-----------------------------------------------------------------------------
-- |
-- Module      :  Plugins.Monitors.Batt
-- Copyright   :  (c) Andrea Rossato
-- License     :  BSD-style (see LICENSE)
--
-- Maintainer  :  Andrea Rossato <andrea.rossato@unibz.it>
-- Stability   :  unstable
-- Portability :  unportable
--
-- A battery monitor for Xmobar
--
-----------------------------------------------------------------------------

module Plugins.Monitors.Batt where

import qualified Data.ByteString.Lazy.Char8 as B
import Plugins.Monitors.Common
import System.Posix.Files (fileExist)

data Batt = Batt Float String
          | NA

battConfig :: IO MConfig
battConfig = mkMConfig
       "Batt: <left>" -- template
       ["left","status"] -- available replacements

type File = (String, String)

file2batfile :: String -> (File, File)
file2batfile s = ( (s' ++ "/charge_full", s' ++ "/energy_full")
                 , (s' ++ "/charge_now" , s' ++ "/energy_now" )
                 )
    where s' = "/sys/class/power_supply/" ++ s

readFileBatt :: (File, File) -> IO (String, String, String)
readFileBatt (f,n) =
    do a  <- rf f
       b  <- rf n
       ac <- fileExist "/sys/class/power_supply/AC0/online"
       c  <- if not ac
             then return []
             else do s <- B.unpack `fmap` catRead "/sys/class/power_supply/AC0/online"
                     return $ if s == "1\n" then "<fc=green>On</fc>" else"<fc=red>Off</fc>"
       return (a,b,c)
    where rf file = do
            fe <- fileExist (fst file)
            if fe
               then B.unpack `fmap` catRead (fst file)
               else do fe' <- fileExist (snd file)
                       if fe'
                          then B.unpack `fmap` catRead (snd file)
                          else return []

parseBATT :: [(File,File)] -> IO Batt
parseBATT bfs =
    do [(a0,b0,c0),(a1,b1,_),(a2,b2,_)] <- mapM readFileBatt (take 3 $ bfs ++ repeat (("",""),("","")))
       let read' s = if s == [] then 0 else read s
           left    = (read' b0 + read' b1 + read' b2) / (read' a0 + read' a1 + read' a2) --present / full
       return $ if isNaN left then NA else Batt left c0

formatBatt :: Float -> Monitor [String]
formatBatt x =
    do let f s = floatToPercent (s / 100)
       l <- showWithColors f (x * 100)
       return [l]

runBatt :: [String] -> Monitor String
runBatt = runBatt' ["BAT0","BAT1","BAT2"]

runBatt' :: [String] -> [String] -> Monitor String
runBatt' bfs _ = do
  c <- io $ parseBATT (map file2batfile bfs)
  case c of
    Batt x s -> do l <- formatBatt x
                   parseTemplate (l ++ [s])
    NA -> return "N/A"