lsv 0.1.15

Three‑pane terminal file viewer (TUI) with preview and Lua configuration
Documentation 
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//! Simple tracing utilities used for diagnostics and integration tests.

use std::{
    fs::OpenOptions,
    path::PathBuf,
};

fn enabled() -> bool
{
    std::env::var("LSV_TRACE")
        .map(|v| !v.is_empty() && v != "0")
        .unwrap_or(false)
}

/// Append a line to the trace log when tracing is enabled (`LSV_TRACE=1`).
pub fn log<S: AsRef<str>>(s: S)
{
    if !enabled()
    {
        return;
    }
    let line = format!("{} {}\n", now_millis(), s.as_ref());
    if let Some(path) = file_path()
    {
        let _ =
            OpenOptions::new().create(true).append(true).open(path).and_then(
                |mut f| {
                    use std::io::Write;
                    f.write_all(line.as_bytes())
                },
            );
    }
}

/// Install a panic hook that logs panic message, location, and backtrace
/// to the trace log and attempts to restore the terminal state so the
/// panic is visible to the user.
pub fn install_panic_hook()
{
    std::panic::set_hook(Box::new(|info| {
        // Extract panic message and location
        let msg = if let Some(s) = info.payload().downcast_ref::<&str>()
        {
            s.to_string()
        }
        else if let Some(s) = info.payload().downcast_ref::<String>()
        {
            s.clone()
        }
        else
        {
            String::from("<non-string panic payload>")
        };
        let loc = info
            .location()
            .map(|l| format!("{}:{}", l.file(), l.line()))
            .unwrap_or_else(|| "<unknown>".to_string());
        // Capture a backtrace when available
        let bt = std::backtrace::Backtrace::force_capture();
        log(format!("[panic] {msg} @ {loc}"));
        log(format!("[panic] backtrace:\n{bt}"));
        // Best-effort terminal restore so the panic is visible
        let _ = crossterm::terminal::disable_raw_mode();
        let mut out = std::io::stdout();
        let _ =
            crossterm::execute!(out, crossterm::terminal::LeaveAlternateScreen);
    }));
}

fn file_path() -> Option<PathBuf>
{
    if let Ok(fp) = std::env::var("LSV_TRACE_FILE")
    {
        return Some(PathBuf::from(fp));
    }
    if let Ok(tmp) = std::env::var("TMPDIR")
        && !tmp.is_empty()
    {
        return Some(PathBuf::from(tmp).join("lsv-trace.log"));
    }
    // Cross-platform fallback to the system temp directory
    Some(std::env::temp_dir().join("lsv-trace.log"))
}

fn now_millis() -> u128
{
    use std::time::{
        SystemTime,
        UNIX_EPOCH,
    };
    SystemTime::now()
        .duration_since(UNIX_EPOCH)
        .map(|d| d.as_millis())
        .unwrap_or(0)
}