kraal 0.2.0

use alacritty_terminal::event::VoidListener;
use alacritty_terminal::grid::Dimensions;
use alacritty_terminal::index::{Column, Line};
use alacritty_terminal::term::{Config, Term};
use alacritty_terminal::vte::ansi::{Color as AColor, Processor, Rgb};
use base64::Engine;
use ratatui::buffer::Buffer;
use ratatui::layout::Rect;
use ratatui::style::Color;

use super::scan::{MAX_APC, Scanner};
use super::*;

struct Size(usize, usize);

impl Dimensions for Size {
    fn total_lines(&self) -> usize {
        self.1
    }
    fn screen_lines(&self) -> usize {
        self.1
    }
    fn columns(&self) -> usize {
        self.0
    }
}

fn term(cols: usize, lines: usize) -> Term<VoidListener> {
    Term::new(Config::default(), &Size(cols, lines), VoidListener)
}

fn shared(available: bool) -> Arc<Shared> {
    let s = Arc::new(Shared::new(true, 64 << 20));
    s.set_available(available);
    s.set_cell(10, 20);
    s
}

fn b64(data: &[u8]) -> String {
    base64::engine::general_purpose::STANDARD.encode(data)
}

/// A kitty command for a `w × h` image of one colour, sent as RGB.
fn rgb_image(keys: &str, w: u32, h: u32) -> Vec<u8> {
    let data: Vec<u8> = (0..w * h).flat_map(|_| [200u8, 10, 10]).collect();
    format!("\x1b_G{keys},f=24,s={w},v={h};{}\x1b\\", b64(&data)).into_bytes()
}

/// Feed `bytes` as a pane does: text to the emulator, images to `g`; the replies.
fn feed(g: &mut PaneGraphics, t: &mut Term<VoidListener>, bytes: &[u8]) -> Vec<u8> {
    let mut parser: Processor = Processor::new();
    let mut replies = Vec::new();
    for piece in g.split(bytes) {
        match piece {
            Piece::Text(text) => parser.advance(t, &text),
            image => replies.extend(g.handle(image, t).unwrap_or_default()),
        }
    }
    replies
}

fn cell_at(t: &Term<VoidListener>, line: i32, col: usize) -> Option<Placeholder> {
    Placeholder::of_cell(&t.grid()[Line(line)][Column(col)])
}

#[test]
fn image_sequences_are_taken_out_wherever_reads_cut_them() {
    let stream: &[u8] = b"a\x1b_Gf=100,a=T;QUJD\x1b\\b\x1bP0;1q#0~~-\x1b\\c\x1b[1md\x1bPzz\x1b\\e";
    for size in 1..stream.len() {
        let mut s = Scanner::default();
        let mut pieces = Vec::new();
        for chunk in stream.chunks(size) {
            pieces.extend(s.split(chunk));
        }
        // Text pieces cut by the reads come back together.
        let mut merged: Vec<Piece> = Vec::new();
        for p in pieces {
            match (merged.last_mut(), p) {
                (Some(Piece::Text(a)), Piece::Text(b)) => a.extend(b),
                (_, p) => merged.push(p),
            }
        }
        assert_eq!(
            merged,
            vec![
                Piece::Text(b"a".to_vec()),
                Piece::Kitty(b"f=100,a=T;QUJD".to_vec()),
                Piece::Text(b"b".to_vec()),
                Piece::Sixel { params: b"0;1".to_vec(), data: b"#0~~-".to_vec() },
                // A DCS that is not sixel, and the rest, go to the emulator as they came.
                Piece::Text(b"c\x1b[1md\x1bPzz\x1b\\e".to_vec()),
            ],
            "chunks of {size}"
        );
    }
}

#[test]
fn a_cancelled_or_oversized_command_is_dropped() {
    let mut s = Scanner::default();
    assert_eq!(s.split(b"x\x1b_Ga=T\x18y"), vec![Piece::Text(b"xy".to_vec())]);
    let mut s = Scanner::default();
    let mut huge = b"\x1b_Ga=T;".to_vec();
    huge.resize(MAX_APC + 100, b'A');
    huge.extend_from_slice(b"\x1b\\z");
    assert_eq!(s.split(&huge), vec![Piece::Text(b"z".to_vec())]);
    // An ESC inside a command starts a new sequence.
    let mut s = Scanner::default();
    assert_eq!(s.split(b"\x1b_Ga=T\x1b[1m"), vec![Piece::Text(b"\x1b[1m".to_vec())]);
}

