dev_prune/tui/
mod.rs

1// Copyright 2026 VKrishna04
2// SPDX-License-Identifier: Apache-2.0
3
4// Terminal UI components for dev-prune.
5
6use std::io::{Stdout, stdout};
7use std::panic::PanicHookInfo;
8use std::sync::Arc;
9use std::time::Duration;
10
11use anyhow::Result;
12use crossterm::ExecutableCommand;
13use crossterm::cursor::Show;
14use crossterm::event;
15use crossterm::terminal::{
16    EnterAlternateScreen, LeaveAlternateScreen, disable_raw_mode, enable_raw_mode,
17};
18use ratatui::Terminal;
19use ratatui::backend::CrosstermBackend;
20
21pub mod config_view;
22pub mod selection_view;
23pub mod status_view;
24
25/// Put the terminal back the way it was found.
26///
27/// Every step is best-effort and independent: if leaving the alternate screen fails there
28/// is still a raw-mode flag to clear, and a terminal left in raw mode with a hidden cursor
29/// is a terminal the user has to close and reopen.
30fn restore_terminal() {
31    let _ = disable_raw_mode();
32    let _ = stdout().execute(LeaveAlternateScreen);
33    let _ = stdout().execute(Show);
34}
35
36/// An entered full-screen terminal session that always exits cleanly.
37///
38/// The three ways out of a TUI are a normal return, an error, and a panic. Before this
39/// guard existed each view handled the first by hand and leaked the terminal on the other
40/// two — `?` between "raw mode on" and the restore call would return with the screen still
41/// swapped and echo still off, which reads to the user as a hung shell.
42pub(crate) struct Tui {
43    pub terminal: Terminal<CrosstermBackend<Stdout>>,
44    prior_hook: Arc<dyn Fn(&PanicHookInfo<'_>) + Sync + Send + 'static>,
45}
46
47impl Tui {
48    /// Enter raw mode and the alternate screen, and arm the restore paths.
49    pub fn new() -> Result<Self> {
50        let prior_hook: Arc<dyn Fn(&PanicHookInfo<'_>) + Sync + Send> =
51            Arc::from(std::panic::take_hook());
52
53        // Restore first, then let the previous hook print: a panic message rendered into
54        // the alternate screen vanishes the moment the screen is dropped.
55        let hook_for_panic = Arc::clone(&prior_hook);
56        std::panic::set_hook(Box::new(move |info| {
57            restore_terminal();
58            hook_for_panic(info);
59        }));
60
61        if let Err(e) = enable_raw_mode() {
62            // The panic hook above is already armed; put the caller's back before
63            // handing the error up, exactly as the late-failure arm below does.
64            std::panic::set_hook(Box::new(move |info| prior_hook(info)));
65            return Err(e.into());
66        }
67        if let Err(e) = stdout().execute(EnterAlternateScreen) {
68            // Raw mode is on but `Self` will never exist, so `Drop` cannot turn it
69            // off — returning through `?` here left the shell in raw mode.
70            restore_terminal();
71            std::panic::set_hook(Box::new(move |info| prior_hook(info)));
72            return Err(e.into());
73        }
74
75        match Terminal::new(CrosstermBackend::new(stdout())) {
76            Ok(terminal) => Ok(Self {
77                terminal,
78                prior_hook,
79            }),
80            Err(e) => {
81                // Constructing the backend failed *after* the screen was swapped. `Drop`
82                // never runs for a `Self` that was never built, so both the screen and
83                // the panic hook have to be put back by hand here. Note this is a
84                // `set_hook`, not a `take_hook`: taking would install std's default and
85                // silently discard whatever hook the caller had before.
86                restore_terminal();
87                std::panic::set_hook(Box::new(move |info| prior_hook(info)));
88                Err(e.into())
89            }
90        }
91    }
92
93    /// Discard input that arrived before the view was ready for it.
94    ///
95    /// The Enter keypress that launched the command is still queued when the loop starts,
96    /// and on Windows its KeyPress/KeyRelease pair arrives inside the loop and confirms
97    /// the selection instantly. The sleep gives the console time to deliver it so that the
98    /// drain below has something to drain.
99    pub fn drain_stale_input(&self, settle: Duration) {
100        std::thread::sleep(settle);
101        // Deliberately not `?`: a failure to drain must never abort the view.
102        while matches!(event::poll(Duration::from_millis(50)), Ok(true)) {
103            let _ = event::read();
104        }
105    }
106}
107
108impl Drop for Tui {
109    fn drop(&mut self) {
110        restore_terminal();
111        let _ = self.terminal.show_cursor();
112        // Hand the panic hook back to whoever owned it, rather than to std's default.
113        let prior = Arc::clone(&self.prior_hook);
114        std::panic::set_hook(Box::new(move |info| prior(info)));
115    }
116}
dev_prune/tui/mod.rs

dev_prune/tui/
mod.rs
