// X-Plane Cockpit desktop launcher.
//
// A small control panel that: (1) lets the user point at their X-Plane 12
// install, (2) starts/stops the bundled Node "bridge" server (a Bun-compiled
// sidecar), and (3) shows the LAN URL tablets open to see the G1000 cockpit.
// The cockpit web files travel with the app as a resource (WEB_DIST). A system
// tray keeps the server running when the window is closed.

use std::net::TcpListener;
use std::path::PathBuf;
use std::sync::Mutex;

use serde::Serialize;
use tauri::menu::{MenuBuilder, MenuItem, PredefinedMenuItem};
use tauri::tray::{TrayIconBuilder, TrayIconEvent};
use tauri::{Emitter, Manager, State};
use tauri_plugin_clipboard_manager::ClipboardExt;
use tauri_plugin_shell::process::{CommandChild, CommandEvent};
use tauri_plugin_shell::ShellExt;

#[derive(Default)]
struct ServerState {
    child: Mutex<Option<CommandChild>>,
    port: Mutex<u16>,
    url: Mutex<String>,
}

#[derive(Serialize, Clone)]
struct ServerInfo {
    ip: String,
    port: u16,
    url: String,
}

fn lan_ipv4() -> String {
    local_ip_address::local_ip()
        .map(|ip| ip.to_string())
        .unwrap_or_else(|_| "127.0.0.1".to_string())
}

#[tauri::command]
fn lan_ip() -> String {
    lan_ipv4()
}

// Can we bind this TCP port on the LAN interface? (i.e. is it free)
fn is_port_free(port: u16) -> bool {
    TcpListener::bind(("0.0.0.0", port)).is_ok()
}

#[tauri::command]
fn port_free(port: u16) -> bool {
    is_port_free(port)
}

// First free port at/after `start` (so the UI can offer an alternative).
#[tauri::command]
fn suggest_port(start: u16) -> u16 {
    let mut p = start.max(1024);
    for _ in 0..200 {
        if is_port_free(p) {
            return p;
        }
        p = p.saturating_add(1);
    }
    start
}

#[tauri::command]
fn default_xplane_path() -> Option<String> {
    let home = std::env::var("HOME")
        .or_else(|_| std::env::var("USERPROFILE"))
        .unwrap_or_default();
    let candidates = [
        format!("{home}/X-Plane 12"),
        format!("{home}/Desktop/X-Plane 12"),
        "/Applications/X-Plane 12".to_string(),
        "C:/X-Plane 12".to_string(),
        "D:/X-Plane 12".to_string(),
    ];
    candidates
        .into_iter()
        .find(|c| PathBuf::from(c).join("Resources").join("default data").is_dir())
}

#[tauri::command]
fn valid_xplane_path(path: String) -> bool {
    !path.is_empty()
        && PathBuf::from(&path)
            .join("Resources")
            .join("default data")
            .is_dir()
}

#[tauri::command]
fn server_running(state: State<ServerState>) -> bool {
    state.child.lock().unwrap().is_some()
}

#[tauri::command]
async fn start_server(
    app: tauri::AppHandle,
    state: State<'_, ServerState>,
    xplane_path: String,
    port: u16,
    demo: bool,
) -> Result<ServerInfo, String> {
    if state.child.lock().unwrap().is_some() {
        let p = *state.port.lock().unwrap();
        let ip = lan_ipv4();
        return Ok(ServerInfo { url: format!("http://{ip}:{p}"), ip, port: p });
    }
    if !is_port_free(port) {
        return Err(format!("Port {port} ist belegt — wähle einen anderen."));
    }

    let web_dist = app
        .path()
        .resolve("web", tauri::path::BaseDirectory::Resource)
        .map_err(|e| format!("resource path: {e}"))?;

    let mut cmd = app
        .shell()
        .sidecar("xpbridge")
        .map_err(|e| format!("sidecar: {e}"))?
        .env("BRIDGE_PORT", port.to_string())
        .env("BRIDGE_HOST", "0.0.0.0")
        .env("WEB_DIST", web_dist.to_string_lossy().to_string());

    if !xplane_path.is_empty() {
        cmd = cmd.env("XPLANE_ROOT", xplane_path);
    }
    if demo {
        cmd = cmd.env("DEMO", "1");
    }

    let (mut rx, child) = cmd.spawn().map_err(|e| format!("spawn: {e}"))?;

    let app2 = app.clone();
    tauri::async_runtime::spawn(async move {
        while let Some(event) = rx.recv().await {
            let line = match event {
                CommandEvent::Stdout(b) | CommandEvent::Stderr(b) => {
                    String::from_utf8_lossy(&b).to_string()
                }
                CommandEvent::Terminated(_) => {
                    let _ = app2.emit("server-exited", ());
                    break;
                }
                _ => continue,
            };
            let _ = app2.emit("server-log", line);
        }
    });

    let ip = lan_ipv4();
    let url = format!("http://{ip}:{port}");
    *state.child.lock().unwrap() = Some(child);
    *state.port.lock().unwrap() = port;
    *state.url.lock().unwrap() = url.clone();

