marver 0.0.28

//! Terminal emulation for tmux panes.

pub mod keys;

use std::collections::HashMap;

use ratatui::buffer::Buffer;
use ratatui::layout::Rect;
use ratatui::widgets::Widget;
use tui_term::widget::PseudoTerminal;

use crate::tmux;

pub use keys::{encode as encode_key, send_keys_command};

/// Lines of scrollback kept per pane.
pub const DEFAULT_SCROLLBACK: usize = 10_000;

/// Out-of-band state a program sets, which `vt100` reports through callbacks
/// rather than storing on the screen.
#[derive(Debug, Default, Clone)]
pub struct PaneState {
    title: Option<String>,
    bell: bool,
}

impl vt100::Callbacks for PaneState {
    fn set_window_title(&mut self, _: &mut vt100::Screen, title: &[u8]) {
        self.title = Some(String::from_utf8_lossy(title).into_owned());
    }

    fn audible_bell(&mut self, _: &mut vt100::Screen) {
        self.bell = true;
    }
}

/// One emulated pane.
pub struct PaneTerminal {
    parser: vt100::Parser<PaneState>,
}

impl PaneTerminal {
    /// `size` is `(cols, rows)`.
    pub fn new(size: (u16, u16), scrollback: usize) -> Self {
        let (cols, rows) = size;
        Self {
            parser: vt100::Parser::new_with_callbacks(rows, cols, scrollback, PaneState::default()),
        }
    }

    /// Feed raw bytes from a `%output` notification.
    pub fn feed(&mut self, bytes: &[u8]) {
        self.parser.process(bytes);
    }

    /// Resize the emulated screen. `size` is `(cols, rows)`.
    pub fn resize(&mut self, size: (u16, u16)) {
        let (cols, rows) = size;
        self.parser.screen_mut().set_size(rows, cols);
    }

    /// `(cols, rows)`.
    pub fn size(&self) -> (u16, u16) {
        let (rows, cols) = self.parser.screen().size();
        (cols, rows)
    }

    pub fn screen(&self) -> &vt100::Screen {
        self.parser.screen()
    }

    /// How far back from the live screen this pane is showing, in lines.
    pub fn scrollback(&self) -> usize {
        self.parser.screen().scrollback()
    }

    /// Move the view `delta` lines back through what the agent printed;
    /// negative comes forward again. Returns whether it actually moved, so a
    /// wheel notch at the end of the scrollback costs no redraw.
    pub fn scroll_by(&mut self, delta: isize) -> bool {
        let was = self.scrollback();
        let want = was.saturating_add_signed(delta);
        self.parser.screen_mut().set_scrollback(want);
        // Clamped by vt100 to what there is, so ask rather than assume.
        self.scrollback() != was
    }

    /// Jump back to the live screen.
    pub fn scroll_to_bottom(&mut self) {
        self.parser.screen_mut().set_scrollback(0);
    }

    /// Visible text, without styling. Primarily for assertions.
    pub fn contents(&self) -> String {
        self.parser.screen().contents()
    }

    /// Cursor as `(col, row)`.
    pub fn cursor(&self) -> (u16, u16) {
        let (row, col) = self.parser.screen().cursor_position();
        (col, row)
    }

    /// The title the program set, if it set one.
    pub fn title(&self) -> Option<&str> {
        self.parser.callbacks().title.as_deref()
    }

    /// Whether the pane rang the bell since this was last cleared.
    pub fn bell(&self) -> bool {
        self.parser.callbacks().bell
    }

    /// Consume a pending bell, returning whether there was one.
    pub fn take_bell(&mut self) -> bool {
        std::mem::replace(&mut self.parser.callbacks_mut().bell, false)
    }

    /// A ratatui widget rendering this pane's current screen.
    pub fn widget(&self) -> PseudoTerminal<'_, vt100::Screen> {
        PseudoTerminal::new(self.parser.screen())
    }
}

impl Widget for &PaneTerminal {
    fn render(self, area: Rect, buf: &mut Buffer) {
        self.widget().render(area, buf);
    }
}

/// Every pane marver is emulating, keyed by tmux pane id (`%0`, `%1`, ...).
pub struct Panes {
    panes: HashMap<String, PaneTerminal>,
    size: (u16, u16),
    scrollback: usize,
}

impl Panes {
    /// `size` is `(cols, rows)`, applied to panes as they appear.
    pub fn new(size: (u16, u16), scrollback: usize) -> Self {
        Self {
            panes: HashMap::new(),
            size,
            scrollback,
        }
    }