#[test]
fn every_diacritic_is_a_zero_width_mark() {
    use unicode_width::UnicodeWidthChar;
    assert_eq!(PLACEHOLDER.width(), Some(1));
    for d in DIACRITICS {
        assert_eq!(d.width(), Some(0), "{d:?}");
    }
}

#[test]
fn a_placed_image_becomes_placeholder_cells_at_the_cursor() {
    let mut g = PaneGraphics::new(shared(true));
    let mut t = term(20, 6);
    let replies = feed(&mut g, &mut t, b"ab");
    assert!(replies.is_empty());
    // 3 columns by 2 rows, then text after it.
    let replies = feed(&mut g, &mut t, &rgb_image("a=T,i=5,c=3,r=2", 4, 4));
    assert_eq!(replies, b"\x1b_Gi=5;OK\x1b\\");
    let (kid, shown) = g.shown().next().unwrap();
    assert_eq!(kid >> 24, KRAAL_ID >> 24);
    assert_eq!(shown.placements, vec![(0, 3, 2)]);
    for (line, col, row, column) in [(0, 2, 0, 0), (0, 4, 0, 2), (1, 2, 1, 0), (1, 4, 1, 2)] {
        let p = cell_at(&t, line, col).unwrap();
        assert_eq!((p.id, p.row, p.col), (kid, row, column), "line {line} col {col}");
    }
    assert!(cell_at(&t, 0, 5).is_none() && cell_at(&t, 1, 1).is_none());
    // The cursor is after the image, on its last row; what follows keeps its own colours.
    assert_eq!(t.grid().cursor.point, alacritty_terminal::index::Point::new(Line(1), Column(5)));
    feed(&mut g, &mut t, b"z");
    assert_eq!(t.grid()[Line(1)][Column(5)].c, 'z');
    assert_ne!(
        t.grid()[Line(1)][Column(5)].fg,
        AColor::Spec(Rgb { r: (kid >> 16) as u8, g: (kid >> 8) as u8, b: kid as u8 })
    );
}

#[test]
fn an_image_wider_than_the_screen_is_cut_and_c1_keeps_the_cursor() {
    let mut g = PaneGraphics::new(shared(true));
    let mut t = term(10, 4);
    feed(&mut g, &mut t, b"\x1b[1;8H");
    feed(&mut g, &mut t, &rgb_image("a=T,C=1,c=6,r=2,q=1", 2, 2));
    let (_, shown) = g.shown().next().unwrap();
    assert_eq!(shown.placements, vec![(0, 3, 2)], "three columns fit");
    assert!(cell_at(&t, 1, 9).is_some());
    assert_eq!(t.grid().cursor.point, alacritty_terminal::index::Point::new(Line(0), Column(7)));
}

#[test]
fn queries_are_answered_only_when_a_terminal_can_show_images() {
    let query = b"\x1b_Gi=31,s=1,v=1,a=q,t=d,f=24;AAAA\x1b\\";
    let mut t = term(10, 4);
    let mut g = PaneGraphics::new(shared(false));
    assert!(feed(&mut g, &mut t, query).is_empty(), "like a terminal without images");
    let mut g = PaneGraphics::new(shared(true));
    assert_eq!(feed(&mut g, &mut t, query), b"\x1b_Gi=31;OK\x1b\\");
    assert_eq!(g.shown().count(), 0, "a query keeps nothing");
    assert_eq!(g.device_attributes("\x1b[?6c"), "\x1b[?62;4;22c");
    assert_eq!(PaneGraphics::new(shared(false)).device_attributes("\x1b[?6c"), "\x1b[?6c");
}

#[test]
fn files_and_shared_memory_are_refused_alike() {
    let mut g = PaneGraphics::new(shared(true));
    let mut t = term(10, 4);
    for medium in ["f", "t", "s"] {
        let cmd = format!("\x1b_Gi=3,a=T,f=100,t={medium};{}\x1b\\", b64(b"/etc/passwd"));
        assert_eq!(feed(&mut g, &mut t, cmd.as_bytes()), b"\x1b_Gi=3;EBADF:Failed to read image file\x1b\\");
    }
    assert_eq!(g.shown().count(), 0);
}

