Prelude.hs

{-# OPTIONS_GHC -Wno-dodgy-imports #-}
{-# LANGUAGE BangPatterns        #-}
{-# LANGUAGE InstanceSigs        #-}
{-# LANGUAGE LambdaCase          #-}
{-# LANGUAGE ScopedTypeVariables #-}
{-# LANGUAGE TypeFamilies        #-}
--------------------------------------------------------------------
-- |
-- Module      :  XMonad.Prelude
-- Description :  Utility functions and re-exports.
-- Copyright   :  (c) 2021  Tony Zorman
-- License     :  BSD3-style (see LICENSE)
--
-- Maintainer  :  Tony Zorman <soliditsallgood@mailbox.org>
--
-- Utility functions and re-exports for a more ergonomic developing
-- experience.  Users themselves will not find much use here.
--
--------------------------------------------------------------------
module XMonad.Prelude (
    module Exports,
    fi,
    chunksOf,
    (.:),
    (!?),
    NonEmpty((:|)),
    notEmpty,
    safeGetWindowAttributes,
    mkAbsolutePath,
    findM,

    -- * Keys
    keyToString,
    keymaskToString,
    cleanKeyMask,
    regularKeys,
    allSpecialKeys,
    specialKeys,
    multimediaKeys,
    functionKeys,
    WindowScreen,

    -- * Infinite streams
    Stream(..),
    (+~),
    cycleS,
    takeS,
    toList,
    fromList,
) where

import Foreign (alloca, peek)
import XMonad

import Control.Applicative as Exports
import Control.Monad       as Exports
import Data.Bool           as Exports
import Data.Char           as Exports
import Data.Foldable       as Exports hiding (toList)
import Data.Function       as Exports
import Data.Functor        as Exports hiding (unzip)
import Data.List           as Exports hiding ((!?))
import Data.Maybe          as Exports
import Data.Monoid         as Exports
import Data.Traversable    as Exports

import qualified Data.Map.Strict as Map

import Control.Arrow ((&&&), first)
import Control.Exception (SomeException, handle)
import Data.Bifunctor (bimap)
import Data.Bits
import Data.List.NonEmpty (NonEmpty ((:|)))
import Data.Tuple (swap)
import GHC.Exts (IsList(..))
import GHC.Stack
import System.Directory (getHomeDirectory)
import System.Environment (getEnv)
import qualified XMonad.StackSet as W

-- | Short for 'fromIntegral'.
fi :: (Integral a, Num b) => a -> b
fi = fromIntegral

-- | Given a maximum length, splits a list into sublists
--
-- >>> chunksOf 5 (take 30 $ repeat 'a')
-- ["aaaaa","aaaaa","aaaaa","aaaaa","aaaaa","aaaaa"]
chunksOf :: Int -> [a] -> [[a]]
chunksOf _ [] = []
chunksOf i xs = chunk : chunksOf i rest
  where !(chunk, rest) = splitAt i xs

-- | Safe version of '(!!)'.
(!?) :: [a] -> Int -> Maybe a
(!?) xs n | n < 0 = Nothing
          | otherwise = listToMaybe $ drop n xs

-- | Multivariable composition.
--
-- > f .: g ≡ (f .) . g ≡ \c d -> f (g c d)
(.:) :: (a -> b) -> (c -> d -> a) -> c -> d -> b
(.:) = (.) . (.)

-- | Like 'find', but takes a monadic function instead; retains the
-- short-circuiting behaviour of the non-monadic version.
--
-- For example,
--
-- > findM (\a -> putStr (show a <> " ") >> pure False) [1..10]
--
-- would print "1 2 3 4 5 6 7 8 9 10" and return @Nothing@, while
--
-- > findM (\a -> putStr (show a <> " ") >> pure True) [1..10]
--
-- would print @"1"@ and return @Just 1@.
findM :: Monad m => (a -> m Bool) -> [a] -> m (Maybe a)
findM p = foldr (\x -> ifM (p x) (pure $ Just x)) (pure Nothing)