    /// Route a control-mode event to the pane it concerns.
    pub fn apply(&mut self, event: &tmux::Event) -> bool {
        match event {
            tmux::Event::Output { pane, data } => {
                let size = self.size;
                let scrollback = self.scrollback;
                self.panes
                    .entry(pane.clone())
                    .or_insert_with(|| PaneTerminal::new(size, scrollback))
                    .feed(data);
                true
            }
            _ => false,
        }
    }

    pub fn get(&self, pane: &str) -> Option<&PaneTerminal> {
        self.panes.get(pane)
    }

    pub fn get_mut(&mut self, pane: &str) -> Option<&mut PaneTerminal> {
        self.panes.get_mut(pane)
    }

    /// Start emulating a pane before it has produced output.
    pub fn ensure(&mut self, pane: &str) -> &mut PaneTerminal {
        let size = self.size;
        let scrollback = self.scrollback;
        self.panes
            .entry(pane.to_string())
            .or_insert_with(|| PaneTerminal::new(size, scrollback))
    }

    pub fn remove(&mut self, pane: &str) -> Option<PaneTerminal> {
        self.panes.remove(pane)
    }

    /// Pane ids, sorted so iteration order is stable between frames.
    pub fn ids(&self) -> Vec<&str> {
        let mut ids: Vec<&str> = self.panes.keys().map(String::as_str).collect();
        ids.sort();
        ids
    }

    pub fn len(&self) -> usize {
        self.panes.len()
    }

    pub fn is_empty(&self) -> bool {
        self.panes.is_empty()
    }

    /// Resize every pane, and any created later. `size` is `(cols, rows)`.
    pub fn resize(&mut self, size: (u16, u16)) {
        self.size = size;
        for pane in self.panes.values_mut() {
            pane.resize(size);
        }
    }

    /// `(cols, rows)` new panes are created at.
    pub fn size(&self) -> (u16, u16) {
        self.size
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    fn output(pane: &str, data: &[u8]) -> tmux::Event {
        tmux::Event::Output {
            pane: pane.to_string(),
            data: data.to_vec(),
        }
    }

    fn term() -> PaneTerminal {
        PaneTerminal::new((20, 5), 100)
    }

    /// A pane holding `count` numbered lines, more than fit on screen.
    fn scrolled(count: usize) -> PaneTerminal {
        let mut pane = term();
        for n in 0..count {
            pane.feed(format!("line {n}\r\n").as_bytes());
        }
        pane
    }

    #[test]
    fn a_pane_can_be_scrolled_back_through_what_it_printed() {
        // 10k lines were being kept and none of them could be reached.
        let mut pane = scrolled(30);
        assert_eq!(pane.scrollback(), 0, "starts on the live screen");
        assert!(pane.contents().contains("line 29"));

        assert!(pane.scroll_by(10));

        assert_eq!(pane.scrollback(), 10);
        assert!(pane.contents().contains("line 19"), "{}", pane.contents());
        assert!(!pane.contents().contains("line 29"));
    }

    #[test]
    fn scrolling_past_the_ends_stops_rather_than_wrapping() {
        let mut pane = scrolled(30);

        // Further back than there is history.
        pane.scroll_by(10_000);
        let all_the_way = pane.scrollback();
        assert!(all_the_way > 0);
        assert!(
            !pane.scroll_by(10),
            "already at the top, so nothing moved and no redraw is owed"
        );

        // And forward again past the live screen.
        pane.scroll_by(-10_000);
        assert_eq!(pane.scrollback(), 0);
        assert!(!pane.scroll_by(-10));
    }

    #[test]
    fn a_pane_can_be_brought_back_to_what_is_happening_now() {
        let mut pane = scrolled(30);
        pane.scroll_by(15);

        pane.scroll_to_bottom();

        assert_eq!(pane.scrollback(), 0);
        assert!(pane.contents().contains("line 29"));
    }

    /// The rendered text of a widget, one string per row.
    fn render(term: &PaneTerminal, cols: u16, rows: u16) -> Vec<String> {
        let area = Rect::new(0, 0, cols, rows);
        let mut buf = Buffer::empty(area);
        term.render(area, &mut buf);
        (0..rows)
            .map(|y| {
                (0..cols)
                    .map(|x| buf[(x, y)].symbol().to_string())
                    .collect::<String>()
                    .trim_end()
                    .to_string()
            })
            .collect()
    }

