-- |
-- Copyright   : (c) 2015 Egor Tensin <Egor.Tensin@gmail.com>
-- License     : MIT
-- Maintainer  : Egor.Tensin@gmail.com
-- Stability   : experimental

module Main (main) where

import Control.Monad   (void, when)
import Data.List       ((\\))
import System.IO.Error (ioError, isDoesNotExistError)

import           Options.Applicative
import qualified Windows.Environment as Env

import Prompt
import PromptMessage

data Options = Options
    { optName   :: Env.VarName
    , optYes    :: Bool
    , optGlobal :: Bool
    , optPaths  :: [Env.VarValue]
    } deriving (Eq, Show)

optionParser :: Parser Options
optionParser = Options
    <$> optNameDesc
    <*> optYesDesc
    <*> optGlobalDesc
    <*> optPathsDesc
  where
    optNameDesc = strOption
         $ long "name" <> short 'n'
        <> metavar "NAME" <> value "PATH"
        <> help "Variable name ('PATH' by default)"
    optYesDesc = switch
         $ long "yes" <> short 'y'
        <> help "Skip confirmation prompt"
    optGlobalDesc = switch
         $ long "global" <> short 'g'
        <> help "Remove for all users"
    optPathsDesc = many $ argument str
         $ metavar "PATH"
        <> help "Directories to remove"

main :: IO ()
main = execParser parser >>= removePath
  where
    parser = info (helper <*> optionParser) $
        fullDesc <> progDesc "Remove directories from your PATH"

removePath :: Options -> IO ()
removePath options = do
    removePathFrom Env.CurrentUser
    when forAllUsers $
        removePathFrom Env.AllUsers
  where
    varName = optName options
    pathsToRemove = optPaths options

    forAllUsers = optGlobal options

    skipPrompt = optYes options

    removePathFrom profile = do
        oldValue <- Env.query profile varName
        either ignoreMissing (doRemovePathFrom profile) oldValue

    ignoreMissing e
        | isDoesNotExistError e = return ()
        | otherwise = ioError e

    doRemovePathFrom profile oldValue = do
        let oldPaths = Env.pathSplit oldValue
        let newPaths = oldPaths \\ pathsToRemove
        when (length oldPaths /= length newPaths) $ do
            let newValue = Env.pathJoin newPaths
            let promptAnd = if skipPrompt
                then withoutPrompt
                else withPrompt $ engraveMessage profile varName oldValue newValue
            let engrave = Env.engrave profile varName newValue
            void $ promptAnd engrave