hammerspoon-init.lua

--------------------
-- Window Chooser -- 🚻
--------------------
-- Originally: https://github.com/dmgerman/dmg-hammerspoon/blob/f8da75d121c37df40c0971336eb3f67c73d67187/dmg.spoon/init.lua#L115-L224
WC = {}

WC.wf = hs.window.filter.new()
WC.wf:setDefaultFilter{}

WC.currentWindows = {}

for i, v in ipairs(WC.wf:getWindows()) do
  table.insert(WC.currentWindows, v)
end

local function on_window_event(w, appName, event)
  if event == "windowDestroyed" then
    for i, v in ipairs(WC.currentWindows) do
      if v == w then
        table.remove(WC.currentWindows, i)
        return
      end
    end
    return
  end
  if event == "windowCreated" then
    table.insert(WC.currentWindows, 1, w)
    return
  end
  if event == "windowFocused" then
    -- Hack: move `w` to the beginning of the table when it's focused.
    on_window_event(w, appName, "windowDestroyed")
    on_window_event(w, appName, "windowCreated")
  end
end
WC.wf:subscribe(hs.window.filter.windowCreated, on_window_event)
WC.wf:subscribe(hs.window.filter.windowDestroyed, on_window_event)
WC.wf:subscribe(hs.window.filter.windowFocused, on_window_event)

local function list_window_choices()
  local windowChoices = {}
  for i, w in ipairs(WC.currentWindows) do
    if w ~= hs.window.focusedWindow() then
      local app = w:application()
      if not app then
        -- Not sure why `app` is sometimes nil.
        table.remove(WC.currentWindows, i)
      end
      -- `text` is the label we'll show for this window.
      -- If the window has a title, e.g. "Sandbox", then prepend it to the app
      -- name to get "Sandbox - Microsoft Excel".
      local text = app:name()
      if w:title() ~= "" and w:title() ~= text then
        text = w:title() .. " — " .. text
      end
      table.insert(windowChoices, {
        text = text,
        subText = app:name(),
        uuid = i,
        image = hs.image.imageFromAppBundle(app:bundleID()),
        win = w
      })
      end
    end
    return windowChoices;
  end

WC.chooser = hs.chooser.new(function (choice)
  if not choice then
    return
  end
  local v = choice["win"]
  if v then
    v:focus()
  end
end)

hs.hotkey.bind({"alt"}, "Tab", function ()
  local choices = list_window_choices()
  WC.chooser:choices(choices)
  WC.chooser:query('')
  WC.chooser:show()
end)