From ffe5933b179713c60190abcb19d80dda590a00ef Mon Sep 17 00:00:00 2001
From: Jim Myhrberg <contact@jimeh.me>
Date: Mon, 13 Jan 2025 19:57:57 +0000
Subject: [PATCH] feat(hammerspoon): add app_hider.lua which allows hiding apps
 on loss of focus

---
 hammerspoon/app_hider.lua  | 91 ++++++++++++++++++++++++++++++++++++++
 hammerspoon/hosts/noct.lua |  5 +++
 2 files changed, 96 insertions(+)
 create mode 100644 hammerspoon/app_hider.lua

diff --git a/hammerspoon/app_hider.lua b/hammerspoon/app_hider.lua
new file mode 100644
index 0000000..ad9cfbc
--- /dev/null
+++ b/hammerspoon/app_hider.lua
@@ -0,0 +1,91 @@
+--- === app_hider ===
+---
+--- A Hammerspoon module which hides specified applications when they are
+--- deactivated (lose focus).
+
+local obj = {}
+local autoHideApps = {}
+
+local function shouldAutoHide(appName)
+  for _, name in ipairs(autoHideApps) do
+    if appName == name then
+      return true
+    end
+  end
+  return false
+end
+
+local function appWatcherCallback(appName, eventType, appObject)
+  if eventType == hs.application.watcher.deactivated and shouldAutoHide(appName) then
+    appObject:hide()
+  end
+end
+
+local appWatcher = hs.application.watcher.new(appWatcherCallback)
+obj.started = false
+
+function obj:start()
+  if obj.started then
+    return
+  end
+
+  appWatcher:start()
+  obj.started = true
+end
+
+function obj:stop()
+  if not obj.started then
+    return
+  end
+
+  appWatcher:stop()
+  obj.started = false
+end
+
+--- app_hider:autoHide(appName)
+--- Method
+--- Adds an application to the auto-hide list.
+---
+--- Parameters:
+--- * appName - A string with the name of the application to auto-hide.
+function obj:autoHide(appName)
+  if not appName or type(appName) ~= "string" then
+    print("Error: Invalid app name provided to autoHide.")
+    return
+  end
+
+  obj:start() -- Ensure the watcher is running
+
+  -- Prevent duplicates in the autoHideApps table
+  for _, name in ipairs(autoHideApps) do
+    if name == appName then
+      print("App already in auto-hide list: " .. appName)
+      return
+    end
+  end
+
+  table.insert(autoHideApps, appName)
+end
+
+--- app_hider:remove(appName)
+--- Method
+--- Removes an application from the auto-hide list.
+---
+--- Parameters:
+--- * appName - A string with the name of the application to remove from the
+---             auto-hide list.
+function obj:remove(appName)
+  for i, name in ipairs(autoHideApps) do
+    if name == appName then
+      table.remove(autoHideApps, i)
+      break
+    end
+  end
+
+  -- Stop the watcher if the list is empty
+  if #autoHideApps == 0 and obj.started then
+    obj:stop()
+  end
+end
+
+return obj
diff --git a/hammerspoon/hosts/noct.lua b/hammerspoon/hosts/noct.lua
index 6c88f66..aafae7e 100644
--- a/hammerspoon/hosts/noct.lua
+++ b/hammerspoon/hosts/noct.lua
@@ -5,6 +5,7 @@ local obj = {}
 --------------------------------------------------------------------------------
 
 local apptoggle = require('app_toggle')
+local apphider = require('app_hider')
 
 local function init_hotkeys()
   hs.hotkey.bind({ 'cmd', 'alt', 'ctrl' }, 'S', apptoggle.showAppInfo)
@@ -32,6 +33,10 @@ local function init_hotkeys()
     { 'Code - Insiders', '/Applications/Visual Studio Code - Insiders.app' },
     { 'Code', '/Applications/Visual Studio Code.app' }
   )
+
+  -- Use Ghostty as my primary terminal application.
+  -- apptoggle:bind({ 'cmd', 'ctrl' }, 'R', { 'Ghostty' })
+  -- apphider:autoHide('Ghostty') -- auto-hide Ghostty when it loses focus
 end
 
 --------------------------------------------------------------------------------