hammerspoon: disable Karabiner-Elements on sleep

Trying to work around the issue noted in the comment:

  pqrs-org/Karabiner-Elements#1645

Possibly also related to:

  pqrs-org/Karabiner-Elements#545

Seems that under high CPU load (which might be happening at wake-up
time) Karabiner may be exacerbating a tendency of the OS to jam the
keyboard. I've had a number of hard-resets as a result of this lately:

  https://wincent.com/snippets/1159

The commands used to enable/disable here taken from:

  https://github.com/tekezo/Karabiner-Elements/blob/b38990db3/src/share/launchctl_utility.hpp#L18-L43

roles/dotfiles/files/.hammerspoon/init.lua

@@ -5,6 +5,7 @@ hs.window.animationDuration = 0 -- disable animations
 
 local events = require 'events'
 local iterm = require 'iterm'
+local karabiner = require 'karabiner'
 local log = require 'log'
 local reloader = require 'reloader'
 
@@ -348,6 +349,7 @@ end)
 hs.urlevent.bind('screencast', prepareScreencast)
 
 iterm.init()
+karabiner.init()
 reloader.init()
 initEventHandling()
 events.subscribe('reload', tearDownEventHandling)

roles/dotfiles/files/.hammerspoon/karabiner.lua

@@ -0,0 +1,41 @@
+--
+-- Attempted workaround for:
+-- https://github.com/tekezo/Karabiner-Elements/issues/1645
+--
+
+local events = require 'events'
+local log = require 'log'
+
+local trim = (function(s)
+  return s:gsub("(.-)%s*$", "%1")
+end)
+
+local uid = trim(hs.execute('id -u'))
+
+local disable = (function()
+  log.i('Disabling Karabiner')
+  hs.execute('launchctl bootout gui/' .. uid .. ' /Library/LaunchAgents/org.pqrs.karabiner.karabiner_console_user_server.plist')
+  hs.execute('launchctl disable gui/' .. uid .. '/org.pqrs.karabiner.karabiner_console_user_server')
+end)
+
+local enable = (function()
+  log.i('Enabling Karabiner')
+  hs.execute('launchctl enable gui/' .. uid .. '/org.pqrs.karabiner.karabiner_console_user_server')
+  hs.execute('launchctl bootstrap gui/' .. uid .. ' /Library/LaunchAgents/org.pqrs.karabiner.karabiner_console_user_server.plist')
+  hs.execute('launchctl enable gui/' .. uid .. '/org.pqrs.karabiner.karabiner_console_user_server')
+end)
+
+return {
+  init = (function()
+    local watcher = hs.caffeinate.watcher.new(
+      function(event)
+        if event == hs.caffeinate.watcher.systemWillSleep then
+          disable()
+        elseif event == hs.caffeinate.watcher.screensDidUnlock then
+          enable()
+        end
+      end
+    )
+    watcher:start()
+  end),
+}