-- | 'Data.List.NonEmpty.fromList' with a better error message. Useful to
-- silence GHC's Pattern match(es) are non-exhaustive warning in places where
-- the programmer knows it's always non-empty, but it's infeasible to express
-- that in the type system.
notEmpty :: HasCallStack => [a] -> NonEmpty a
notEmpty [] = error "unexpected empty list"
notEmpty (x:xs) = x :| xs

-- | A safe version of 'Graphics.X11.Xlib.Extras.getWindowAttributes'.
safeGetWindowAttributes :: Window -> X (Maybe WindowAttributes)
safeGetWindowAttributes w = withDisplay $ \dpy -> io . alloca $ \p ->
  xGetWindowAttributes dpy w p >>= \case
    0 -> pure Nothing
    _ -> Just <$> peek p

-- | (Naïvely) turn a relative path into an absolute one.
--
-- * If the path starts with @\/@, do nothing.
--
-- * If it starts with @~\/@, replace that with the actual home
-- * directory.
--
-- * If it starts with @$@, read the name of an environment
-- * variable and replace it with the contents of that.
--
-- * Otherwise, prepend the home directory and @\/@ to the path.
mkAbsolutePath :: MonadIO m => FilePath -> m FilePath
mkAbsolutePath ps = do
  home <- io getHomeDirectory
  case ps of
    '/'       : _ -> pure ps
    '~' : '/' : _ -> pure (home <> drop 1 ps)
    '$'       : _ -> let (v,ps') = span (`elem` ("_"<>['A'..'Z']<>['a'..'z']<>['0'..'9'])) (drop 1 ps)
                      in io ((\(_ :: SomeException) -> pure "") `handle` getEnv v) Exports.<&> (<> ps')
    _             -> pure (home <> ('/' : ps))
{-# SPECIALISE mkAbsolutePath :: FilePath -> IO FilePath #-}
{-# SPECIALISE mkAbsolutePath :: FilePath -> X  FilePath #-}

-----------------------------------------------------------------------
-- Keys

-- | Convert a modifier mask into a useful string.
keymaskToString :: KeyMask -- ^ Num lock mask
                -> KeyMask -- ^ Modifier mask
                -> String
keymaskToString numLockMask msk =
  concat . reverse . fst . foldr go ([], msk) $ masks
 where
  masks :: [(KeyMask, String)]
  masks = map (\m -> (m, show m))
              [0 .. toEnum (finiteBitSize msk - 1)]
       ++ [ (numLockMask, "num-" )
          , (lockMask,    "lock-")
          , (controlMask, "C-"   )
          , (shiftMask,   "S-"   )
          , (mod5Mask,    "M5-"  )
          , (mod4Mask,    "M4-"  )
          , (mod3Mask,    "M3-"  )
          , (mod2Mask,    "M2-"  )
          , (mod1Mask,    "M1-"  )
          ]

  go :: (KeyMask, String) -> ([String], KeyMask) -> ([String], KeyMask)
  go (m, s) a@(ss, v)
    | v == 0       = a
    | v .&. m == m = (s : ss, v .&. complement m)
    | otherwise    = a

-- | Convert a full key combination; i.e., a 'KeyMask' and 'KeySym'
-- pair, into a string.
keyToString :: (KeyMask, KeySym) -> String
keyToString = uncurry (++) . bimap (keymaskToString 0) ppKeysym
 where
  ppKeysym :: KeySym -> String
  ppKeysym x = case specialMap Map.!? x of
    Just s  -> "<" <> s <> ">"
    Nothing -> case regularMap Map.!? x of
      Nothing -> keysymToString x
      Just s  -> s

  regularMap = Map.fromList (map swap regularKeys)
  specialMap = Map.fromList (map swap allSpecialKeys)

