become a proper stack project

1 files changed, 81 insertions, 0 deletions

diff --git a/src/EnvUtils.hs b/src/EnvUtils.hs
new file mode 100644
index 0000000..7e9bc96
--- /dev/null
+++ b/src/EnvUtils.hs
@@ -0,0 +1,81 @@
+{-
+ - Copyright 2015 Egor Tensin <Egor.Tensin@gmail.com>
+ - This file is licensed under the terms of the MIT License.
+ - See LICENSE.txt for details.
+-}
+
+module EnvUtils ( saveToRegistry
+                , saveToRegistryWithPrompt
+                , queryFromRegistry
+                , wipeFromRegistry
+                , wipeFromRegistryWithPrompt
+                , getEnv
+                , splitPaths
+                , joinPaths
+                , RegistryBasedEnvironment ( CurrentUserEnvironment, AllUsersEnvironment ) ) where
+
+import Control.Monad ( liftM, when )
+import Data.List ( intercalate )
+import Data.List.Split ( splitOn )
+import Data.Maybe ( fromMaybe )
+import qualified System.Environment ( lookupEnv )
+import System.IO.Error ( catchIOError, isDoesNotExistError )
+
+import qualified RegUtils
+import qualified Utils ( promptToContinue )
+
+data RegistryBasedEnvironment = CurrentUserEnvironment
+                              | AllUsersEnvironment
+                              deriving (Eq, Show)
+
+registrySubKeyPath :: RegistryBasedEnvironment -> String
+registrySubKeyPath CurrentUserEnvironment = "Environment"
+registrySubKeyPath AllUsersEnvironment = "SYSTEM\\CurrentControlSet\\Control\\Session Manager\\Environment"
+
+registryKey CurrentUserEnvironment = RegUtils.hkcu
+registryKey AllUsersEnvironment = RegUtils.hklm
+
+registryKeyPath :: RegistryBasedEnvironment -> String
+registryKeyPath CurrentUserEnvironment = "HKCU\\" ++ registrySubKeyPath CurrentUserEnvironment
+registryKeyPath AllUsersEnvironment = "HKLM\\" ++ registrySubKeyPath AllUsersEnvironment
+
+saveToRegistry :: RegistryBasedEnvironment -> String -> String -> IO ()
+saveToRegistry env = RegUtils.setString (registryKey env) (registrySubKeyPath env)
+
+saveToRegistryWithPrompt :: RegistryBasedEnvironment -> String -> String -> IO ()
+saveToRegistryWithPrompt env name value = do
+  putStrLn $ "Saving variable '" ++ name ++ "' to '" ++ registryKeyPath env ++ "'..."
+  oldValue <- queryFromRegistry env name
+  putStrLn $ "\tOld value: " ++ oldValue
+  putStrLn $ "\tNew value: " ++ value
+  agreed <- Utils.promptToContinue
+  when agreed $ saveToRegistry env name value
+
+queryFromRegistry :: RegistryBasedEnvironment -> String -> IO String
+queryFromRegistry env name = catchIOError (RegUtils.getString (registryKey env) (registrySubKeyPath env) name) emptyIfDoesNotExist
+  where
+    emptyIfDoesNotExist :: IOError -> IO String
+    emptyIfDoesNotExist e = if isDoesNotExistError e then return "" else ioError e
+
+wipeFromRegistry :: RegistryBasedEnvironment -> String -> IO ()
+wipeFromRegistry env name = catchIOError (RegUtils.delValue (registryKey env) (registrySubKeyPath env) name) ignoreIfDoesNotExist
+  where
+    ignoreIfDoesNotExist :: IOError -> IO ()
+    ignoreIfDoesNotExist e = if isDoesNotExistError e then return () else ioError e
+
+wipeFromRegistryWithPrompt :: RegistryBasedEnvironment -> String -> IO ()
+wipeFromRegistryWithPrompt env name = do
+  putStrLn $ "Deleting variable '" ++ name ++ "' from '" ++ registryKeyPath env ++ "'..."
+  agreed <- Utils.promptToContinue
+  when agreed $ wipeFromRegistry env name
+
+getEnv :: String -> IO String
+getEnv = liftM (fromMaybe "") . System.Environment.lookupEnv
+
+pathSep = ";"
+
+splitPaths :: String -> [String]
+splitPaths = filter (not . null) . splitOn pathSep
+
+joinPaths :: [String] -> String
+joinPaths = intercalate pathSep . filter (not . null)