keyring-0.1.0.4: Example.hs

-- Copyright (c) 2014 Sebastian Wiesner <swiesner@lunaryorn.com>

-- Permission is hereby granted, free of charge, to any person obtaining a copy
-- of this software and associated documentation files (the "Software"), to deal
-- in the Software without restriction, including without limitation the rights
-- to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
-- copies of the Software, and to permit persons to whom the Software is
-- furnished to do so, subject to the following conditions:

-- The above copyright notice and this permission notice shall be included in
-- all copies or substantial portions of the Software.

-- THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
-- IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
-- FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
-- AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
-- LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
-- OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
-- THE SOFTWARE.

module Main where

import System.Keyring (Service(..),Username(..),Password(..)
                      ,getPassword,setPassword
                      ,KeyringError)

import Control.Exception (catch)
import Control.Monad (liftM)
import Data.Version (showVersion)
import System.Exit (exitFailure)
import System.IO (hPutStrLn,hPrint,hFlush,stderr,stdout)
import Text.Printf (printf)

import Paths_keyring (version)

ask :: String -> IO String
ask prompt = do
  putStr prompt
  hFlush stdout
  getLine

service :: Service
service = Service "haskell-keyring-example"

handleKeyringError :: KeyringError -> IO ()
handleKeyringError exc =
  hPrint stderr exc >> exitFailure

roundTrip :: Username -> IO ()
roundTrip username = do
   password <- ask "A password (VISIBLE): "
   setPassword service username (Password password)
   result <- getPassword service username
   case result of
     (Just (Password storedPassword)) -> do
       let matching = if password == storedPassword then "ok" else "MISMATCH"
       printf "Password in keyring: %s (%s)\n" storedPassword matching
     Nothing -> hPutStrLn stderr "Error: Password NOT saved!" >> exitFailure

tryGetPassword :: IO ()
tryGetPassword = do
  username <- liftM Username (ask "A username: ")
  password <- getPassword service username
  case password of
    (Just (Password pw)) -> putStr "Your Password: " >> putStrLn pw
    Nothing -> putStrLn "No password in keyring" >> roundTrip username

showVersionInfo :: IO ()
showVersionInfo = printf "Keyring %s\n" (showVersion version)

main :: IO ()
main = do
  showVersionInfo
  catch tryGetPassword handleKeyringError