content: -----------------------------------------------------------------------------
  -- |
  -- Module      :  Distribution.GetOpt
  -- Copyright   :  (c) Sven Panne 2002-2005
  -- License     :  BSD-style (see the file libraries/base/LICENSE)
  --
  -- Maintainer  :  libraries@haskell.org
  -- Portability :  portable
  --
  -- This is a fork of "System.Console.GetOpt" with the following changes:
  --
  -- * Treat "cabal --flag command" as "cabal command --flag" e.g.
  --   "cabal -v configure" to mean "cabal configure -v" For flags that are
  --   not recognised as global flags, pass them on to the sub-command. See
  --   the difference in 'shortOpt'.
  --
  -- * Line wrapping in the 'usageInfo' output, plus a more compact
  --   rendering of short options, and slightly less padding.
  --
  -- If you want to take on the challenge of merging this with the GetOpt
  -- from the base package then go for it!
  --
  module Distribution.GetOpt (
     -- * GetOpt
     getOpt, getOpt',
     usageInfo,
     ArgOrder(..),
     OptDescr(..),
     ArgDescr(..),
  
     -- * Example
     -- | See "System.Console.GetOpt" for examples
  ) where
  
  import Prelude ()
  import Distribution.Compat.Prelude
  import System.Console.GetOpt
           ( ArgOrder(..), OptDescr(..), ArgDescr(..) )
  
  data OptKind a                -- kind of cmd line arg (internal use only):
     = Opt       a                --    an option
     | UnreqOpt  String           --    an un-recognized option
     | NonOpt    String           --    a non-option
     | EndOfOpts                  --    end-of-options marker (i.e. "--")
     | OptErr    String           --    something went wrong...
  
  -- | Return a string describing the usage of a command, derived from
  -- the header (first argument) and the options described by the
  -- second argument.
  usageInfo :: String                    -- header
            -> [OptDescr a]              -- option descriptors
            -> String                    -- nicely formatted decription of options
  usageInfo header optDescr = unlines (header:table)
     where (ss,ls,ds) = unzip3 [ (intercalate ", " (map (fmtShort ad) sos)
                                 ,concatMap (fmtLong  ad) (take 1 los)
                                 ,d)
                               | Option sos los ad d <- optDescr ]
           ssWidth    = (maximum . map length) ss
           lsWidth    = (maximum . map length) ls
           dsWidth    = 30 `max` (80 - (ssWidth + lsWidth + 3))
           table      = [ " " ++ padTo ssWidth so' ++
                          " " ++ padTo lsWidth lo' ++
                          " " ++ d'
                        | (so,lo,d) <- zip3 ss ls ds
                        , (so',lo',d') <- fmtOpt dsWidth so lo d ]
           padTo n x  = take n (x ++ repeat ' ')
  
  fmtOpt :: Int -> String -> String -> String -> [(String, String, String)]
  fmtOpt descrWidth so lo descr =
     case wrapText descrWidth descr of
       []     -> [(so,lo,"")]
       (d:ds) -> (so,lo,d) : [ ("","",d') | d' <- ds ]
  
  fmtShort :: ArgDescr a -> Char -> String
  fmtShort (NoArg  _   ) so = "-" ++ [so]
  fmtShort (ReqArg _  _) so = "-" ++ [so]
  fmtShort (OptArg _  _) so = "-" ++ [so]
    -- unlike upstream GetOpt we omit the arg name for short options
  
  fmtLong :: ArgDescr a -> String -> String
  fmtLong (NoArg  _   ) lo = "--" ++ lo
  fmtLong (ReqArg _ ad) lo = "--" ++ lo ++ "=" ++ ad
  fmtLong (OptArg _ ad) lo = "--" ++ lo ++ "[=" ++ ad ++ "]"
  
  wrapText :: Int -> String -> [String]
  wrapText width = map unwords . wrap 0 [] . words
    where wrap :: Int -> [String] -> [String] -> [[String]]
          wrap 0   []   (w:ws)
            | length w + 1 > width
            = wrap (length w) [w] ws
          wrap col line (w:ws)
            | col + length w + 1 > width
            = reverse line : wrap 0 [] (w:ws)
          wrap col line (w:ws)
            = let col' = col + length w + 1
               in wrap col' (w:line) ws
          wrap _ []   [] = []
          wrap _ line [] = [reverse line]
  
  {-|
  Process the command-line, and return the list of values that matched
  (and those that didn\'t). The arguments are:
  
  * The order requirements (see 'ArgOrder')
  
  * The option descriptions (see 'OptDescr')
  
  * The actual command line arguments (presumably got from
    'System.Environment.getArgs').
  