-- | Strip numlock, capslock, mouse buttons and XKB group from a 'KeyMask',
-- leaving only modifier keys like Shift, Control, Super, Hyper in the mask
-- (hence the \"Key\" in \"cleanKeyMask\").
--
-- Core's 'cleanMask' only strips the first two because key events from
-- passive grabs (key bindings) are stripped of mouse buttons and XKB group by
-- the X server already for compatibility reasons. For more info, see:
-- <https://www.x.org/releases/X11R7.7/doc/kbproto/xkbproto.html#Delivering_a_Key_or_Button_Event_to_a_Client>
cleanKeyMask :: X (KeyMask -> KeyMask)
cleanKeyMask = cleanKeyMask' <$> gets numberlockMask

cleanKeyMask' :: KeyMask -> KeyMask -> KeyMask
cleanKeyMask' numLockMask mask =
    mask .&. complement (numLockMask .|. lockMask) .&. (button1Mask - 1)

-- | A list of "regular" (extended ASCII) keys.
regularKeys :: [(String, KeySym)]
regularKeys = map (first (:[]))
            $ zip ['!'             .. '~'          ] -- ASCII
                  [xK_exclam       .. xK_asciitilde]
           <> zip ['\xa0'          .. '\xff'       ] -- Latin1
                  [xK_nobreakspace .. xK_ydiaeresis]

-- | A list of all special key names and their associated KeySyms.
allSpecialKeys :: [(String, KeySym)]
allSpecialKeys = functionKeys <> specialKeys <> multimediaKeys

-- | A list pairing function key descriptor strings (e.g. @\"\<F2\>\"@)
-- with the associated KeySyms.
functionKeys :: [(String, KeySym)]
functionKeys = [ ('F' : show n, k)
               | (n,k) <- zip ([1..24] :: [Int]) [xK_F1..]
               ]

-- | A list of special key names and their corresponding KeySyms.
specialKeys :: [(String, KeySym)]
specialKeys =
  [ ("Backspace"  , xK_BackSpace)
  , ("Tab"        , xK_Tab)
  , ("Return"     , xK_Return)
  , ("Pause"      , xK_Pause)
  , ("Num_Lock"   , xK_Num_Lock)
  , ("Caps_Lock"  , xK_Caps_Lock)
  , ("Scroll_lock", xK_Scroll_Lock)
  , ("Sys_Req"    , xK_Sys_Req)
  , ("Print"      , xK_Print)
  , ("Escape"     , xK_Escape)
  , ("Esc"        , xK_Escape)
  , ("Delete"     , xK_Delete)
  , ("Home"       , xK_Home)
  , ("Left"       , xK_Left)
  , ("Up"         , xK_Up)
  , ("Right"      , xK_Right)
  , ("Down"       , xK_Down)
  , ("L"          , xK_Left)
  , ("U"          , xK_Up)
  , ("R"          , xK_Right)
  , ("D"          , xK_Down)
  , ("Page_Up"    , xK_Page_Up)
  , ("Page_Down"  , xK_Page_Down)
  , ("End"        , xK_End)
  , ("Insert"     , xK_Insert)
  , ("Break"      , xK_Break)
  , ("Space"      , xK_space)
  , ("Control_L"  , xK_Control_L)
  , ("Control_R"  , xK_Control_R)
  , ("Shift_L"    , xK_Shift_L)
  , ("Shift_R"    , xK_Shift_R)
  , ("Alt_L"      , xK_Alt_L)
  , ("Alt_R"      , xK_Alt_R)
  , ("Meta_L"     , xK_Meta_L)
  , ("Meta_R"     , xK_Meta_R)
  , ("Super_L"    , xK_Super_L)
  , ("Super_R"    , xK_Super_R)
  , ("Hyper_L"    , xK_Hyper_L)
  , ("Hyper_R"    , xK_Hyper_R)
  , ("KP_Space"   , xK_KP_Space)
  , ("KP_Tab"     , xK_KP_Tab)
  , ("KP_Enter"   , xK_KP_Enter)
  , ("KP_F1"      , xK_KP_F1)
  , ("KP_F2"      , xK_KP_F2)
  , ("KP_F3"      , xK_KP_F3)
  , ("KP_F4"      , xK_KP_F4)
  , ("KP_Home"    , xK_KP_Home)
  , ("KP_Left"    , xK_KP_Left)
  , ("KP_Up"      , xK_KP_Up)
  , ("KP_Right"   , xK_KP_Right)
  , ("KP_Down"    , xK_KP_Down)
  , ("KP_Prior"   , xK_KP_Prior)
  , ("KP_Page_Up" , xK_KP_Page_Up)
  , ("KP_Next"    , xK_KP_Next)
  , ("KP_Page_Down", xK_KP_Page_Down)
  , ("KP_End"     , xK_KP_End)
  , ("KP_Begin"   , xK_KP_Begin)
  , ("KP_Insert"  , xK_KP_Insert)
  , ("KP_Delete"  , xK_KP_Delete)
  , ("KP_Equal"   , xK_KP_Equal)
  , ("KP_Multiply", xK_KP_Multiply)
  , ("KP_Add"     , xK_KP_Add)
  , ("KP_Separator", xK_KP_Separator)
  , ("KP_Subtract", xK_KP_Subtract)
  , ("KP_Decimal" , xK_KP_Decimal)
  , ("KP_Divide"  , xK_KP_Divide)
  , ("KP_0"       , xK_KP_0)
  , ("KP_1"       , xK_KP_1)
  , ("KP_2"       , xK_KP_2)
  , ("KP_3"       , xK_KP_3)
  , ("KP_4"       , xK_KP_4)
  , ("KP_5"       , xK_KP_5)
  , ("KP_6"       , xK_KP_6)
  , ("KP_7"       , xK_KP_7)
  , ("KP_8"       , xK_KP_8)
  , ("KP_9"       , xK_KP_9)
  , ("Menu"       , xK_Menu)
  ]

