ruohki
b258b6d262
- init_terminal() enables raw mode and clears main screen via Viewport::Fullscreen - No alternate screen buffer used (deliberate BBS immersive approach) - restore_terminal() disables raw mode and shows cursor using let _ for all calls - install_panic_hook() restores terminal, prints BBS-themed message, delegates to original hook - Use ratatui::crossterm re-export (crossterm is transitive dep only) - All panic hook operations use let _ or eprintln! — no unwrap() or ? inside hook
94 lines
4.0 KiB
Rust
94 lines
4.0 KiB
Rust
//! Terminal initialization, restoration, and panic hook for bbs-md.
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//!
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//! # Design
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//!
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//! This module uses the main screen buffer (no alternate screen) for the immersive BBS feel.
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//! On exit, TUI output remains visible in the terminal scroll history — the user can scroll
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//! up to review what they read, and the goodbye message persists after the process exits.
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//!
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//! # Broken Pipe Safety (LIFE-04)
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//!
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//! All write operations in the TUI must use `let _ =` or handle `ErrorKind::BrokenPipe`.
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//! SSH connections can close mid-write; Rust propagates this as `ErrorKind::BrokenPipe`.
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//! The actual enforcement happens in the event loop (Plan 03), but `restore_terminal()`
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//! already follows this pattern with `let _ =` on every call.
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//!
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//! # Important
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//!
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//! Do NOT call `ratatui::restore()` — it enters alternate screen via `LeaveAlternateScreen`,
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//! which we never entered. Use `restore_terminal()` from this module instead.
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use std::io::stdout;
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use ratatui::crossterm::{
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execute,
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terminal::{enable_raw_mode, disable_raw_mode, Clear, ClearType},
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cursor::{MoveTo, Show},
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};
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use ratatui::{backend::CrosstermBackend, Terminal, TerminalOptions, Viewport};
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/// Type alias for the terminal used throughout the application.
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pub type Term = Terminal<CrosstermBackend<std::io::Stdout>>;
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/// Initialize the terminal on the main screen buffer with raw mode enabled.
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///
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/// This does NOT enter the alternate screen buffer. Instead it clears the main screen
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/// so the TUI occupies the user's actual terminal. On exit, TUI output remains in
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/// scroll history.
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///
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/// # Errors
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///
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/// Returns an error if raw mode cannot be enabled or if the screen cannot be cleared.
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pub fn init_terminal() -> std::io::Result<Term> {
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enable_raw_mode()?;
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execute!(stdout(), Clear(ClearType::All), MoveTo(0, 0))?;
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let backend = CrosstermBackend::new(stdout());
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Terminal::with_options(backend, TerminalOptions {
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viewport: Viewport::Fullscreen,
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})
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}
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/// Restore the terminal to a usable state.
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///
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/// Disables raw mode and shows the cursor. Every operation uses `let _ =` to suppress
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/// errors — this function is called from cleanup paths including the panic hook, where
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/// panicking would hide the original error.
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///
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/// Do NOT call `ratatui::restore()` — it unconditionally calls `LeaveAlternateScreen`,
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/// which corrupts the terminal since we never entered the alternate screen.
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pub fn restore_terminal() {
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let _ = disable_raw_mode();
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let _ = execute!(std::io::stdout(), Show);
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}
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/// Install the custom panic hook with BBS-friendly user messaging.
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///
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/// The hook:
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/// 1. Restores the terminal (disables raw mode, shows cursor)
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/// 2. Prints a friendly BBS-themed message to stderr (visible to the user)
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/// 3. Delegates to the original panic hook for technical details (captured by systemd/SSH log)
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///
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/// Install this before terminal initialization so any panic during init also triggers cleanup.
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pub fn install_panic_hook() {
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let original_hook = std::panic::take_hook();
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std::panic::set_hook(Box::new(move |panic_info| {
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// Restore terminal — use let _ to avoid double-panic if cleanup itself fails
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let _ = ratatui::crossterm::terminal::disable_raw_mode();
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let _ = ratatui::crossterm::execute!(
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std::io::stdout(),
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ratatui::crossterm::cursor::Show
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);
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// Friendly message visible to the user in their terminal.
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// Use \r\n because we may still be in raw mode if disable_raw_mode failed.
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eprintln!("\r\n+----------------------------------------------+");
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eprintln!("| SYSTEM ERROR: An unexpected fault occurred. |");
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eprintln!("| The BBS has exited safely. |");
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eprintln!("| SysOp has been notified. |");
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eprintln!("+----------------------------------------------+\r");
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// Delegate to the original hook — prints backtrace to stderr,
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// captured by journald or available in the SSH session log.
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original_hook(panic_info);
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}));
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}
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