AwesomeWM config fragment: Jump to previous/next screen when last left/right client

focus_next_horizontal_client.lua

-- begin extract
  awful.key({modkey}, "Left",
      function()
        focus_next_horizontal_client("left")
      end,
      {description = "focus left", group = "client"}
   ),
   awful.key({modkey}, "Right",
      function()
        focus_next_horizontal_client("right")
      end,
      {description = "focus right", group = "client"}
   ),
-- end extract

local function focus_next_horizontal_client(direction)

  local current_client = client.focus

  awful.client.focus.bydirection(direction)
  local new_client = client.focus

  if current_client == new_client then
    if direction == "left" then
      awful.screen.focus_relative(-1)
    else
      awful.screen.focus_relative(1)
    end
  else
    raise_client()
  end
end
 
-- raise focused client
local function raise_client()
   if client.focus then
      client.focus:raise()
   end
end