-- | List of multimedia keys. If Xlib does not know about some keysym
-- it's omitted from the list ('stringToKeysym' returns 'noSymbol' in
-- this case).
multimediaKeys :: [(String, KeySym)]
multimediaKeys = filter ((/= noSymbol) . snd) . map (id &&& stringToKeysym) $
  [ "XF86ModeLock"
  , "XF86MonBrightnessUp"
  , "XF86MonBrightnessDown"
  , "XF86KbdLightOnOff"
  , "XF86KbdBrightnessUp"
  , "XF86KbdBrightnessDown"
  , "XF86Standby"
  , "XF86AudioLowerVolume"
  , "XF86AudioMute"
  , "XF86AudioRaiseVolume"
  , "XF86AudioPlay"
  , "XF86AudioStop"
  , "XF86AudioPrev"
  , "XF86AudioNext"
  , "XF86HomePage"
  , "XF86Mail"
  , "XF86Start"
  , "XF86Search"
  , "XF86AudioRecord"
  , "XF86Calculator"
  , "XF86Memo"
  , "XF86ToDoList"
  , "XF86Calendar"
  , "XF86PowerDown"
  , "XF86ContrastAdjust"
  , "XF86RockerUp"
  , "XF86RockerDown"
  , "XF86RockerEnter"
  , "XF86Back"
  , "XF86Forward"
  , "XF86Stop"
  , "XF86Refresh"
  , "XF86PowerOff"
  , "XF86WakeUp"
  , "XF86Eject"
  , "XF86ScreenSaver"
  , "XF86WWW"
  , "XF86Sleep"
  , "XF86Favorites"
  , "XF86AudioPause"
  , "XF86AudioMedia"
  , "XF86MyComputer"
  , "XF86VendorHome"
  , "XF86LightBulb"
  , "XF86Shop"
  , "XF86History"
  , "XF86OpenURL"
  , "XF86AddFavorite"
  , "XF86HotLinks"
  , "XF86BrightnessAdjust"
  , "XF86Finance"
  , "XF86Community"
  , "XF86AudioRewind"
  , "XF86BackForward"
  , "XF86Launch0"
  , "XF86Launch1"
  , "XF86Launch2"
  , "XF86Launch3"
  , "XF86Launch4"
  , "XF86Launch5"
  , "XF86Launch6"
  , "XF86Launch7"
  , "XF86Launch8"
  , "XF86Launch9"
  , "XF86LaunchA"
  , "XF86LaunchB"
  , "XF86LaunchC"
  , "XF86LaunchD"
  , "XF86LaunchE"
  , "XF86LaunchF"
  , "XF86ApplicationLeft"
  , "XF86ApplicationRight"
  , "XF86Book"
  , "XF86CD"
  , "XF86Calculater"
  , "XF86Clear"
  , "XF86Close"
  , "XF86Copy"
  , "XF86Cut"
  , "XF86Display"
  , "XF86DOS"
  , "XF86Documents"
  , "XF86Excel"
  , "XF86Explorer"
  , "XF86Game"
  , "XF86Go"
  , "XF86iTouch"
  , "XF86LogOff"
  , "XF86Market"
  , "XF86Meeting"
  , "XF86MenuKB"
  , "XF86MenuPB"
  , "XF86MySites"
  , "XF86New"
  , "XF86News"
  , "XF86OfficeHome"
  , "XF86Open"
  , "XF86Option"
  , "XF86Paste"
  , "XF86Phone"
  , "XF86Q"
  , "XF86Reply"
  , "XF86Reload"
  , "XF86RotateWindows"
  , "XF86RotationPB"
  , "XF86RotationKB"
  , "XF86Save"
  , "XF86ScrollUp"
  , "XF86ScrollDown"
  , "XF86ScrollClick"
  , "XF86Send"
  , "XF86Spell"
  , "XF86SplitScreen"
  , "XF86Support"
  , "XF86TaskPane"
  , "XF86Terminal"
  , "XF86Tools"
  , "XF86Travel"
  , "XF86UserPB"
  , "XF86User1KB"
  , "XF86User2KB"
  , "XF86Video"
  , "XF86WheelButton"
  , "XF86Word"
  , "XF86Xfer"
  , "XF86ZoomIn"
  , "XF86ZoomOut"
  , "XF86Away"
  , "XF86Messenger"
  , "XF86WebCam"
  , "XF86MailForward"
  , "XF86Pictures"
  , "XF86Music"
  , "XF86TouchpadToggle"
  , "XF86AudioMicMute"
  , "XF86_Switch_VT_1"
  , "XF86_Switch_VT_2"
  , "XF86_Switch_VT_3"
  , "XF86_Switch_VT_4"
  , "XF86_Switch_VT_5"
  , "XF86_Switch_VT_6"
  , "XF86_Switch_VT_7"
  , "XF86_Switch_VT_8"
  , "XF86_Switch_VT_9"
  , "XF86_Switch_VT_10"
  , "XF86_Switch_VT_11"
  , "XF86_Switch_VT_12"
  , "XF86_Ungrab"
  , "XF86_ClearGrab"
  , "XF86_Next_VMode"
  , "XF86_Prev_VMode"
  , "XF86Bluetooth"
  , "XF86WLAN"
  ]

