feat: WIP prediction

src/client.rs

@@ -87,4 +87,40 @@ impl Client {
         self.user = None;
         self.entered = false;
     }
+
+    pub fn move_by_delta(
+        &mut self,
+        _point: isize,
+        _delta: isize,
+        _filename: Option<String>,
+    ) -> Option<String> {
+        let user = self.user_mut();
+
+        // Exit when user hasn't been created.
+        if user.is_none() {
+            return None;
+        }
+
+        let user = user.unwrap();
+        let filename = user.path.clone();
+
+        // Exit when current user isn't in any valid file.
+        if filename.is_none() {
+            return None;
+        }
+
+        let filename = filename.unwrap();
+
+        if !_filename.is_none() {
+            let _filename = _filename.unwrap();
+
+            if filename != _filename {
+                return None;
+            }
+        }
+
+        user.move_by_delta(_point, _delta);
+
+        Some(filename)
+    }
 }

src/handler/buffer.rs

@@ -22,6 +22,22 @@ pub mod update {
 
     const METHOD: &str = "buffer::update";
 
+    fn predict_movement(addr: &SocketAddr, room: &mut Room, point: isize, delta: isize) {
+        let client = room.get_client_mut(addr).unwrap();
+
+        let filename = client.move_by_delta(point, delta, None);
+
+        let clients = room.get_clients_mut();
+
+        for (_addr, _client) in clients.iter_mut() {
+            if _addr == addr {
+                continue;
+            }
+
+            _client.move_by_delta(point, delta, filename.clone());
+        }
+    }
+
     pub async fn handle(channel: &mut Channel, room: &Arc<Mutex<Room>>, json: &Value) {
         let addr = &channel.get_connection().addr;
         let mut room = room.lock().await;
@@ -32,6 +48,22 @@ pub mod update {
         let end = data_isize(json, "end").unwrap();
         let contents = data_str(json, "contents").unwrap();
 
+        // Predict movement.
+        {
+            let delta = if add_or_delete == "delete" {
+                beg - end
+            } else {
+                end - beg
+            };
+
+            // Nothing has changed; return it.
+            if delta == 0 {
+                return;
+            }
+
+            predict_movement(&addr, &mut room, beg, delta);
+        }
+
         // Update the buffer view.
         let file = room.get_file_create_mut(&addr, &path, None);
         let file = file.unwrap();

src/user.rs

@@ -56,4 +56,34 @@ impl User {
         self.color_cursor = color_cursor;
         self.color_region = color_region;
     }
+
+    /// Move point information by delta.
+    ///
+    /// # Arguments
+    ///
+    /// * `_point` - Only effect point after the origin.
+    /// * `_delta` - Movement delta.
+    pub fn move_by_delta(&mut self, _point: isize, _delta: isize) {
+        // Point must exists.
+        if self.point.is_none() {
+            return;
+        }
+
+        let point = self.point.unwrap();
+
+        // Shift the point.
+        if _point <= point {
+            self.point = Some(point + _delta);
+
+            // `region_beg`. and `region_end` must exists at the same time.
+            if !self.region_beg.is_none() {
+                let region_beg = self.region_beg.unwrap();
+                let region_end = self.region_end.unwrap();
+
+                // Shift the region.
+                self.region_beg = Some(region_beg + _delta);
+                self.region_end = Some(region_end + _delta);
+            }
+        }
+    }
 }