    Ok(ServerInfo { url, ip, port })
}

#[tauri::command]
fn stop_server(state: State<ServerState>) -> Result<(), String> {
    if let Some(child) = state.child.lock().unwrap().take() {
        child.kill().map_err(|e| format!("kill: {e}"))?;
    }
    *state.url.lock().unwrap() = String::new();
    Ok(())
}

fn kill_sidecar(app: &tauri::AppHandle) {
    if let Some(state) = app.try_state::<ServerState>() {
        if let Some(child) = state.child.lock().unwrap().take() {
            let _ = child.kill();
        }
    }
}

#[cfg_attr(mobile, tauri::mobile_entry_point)]
pub fn run() {
    tauri::Builder::default()
        .plugin(tauri_plugin_shell::init())
        .plugin(tauri_plugin_dialog::init())
        .plugin(tauri_plugin_opener::init())
        .plugin(tauri_plugin_clipboard_manager::init())
        .plugin(tauri_plugin_updater::Builder::new().build())
        .plugin(tauri_plugin_process::init())
        .manage(ServerState::default())
        .invoke_handler(tauri::generate_handler![
            lan_ip,
            port_free,
            suggest_port,
            default_xplane_path,
            valid_xplane_path,
            server_running,
            start_server,
            stop_server
        ])
        .setup(|app| {
            build_tray(app.handle())?;
            Ok(())
        })
        // Closing the window hides it instead of quitting, so the server keeps
        // serving tablets in the background. Quit from the tray.
        .on_window_event(|window, event| {
            if let tauri::WindowEvent::CloseRequested { api, .. } = event {
                api.prevent_close();
                let _ = window.hide();
            }
        })
        .run(tauri::generate_context!())
        .expect("error while running tauri application");
}

fn build_tray(app: &tauri::AppHandle) -> tauri::Result<()> {
    let show = MenuItem::with_id(app, "show", "Panel anzeigen", true, None::<&str>)?;
    let open = MenuItem::with_id(app, "open", "Cockpit öffnen", true, None::<&str>)?;
    let copy = MenuItem::with_id(app, "copy", "URL kopieren", true, None::<&str>)?;
    let toggle = MenuItem::with_id(app, "toggle", "Server starten / stoppen", true, None::<&str>)?;
    let quit = MenuItem::with_id(app, "quit", "Beenden", true, None::<&str>)?;
    let sep = PredefinedMenuItem::separator(app)?;
    let menu = MenuBuilder::new(app)
        .item(&show)
        .item(&open)
        .item(&copy)
        .item(&sep)
        .item(&toggle)
        .item(&sep)
        .item(&quit)
        .build()?;

    TrayIconBuilder::with_id("main")
        .icon(app.default_window_icon().unwrap().clone())
        .tooltip("X-Plane Cockpit")
        .menu(&menu)
        .show_menu_on_left_click(false)
        .on_menu_event(|app, event| match event.id().as_ref() {
            "show" => show_main(app),
            "open" => { let _ = app.emit("tray-open", ()); }
            "copy" => {
                if let Some(state) = app.try_state::<ServerState>() {
                    let url = state.url.lock().unwrap().clone();
                    if !url.is_empty() {
                        let _ = app.clipboard().write_text(url);
                    }
                }
            }
            "toggle" => { let _ = app.emit("tray-toggle", ()); }
            "quit" => { kill_sidecar(app); app.exit(0); }
            _ => {}
        })
        .on_tray_icon_event(|tray, event| {
            if let TrayIconEvent::Click { .. } = event {
                show_main(tray.app_handle());
            }
        })
        .build(app)?;
    Ok(())
}

fn show_main(app: &tauri::AppHandle) {
    if let Some(win) = app.get_webview_window("main") {
        let _ = win.show();
        let _ = win.set_focus();
    }
}