#[test]
fn chunks_numbers_and_quiet_replies() {
    let mut g = PaneGraphics::new(shared(true));
    let mut t = term(20, 6);
    let data: Vec<u8> = (0..4 * 4).flat_map(|_| [1u8, 2, 3, 255]).collect();
    let all = b64(&data);
    let (a, b) = all.split_at(32);
    let first = format!("\x1b_GI=9,f=32,s=4,v=4,m=1;{a}\x1b\\");
    let last = format!("\x1b_Gm=0;{b}\x1b\\");
    assert!(feed(&mut g, &mut t, first.as_bytes()).is_empty());
    let reply = String::from_utf8(feed(&mut g, &mut t, last.as_bytes())).unwrap();
    // A numbered image gets an id of kraal's, given back with the number.
    let id: u32 = reply.strip_prefix("\x1b_Gi=").unwrap().split(',').next().unwrap().parse().unwrap();
    assert_eq!(reply, format!("\x1b_Gi={id},I=9;OK\x1b\\"));
    // Placed by its number; q=1 silences the OK, q=2 errors too.
    assert!(feed(&mut g, &mut t, b"\x1b_Ga=p,I=9,q=1\x1b\\").is_empty());
    assert_eq!(g.shown().count(), 1);
    assert!(feed(&mut g, &mut t, b"\x1b_Ga=p,i=77,q=2\x1b\\").is_empty());
    assert_eq!(feed(&mut g, &mut t, b"\x1b_Ga=p,i=77\x1b\\"), b"\x1b_Gi=77;ENOENT:no such image\x1b\\");
}

#[test]
fn deleted_images_render_blank_and_others_show() {
    let mut g = PaneGraphics::new(shared(true));
    let mut t = term(20, 6);
    feed(&mut g, &mut t, &rgb_image("a=T,i=1,c=2,r=1,q=2", 2, 2));
    feed(&mut g, &mut t, b"\r\n");
    feed(&mut g, &mut t, &rgb_image("a=T,i=2,c=2,r=1,q=2", 2, 2));
    assert_eq!(g.shown().count(), 2);
    let render = |g: &PaneGraphics, t: &Term<VoidListener>, show: bool| {
        let area = Rect::new(0, 0, 20, 6);
        let mut buf = Buffer::empty(area);
        crate::pane::render_term(t, area, &mut buf, None);
        g.show_cells(area, &mut buf, show);
        buf
    };
    let buf = render(&g, &t, true);
    assert!(buf[(0, 0)].symbol().starts_with(PLACEHOLDER) && buf[(0, 1)].symbol().starts_with(PLACEHOLDER));
    assert!(matches!(buf[(0, 0)].fg, Color::Rgb(..)));
    // A client that cannot show images sees blanks, never the placeholder character.
    let buf = render(&g, &t, false);
    assert_eq!(buf[(0, 0)].symbol(), " ");
    feed(&mut g, &mut t, b"\x1b_Ga=d,d=I,i=1\x1b\\");
    assert_eq!(g.shown().count(), 1);
    let buf = render(&g, &t, true);
    assert_eq!(buf[(0, 0)].symbol(), " ");
    assert!(buf[(0, 1)].symbol().starts_with(PLACEHOLDER));
    // By position: the image under the cursor's cell (1-based x, y).
    feed(&mut g, &mut t, b"\x1b_Ga=d,d=p,x=1,y=2\x1b\\");
    assert_eq!(g.shown().count(), 0);
}

#[test]
fn a_programs_own_placeholders_name_its_image_through_kraal() {
    let mut g = PaneGraphics::new(shared(true));
    let mut t = term(20, 6);
    // A virtual placement, then the program prints placeholders for id 42 (256-colour), with
    // the row diacritic only on the first cell, as kitty allows.
    feed(&mut g, &mut t, &rgb_image("a=T,U=1,i=42,c=3,r=1,q=2", 3, 1));
    let (kid, shown) = g.shown().next().unwrap();
    assert_eq!(shown.placements, vec![(0, 3, 1)]);
    assert!(t.grid()[Line(0)][Column(0)].c == ' ', "a virtual placement writes nothing");
    let text = format!("\x1b[38;5;42m{PLACEHOLDER}\u{0305}{PLACEHOLDER}{PLACEHOLDER}\x1b[39m");
    feed(&mut g, &mut t, text.as_bytes());
    let area = Rect::new(0, 0, 20, 6);
    let mut buf = Buffer::empty(area);
    crate::pane::render_term(&t, area, &mut buf, None);
    g.show_cells(area, &mut buf, true);
    for col in 0..3u16 {
        let p = Placeholder::of_symbol(buf[(col, 0)].symbol(), buf[(col, 0)].fg).unwrap();
        assert_eq!((p.id, p.row, p.col), (kid, 0, col as usize), "column {col}");
    }
    // An id nothing shows renders blank.
    let text = format!("\r\n\x1b[38;5;43m{PLACEHOLDER}\x1b[39m");
    feed(&mut g, &mut t, text.as_bytes());
    let mut buf = Buffer::empty(area);
    crate::pane::render_term(&t, area, &mut buf, None);
    g.show_cells(area, &mut buf, true);
    assert_eq!(buf[(0, 1)].symbol(), " ");
}

