {
            let vc = cell_start + k;
            if vc < col_scroll {
                continue;
            }
            if viewport_width > 0 && vc >= viewport_right {
                break;
            }
            // Guide override: any whitespace cell may be replaced
            // by an indent-guide glyph. Jump labels still take
            // precedence over guides (they're emitted via `ch`
            // below when no guide is present). The tab
            // whitespace marker (`→`) yields to a guide so
            // `show_whitespace = true` doesn't hide the bar on
            // the leading tab cell.
            let jump_lead =
                original == '\t' && k == 0 && ch != '\t' && jump_label_at(col).is_some();
            let guide = if is_ws && !jump_lead {
                guide_at(vc)
            } else {
                None
            };
            let (out_ch, out_style) = if let Some(g) = guide {
                (g.glyph, guide_style(g))
            } else if original == '\t' {
                if k == 0 && ch != '\t' {
                    (ch, style)
                } else {
                    (' ', style)
                }
            } else if k == 0 {
                (ch, style)
            } else {
                // Trailing cell of a wide glyph: ratatui renders the
                // wide char across both cells from a single span entry,
                // so the leading-cell push above already covers this
                // column. When the leading cell was clipped on the
                // left by `col_scroll`, emit a filler space instead so
                // downstream columns don't shift.
                if cell_start >= col_scroll {
                    continue;
                }
                (' ', style)
            };
            push_cell(
                &mut spans,
                &mut buf,
                &mut buf_style,
                &mut started,
                out_ch,
                out_style,
            );
        }
    }
    // Pad past EOL with guide cells when a scope's guide column
    // lives to the right of the last char on this line (typical for
    // a body row that's shorter than its enclosing scope's column,
    // e.g. a comment with less indent inside a deeper block).
    if let Some(m) = max_guide_col
        && visual_col <= m
    {
        for vc in visual_col.max(col_scroll)..=m {
            if viewport_width > 0 && vc >= viewport_right {
                break;
            }
            let (ch, style) = match guide_at(vc) {
                Some(g) => (g.glyph, guide_style(g)),
                None => (' ', Style::default()),
            };
            push_cell(
                &mut spans,
                &mut buf,
                &mut buf_style,
                &mut started,
                ch,
                style,
            );
        }
        visual_col = visual_col.max(m + 1);
    }
    if !buf.is_empty() {
        spans.push(Span::styled(buf, buf_style));
    }
    // Past-end extra cursor — paint one extra cell so a cursor sitting
    // one column past the last char (the natural Insert-mode position
    // after typing) stays visible. Only when it falls inside the
    // horizontal viewport.
    if is_extra_cursor(chars.len())
        && visual_col >= col_scroll
        && (viewport_width == 0 || visual_col < viewport_right)
    {
        spans.push(Span::styled(
            " ".to_string(),
            extra_cursor_style(Style::default()),
        ));
    }
    spans
}

/// Style overlay applied to every extra-cursor cell. Solid background
/// so the cell stays visible against any underlying syntax / search /
/// selection layer.
fn extra_cursor_style(base: Style) -> Style {
    base.bg(EXTRA_CURSOR_BG)
}

/// Lower the active `gw` jump state into a `(row, col) → char` overlay
/// map suitable for the per-line renderer.
///
/// - Before any keystroke: each label contributes its first char at
///   the target col, and (when present) its second char at col+1.
/// - After the first keystroke: only labels whose `first` matches the
///   typed char survive; they show as just their second char at the
///   target col. Single-char labels never reach this state because
///   `handle_jump_key` short-circuits to the jump.
fn build_jump_overlay(state: Option<&JumpState>) -> HashMap<(usize, usize), char> {
    let mut out = HashMap::new();
    let Some(s) = state else { return out };
    match s.typed_first {
        None => {
            for label in &s.labels {
                out.insert((label.pos.row, label.pos.col), label.first);
                if let Some(c2) = label.second {
                    out.insert((label.pos.row, label.pos.col + 1), c2);
                }
            }
        }
        Some(first) => {
            for label in &s.labels {
                if label.first != first {
                    continue;
                }
                if let Some(c2) = label.second {
                    out.insert((label.pos.row, label.pos.col), c2);
                }
            }
        }
    }
    out
}

/// All matches of `query` in `line`, returned as half-open char
/// ranges. Empty `query` returns no hits, so callers don't accidentally
/// paint the entire buffer when no search is active.
fn find_matches_in_line(line: &str, query: &str) -> Vec<(usize, usize)> {
    if query.is_empty() {
        return Vec::new();
    }
    let q_chars = query.chars().count();
    let mut hits = Vec::new();
    let mut search_from = 0;
    while let Some(byte_idx) = line[search_from..].find(query) {
        let abs_byte = search_from + byte_idx;
        let start_col = line[..abs_byte].chars().count();
        hits.push((start_col, start_col + q_chars));
        // Advance past this match so we don't re-find overlapping
        // occurrences. `query.len()` is byte length, which is safe to
        // add at a UTF-8 boundary.
        search_from = abs_byte + query.len();
        if search_from >= line.len() {
            break;
        }
    }
    hits
}

