// Prevents an extra console window on Windows in release builds.
#![cfg_attr(not(debug_assertions), windows_subsystem = "windows")]

use guara_core::service::Engine;
use std::sync::Arc;

struct State(Arc<Engine>);

/// Single bridge between the UI and the core (same methods as `guara ui` mode).
#[tauri::command]
async fn rpc(
    state: tauri::State<'_, State>,
    method: String,
    params: serde_json::Value,
) -> Result<serde_json::Value, String> {
    let eng = state.0.clone();
    tauri::async_runtime::spawn_blocking(move || {
        eng.rpc(&method, params).map_err(|e| e.to_string())
    })
    .await
    .map_err(|e| e.to_string())?
}

#[tauri::command]
fn update_check(state: tauri::State<'_, State>) -> Result<serde_json::Value, String> {
    let status = state.0.update_check().map_err(|e| e.to_string())?;
    serde_json::to_value(status).map_err(|e| e.to_string())
}

#[tauri::command]
fn update_apply(state: tauri::State<'_, State>) -> Result<String, String> {
    state.0.update_apply().map_err(|e| e.to_string())
}

/// `true` when the process already has sufficient privileges to read raw disks.
/// On Windows the manifest already requires administrator privileges before launch,
/// so this is always `true` here.
#[tauri::command]
fn is_elevated() -> bool {
    #[cfg(unix)]
    {
        unsafe { libc::geteuid() == 0 }
    }
    #[cfg(windows)]
    {
        true
    }
}

/// Relaunches the app with administrator privileges (Linux/macOS). On Windows the
/// manifest already enforces elevation. The new instance terminates this one on startup; if
/// authorization fails, this window stays open and the UI displays the reason.
#[tauri::command]
fn relaunch_elevated(app: tauri::AppHandle) -> Result<(), String> {
    #[cfg(any(target_os = "linux", target_os = "macos"))]
    {
        do_relaunch_elevated(app)
    }
    #[cfg(windows)]
    {
        let _ = app;
        Err("o Guará já roda como administrador no Windows".into())
    }
}

#[cfg(any(target_os = "linux", target_os = "macos"))]
fn do_relaunch_elevated(app: tauri::AppHandle) -> Result<(), String> {
    use tauri::Emitter;
    let exe = elevated_exe()?;
    let cfg = guara_core::settings::config_dir();
    let log = std::env::temp_dir().join(format!("guara-elevate-{}.log", std::process::id()));
    let _ = std::fs::write(&log, b"");
    let out = std::fs::OpenOptions::new()
        .append(true)
        .open(&log)
        .map_err(|e| e.to_string())?;
    let err = out.try_clone().map_err(|e| e.to_string())?;
    let pid = std::process::id().to_string();

    #[cfg(target_os = "linux")]
    let mut cmd = {
        let mut c = std::process::Command::new("pkexec");
        c.arg("/usr/bin/env");
        for k in [
            "DISPLAY",
            "WAYLAND_DISPLAY",
            "XAUTHORITY",
            "XDG_RUNTIME_DIR",
            "DBUS_SESSION_BUS_ADDRESS",
            "GDK_BACKEND",
        ] {
            if let Ok(v) = std::env::var(k) {
                c.arg(format!("{k}={v}"));
            }
        }
        c.arg(format!("GUARA_CONFIG_DIR={}", cfg.display()));
        c.arg(format!("GUARA_REPLACE_PID={pid}"));
        c.arg(&exe);
        c
    };
    #[cfg(target_os = "macos")]
    let mut cmd = {
        let shell = format!(
            "GUARA_CONFIG_DIR='{}' GUARA_REPLACE_PID={} '{}' >/dev/null 2>&1 &",
            cfg.display(),
            pid,
            exe.display()
        );
        let script = format!(
            "do shell script \"{}\" with administrator privileges",
            shell.replace('\\', "\\\\").replace('"', "\\\"")
        );
        let mut c = std::process::Command::new("osascript");
        c.args(["-e", &script]);
        c
    };
    cmd.stdout(out).stderr(err);
    let mut child = cmd
        .spawn()
        .map_err(|e| format!("não foi possível pedir privilégios: {e}"))?;
    std::thread::spawn(move || {
        // On Linux, pkexec only exits with success when the elevated app closes (and the elevated
        // app will have already terminated this process). Any failure before that becomes a warning.
        let status = child.wait();
        if matches!(&status, Ok(s) if s.success()) {
            let _ = std::fs::remove_file(&log);
            return;
        }
        let detail = std::fs::read_to_string(&log).unwrap_or_default();
        let msg = match status.ok().and_then(|s| s.code()) {
            Some(126) => "Autorização cancelada.".to_string(),
            Some(127) => "Não foi possível autenticar como administrador.".to_string(),
            _ => format!(
                "Não foi possível reiniciar como administrador. {}",
                detail.lines().last().unwrap_or("").trim()
            ),
        };
        let _ = app.emit("elevate-failed", msg);
        let _ = std::fs::remove_file(&log);
    });
    Ok(())
}

/// Executable path accessible to root. Inside an AppImage, `current_exe` points
/// inside a user FUSE mount that root cannot access: use the
/// `.AppImage` file itself (`APPIMAGE` environment variable).
#[cfg(any(target_os = "linux", target_os = "macos"))]
fn elevated_exe() -> Result<std::path::PathBuf, String> {
    if let Some(p) = std::env::var_os("APPIMAGE")
        .map(std::path::PathBuf::from)
        .filter(|p| p.is_file())
    {
        return Ok(p);
    }
    std::env::current_exe().map_err(|e| e.to_string())
}

