1 files changed, 84 insertions, 0 deletions
diff --git a/app/ListPaths.hs b/app/ListPaths.hs
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+-- |
+-- 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      (filterM)
+import Control.Monad.Trans.Class  (lift)
+import Control.Monad.Trans.Except (runExceptT)
+import Data.Maybe         (fromMaybe)
+import System.Directory   (doesDirectoryExist)
+import System.Environment (lookupEnv)
+import System.IO.Error    (ioError)
+
+import Options.Applicative
+
+import qualified WindowsEnv
+
+data WhichPaths = All | ExistingOnly | MissingOnly
+                deriving (Eq, Show)
+
+shouldListPath :: WhichPaths -> WindowsEnv.VarValue -> IO Bool
+shouldListPath All = return . const True
+shouldListPath ExistingOnly = doesDirectoryExist
+shouldListPath MissingOnly  = fmap not . doesDirectoryExist
+
+data Source = Environment | Registry WindowsEnv.Profile
+            deriving (Eq, Show)
+
+data Options = Options
+    { optName       :: WindowsEnv.VarName
+    , optWhichPaths :: WhichPaths
+    , optSource     :: Source
+    } deriving (Eq, Show)
+
+optionParser :: Parser Options
+optionParser = Options
+    <$> optNameDesc
+    <*> optWhichPathsDesc
+    <*> optSourceDesc
+  where
+    optNameDesc = strOption
+         $ long "name" <> short 'n'
+        <> metavar "NAME" <> value "PATH"
+        <> help "Variable name ('PATH' by default)"
+    optWhichPathsDesc = pure All
+        <|> flag' ExistingOnly (long "existing" <> short 'e'
+            <> help "List existing paths only")
+        <|> flag' MissingOnly (long "missing" <> short 'm'
+            <> help "List missing paths only")
+    optSourceDesc = pure Environment
+        <|> flag' (Registry WindowsEnv.CurrentUser) (long "user" <> short 'u'
+            <> help "List current user's paths only")
+        <|> flag' (Registry WindowsEnv.AllUsers) (long "global" <> short 'g'
+            <> help "List global (all users') paths only")
+
+main :: IO ()
+main = execParser parser >>= listPaths
+  where
+    parser = info (helper <*> optionParser) $
+        fullDesc <> progDesc "List directories in your PATH"
+
+listPaths :: Options -> IO ()
+listPaths options = runExceptT doListPaths >>= either ioError return
+  where
+    varName = optName options
+    whichPaths = optWhichPaths options
+    source = optSource options
+
+    query = queryFrom source
+
+    queryFrom Environment = lift $ fromMaybe "" <$> lookupEnv varName
+    queryFrom (Registry profile) = WindowsEnv.query profile varName
+
+    filterPaths = filterM $ shouldListPath whichPaths
+
+    doListPaths = do
+        paths <- WindowsEnv.pathSplit <$> query
+        lift $ do
+            pathsToPrint <- filterPaths paths
+            mapM_ putStrLn pathsToPrint