/// Update and return the viewport scroll position. Sticky: the scroll
/// only moves when the cursor would otherwise fall outside the
/// visible `height`-row window. Cursor-above-viewport scrolls up so
/// the cursor sits on the top line; cursor-below-viewport scrolls
/// down so the cursor sits on the bottom line. Otherwise the existing
/// scroll is preserved — which is what fixes "cursor stuck at the
/// bottom" on upward movement.
///
/// `row_diag` is the per-row diagnostic summary; rows with diagnostics
/// each consume one extra visual row, so the "does the cursor fit"
/// check uses visual heights rather than raw source-row counts.
fn compute_scroll(app: &App, height: usize, row_diag: &HashMap<usize, RowDiag>) -> usize {
    let cur = app.buffer.cursor.row;
    let mut scroll = app.buffer.scroll.get();
    // Deferred centering from a picker-driven jump that fired before
    // the viewport size was known. Take-and-clear so it's a one-shot
    // override, then fall through to publishing the new scroll/height.
    if app.buffer.pending_center.replace(false) && height > 0 {
        let last = app.buffer.lines.len().saturating_sub(1);
        let max_scroll = last.saturating_sub(height.saturating_sub(1));
        scroll = cur.saturating_sub(height / 2).min(max_scroll);
        app.buffer.scroll.set(scroll);
        app.buffer.viewport_height.set(height);
        return scroll;
    }
    // Shrink the scroll-off to 0 on viewports too small to give the
    // cursor room on both sides; otherwise the padding would fight
    // itself and lock the cursor in place.
    let off = if height > 2 * SCROLL_OFF + 1 {
        SCROLL_OFF
    } else {
        0
    };

    if cur < scroll + off {
        scroll = cur.saturating_sub(off);
    } else if height > 0 {
        // Walk rows [scroll..cur], accumulating each row's visual
        // height (1 + 1 if it has diagnostics). Advance scroll forward
        // until the cursor's source row fits with `off` rows of room
        // below it — i.e. `consumed_above_cursor < height - off`. Past
        // EOF this lets scroll exceed `last - height + 1`; the render
        // loop just stops emitting rows when source lines run out.
        let effective_height = height.saturating_sub(off);
        loop {
            if scroll >= cur {
                break;
            }
            let mut consumed: usize = 0;
            for row in scroll..cur {
                consumed += 1 + row_diag.get(&row).map_or(0, |_| 1);
                if consumed >= effective_height {
                    break;
                }
            }
            if consumed < effective_height {
                break;
            }
            scroll += 1;
        }
    }
    // Keep at least the last source line visible — don't let past-EOF
    // padding push every real row off the top.
    let last_row = app.buffer.lines.len().saturating_sub(1);
    scroll = scroll.min(last_row);
    app.buffer.scroll.set(scroll);
    // Publish the height so `H`/`M`/`L` and the `<C-d>`/`<C-u>` family
    // (handled in the input thread) can read what's currently visible.
    app.buffer.viewport_height.set(height);
    scroll
}

/// Update and return the horizontal scroll offset. Sticky like
/// [`compute_scroll`]: shifts the visible window only when the cursor's
/// visual column would otherwise fall outside `[col_scroll, col_scroll
/// + width)`. `width == 0` collapses to no scroll (degenerate frame).
fn compute_col_scroll(app: &App, width: usize, tab_width: usize) -> usize {
    if width == 0 {
        app.buffer.col_scroll.set(0);
        return 0;
    }
    let line = &app.buffer.lines[app.buffer.cursor.row];
    let visual_col = visual_col_of(line, app.buffer.cursor.col, tab_width);
    let mut col_scroll = app.buffer.col_scroll.get();
    if visual_col < col_scroll {
        col_scroll = visual_col;
    } else if visual_col >= col_scroll + width {
        col_scroll = visual_col + 1 - width;
    }
    app.buffer.col_scroll.set(col_scroll);
    col_scroll
}

/// Per-source-row diagnostic summary used for inline rendering. We
/// fold every diagnostic that *starts* on a row into a single virtual
/// line: the worst-severity message, with `(+N)` appended when more
/// than one diagnostic shares the row. Capping at one virtual row per
/// source row keeps the visual layout — and the cursor-y math — simple.
pub(super) struct RowDiag {
    pub severity: Severity,
    pub message: String,
    pub extra: usize,
}

/// Build the row → summary lookup, applying the cursor-vs-other-row
/// filter: the cursor's row shows any severity, every other row only
/// surfaces `Error` diagnostics inline. Keeps the buffer quiet when
/// the cursor is elsewhere — warnings/info/hints stay accessible via
/// the gutter sign and the status-bar toast.
fn build_row_diag_summary(app: &App, cursor_row: usize) -> HashMap<usize, RowDiag> {
    let mut out: HashMap<usize, RowDiag> = HashMap::new();
    let Some(diags) = app.current_diagnostics() else {
        return out;
    };
    for d in diags {
        let row = d.range.start.line as usize;
        if row != cursor_row && d.severity != Severity::Error {
            continue;
        }
        // First line only — multi-line messages would blow past our
        // single-virtual-row budget.
        let msg = d.message.lines().next().unwrap_or("").to_string();
        match out.get_mut(&row) {
            None => {
                out.insert(
                    row,
                    RowDiag {
                        severity: d.severity,
                        message: msg,
                        extra: 0,
                    },
                );
            }
            Some(existing) => {
                if (d.severity as u8) < (existing.severity as u8) {
                    existing.severity = d.severity;
                    existing.message = msg;
                }
                existing.extra += 1;
            }
        }
    }
    out
}

