1 files changed, 52 insertions, 0 deletions
diff --git a/src/watch/notify_event.rs b/src/watch/notify_event.rs
new file mode 100644
index 0000000..7471640
--- /dev/null
+++ b/src/watch/notify_event.rs
@@ -0,0 +1,52 @@
+use notify_debouncer_mini::{DebounceEventResult, DebouncedEventKind};
+use std::sync::mpsc::Sender;
+
+use super::WatchEvent;
+
+pub struct NotifyEventHandler {
+    pub tx: Sender<WatchEvent>,
+    /// Used to report which exercise was modified.
+    pub exercise_names: &'static [&'static [u8]],
+}
+
+impl notify_debouncer_mini::DebounceEventHandler for NotifyEventHandler {
+    fn handle_event(&mut self, input_event: DebounceEventResult) {
+        let output_event = match input_event {
+            Ok(input_event) => {
+                let Some(exercise_ind) = input_event
+                    .iter()
+                    .filter_map(|input_event| {
+                        if input_event.kind != DebouncedEventKind::Any {
+                            return None;
+                        }
+
+                        let file_name = input_event.path.file_name()?.to_str()?.as_bytes();
+
+                        if file_name.len() < 4 {
+                            return None;
+                        }
+                        let (file_name_without_ext, ext) = file_name.split_at(file_name.len() - 3);
+
+                        if ext != b".rs" {
+                            return None;
+                        }
+
+                        self.exercise_names
+                            .iter()
+                            .position(|exercise_name| *exercise_name == file_name_without_ext)
+                    })
+                    .min()
+                else {
+                    return;
+                };
+
+                WatchEvent::FileChange { exercise_ind }
+            }
+            Err(e) => WatchEvent::NotifyErr(e),
+        };
+
+        // An error occurs when the receiver is dropped.
+        // After dropping the receiver, the debouncer guard should also be dropped.
+        let _ = self.tx.send(output_event);
+    }
+}