module Main where

import Data.List (isPrefixOf)
import Data.Maybe (fromMaybe)
import System.Environment (lookupEnv)
import System.IO (readFile')

readUptime :: String -> Int
readUptime "" = 0
readUptime uptime
        | length (words uptime) > 1 = floor (read . head . words $ uptime :: Float)
        | otherwise = floor (read uptime :: Float)

getUptime :: Int -> String
getUptime uptime
        | uptime < 60 = remS
        | uptime < 3600 = unwords [remM, remS]
        | otherwise = unwords [remH, remM, remS]
    where
        totalM = uptime `div` 60
        remS = show (uptime `mod` 60) ++ "s"
        remM = show (totalM `mod` 60) ++ "m"
        remH = show (totalM `div` 60) ++ "h"

getKVer :: String -> String
getKVer "" = ""
getKVer info
        | length (words info) < 3 = head (words info)
        | otherwise = (\(k : ks) -> k ++ " " ++ (head . tail) ks) . words $ info

findPrettyName :: [String] -> String
findPrettyName (o : os)
        | "PRETTY_NAME" `isPrefixOf` o = (reverse . tail . init . takeWhile (/= '=') . reverse) o
        | otherwise = findPrettyName os

parseKBFromMeminfo :: String -> Int
parseKBFromMeminfo "" = 0
parseKBFromMeminfo line = read (head . tail . words $ line) :: Int

getMemory :: String -> String
getMemory meminfo
        | length (lines meminfo) < 2 = "N/A"
        | otherwise = memAvail ++ "/" ++ memTotal
    where
        memTotal = show (parseKBFromMeminfo (head $ lines meminfo) `div` 1000) ++ "MB"
        memAvail = show (parseKBFromMeminfo (head . tail . tail $ lines meminfo) `div` 1000) ++ "MB"

getWM :: Maybe String -> Maybe String -> String
getWM (Just desktop) (Just session) = desktop ++ " (" ++ session ++ ")"
getWM _ _ = "Unknown"

main :: IO ()
main = do
        uptime <- readFile' "/proc/uptime"
        version <- readFile' "/proc/version"
        osRelease <- readFile' "/etc/os-release"
        hostname <- readFile' "/proc/sys/kernel/hostname"
        meminfo <- readFile' "/proc/meminfo"
        username <- lookupEnv "USER"
        currentDesktop <- lookupEnv "XDG_CURRENT_DESKTOP"
        sessionType <- lookupEnv "XDG_SESSION_TYPE"
        locale <- lookupEnv "LANG"
        putStr
                ( unlines
                        [ "\x1b[1;35m  █         \x1b[1;34m" ++ fromMaybe "username" username ++ "@" ++ init hostname
                        , "\x1b[1;35m   █        \x1b[1;34m"
                        , "\x1b[1;35m    █       \x1b[1;34m" ++ "up\t" ++ (getUptime . readUptime) uptime
                        , "\x1b[1;35m     █      \x1b[1;34m" ++ "wm\t" ++ getWM currentDesktop sessionType
                        , "\x1b[1;35m    ███     \x1b[1;34m" ++ "krl\t" ++ getKVer version
                        , "\x1b[1;35m   █  ██    \x1b[1;34m" ++ "os\t" ++ (findPrettyName . lines) osRelease
                        , "\x1b[1;35m  █    ██   \x1b[1;34m" ++ "lcl\t" ++ fromMaybe "??_??" locale
                        , "\x1b[1;35m █      ██  \x1b[1;34m" ++ "mem\t" ++ getMemory meminfo
                        ]
                )