-----------------------------------------------------------------------------
-- |
-- Module      :  XMonad.Hooks.DynamicLog
-- Copyright   :  (c) Don Stewart <dons@cse.unsw.edu.au>
-- License     :  BSD3-style (see LICENSE)
--
-- Maintainer  :  Don Stewart <dons@cse.unsw.edu.au>
-- Stability   :  unstable
-- Portability :  unportable
--
-- xmonad calls the logHook with every internal state update, which is
-- useful for (among other things) outputting status information to an
-- external status bar program such as xmobar or dzen.  DynamicLog
-- provides several drop-in logHooks for this purpose, as well as
-- flexible tools for specifying your own formatting.
--
-----------------------------------------------------------------------------

module XMonad.Hooks.DynamicLog (
    -- * Usage
    -- $usage

    -- * Drop-in loggers
    dzen,
    dynamicLog,
    dynamicLogDzen,
    dynamicLogXmobar,
    dynamicLogXinerama,

    -- * Build your own formatter
    dynamicLogWithPP,
    dynamicLogString,
    PP(..), defaultPP, dzenPP, xmobarPP, sjanssenPP, byorgeyPP,

    -- * Formatting utilities
    wrap, pad, shorten,
    xmobarColor, dzenColor, dzenEscape,

    -- * Internal formatting functions
    pprWindowSet,
    pprWindowSetXinerama

    -- * To Do
    -- $todo

  ) where

--
-- Useful imports
--
import XMonad
import Data.Maybe ( isJust, catMaybes )
import Data.List
import Data.Ord ( comparing )
import qualified XMonad.StackSet as S
import System.IO
import XMonad.Util.WorkspaceCompare
import XMonad.Util.NamedWindows
import XMonad.Util.Run
import XMonad.Hooks.UrgencyHook

-- $usage
-- You can use this module with the following in your @~\/.xmonad\/xmonad.hs@:
--
-- >    import XMonad
-- >    import XMonad.Hooks.DynamicLog
--
-- If you just want a quick-and-dirty status bar with zero effort, try
-- the 'dzen' function, which sets up a dzen status bar with a default
-- format:
--
-- > main = dzen xmonad
--
-- or, to use this with your own custom xmonad configuration,
--
-- > main = dzen $ \conf -> xmonad $ conf { <your customizations> }
--
-- Alternatively, you can choose among several default status bar
-- formats ('dynamicLog', 'dynamicLogDzen', 'dynamicLogXmobar', or
-- 'dynamicLogXinerama') by simply setting your logHook to the
-- appropriate function, for instance:
--
-- > main = xmonad $ defaultConfig {
-- >    ...
-- >    logHook = dynamicLog
-- >    ...
-- >  }
--
-- For more flexibility, you can also use 'dynamicLogWithPP' and supply
-- your own pretty-printing format (by either defining one from scratch,
-- or customizing one of the provided examples).
-- For example:
--
-- >    -- use sjanssen's pretty-printer format, but with the sections
-- >    -- in reverse
-- >    logHook = dynamicLogWithPP $ sjanssenPP { ppOrder = reverse }
--
-- Note that setting the @logHook@ only sets up xmonad's output; you
-- are responsible for starting your own status bar program (e.g. dzen
-- or xmobar) and making sure xmonad's output is piped into it
-- appropriately, either by putting it in your @.xsession@ or similar
-- file, or by using @spawnPipe@ in your @main@ function, for example:
--
-- > main = do
-- >     h <- spawnPipe "xmobar -options -foo -bar"
-- >     xmonad $ defaultConfig {
-- >       ...
-- >       logHook = dynamicLogWithPP $ defaultPP { ppOutput = hPutStrLn h }
--
-- If you use @spawnPipe@, be sure to redefine the 'ppOutput' field of
-- your pretty-printer as in the example above; by default the status
-- will be printed to stdout rather than the pipe you create.
--
-- Even if you don't use a statusbar, you can still use
-- 'dynamicLogString' to show on-screen notifications in response to
-- some events. For example, to show the current layout when it
-- changes, you could make a keybinding to cycle the layout and
-- display the current status:
--
-- >    , ((mod1Mask, xK_a     ), sendMessage NextLayout >> (dynamicLogString myPP >>= \d->spawn $"xmessage "++d))
--