-- | The specialized 'W.Screen' derived from 'WindowSet'.
type WindowScreen -- FIXME move to core
    = W.Screen WorkspaceId (Layout Window) Window ScreenId ScreenDetail

-- | An infinite stream type
data Stream a = !a :~ Stream a
infixr 5 :~

instance Functor Stream where
  fmap :: (a -> b) -> Stream a -> Stream b
  fmap f = go
   where go (x :~ xs) = f x :~ go xs

instance IsList (Stream a) where
  type (Item (Stream a)) = a

  fromList :: [a] -> Stream a
  fromList (x : xs) = x :~ fromList xs
  fromList []       = errorWithoutStackTrace "XMonad.Prelude.Stream.fromList: Can't create stream out of finite list."

  toList :: Stream a -> [a]
  toList (x :~ xs) = x : toList xs

-- | Absorb a list into an infinite stream.
(+~) :: [a] -> Stream a -> Stream a
xs +~ s = foldr (:~) s xs
infixr 5 +~

-- | Absorb a non-empty list into an infinite stream.
cycleS :: NonEmpty a -> Stream a
cycleS (x :| xs) = s where s = x :~ xs +~ s

-- | @takeS n stream@ returns the first @n@ elements of @stream@; if @n < 0@,
-- this returns the empty list.
takeS :: Int -> Stream a -> [a]
takeS n = take n . toList