+use std::sync::Mutex;
+
+use block2::{Block, RcBlock};
+use objc2::Encoding;
+
+use crate::{Error, List, Update};
+
+// The "objc2" project aims to provide bindings for all frameworks but Network.framework
+// isn't ready yet so let's kick it old-school
+
+struct nw_path_monitor;
+type nw_path_monitor_t = *mut nw_path_monitor;
+struct nw_path;
+struct dispatch_queue;
+type dispatch_queue_t = *mut dispatch_queue;
+const QOS_CLASS_BACKGROUND: usize = 0x09;
+
+unsafe impl objc2::Encode for nw_path {
+ const ENCODING: Encoding = usize::ENCODING;
+}
+
+#[link(name = "Network", kind = "framework")]
+extern "C" {
+ fn nw_path_monitor_create() -> nw_path_monitor_t;
+ fn nw_path_monitor_set_update_handler(
+ monitor: nw_path_monitor_t,
+ update_handler: &Block<dyn Fn(nw_path)>,
+ );
+ fn nw_path_monitor_set_queue(monitor: nw_path_monitor_t, queue: dispatch_queue_t);
+ fn nw_path_monitor_start(monitor: nw_path_monitor_t);
+ fn nw_path_monitor_cancel(monitor: nw_path_monitor_t);
+
+ fn dispatch_get_global_queue(identifier: usize, flag: usize) -> dispatch_queue_t;
+}
+
+pub(crate) struct WatchHandle {
+ path_monitor: nw_path_monitor_t,
+}
+
+impl Drop for WatchHandle {
+ fn drop(&mut self) {
+ unsafe { nw_path_monitor_cancel(self.path_monitor); }
+ }
+}
+
+struct CallbackState {
+ prev_list: List,
+ callback: Box<dyn FnMut(Update) + Send + 'static>,
+}
+
+pub(crate) fn watch_interfaces<F: FnMut(Update) + Send + 'static>(
+ callback: F,
+) -> Result<WatchHandle, Error> {
+ let state = CallbackState {
+ prev_list: List::default(),
+ callback: Box::new(callback),
+ };
+ // Blocks are Fn, not FnMut
+ let state = Mutex::new(state);
+ let block = RcBlock::new(move |_: nw_path| {
+ let mut state = state.lock().unwrap();
+ let Ok(new_list) = crate::list::list_interfaces() else {
+ return;
+ };
+ if new_list == state.prev_list {
+ return;
+ }
+ let update = Update {
+ interfaces: new_list.0.clone(),
+ diff: new_list.diff_from(&state.prev_list),
+ };
+ (state.callback)(update);
+ state.prev_list = new_list;
+ });
+ let path_monitor: nw_path_monitor_t;
+ unsafe {
+ let queue = dispatch_get_global_queue(QOS_CLASS_BACKGROUND, 0);
+ path_monitor = nw_path_monitor_create();
+ nw_path_monitor_set_update_handler(path_monitor, &block);
+ nw_path_monitor_set_queue(path_monitor, queue);
+ nw_path_monitor_start(path_monitor);
+ }
+ Ok(WatchHandle {
+ path_monitor,
+ })
+}