/// Render one virtual diagnostic row. Layout mirrors a real source
/// row's gutter (sign + line-number column + vcs bar) but with blanks
/// so the message column-aligns with the source text above it.
fn diagnostic_line(diag: &RowDiag, inner_text_width: usize) -> Line<'static> {
    let color = severity_color(diag.severity);
    // Blank gutter: 1 (sign) + 5 (line number column) + 1 (vcs bar).
    let gutter = " ".repeat((GUTTER_SIGN_WIDTH + 5 + GUTTER_VCS_WIDTH) as usize);
    let mut text = String::from("↳ ");
    text.push_str(&diag.message);
    if diag.extra > 0 {
        text.push_str(&format!(" (+{})", diag.extra));
    }
    if inner_text_width > 0 && text.chars().count() > inner_text_width {
        let mut t: String = text
            .chars()
            .take(inner_text_width.saturating_sub(1))
            .collect();
        t.push('…');
        text = t;
    }
    Line::from(vec![
        Span::raw(gutter),
        Span::styled(
            text,
            Style::default()
                .fg(color)
                .add_modifier(ratatui::style::Modifier::ITALIC),
        ),
    ])
}

/// Render an inactive pane's buffer. Deliberately a thin renderer:
/// gutter (line numbers + VCS bars) and lines with syntax highlighting,
/// but no diagnostics, no selection, no extra cursors, no jump-label
/// overlay, no search-hit painting — those overlays all belong to the
/// active pane. Scroll is anchored on the inactive pane's own
/// `Buffer.cursor.row` / `Buffer.scroll`, so each pane remembers where
/// the user was last looking.
pub(super) fn draw_buffer_inactive(f: &mut Frame, buf: &Buffer, eff: &EditorConfig, area: Rect) {
    let height = area.height as usize;
    let cur = buf.cursor.row;
    let mut scroll = buf.scroll.get();
    let off = if height > 2 * SCROLL_OFF + 1 {
        SCROLL_OFF
    } else {
        0
    };
    if cur < scroll + off {
        scroll = cur.saturating_sub(off);
    } else if height > 0 && cur + off >= scroll + height {
        scroll = (cur + off + 1).saturating_sub(height);
    }
    let last_row = buf.lines.len().saturating_sub(1);
    scroll = scroll.min(last_row);
    buf.scroll.set(scroll);
    buf.viewport_height.set(height);
    let last_visible = scroll + height;
    let captures = buf
        .highlighter
        .as_ref()
        .map(|h| h.captures_in_rows(scroll, last_visible))
        .unwrap_or_default();
    let vcs_statuses = buf.vcs_statuses();
    let tab_width = eff.tab_width.max(1);
    let show_whitespace = eff.show_whitespace;
    let inner_text_width =
        area.width
            .saturating_sub(GUTTER_SIGN_WIDTH + 5 + GUTTER_VCS_WIDTH) as usize;
    // Track col_scroll on the inactive pane's own cell so horizontal
    // jumps still work when the user re-focuses it.
    let line = buf.lines.get(cur).map(String::as_str).unwrap_or("");
    let visual_col = visual_col_of(line, buf.cursor.col, tab_width);
    let mut col_scroll = buf.col_scroll.get();
    if inner_text_width > 0 {
        if visual_col < col_scroll {
            col_scroll = visual_col;
        } else if visual_col >= col_scroll + inner_text_width {
            col_scroll = visual_col + 1 - inner_text_width;
        }
    } else {
        col_scroll = 0;
    }
    buf.col_scroll.set(col_scroll);

    let mut visible: Vec<Line> = Vec::with_capacity(height);
    for (visual_y, (i, line)) in (0_usize..).zip(buf.lines.iter().enumerate().skip(scroll)) {
        if visual_y >= height {
            break;
        }
        let mut spans = vec![sign_span(None)];
        let num = format!("{:>4} ", i + 1);
        spans.push(Span::styled(num, Style::default().fg(Color::DarkGray)));
        let vcs_status = vcs_statuses.get(i).copied().flatten();
        spans.push(vcs_bar_span(vcs_status));
        spans.extend(render_line(
            i,
            line,
            None,
            &captures,
            &[],
            &[],
            &[],
            &[],
            &[],
            tab_width,
            col_scroll,
            inner_text_width,
            show_whitespace,
        ));
        visible.push(Line::from(spans));
    }
    f.render_widget(Paragraph::new(visible), area);
}

fn severity_color(sev: Severity) -> Color {
    match sev {
        Severity::Error => Color::Red,
        Severity::Warning => Color::Yellow,
        Severity::Info => Color::LightBlue,
        Severity::Hint => Color::DarkGray,
    }
}