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{-| Base common functionality.

This module holds common functionality shared across Ganeti daemons,

HTools and any other programs.

-}

{-

Copyright (C) 2009, 2010, 2011, 2012 Google Inc.

This program is free software; you can redistribute it and/or modify

it under the terms of the GNU General Public License as published by

the Free Software Foundation; either version 2 of the License, or

(at your option) any later version.

This program is distributed in the hope that it will be useful, but

WITHOUT ANY WARRANTY; without even the implied warranty of

MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

General Public License for more details.

You should have received a copy of the GNU General Public License

along with this program; if not, write to the Free Software

Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA

02110-1301, USA.

-}

module Ganeti.Common

  ( GenericOptType

  , StandardOptions(..)

  , oShowHelp

  , oShowVer

  , usageHelp

  , versionInfo

  , reqWithConversion

  , parseYesNo

  , parseOpts

  , parseOptsInner

  ) where

import Control.Monad (foldM)

import qualified Data.Version

import System.Console.GetOpt

import System.Exit

import System.Info

import System.IO

import Text.Printf (printf)

import Ganeti.BasicTypes

import qualified Ganeti.Version as Version (version)

-- | Abrreviation for the option type.

type GenericOptType a = OptDescr (a -> Result a)

-- | Type class for options which support help and version.

class StandardOptions a where

  helpRequested :: a -> Bool

  verRequested  :: a -> Bool

  requestHelp   :: a -> a

  requestVer    :: a -> a

-- | Options to request help output.

oShowHelp :: (StandardOptions a) => GenericOptType a

oShowHelp = Option "h" ["help"] (NoArg (Ok . requestHelp))

            "show help"

oShowVer :: (StandardOptions a) => GenericOptType a

oShowVer = Option "V" ["version"] (NoArg (Ok . requestVer))

           "show the version of the program"

-- | Usage info.

usageHelp :: String -> [GenericOptType a] -> String

usageHelp progname =

  usageInfo (printf "%s %s\nUsage: %s [OPTION...]"

             progname Version.version progname)

-- | Show the program version info.

versionInfo :: String -> String

versionInfo progname =

  printf "%s %s\ncompiled with %s %s\nrunning on %s %s\n"

         progname Version.version compilerName

         (Data.Version.showVersion compilerVersion)

         os arch

-- | Helper for parsing a yes\/no command line flag.

parseYesNo :: Bool         -- ^ Default value (when we get a @Nothing@)

           -> Maybe String -- ^ Parameter value

           -> Result Bool  -- ^ Resulting boolean value

parseYesNo v Nothing      = return v

parseYesNo _ (Just "yes") = return True

parseYesNo _ (Just "no")  = return False

parseYesNo _ (Just s)     = fail ("Invalid choice '" ++ s ++

                                  "', pass one of 'yes' or 'no'")

-- | Helper function for required arguments which need to be converted

-- as opposed to stored just as string.

reqWithConversion :: (String -> Result a)

                  -> (a -> b -> Result b)

                  -> String

                  -> ArgDescr (b -> Result b)

reqWithConversion conversion_fn updater_fn =

  ReqArg (\string_opt opts -> do

            parsed_value <- conversion_fn string_opt

            updater_fn parsed_value opts)

-- | Command line parser, using a generic 'Options' structure.

parseOpts :: (StandardOptions a) =>

             a                      -- ^ The default options

          -> [String]               -- ^ The command line arguments

          -> String                 -- ^ The program name

          -> [GenericOptType a]     -- ^ The supported command line options

          -> IO (a, [String])       -- ^ The resulting options and

                                    -- leftover arguments

parseOpts defaults argv progname options =

  case parseOptsInner defaults argv progname options of

    Left (code, msg) -> do

      hPutStr (if code == ExitSuccess then stdout else stderr) msg

      exitWith code

    Right result ->

      return result

-- | Inner parse options. The arguments are similar to 'parseOpts',

-- but it returns either a 'Left' composed of exit code and message,

-- or a 'Right' for the success case.

parseOptsInner :: (StandardOptions a) =>

                  a

               -> [String]

               -> String

               -> [GenericOptType a]

               -> Either (ExitCode, String) (a, [String])

parseOptsInner defaults argv progname options  =

  case getOpt Permute options argv of

    (opts, args, []) ->

      case foldM (flip id) defaults opts of

           Bad msg -> Left (ExitFailure 1,

                            "Error while parsing command line arguments:\n"

                            ++ msg ++ "\n")

           Ok parsed ->

             select (Right (parsed, args))

                 [ (helpRequested parsed,

                    Left (ExitSuccess, usageHelp progname options))

                 , (verRequested parsed,

                    Left (ExitSuccess, versionInfo progname))

                 ]

    (_, _, errs) ->

      Left (ExitFailure 2, "Command line error: "  ++ concat errs ++ "\n" ++

            usageHelp progname options)