#[test]
fn the_oldest_images_go_when_the_quota_is_reached() {
    let s = Arc::new(Shared::new(true, 1));
    s.set_available(true);
    let mut g = PaneGraphics::new(s.clone());
    let mut t = term(20, 6);
    feed(&mut g, &mut t, &rgb_image("a=T,i=1,q=2", 2, 2));
    // Even one image is over a quota of one byte: it cannot stay.
    assert_eq!(g.shown().count(), 0);
    assert_eq!(feed(&mut g, &mut t, &rgb_image("a=T,i=2", 2, 2)), b"\x1b_Gi=2;ENOSPC:image storage is full\x1b\\");
    assert_eq!(s.used(), 0, "nothing is left held");
    // With room for one, the second replaces the first.
    // What one picture counts: its PNG and the cost of keeping it.
    let one = {
        let probe = Arc::new(Shared::new(true, usize::MAX));
        let _png = Picture::from_rgba(2, 2, [200, 10, 10, 255].repeat(4), &probe).unwrap();
        probe.used()
    };
    let s = Arc::new(Shared::new(true, one + one / 2));
    s.set_available(true);
    let mut g = PaneGraphics::new(s.clone());
    feed(&mut g, &mut t, &rgb_image("a=T,i=1,q=2", 2, 2));
    feed(&mut g, &mut t, &rgb_image("a=T,i=2,q=2", 2, 2));
    assert_eq!(g.shown().count(), 1);
    assert!(g.shown().all(|(_, sh)| sh.origin == 2));
    assert!(s.used() <= one + one / 2);
    drop(g);
    assert_eq!(s.used(), 0, "a pane's images go with it");
}

#[test]
fn sixel_images_decode_and_take_cells() {
    // Two red columns six pixels high, then a band below in register 1's default blue.
    let img = sixel::decode(b"\"1;1;2;12#0;2;100;0;0#0~~-#1!2~").unwrap();
    assert_eq!((img.width, img.height), (2, 12));
    assert_eq!(&img.pixels[..4], &[255, 0, 0, 255]);
    assert_eq!(&img.pixels[6 * 2 * 4..6 * 2 * 4 + 4], &[51, 51, 204, 255]);
    // Unpainted pixels are transparent.
    let img = sixel::decode(b"#0;2;0;100;0@").unwrap();
    assert_eq!((img.width, img.height), (1, 1));
    assert_eq!(&img.pixels[..], &[0, 255, 0, 255]);
    assert!(sixel::decode(b"!99999999~").is_none(), "too wide");
    assert!(sixel::decode(b"").is_none());

    let mut g = PaneGraphics::new(shared(true));
    let mut t = term(20, 6);
    feed(&mut g, &mut t, b"\x1bPq\"1;1;25;30#0;2;0;0;100#0!25~-!25~-!25~-!25~-!25~\x1b\\");
    let (_, shown) = g.shown().next().unwrap();
    // 25×30 pixels in 10×20 cells: 3 columns, 2 rows; the cursor goes below.
    assert_eq!(shown.placements, vec![(0, 3, 2)]);
    assert_eq!(t.grid().cursor.point.line, Line(2));
}

