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

module Main (main) where

import Control.Monad   (when, void)
import Control.Monad.Trans.Except (catchE, runExceptT, throwE)
import Data.Monoid     ((<>))
import Data.List       (nub)
import System.IO.Error (ioError, isDoesNotExistError)

import Options.Applicative

import qualified WindowsEnv

import Utils.Path
import Utils.Prompt
import Utils.PromptMessage

data Options = Options
    { optName    :: WindowsEnv.Name
    , optYes     :: Bool
    , optGlobal  :: Bool
    , optPrepend :: Bool
    , optPaths   :: [String]
    } deriving (Eq, Show)

optionParser :: Parser Options
optionParser = Options
    <$> optNameDesc
    <*> optYesDesc
    <*> optGlobalDesc
    <*> optPrependDesc
    <*> 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 "Add for all users"
    optPrependDesc = switch
         $ long "prepend" <> short 'p'
        <> help "Prepend to the variable (instead of appending)"
    optPathsDesc = many $ argument str
         $ metavar "PATH"
        <> help "Directories to add"

main :: IO ()
main = execParser parser >>= addPath
  where
    parser = info (helper <*> optionParser) $
        fullDesc <> progDesc "Add directories to your PATH"

addPath :: Options -> IO ()
addPath options = runExceptT doAddPath >>= either ioError return
  where
    varName = optName options
    pathsToAdd = nub $ optPaths options
    forAllUsers = optGlobal options
    skipPrompt = optYes options

    profile
        | forAllUsers = WindowsEnv.AllUsers
        | otherwise   = WindowsEnv.CurrentUser

    prepend = optPrepend options
    appendPaths old new
        | prepend = new ++ old
        | otherwise = old ++ new

    emptyIfMissing e
        | isDoesNotExistError e = return $ WindowsEnv.Value False ""
        | otherwise = throwE e

    doAddPath = do
        newPaths <- pathExpandAll pathsToAdd
        let newExpandable = pathAnyExpanded newPaths
        srcValue <- WindowsEnv.query profile varName `catchE` emptyIfMissing
        let srcExpandable = WindowsEnv.valueExpandable srcValue
        let destExpandable = newExpandable || srcExpandable
        srcPaths <- pathExpandValue srcValue
            { WindowsEnv.valueExpandable = destExpandable }
        let destPaths = appendPaths srcPaths $ filter (`notElem` srcPaths) newPaths
        let destPathsJoined = WindowsEnv.pathJoin $ map pathOriginal destPaths
        let destValue = WindowsEnv.Value destExpandable destPathsJoined
        when (srcValue /= destValue) $ promptAndEngrave srcValue destValue

    promptAndEngrave oldValue newValue = do
        let promptAnd = if skipPrompt
            then withoutPrompt
            else withPrompt $ oldNewMessage profile varName oldValue newValue
        let engrave = WindowsEnv.engrave profile varName newValue
        void $ promptAnd engrave