/// Serves recovered files for preview (`guara://localhost/file/<job>/<id>`),
/// with Range support for video/audio/PDF, reading directly from the source.
fn serve_file(eng: &Engine, req: &tauri::http::Request<Vec<u8>>) -> tauri::http::Response<Vec<u8>> {
    use tauri::http::Response;
    if let Some(rest) = req.uri().path().strip_prefix("/thumb/") {
        let mut it = rest.split('/');
        let (job, id) = (
            it.next().unwrap_or(""),
            it.next().and_then(|s| s.parse::<u64>().ok()),
        );
        let size = req
            .uri()
            .query()
            .and_then(|q| q.split('&').find_map(|kv| kv.strip_prefix("s=")))
            .and_then(|v| v.parse::<u32>().ok())
            .unwrap_or(256);
        let err = |code: u16| {
            Response::builder()
                .status(code)
                .header("Access-Control-Allow-Origin", "*")
                .body(Vec::new())
                .unwrap()
        };
        let Some(id) = id else { return err(400) };
        return match eng.thumb(job, id, size) {
            Ok(b) => Response::builder()
                .status(200)
                .header("Content-Type", "image/jpeg")
                .header("Cache-Control", "private, max-age=3600")
                .header("Access-Control-Allow-Origin", "*")
                .body(b.as_ref().clone())
                .unwrap_or_else(|_| err(500)),
            Err(code) => err(code),
        };
    }
    const CAP: u64 = 8 * 1024 * 1024;
    let mut it = req.uri().path().trim_start_matches("/file/").split('/');
    let (job, id) = (
        it.next().unwrap_or(""),
        it.next().and_then(|s| s.parse::<u64>().ok()),
    );
    let err = |code: u16| {
        Response::builder()
            .status(code)
            .header("Access-Control-Allow-Origin", "*")
            .body(Vec::new())
            .unwrap()
    };
    let Some(id) = id else { return err(400) };
    let range = req.headers().get("range").and_then(|v| v.to_str().ok());
    let slice = match eng.file_slice(job, id, range) {
        Ok(s) => s,
        Err(code) => return err(code),
    };
    let total = slice.total;
    let start = slice.start;
    let want = slice.len();
    let mut headers = slice.headers();
    let partial = slice.partial || want > CAP;
    let Ok(data) = slice.read_all(CAP) else {
        return err(500);
    };
    let mut b = Response::builder().status(if partial { 206 } else { 200 });
    headers.retain(|(k, _)| *k != "Content-Range");
    for (k, v) in &headers {
        b = b.header(*k, v);
    }
    if partial && !data.is_empty() {
        b = b.header(
            "Content-Range",
            format!(
                "bytes {}-{}/{}",
                start,
                start + data.len() as u64 - 1,
                total
            ),
        );
    }
    b.body(data).unwrap_or_else(|_| err(500))
}

fn main() {
    let engine = Arc::new(Engine::new());
    let for_protocol = engine.clone();
    tauri::Builder::default()
        .plugin(tauri_plugin_dialog::init())
        .manage(State(engine))
        .register_asynchronous_uri_scheme_protocol("guara", move |_ctx, request, responder| {
            let eng = for_protocol.clone();
            std::thread::spawn(move || responder.respond(serve_file(&eng, &request)));
        })
        .setup(|app| {
            use tauri::{Listener, Manager};
            // When launched elevated by the unprivileged instance, terminate the old process.
            #[cfg(unix)]
            if let Some(pid) = std::env::var("GUARA_REPLACE_PID")
                .ok()
                .and_then(|p| p.parse::<i32>().ok())
            {
                std::thread::spawn(move || {
                    std::thread::sleep(std::time::Duration::from_millis(1200));
                    // SAFETY: only sends SIGTERM to the previous process owned by the invoking user.
                    unsafe {
                        if libc::geteuid() == 0 {
                            libc::kill(pid, libc::SIGTERM);
                        }
                    }
                });
            }

            // The window starts hidden (tauri.conf.json: "visible": false) so the
            // unprivileged instance never flashes on screen before being replaced.
            // Reading raw disks requires root: request elevation as soon as the app
            // launches, without waiting for the user to look for a button, and only
            // show a window once we know which one it is — the elevated relaunch's,
            // or this same one if elevation turned out not to be needed/possible.
            #[cfg(any(target_os = "linux", target_os = "macos"))]
            {
                if unsafe { libc::geteuid() != 0 } && std::env::var("GUARA_REPLACE_PID").is_err() {
                    use tauri::Emitter;
                    let handle = app.handle().clone();
                    let handle_for_failure = app.handle().clone();
                    std::thread::spawn(move || {
                        // do_relaunch_elevated only emits "elevate-failed" itself once the
                        // child process has actually spawned and later exits non-zero. If it
                        // fails earlier (pkexec/osascript missing, exe path unresolved, log
                        // file unwritable), it returns Err directly without emitting anything
                        // — emit it here too, or the hidden window would never reappear.
                        if let Err(e) = do_relaunch_elevated(handle) {
                            let _ = handle_for_failure.emit("elevate-failed", e);
                        }
                    });
                    // Whichever path emits it, make sure the window comes back so the
                    // user sees the warning instead of a silently stuck, invisible app.
                    if let Some(win) = app.get_webview_window("main") {
                        app.handle().listen("elevate-failed", move |_| {
                            let _ = win.show();
                        });
                    }
                } else if let Some(win) = app.get_webview_window("main") {
                    let _ = win.show();
                }
            }
            #[cfg(not(any(target_os = "linux", target_os = "macos")))]
            if let Some(win) = app.get_webview_window("main") {
                let _ = win.show();
            }
            Ok(())
        })
        .invoke_handler(tauri::generate_handler![
            rpc,
            is_elevated,
            relaunch_elevated,
            update_check,
            update_apply
        ])
        .run(tauri::generate_context!())
        .expect("erro ao iniciar o Guará");
}