    #[test]
    fn plain_text_lands_on_the_screen() {
        let mut term = term();
        term.feed(b"hello");
        assert!(term.contents().contains("hello"));
    }

    #[test]
    fn dimensions_are_cols_by_rows_not_transposed() {
        // A non-square size is the only way this bug shows up.
        let term = PaneTerminal::new((80, 24), 0);
        assert_eq!(term.size(), (80, 24));
        let (rows, cols) = term.screen().size();
        assert_eq!((rows, cols), (24, 80), "vt100 takes rows first");
    }

    #[test]
    fn resizing_keeps_the_cols_rows_order() {
        let mut term = term();
        term.resize((100, 30));
        assert_eq!(term.size(), (100, 30));
    }

    #[test]
    fn escape_sequences_are_interpreted_not_printed() {
        let mut term = term();
        term.feed(b"\x1b[31mred\x1b[0m");
        let contents = term.contents();
        assert!(contents.contains("red"));
        assert!(
            !contents.contains('\x1b'),
            "the escape must be consumed, got {contents:?}"
        );
    }

    #[test]
    fn cursor_movement_is_tracked_as_col_row() {
        let mut term = term();
        // CUP is row;col, one-based.
        term.feed(b"\x1b[3;7H");
        assert_eq!(term.cursor(), (6, 2), "reported as (col, row), zero-based");
    }

    #[test]
    fn carriage_return_overwrites_rather_than_appends() {
        let mut term = term();
        term.feed(b"first\rsecond");
        let first_line = term.contents().lines().next().unwrap().to_string();
        assert_eq!(first_line, "second");
    }

    #[test]
    fn clearing_the_screen_works() {
        let mut term = term();
        term.feed(b"junk");
        term.feed(b"\x1b[2J\x1b[H");
        assert_eq!(term.contents().trim(), "");
    }

    #[test]
    fn bytes_split_across_feeds_still_parse() {
        // tmux delivers output in whatever chunks it likes, including one that
        // ends mid-escape-sequence.
        let mut term = term();
        term.feed(b"\x1b[");
        term.feed(b"31m");
        term.feed(b"split");
        assert!(term.contents().contains("split"));
        assert!(!term.contents().contains('['));
    }

    #[test]
    fn a_title_is_captured_when_set() {
        let mut term = term();
        assert_eq!(term.title(), None);
        term.feed(b"\x1b]2;my title\x07");
        assert_eq!(term.title(), Some("my title"));
    }

    #[test]
    fn renders_into_a_ratatui_buffer() {
        let mut term = PaneTerminal::new((10, 3), 0);
        term.feed(b"ab\r\ncd");
        // The cursor is painted as a block at its position, which is why row 1
        // is "cd█" and not "cd".
        assert_eq!(render(&term, 10, 3), ["ab", "cd█", ""]);
    }

    #[test]
    fn rendering_preserves_colour() {
        let mut term = PaneTerminal::new((10, 1), 0);
        term.feed(b"\x1b[31mR\x1b[0m");
        let area = Rect::new(0, 0, 10, 1);
        let mut buf = Buffer::empty(area);
        (&term).render(area, &mut buf);
        // SGR 31 arrives as palette entry 1, not the named Color::Red.
        assert_eq!(
            buf[(0, 0)].fg,
            ratatui::style::Color::Indexed(1),
            "styling must survive the widget"
        );
    }

    #[test]
    fn a_bell_is_recorded_and_consumable() {
        let mut term = term();
        assert!(!term.bell());
        term.feed(b"before\x07after");
        assert!(term.bell(), "BEL should be noticed");
        assert!(term.take_bell());
        assert!(!term.bell(), "taking the bell clears it");
        assert!(
            term.contents().contains("beforeafter"),
            "BEL must not print"
        );
    }

    #[test]
    fn output_events_reach_the_right_pane() {
        let mut panes = Panes::new((20, 5), 100);
        panes.apply(&output("%0", b"zero"));
        panes.apply(&output("%1", b"one"));

        assert!(panes.get("%0").unwrap().contents().contains("zero"));
        assert!(panes.get("%1").unwrap().contents().contains("one"));
        assert!(
            !panes.get("%0").unwrap().contents().contains("one"),
            "panes must not bleed into each other"
        );
    }