-- $todo
--
--   * incorporate dynamicLogXinerama into the PP framework somehow
--
--   * add an xmobarEscape function

-- | Run xmonad with a dzen status bar set to some nice defaults. Output
-- is taken from the dynamicLogWithPP hook.
--
-- > main = dzen xmonad
--
-- The intent is that the above config file should provide a nice
-- status bar with minimal effort.  If you want to customize your xmonad
-- configuration while using this, you'll have to do something like
--
-- > main = dzen $ \conf -> xmonad $ conf { <your customized settings...> }
--
-- If you wish to customize the status bar format at all, you'll have to
-- use something like 'dynamicLogWithPP' instead.
--
dzen :: (XConfig (Choose Tall (Choose (Mirror Tall) Full)) -> IO ()) -> IO ()
dzen f = do
  h <- spawnPipe ("dzen2" ++ " " ++ flags)
  f $ defaultConfig
           { defaultGaps = [(15,0,0,0)] -- for fixed
           , logHook = dynamicLogWithPP dzenPP
                          { ppOutput = hPutStrLn h } }
 where
    fg      = "'#a8a3f7'" -- n.b quoting
    bg      = "'#3f3c6d'"
    flags   = "-e '' -w 400 -ta l -fg " ++ fg ++ " -bg " ++ bg

-- | An example log hook, which prints status information to stdout in
-- the default format:
--
-- > 1 2 [3] 4 7 : full : title
--
-- That is, the currently populated workspaces, the current
-- workspace layout, and the title of the focused window.
--
-- To customize the output format, see 'dynamicLogWithPP'.
--
dynamicLog :: X ()
dynamicLog = dynamicLogWithPP defaultPP

-- | An example log hook that emulates dwm's status bar, using colour
-- codes printed to dzen.  Requires dzen. Workspaces, xinerama,
-- layouts and the window title are handled.
dynamicLogDzen :: X ()
dynamicLogDzen = dynamicLogWithPP dzenPP

-- | These are good defaults to be used with the xmobar status bar.
dynamicLogXmobar :: X ()
dynamicLogXmobar = dynamicLogWithPP xmobarPP

-- | Format the current status using the supplied pretty-printing format,
--   and write it to stdout.
dynamicLogWithPP :: PP -> X ()
dynamicLogWithPP pp = dynamicLogString pp >>= io . ppOutput pp

-- | The same as 'dynamicLogWithPP', except it simply returns the status
--   as a formatted string without actually printing it to stdout, to
--   allow for further processing, or use in some application other than
--   a status bar.
dynamicLogString :: PP -> X String
dynamicLogString pp = do

    winset <- gets windowset
    urgents <- readUrgents
    sort' <- ppSort pp

    -- layout description
    let ld = description . S.layout . S.workspace . S.current $ winset

    -- workspace list
    let ws = pprWindowSet sort' urgents pp winset

    -- window title
    wt <- maybe (return "") (fmap show . getName) . S.peek $ winset

    -- run extra loggers, ignoring any that generate errors.
    extras <- sequence $ map (flip catchX (return Nothing)) $ ppExtras pp

    return $ sepBy (ppSep pp) . ppOrder pp $
                        [ ws
                        , ppLayout pp ld
                        , ppTitle  pp wt
                        ]
                        ++ catMaybes extras

-- | Format the workspace information, given a workspace sorting function,
--   a list of urgent windows, a pretty-printer format, and the current
--   WindowSet.
pprWindowSet :: WorkspaceSort -> [Window] -> PP -> WindowSet -> String
pprWindowSet sort' urgents pp s = sepBy (ppWsSep pp) . map fmt . sort' $
            map S.workspace (S.current s : S.visible s) ++ S.hidden s
   where this     = S.tag (S.workspace (S.current s))
         visibles = map (S.tag . S.workspace) (S.visible s)

         fmt w = printer pp (S.tag w)
          where printer | S.tag w == this                                               = ppCurrent
                        | S.tag w `elem` visibles                                       = ppVisible
                        | any (\x -> maybe False (== S.tag w) (S.findTag x s)) urgents  = \ppC -> ppUrgent ppC . ppHidden ppC
                        | isJust (S.stack w)                                            = ppHidden
                        | otherwise                                                     = ppHiddenNoWindows

