1 files changed, 66 insertions, 0 deletions
diff --git a/apps/Utils.hs b/apps/Utils.hs
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--- /dev/null
+++ b/apps/Utils.hs
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+{-
+ - 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 Utils
+    ( withPrompt
+    , withoutPrompt
+
+    , engraveBanner
+    , wipeBanner
+    ) where
+
+import Control.Monad (liftM, void, when)
+import Data.Maybe    (fromJust, isJust)
+import Data.Char     (toLower)
+import System.IO     (hFlush, stdout)
+import Text.Printf   (printf)
+
+import Environment   (Profile, profileKeyPath, VarName, VarValue)
+
+prompt :: String -> IO String
+prompt banner = do
+    putStr banner
+    hFlush stdout
+    getLine
+
+promptYesNo :: String -> IO Bool
+promptYesNo banner = do
+    response <- liftM (map toLower) $ prompt banner
+    if response `elem` yeses
+        then return True
+        else if response `elem` noes
+            then return False
+            else promptToContinue
+  where
+    yeses = ["y", "yes"]
+    noes = ["n", "no"]
+    
+promptToContinue :: IO Bool
+promptToContinue = promptYesNo "Continue? (y/n) "
+
+withPrompt :: String -> IO a -> IO Bool
+withPrompt banner m = do
+    putStr banner
+    hFlush stdout
+    agreed <- promptToContinue
+    when agreed $ void m
+    return agreed
+
+withoutPrompt :: IO a -> IO Bool
+withoutPrompt m = m >> return True
+
+engraveBanner :: Profile -> VarName -> Maybe VarValue -> VarValue -> String
+engraveBanner profile name oldValue newValue =
+    header ++ values
+  where
+    header = printf "Saving variable '%s' to '%s'...\n" name (profileKeyPath profile)
+    values = if isJust oldValue
+        then printf "\tOld value: %s\n\tNew value: %s\n" (fromJust oldValue) newValue
+        else printf "\tValue: %s\n" newValue
+
+wipeBanner :: Profile -> VarName -> String
+wipeBanner profile name =
+    printf "Deleting variable '%s' from '%s'...\n" name (profileKeyPath profile)