    #[test]
    fn a_pane_appears_on_its_first_output() {
        let mut panes = Panes::new((20, 5), 100);
        assert!(panes.is_empty());
        // Waiting for an introduction would drop a shell's opening prompt.
        assert!(panes.apply(&output("%7", b"hi")));
        assert_eq!(panes.len(), 1);
        assert!(panes.get("%7").unwrap().contents().contains("hi"));
    }

    #[test]
    fn non_output_events_change_nothing() {
        let mut panes = Panes::new((20, 5), 100);
        assert!(!panes.apply(&tmux::Event::SessionsChanged));
        assert!(!panes.apply(&tmux::Event::Exit { reason: None }));
        assert!(panes.is_empty());
    }

    #[test]
    fn successive_output_accumulates_in_one_pane() {
        let mut panes = Panes::new((20, 5), 100);
        for byte in b"abc" {
            panes.apply(&output("%0", &[*byte]));
        }
        assert_eq!(panes.len(), 1);
        assert!(panes.get("%0").unwrap().contents().contains("abc"));
    }

    #[test]
    fn resize_applies_to_existing_and_future_panes() {
        let mut panes = Panes::new((20, 5), 100);
        panes.apply(&output("%0", b"x"));
        panes.resize((80, 24));

        assert_eq!(panes.get("%0").unwrap().size(), (80, 24));
        panes.apply(&output("%1", b"y"));
        assert_eq!(
            panes.get("%1").unwrap().size(),
            (80, 24),
            "a pane created after the resize must use the new size"
        );
    }

    #[test]
    fn panes_can_be_created_early_and_removed() {
        let mut panes = Panes::new((20, 5), 100);
        panes.ensure("%2").feed(b"early");
        assert!(panes.get("%2").unwrap().contents().contains("early"));
        assert!(panes.remove("%2").is_some());
        assert!(panes.get("%2").is_none());
        assert!(panes.remove("%2").is_none());
    }

    /// The whole pipeline against a real tmux server: a program writes to a
    /// pane, tmux reports it over control mode, the decoder unescapes it, the
    /// emulator interprets it, and the widget renders it.
    #[test]
    fn output_reaches_the_rendered_screen_end_to_end() {
        use crate::tmux::testing::TestServer;
        use crate::tmux::{ControlClient, DEFAULT_SIZE};
        use std::time::Duration;

        let server = TestServer::new();
        let dir = tempfile::TempDir::new().unwrap();
        server
            .tmux
            .new_session("e2e", dir.path(), DEFAULT_SIZE)
            .unwrap();
        let pane = server.tmux.list_panes("e2e").unwrap().remove(0);

        let mut client = ControlClient::attach(&server.tmux, "e2e", DEFAULT_SIZE).unwrap();
        let _ = client.wait_for(Duration::from_secs(10), |e| {
            matches!(e, tmux::Event::SessionChanged { .. })
        });

        client
            .send_command(&format!("send-keys -t {pane} -l 'printf MARVERPIPE'"))
            .unwrap();
        client
            .send_command(&format!("send-keys -t {pane} Enter"))
            .unwrap();

        let mut panes = Panes::new(DEFAULT_SIZE, 100);
        let deadline = std::time::Instant::now() + Duration::from_secs(10);
        let mut rendered = String::new();
        while std::time::Instant::now() < deadline {
            let Ok(event) = client.next_event(Duration::from_millis(500)) else {
                continue;
            };
            panes.apply(&event);
            if let Some(term) = panes.get(&pane) {
                rendered = term.contents();
                if rendered.contains("MARVERPIPE") {
                    break;
                }
            }
        }

        assert!(
            rendered.contains("MARVERPIPE"),
            "screen never showed the output; got {rendered:?}"
        );
        // The load-bearing assertion.
        assert!(
            !rendered.contains("\\033") && !rendered.contains("\\015"),
            "octal escapes were never decoded; got {rendered:?}"
        );
        assert!(
            !rendered.contains('\x1b'),
            "decoded escapes must be interpreted by the emulator, not displayed"
        );
    }

    #[test]
    fn pane_ids_come_back_in_a_stable_order() {
        let mut panes = Panes::new((20, 5), 100);
        for id in ["%2", "%0", "%10", "%1"] {
            panes.apply(&output(id, b"x"));
        }
        assert_eq!(panes.ids(), ["%0", "%1", "%10", "%2"]);
    }
}