-- |
-- Workspace logger with a format designed for Xinerama:
--
-- > [1 9 3] 2 7
--
-- where 1, 9, and 3 are the workspaces on screens 1, 2 and 3, respectively,
-- and 2 and 7 are non-visible, non-empty workspaces.
--
-- Unfortunately, at the present time, the current layout and window title
-- are not shown, and there is no way to incorporate the xinerama
-- workspace format shown above with 'dynamicLogWithPP'.  Hopefully this
-- will change soon.
dynamicLogXinerama :: X ()
dynamicLogXinerama = withWindowSet $ io . putStrLn . pprWindowSetXinerama

pprWindowSetXinerama :: WindowSet -> String
pprWindowSetXinerama ws = "[" ++ unwords onscreen ++ "] " ++ unwords offscreen
  where onscreen  = map (S.tag . S.workspace)
                        . sortBy (comparing S.screen) $ S.current ws : S.visible ws
        offscreen = map S.tag . filter (isJust . S.stack)
                        . sortBy (comparing S.tag) $ S.hidden ws

-- | Wrap a string in delimiters, unless it is empty.
wrap :: String  -- ^ left delimiter
     -> String  -- ^ right delimiter
     -> String  -- ^ output string
     -> String
wrap _ _ "" = ""
wrap l r m  = l ++ m ++ r

-- | Pad a string with a leading and trailing space.
pad :: String -> String
pad = wrap " " " "

-- | Limit a string to a certain length, adding "..." if truncated.
shorten :: Int -> String -> String
shorten n xs | length xs < n = xs
             | otherwise     = (take (n - length end) xs) ++ end
 where
    end = "..."

-- | Output a list of strings, ignoring empty ones and separating the
--   rest with the given separator.
sepBy :: String   -- ^ separator
      -> [String] -- ^ fields to output
      -> String
sepBy sep = concat . intersperse sep . filter (not . null)

-- | Use dzen escape codes to output a string with given foreground
--   and background colors.
dzenColor :: String  -- ^ foreground color: a color name, or #rrggbb format
          -> String  -- ^ background color
          -> String  -- ^ output string
          -> String
dzenColor fg bg = wrap (fg1++bg1) (fg2++bg2)
 where (fg1,fg2) | null fg = ("","")
                 | otherwise = ("^fg(" ++ fg ++ ")","^fg()")
       (bg1,bg2) | null bg = ("","")
                 | otherwise = ("^bg(" ++ bg ++ ")","^bg()")

-- | Escape any dzen metacharacters.
dzenEscape :: String -> String
dzenEscape = concatMap (\x -> if x == '^' then "^^" else [x])

-- | Use xmobar escape codes to output a string with given foreground
--   and background colors.
xmobarColor :: String  -- ^ foreground color: a color name, or #rrggbb format
            -> String  -- ^ background color
            -> String  -- ^ output string
            -> String
xmobarColor fg bg = wrap t "</fc>"
 where t = concat ["<fc=", fg, if null bg then "" else "," ++ bg, ">"]

-- ??? add an xmobarEscape function?

