fix(wm): skip layout calc for empty workspaces

While investigating issue #2 I was able to reproduce it and view the
panic that causes the komorebi process to become non-responsive.

When switching to a columnar layout (which is the default for the 2nd
workspace in the sample ahk config), there is the possibility to cause a
divide by zero panic if the len passed to Layout::calculate is 0.

I have remedied this by changing the type of len from usize to
NonZeroUsize, and also by ensuring that Layout::calculate is only called
from within the komorebi crate if the workspace has at least one
container.

While moving containers around I also noticed that creating a new
container for a window may also cause a panic if focused_idx + 1 is
greater than the length of the VecDeque of containers, so this was
addressed by pushing to the back of the VecDeque in that case.

re #2

komorebi-core/src/layout.rs

@@ -1,3 +1,5 @@
+use std::num::NonZeroUsize;
+
 use clap::Clap;
 use serde::Deserialize;
 use serde::Serialize;
@@ -127,11 +129,12 @@ impl Layout {
  pub fn calculate(
  &self,
  area: &Rect,
- len: usize,
+ len: NonZeroUsize,
  container_padding: Option<i32>,
  layout_flip: Option<LayoutFlip>,
  resize_dimensions: &[Option<Rect>],
  ) -> Vec<Rect> {
+ let len = usize::from(len);
  let mut dimensions = match self {
  Layout::BSP => recursive_fibonacci(
  0,

komorebi/src/container.rs

@@ -33,12 +33,6 @@ impl PartialEq for &Container {
 }
 
 impl Container {
- pub fn hide(&mut self) {
- for window in self.windows_mut() {
- window.hide();
- }
- }
-
  pub fn load_focused_window(&mut self) {
  let focused_idx = self.focused_window_idx();
  for (i, window) in self.windows_mut().iter_mut().enumerate() {

komorebi/src/ring.rs

@@ -59,6 +59,7 @@ macro_rules! impl_ring_elements {
  self.[<$element:lower s>].elements_mut()
  }
 
+ #[allow(dead_code)]
  pub fn [<focused_ $element:lower>](&self) -> Option<&$element> {
  self.[<$element:lower s>].focused()
  }

komorebi/src/window.rs

@@ -154,6 +154,7 @@ impl Window {
  WindowsApi::set_focus(self.hwnd())
  }
 
+ #[allow(dead_code)]
  pub fn update_style(self, style: GwlStyle) -> Result<()> {
  WindowsApi::update_style(self.hwnd(), isize::try_from(style.bits())?)
  }

komorebi/src/window_manager.rs

@@ -1,5 +1,6 @@
 use std::collections::VecDeque;
 use std::io::ErrorKind;
+use std::num::NonZeroUsize;
 use std::sync::Arc;
 use std::sync::Mutex;
 
@@ -126,7 +127,9 @@ impl WindowManager {
  ) {
  let unaltered = workspace.layout().calculate(
  &work_area,
- len,
+ NonZeroUsize::new(len).context(
+ "there must be at least one container to calculate a workspace layout",
+ )?,
  workspace.container_padding(),
  workspace.layout_flip(),
  &[],

komorebi/src/windows_api.rs

@@ -371,6 +371,7 @@ impl WindowsApi {
  }
  }
 
+ #[allow(dead_code)]
  fn set_window_long_ptr_w(
  hwnd: HWND,
  index: WINDOW_LONG_PTR_INDEX,
@@ -396,6 +397,7 @@ impl WindowsApi {
  }))
  }
 
+ #[allow(dead_code)]
  pub fn update_style(hwnd: HWND, new_value: isize) -> Result<()> {
  Self::set_window_long_ptr_w(hwnd, GWL_STYLE, new_value)
  }

komorebi/src/winevent.rs

@@ -1,3 +1,5 @@
+use strum::Display;
+
 use bindings::Windows::Win32::UI::WindowsAndMessaging::EVENT_AIA_END;
 use bindings::Windows::Win32::UI::WindowsAndMessaging::EVENT_AIA_START;
 use bindings::Windows::Win32::UI::WindowsAndMessaging::EVENT_CONSOLE_CARET;
@@ -83,8 +85,9 @@ use bindings::Windows::Win32::UI::WindowsAndMessaging::EVENT_UIA_EVENTID_START;
 use bindings::Windows::Win32::UI::WindowsAndMessaging::EVENT_UIA_PROPID_END;
 use bindings::Windows::Win32::UI::WindowsAndMessaging::EVENT_UIA_PROPID_START;
 
-#[derive(Clone, Copy, PartialEq, Debug, strum::Display)]
+#[derive(Clone, Copy, PartialEq, Debug, Display)]
 #[repr(u32)]
+#[allow(dead_code)]
 pub enum WinEvent {
  AiaEnd = EVENT_AIA_END,
  AiaStart = EVENT_AIA_START,

komorebi/src/workspace.rs

@@ -1,4 +1,5 @@
 use std::collections::VecDeque;
+use std::num::NonZeroUsize;
 
 use color_eyre::eyre::ContextCompat;
 use color_eyre::Result;
@@ -110,10 +111,12 @@ impl Workspace {
  if let Some(window) = container.focused_window_mut() {
  window.set_position(&adjusted_work_area, true)?;
  }
- } else {
+ } else if !self.containers().is_empty() {
  let layouts = self.layout().calculate(
  &adjusted_work_area,
- self.containers().len(),
+ NonZeroUsize::new(self.containers().len()).context(
+ "there must be at least one container to calculate a workspace layout",
+ )?,
  self.container_padding(),
  self.layout_flip(),
  self.resize_dimensions(),
@@ -409,14 +412,24 @@ impl Workspace {
  }
 
  pub fn new_container_for_window(&mut self, window: Window) {
- let focused_idx = self.focused_container_idx();
+ let next_idx = self.focused_container_idx() + 1;
 
  let mut container = Container::default();
  container.add_window(window);
 
- self.containers_mut().insert(focused_idx + 1, container);
- self.resize_dimensions_mut().insert(focused_idx + 1, None);
- self.focus_container(focused_idx + 1);
+ if next_idx > self.containers().len() {
+ self.containers_mut().push_back(container);
+ } else {
+ self.containers_mut().insert(next_idx, container);
+ }
+
+ if next_idx > self.resize_dimensions().len() {
+ self.resize_dimensions_mut().push(None);
+ } else {
+ self.resize_dimensions_mut().insert(next_idx, None);
+ }
+
+ self.focus_container(next_idx);
  }
 
  pub fn new_floating_window(&mut self) -> Result<()> {