#[test]
fn outer_terminal_commands_are_plain_and_chunked() {
    let s = shared(true);
    let picture = Picture::new(vec![7u8; 10_000], 1, 1, &s);
    let mut out = Vec::new();
    transmit(KRAAL_ID | 5, &picture, &mut out);
    let text = String::from_utf8(out).unwrap();
    assert!(text.starts_with(&format!("\x1b_Ga=t,f=100,i={},q=2,m=1;", KRAAL_ID | 5)));
    assert!(text.ends_with("\x1b\\"));
    assert_eq!(text.matches("\x1b_G").count(), 10_000_usize.div_ceil(3) * 4 / 4096 + 1);
    let mut out = Vec::new();
    place(9, 3, 4, 2, &mut out);
    assert_eq!(out, b"\x1b_Ga=p,U=1,i=9,p=3,c=4,r=2,q=2\x1b\\");
    assert_eq!(probe_answer(&format!("\x1b_Gi={PROBE_ID};OK\x1b\\")), Some(true));
    assert_eq!(probe_answer(&format!("\x1b_Gi={PROBE_ID};ENOTSUPPORTED\x1b\\")), Some(false));
    assert_eq!(probe_answer("\x1b[?62c"), None);
    assert_eq!(cell_size_answer("\x1b[6;20;9t"), Some((9, 20)));
    assert_eq!(terminal_name("\x1bP>|ghostty 1.1.3\x1b\\").as_deref(), Some("ghostty 1.1.3"));
    assert!(draws_placeholders("kitty(0.39.1)") && draws_placeholders("ghostty 1.1.3"));
    assert!(!draws_placeholders("WezTerm 20240203-110809-5046fc22"));
}

#[test]
fn terminal_replies_reach_the_server_whole() {
    let mut p = crate::input::InputParser::new();
    let mut events = p.feed(format!("\x1b_Gi={PROBE_ID};OK\x1b\\\x1bP>|kitty(0.39.1)\x1b\\\x1b[6;20;9t").as_bytes());
    events.extend(p.flush());
    let raw: Vec<String> = events
        .into_iter()
        .filter_map(|e| match e {
            crate::input::InputEvent::Raw(r) => Some(String::from_utf8_lossy(&r).into_owned()),
            _ => None,
        })
        .collect();
    assert_eq!(
        raw,
        vec![
            format!("\x1b_Gi={PROBE_ID};OK\x1b\\"),
            "\x1bP>|kitty(0.39.1)\x1b\\".to_string(),
            "\x1b[6;20;9t".to_string()
        ]
    );
}

/// A quota that holds `n` pictures of `w × h` sent as RGB.
fn quota_for(n: usize, w: u32, h: u32) -> Arc<Shared> {
    let probe = Arc::new(Shared::new(true, usize::MAX));
    let _png = Picture::from_rgba(w, h, [200, 10, 10, 255].repeat((w * h) as usize), &probe).unwrap();
    let s = Arc::new(Shared::new(true, probe.used() * n + probe.used() / 2));
    s.set_available(true);
    s.set_cell(10, 20);
    s
}

#[test]
fn cropped_placements_count_in_the_quota() {
    // Room for three pictures: the upload, and two parts of it at most.
    let s = quota_for(3, 8, 8);
    let mut g = PaneGraphics::new(s.clone());
    let mut t = term(40, 10);
    feed(&mut g, &mut t, &rgb_image("a=t,i=1,q=2", 8, 8));
    let quota = s.used() * 3 + s.used() / 2;
    for x in 0..20 {
        feed(&mut g, &mut t, format!("\x1b_Ga=p,i=1,x={},w=4,C=1,q=2\x1b\\", x % 4).as_bytes());
        assert!(s.used() <= quota, "placement {x}: {} over {quota}", s.used());
    }
    assert!(g.shown().count() <= 3);
}

#[test]
fn placements_are_bounded_and_those_written_over_are_forgotten() {
    let mut g = PaneGraphics::new(shared(true));
    let mut t = term(20, 4);
    feed(&mut g, &mut t, &rgb_image("a=t,i=1,q=2", 2, 2));
    // The same cell, placed over and over: what was written over goes.
    for _ in 0..200 {
        feed(&mut g, &mut t, b"\x1b[H\x1b_Ga=p,i=1,c=1,r=1,C=1,q=2\x1b\\");
    }
    assert!(g.shown().count() <= 2 * SWEEP_START, "{} images kept", g.shown().count());
    // One per line: those still in the screen or its history stay, the others go.
    let mut g = PaneGraphics::new(shared(true));
    let mut t = term(20, 4);
    feed(&mut g, &mut t, &rgb_image("a=t,i=1,q=2", 2, 2));
    for _ in 0..2 * SWEEP_START {
        feed(&mut g, &mut t, b"\x1b_Ga=p,i=1,c=1,r=1,q=2\x1b\\\r\n");
    }
    assert_eq!(g.shown().count(), 2 * SWEEP_START, "all in the history");
    let mut short = Term::new(Config { scrolling_history: 2, ..Config::default() }, &Size(20, 4), VoidListener);
    let mut g = PaneGraphics::new(shared(true));
    feed(&mut g, &mut short, &rgb_image("a=t,i=1,q=2", 2, 2));
    for _ in 0..2 * SWEEP_START {
        feed(&mut g, &mut short, b"\x1b_Ga=p,i=1,c=1,r=1,q=2\x1b\\\r\n");
    }
    assert!(g.shown().count() < SWEEP_START, "{} kept with a history of 2 lines", g.shown().count());
    // A program's own placeholders: placements of one image are bounded.
    let mut g = PaneGraphics::new(shared(true));
    feed(&mut g, &mut t, &rgb_image("a=t,i=7,q=2", 2, 2));
    for p in 1..=200 {
        feed(&mut g, &mut t, format!("\x1b_Ga=p,U=1,i=7,p={p},c=1,r=1,q=2\x1b\\").as_bytes());
    }
    let (_, shown) = g.shown().next().unwrap();
    assert_eq!(shown.placements.len(), MAX_PLACEMENTS);
    assert_eq!(shown.placements.last().map(|p| p.0), Some(200), "the newest stay");
}

