From 0fec9d3fdf9bc86187f9f670dafd2ef57fe03f29 Mon Sep 17 00:00:00 2001
From: Enrico Maria De Angelis <enricomaria.dean6elis@gmail.com>
Date: Thu, 14 Mar 2024 00:08:42 +0000
Subject: Make the Kbd monitor clickable, with click selecting the next layout

---
 doc/plugins.org           |  5 ++--
 src/Xmobar/Plugins/Kbd.hs | 72 ++++++++++++++++++++++++++++++++++++++---------
 2 files changed, 62 insertions(+), 15 deletions(-)

diff --git a/doc/plugins.org b/doc/plugins.org
index 8825281..e408dec 100644
--- a/doc/plugins.org
+++ b/doc/plugins.org
@@ -658,8 +658,9 @@
 ** Keyboard and screen monitors
 *** =Kbd Opts=
 
-    - Registers to XKB/X11-Events and output the currently active keyboard
-      layout. Supports replacement of layout names.
+    - Registers to XKB/X11-Events, output the currently active keyboard
+      layout, and maps left and right clicks to switching to next and
+      previous layouts respectively. Supports replacement of layout names.
 
     - Aliases to =kbd=
 
diff --git a/src/Xmobar/Plugins/Kbd.hs b/src/Xmobar/Plugins/Kbd.hs
index 2214628..3871ca8 100644
--- a/src/Xmobar/Plugins/Kbd.hs
+++ b/src/Xmobar/Plugins/Kbd.hs
@@ -14,9 +14,11 @@
 
 module Xmobar.Plugins.Kbd(Kbd(..)) where
 
-import Data.List (isPrefixOf)
+import Data.Bifunctor (bimap)
+import Data.List (find, tails, isPrefixOf)
 import Data.Maybe (fromMaybe)
-import Data.Char (toLower)
+import Data.Char (toLower, isLetter)
+import Data.Function ((&))
 import Control.Monad (forever)
 import Control.Applicative ((<|>))
 import Graphics.X11.Xlib
@@ -26,6 +28,13 @@ import Xmobar.Run.Exec
 import Xmobar.X11.Events (nextEvent')
 import Xmobar.System.Kbd
 
+-- some strong typing
+newtype Lay = Lay String deriving (Eq)
+newtype Sym = Sym String
+instance Show Sym where show (Sym s) = s
+type KbdOpts' = [(Lay, Sym)]
+typed :: [(String, String)] -> [(Lay, Sym)]
+typed = map (bimap Lay Sym)
 
 -- 'Bad' prefixes of layouts
 noLaySymbols :: [String]
@@ -49,15 +58,22 @@ split p s = case break p s of
   (pref, "") -> [pref]
 
 -- replaces input string if on search list (exact match) with corresponding
--- element on replacement list.
+-- element on replacement list, and returns it paired with the following item
 --
--- if not found, return string unchanged
-searchReplaceLayout :: KbdOpts -> String -> String
-searchReplaceLayout opts s = fromMaybe s $ lookup s opts
-
--- returns the active layout
-getKbdLay :: Display -> KbdOpts -> IO String
-getKbdLay dpy opts = do
+-- if not found, return string unchanged, paired with empty string
+searchReplaceLayout :: KbdOpts' -> String -> (Lay, Lay, Sym)
+searchReplaceLayout opts curr
+  = maybe (Lay "", Lay "", Sym curr)
+          pickSymWithAdjLays
+          (find currLayout (tails $ cycle opts))
+      where
+        pickSymWithAdjLays ((l1, _):(_, s):(l2, _):_) = (l1, l2, s)
+        pickSymWithAdjLays _ = error "This should never happen"
+        currLayout = (Lay curr ==) . (!! 1) . map fst
+
+-- returns the active layout and the following one
+getCurAndNextKbdLays :: Display -> KbdOpts' -> IO (Lay, Lay, Sym)
+getCurAndNextKbdLays dpy opts = do
   lay <- splitLayout <$> getLayoutStr dpy
   grps <- map (map toLower . take 2) <$> getGrpNames dpy
   curLay <- getKbdLayout dpy
@@ -73,6 +89,37 @@ getKbdLay dpy opts = do
 newtype Kbd = Kbd [(String, String)]
   deriving (Read, Show)
 
+attachClickAction :: (Lay, Lay, Sym) -> Sym
+attachClickAction (Lay prv, Lay nxt, txt) = txt & linkTo nxt `onKey` "1"
+                                                & linkTo prv `onKey` "3"
+  where
+    splitLayParensPhon :: String -> (String, String, String)
+    splitLayParensPhon = (\(a, (b, c)) -> (a, b, c))
+                       . second (second (drop 1) . break (== ')') . drop 1)
+                       . break (== '(')
+    parseLayPhon :: String -> (Maybe String, Maybe String)
+    parseLayPhon s = let (l, p, i) = splitLayParensPhon s
+                         l' = if all isLetter l
+                                then Just ("-layout " ++ l)
+                                else Nothing
+                         p' = if (p, i) == ("phonetic", "")
+                                then Just "-variant phonetic"
+                                else Nothing
+                     in (l', p')
+    linkTo :: String -> String -> Sym -> Sym
+    linkTo linked button currLay = Sym $ case parseLayPhon linked of
+          (Nothing, _) -> "??"
+          (Just linkedLay, phon) -> wrapIn setxkbmap button currLay
+            where
+              setxkbmap = unwords ["setxkbmap", linkedLay, fromMaybe "" phon]
+    wrapIn :: String -> String -> Sym -> String
+    wrapIn action buttons (Sym sym) = openingTag ++ sym ++ closingTag
+      where
+        openingTag = "<action=`" ++ action ++ "` button=" ++ buttons ++ ">"
+        closingTag = "</action>"
+    onKey = ($)
+    second = fmap
+
 instance Exec Kbd where
         alias (Kbd _) = "kbd"
         start (Kbd opts) cb = do
@@ -80,7 +127,7 @@ instance Exec Kbd where
             dpy <- openDisplay ""
 
             -- initial set of layout
-            cb =<< getKbdLay dpy opts
+            cb . show . attachClickAction =<< getCurAndNextKbdLays dpy (typed opts)
 
             -- enable listing for
             -- group changes
@@ -91,7 +138,6 @@ instance Exec Kbd where
             allocaXEvent $ \e -> forever $ do
                 nextEvent' dpy e
                 _ <- getEvent e
-                cb =<< getKbdLay dpy opts
+                cb . show . attachClickAction =<< getCurAndNextKbdLays dpy (typed opts)
 
             closeDisplay dpy
-            return ()
-- 
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