-- | The 'PP' type allows the user to customize the formatting of
--   status information.
data PP = PP { ppCurrent :: WorkspaceId -> String
               -- ^ how to print the tag of the currently focused
               -- workspace
             , ppVisible :: WorkspaceId -> String
               -- ^ how to print tags of visible but not focused
               -- workspaces (xinerama only)
             , ppHidden  :: WorkspaceId -> String
               -- ^ how to print tags of hidden workspaces which
               -- contain windows
             , ppHiddenNoWindows :: WorkspaceId -> String
               -- ^ how to print tags of empty hidden workspaces
             , ppUrgent :: WorkspaceId -> String
               -- ^ format to be applied to tags of urgent workspaces.
               -- NOTE that 'ppUrgent' is applied /in addition to/
               -- 'ppHidden'!
             , ppSep :: String
               -- ^ separator to use between different log sections
               -- (window name, layout, workspaces)
             , ppWsSep :: String
               -- ^ separator to use between workspace tags
             , ppTitle :: String -> String
               -- ^ window title format
             , ppLayout :: String -> String
               -- ^ layout name format
             , ppOrder :: [String] -> [String]
               -- ^ how to order the different log sections. By
               --   default, this function receives a list with three
               --   formatted strings, representing the workspaces,
               --   the layout, and the current window title,
               --   respectively. If you have specified any extra
               --   loggers in 'ppExtras', their output will also be
               --   appended to the list.  To get them in the reverse
               --   order, you can just use @ppOrder = reverse@.  If
               --   you don't want to display the current layout, you
               --   could use something like @ppOrder = \\(ws:_:t:_) ->
               --   [ws,t]@, and so on.
             , ppSort :: X ([WindowSpace] -> [WindowSpace])
               -- ^ how to sort the workspaces.  See
               -- "XMonad.Util.WorkspaceCompare" for some useful
               -- sorts.
             , ppExtras :: [X (Maybe String)]
               -- ^ loggers for generating extra information such as
               -- time and date, system load, battery status, and so
               -- on.  See "XMonad.Util.Loggers" for examples, or create
               -- your own!
             , ppOutput :: String -> IO ()
               -- ^ applied to the entire formatted string in order to
               -- output it.  Can be used to specify an alternative
               -- output method (e.g. write to a pipe instead of
               -- stdout), and\/or to perform some last-minute
               -- formatting.
             }

-- | The default pretty printing options, as seen in 'dynamicLog'.
defaultPP :: PP
defaultPP = PP { ppCurrent         = wrap "[" "]"
               , ppVisible         = wrap "<" ">"
               , ppHidden          = id
               , ppHiddenNoWindows = const ""
               , ppUrgent          = id
               , ppSep             = " : "
               , ppWsSep           = " "
               , ppTitle           = shorten 80
               , ppLayout          = id
               , ppOrder           = id
               , ppOutput          = putStrLn
               , ppSort            = getSortByIndex
               , ppExtras          = []
               }

-- | Settings to emulate dwm's statusbar, dzen only.
dzenPP :: PP
dzenPP = defaultPP { ppCurrent  = dzenColor "white" "#2b4f98" . pad
                     , ppVisible  = dzenColor "black" "#999999" . pad
                     , ppHidden   = dzenColor "black" "#cccccc" . pad
                     , ppHiddenNoWindows = const ""
                     , ppUrgent   = dzenColor "red" "yellow"
                     , ppWsSep    = ""
                     , ppSep      = ""
                     , ppLayout   = dzenColor "black" "#cccccc" .
                                    (\ x -> case x of
                                              "TilePrime Horizontal" -> " TTT "
                                              "TilePrime Vertical"   -> " []= "
                                              "Hinted Full"          -> " [ ] "
                                              _                      -> pad x
                                    )
                     , ppTitle    = ("^bg(#324c80) " ++) . dzenEscape
                     }

-- | Some nice xmobar defaults.
xmobarPP :: PP
xmobarPP = defaultPP { ppCurrent = xmobarColor "yellow" "" . wrap "[" "]"
                     , ppTitle   = xmobarColor "green"  "" . shorten 40
                     , ppVisible = wrap "(" ")"
                     }

-- | The options that sjanssen likes to use with xmobar, as an
-- example.  Note the use of 'xmobarColor' and the record update on
-- 'defaultPP'.
sjanssenPP :: PP
sjanssenPP = defaultPP { ppCurrent = xmobarColor "white" "#ff000000"
                       , ppTitle = xmobarColor "#00ee00" "" . shorten 80
                       }

-- | The options that byorgey likes to use with dzen, as another example.
byorgeyPP :: PP
byorgeyPP = defaultPP { ppHiddenNoWindows = showNamedWorkspaces
                      , ppHidden  = dzenColor "black"  "#a8a3f7" . pad
                      , ppCurrent = dzenColor "yellow" "#a8a3f7" . pad
                      , ppUrgent  = dzenColor "red"    "yellow"
                      , ppSep     = " | "
                      , ppWsSep   = ""
                      , ppTitle   = shorten 70
                      , ppOrder   = reverse
                      }
  where showNamedWorkspaces wsId = if any (`elem` wsId) ['a'..'z']
                                       then pad wsId
                                       else ""