#[test]
fn the_alternate_screen_keeps_the_main_screens_images() {
    let mut g = PaneGraphics::new(shared(true));
    let mut t = term(20, 4);
    feed(&mut g, &mut t, &rgb_image("a=t,i=1,q=2", 2, 2));
    feed(&mut g, &mut t, b"\x1b_Ga=p,i=1,c=1,r=1,q=2\x1b\\");
    let main: Vec<u32> = g.shown().map(|(k, _)| k).collect();
    // On the alternate screen, many images over the same cell: the main screen's stays.
    feed(&mut g, &mut t, b"\x1b[?1049h");
    for _ in 0..100 {
        feed(&mut g, &mut t, b"\x1b[H\x1b_Ga=p,i=1,c=1,r=1,C=1,q=2\x1b\\");
    }
    assert!(g.shown().any(|(k, _)| k == main[0]));
    // Back on the main screen, the alternate screen's images go at the next look.
    feed(&mut g, &mut t, b"\x1b[?1049l");
    g.sweep_at = 0;
    feed(&mut g, &mut t, b"\x1b[3;1H\x1b_Ga=p,i=1,c=1,r=1,q=2\x1b\\");
    assert_eq!(g.shown().count(), 2, "the main screen's two");
}

#[test]
fn a_removed_placement_goes_from_the_terminal_and_a_closed_pane_counts_as_a_change() {
    let s = shared(true);
    let mut g = PaneGraphics::new(s.clone());
    let mut t = term(20, 4);
    feed(&mut g, &mut t, &rgb_image("a=T,U=1,i=1,p=7,c=2,r=1,q=2", 2, 2));
    feed(&mut g, &mut t, b"\x1b_Ga=p,U=1,i=1,p=8,c=2,r=1,q=2\x1b\\");
    let live = |g: &PaneGraphics| -> HashMap<u32, Live> {
        g.shown().map(|(k, s)| (k, (s.generation, s.picture.clone(), s.placements.clone()))).collect()
    };
    let mut sent = HashMap::new();
    let mut out = Vec::new();
    assert!(!update_terminal(&mut sent, live(&g), usize::MAX, &mut out));
    let kid = *sent.keys().next().unwrap();
    // Placement 7 removed: the terminal loses the image's placements and gets 8 again.
    feed(&mut g, &mut t, b"\x1b_Ga=d,d=i,i=1,p=7\x1b\\");
    let mut out = Vec::new();
    update_terminal(&mut sent, live(&g), usize::MAX, &mut out);
    let text = String::from_utf8(out).unwrap();
    assert_eq!(
        text,
        format!("\x1b_Ga=d,d=i,i={kid},q=2\x1b\\\x1b_Ga=p,U=1,i={kid},p=8,c=2,r=1,q=2\x1b\\"),
        "no transmission again"
    );
    // The last one removed: the image goes from the terminal.
    feed(&mut g, &mut t, b"\x1b_Ga=d,d=i,i=1,p=8\x1b\\");
    assert_eq!(g.shown().count(), 0);
    let mut out = Vec::new();
    update_terminal(&mut sent, live(&g), usize::MAX, &mut out);
    assert_eq!(out, format!("\x1b_Ga=d,d=I,i={kid},q=2\x1b\\").into_bytes());
    // A pane that closes with images on show is a change clients see.
    feed(&mut g, &mut t, &rgb_image("a=T,i=2,c=1,r=1,q=2", 2, 2));
    let before = s.version();
    drop(g);
    assert_ne!(s.version(), before);
    assert_eq!(s.used(), 0);
}