mod app;
mod config;
mod highlighter;
mod renderer;
mod signals;
mod terminal;
mod vault;

fn main() {
    // ── PRE-TERMINAL PHASE ────────────────────────────────────────────────────
    // Errors here use normal eprintln! — the terminal is not yet in raw mode.

    // 1. Detect login shell BEFORE stripping argv[0]
    //    POSIX: kernel prefixes argv[0] with '-' for login shells.
    let is_login_shell = config::detect_login_shell();

    // 2. Parse CLI (strips the leading dash from argv[0] before clap sees it)
    let cli = config::parse_cli();

    // 3. Resolve config path and load config
    let config_path = config::resolve_config_path(cli.config.as_deref());
    let app_config = match config::load_config(&config_path) {
        Ok(c) => c,
        Err(e) => {
            config::print_config_error(&e);
            std::process::exit(1);
        }
    };

    // 3a. Initialize syntax highlighting (one-time, loads embedded syntax definitions)
    //     Must be called before render_markdown() — highlighter uses OnceLock statics.
    highlighter::init_highlighter();

    // 3b. Load initial document (index.md from vault) and render it.
    //     We query the terminal size here for initial render width.
    //     On resize, the event loop re-renders with the updated width.
    let initial_width = ratatui::crossterm::terminal::size()
        .map(|(w, _)| w)
        .unwrap_or(80);

    let (initial_doc, raw_content) = match vault::load_document(&app_config.vault_path, "index.md") {
        vault::VaultDocument::Loaded { path, content } => {
            let filename = path
                .file_name()
                .map(|n| n.to_string_lossy().to_string())
                .unwrap_or_else(|| "index.md".to_string());
            let lines = renderer::render_markdown(&content, initial_width);
            let doc = app::DocumentState::Loaded { filename, lines };
            (doc, Some(content))
        }
        vault::VaultDocument::Missing { path } => {
            (app::DocumentState::Missing { path }, None)
        }
        vault::VaultDocument::ReadError { path, reason } => {
            (app::DocumentState::Error { path, reason }, None)
        }
    };

    // ── TERMINAL PHASE ────────────────────────────────────────────────────────
    // Install safety envelope BEFORE terminal init so panics during init are caught.

    // 4. Install panic hook first — covers panics during terminal init itself
    terminal::install_panic_hook();

    // 5. Register signal handlers before terminal init — covers early SIGHUP
    //    (e.g. SSH disconnect between login shell launch and first draw)
    let signal_flags = match signals::register_signals() {
        Ok(s) => s,
        Err(e) => {
            eprintln!("SYSTEM ERROR: Cannot register signal handlers: {}", e);
            std::process::exit(1);
        }
    };

    // 6. Initialize terminal (enables raw mode, clears screen, sets Viewport::Fullscreen)
    let mut term = match terminal::init_terminal() {
        Ok(t) => t,
        Err(e) => {
            eprintln!("SYSTEM ERROR: Cannot initialize terminal: {}", e);
            std::process::exit(1);
        }
    };

    // ── EVENT LOOP PHASE ──────────────────────────────────────────────────────

    // 7. Create app state and run the event loop.
    //    raw_content is passed so the event loop can re-render on terminal resize.
    let mut app_state = app::App::new(is_login_shell, app_config, initial_doc, raw_content);
    let shutdown_reason = app_state.run_event_loop(&mut term, &signal_flags);

    // ── SHUTDOWN PHASE ────────────────────────────────────────────────────────
    // Terminal must be restored in EVERY exit path below.

    // 8. Restore terminal — always, regardless of how we got here.
    //    Must happen BEFORE show_goodbye() since goodbye prints to stdout.
    terminal::restore_terminal();

    // 9. Handle the shutdown reason
    match shutdown_reason {
        Ok(app::ShutdownReason::UserQuit) => {
            // User deliberately exited — show BBS goodbye message
            app::show_goodbye();
        }
        Ok(app::ShutdownReason::Signal) => {
            // SIGHUP or SIGTERM — SSH disconnect or graceful OS shutdown.
            // Exit silently: there may be nobody on the other end to see a message.
        }
        Err(e) => {
            // I/O error from the event loop
            if e.kind() == std::io::ErrorKind::BrokenPipe {
                // SSH connection closed while we were writing — silent exit (LIFE-04).
                // Terminal is already restored above; just exit quietly.
            } else {
                // Unexpected I/O error — log to stderr after terminal restore
                eprintln!("SYSTEM ERROR: {}", e);
                std::process::exit(1);
            }
        }
    }
}