  'getOpt' returns a triple consisting of the option arguments, a list
  of non-options, and a list of error messages.
  -}
  getOpt :: ArgOrder a                   -- non-option handling
         -> [OptDescr a]                 -- option descriptors
         -> [String]                     -- the command-line arguments
         -> ([a],[String],[String])      -- (options,non-options,error messages)
  getOpt ordering optDescr args = (os,xs,es ++ map errUnrec us)
     where (os,xs,us,es) = getOpt' ordering optDescr args
  
  {-|
  This is almost the same as 'getOpt', but returns a quadruple
  consisting of the option arguments, a list of non-options, a list of
  unrecognized options, and a list of error messages.
  -}
  getOpt' :: ArgOrder a                         -- non-option handling
          -> [OptDescr a]                       -- option descriptors
          -> [String]                           -- the command-line arguments
          -> ([a],[String], [String] ,[String]) -- (options,non-options,unrecognized,error messages)
  getOpt' _        _        []         =  ([],[],[],[])
  getOpt' ordering optDescr (arg:args) = procNextOpt opt ordering
     where procNextOpt (Opt o)      _                 = (o:os,xs,us,es)
           procNextOpt (UnreqOpt u) _                 = (os,xs,u:us,es)
           procNextOpt (NonOpt x)   RequireOrder      = ([],x:rest,[],[])
           procNextOpt (NonOpt x)   Permute           = (os,x:xs,us,es)
           procNextOpt (NonOpt x)   (ReturnInOrder f) = (f x :os, xs,us,es)
           procNextOpt EndOfOpts    RequireOrder      = ([],rest,[],[])
           procNextOpt EndOfOpts    Permute           = ([],rest,[],[])
           procNextOpt EndOfOpts    (ReturnInOrder f) = (map f rest,[],[],[])
           procNextOpt (OptErr e)   _                 = (os,xs,us,e:es)
  
           (opt,rest) = getNext arg args optDescr
           (os,xs,us,es) = getOpt' ordering optDescr rest
  
  -- take a look at the next cmd line arg and decide what to do with it
  getNext :: String -> [String] -> [OptDescr a] -> (OptKind a,[String])
  getNext ('-':'-':[]) rest _        = (EndOfOpts,rest)
  getNext ('-':'-':xs) rest optDescr = longOpt xs rest optDescr
  getNext ('-': x :xs) rest optDescr = shortOpt x xs rest optDescr
  getNext a            rest _        = (NonOpt a,rest)
  
  -- handle long option
  longOpt :: String -> [String] -> [OptDescr a] -> (OptKind a,[String])
  longOpt ls rs optDescr = long ads arg rs
     where (opt,arg) = break (=='=') ls
           getWith p = [ o  | o@(Option _ xs _ _) <- optDescr
                            , isJust (find (p opt) xs)]
           exact     = getWith (==)
           options   = if null exact then getWith isPrefixOf else exact
           ads       = [ ad | Option _ _ ad _ <- options ]
           optStr    = "--" ++ opt
  
           long (_:_:_)      _        rest     = (errAmbig options optStr,rest)
           long [NoArg  a  ] []       rest     = (Opt a,rest)
           long [NoArg  _  ] ('=':_)  rest     = (errNoArg optStr,rest)
           long [ReqArg _ d] []       []       = (errReq d optStr,[])
           long [ReqArg f _] []       (r:rest) = (Opt (f r),rest)
           long [ReqArg f _] ('=':xs) rest     = (Opt (f xs),rest)
           long [OptArg f _] []       rest     = (Opt (f Nothing),rest)
           long [OptArg f _] ('=':xs) rest     = (Opt (f (Just xs)),rest)
           long _            _        rest     = (UnreqOpt ("--"++ls),rest)
  
  -- handle short option
  shortOpt :: Char -> String -> [String] -> [OptDescr a] -> (OptKind a,[String])
  shortOpt y ys rs optDescr = short ads ys rs
    where options = [ o  | o@(Option ss _ _ _) <- optDescr, s <- ss, y == s ]
          ads     = [ ad | Option _ _ ad _ <- options ]
          optStr  = '-':[y]
  
          short (_:_:_)        _  rest     = (errAmbig options optStr,rest)
          short (NoArg  a  :_) [] rest     = (Opt a,rest)
          short (NoArg  a  :_) xs rest     = (Opt a,('-':xs):rest)
          short (ReqArg _ d:_) [] []       = (errReq d optStr,[])
          short (ReqArg f _:_) [] (r:rest) = (Opt (f r),rest)
          short (ReqArg f _:_) xs rest     = (Opt (f xs),rest)
          short (OptArg f _:_) [] rest     = (Opt (f Nothing),rest)
          short (OptArg f _:_) xs rest     = (Opt (f (Just xs)),rest)
          short []             [] rest     = (UnreqOpt optStr,rest)
          short []             xs rest     = (UnreqOpt (optStr++xs),rest)
          -- This is different vs upstream = (UnreqOpt optStr,('-':xs):rest)
          -- Apparently this was part of the change so that flags that are
          -- not recognised as global flags are passed on to the sub-command.
          -- But why was no equivalent change required for longOpt? So could
          -- this change go upstream?
  
  -- miscellaneous error formatting
  
  errAmbig :: [OptDescr a] -> String -> OptKind a
  errAmbig ods optStr = OptErr (usageInfo header ods)
     where header = "option `" ++ optStr ++ "' is ambiguous; could be one of:"
  
  errReq :: String -> String -> OptKind a
  errReq d optStr = OptErr ("option `" ++ optStr ++ "' requires an argument " ++ d ++ "\n")
  
  errUnrec :: String -> String
  errUnrec optStr = "unrecognized option `" ++ optStr ++ "'\n"
  
  errNoArg :: String -> OptKind a
  errNoArg optStr = OptErr ("option `" ++ optStr ++ "' doesn't allow an argument\n")
  