module Options where

import qualified System.Environment as Env
import System.Console.GetOpt
          (ArgOrder(RequireOrder), OptDescr(Option), ArgDescr(NoArg, ReqArg),
           getOpt, usageInfo, )
import System.Exit (exitSuccess, )

import qualified Control.Monad.Exception.Synchronous as Exc
import qualified Control.Monad.Trans.Class as MT
import Control.Monad (when, )

import Text.Printf (printf, )


data T =
   Cons {
      help :: Bool,
      llvmConfigPath :: FilePath,
      installPath :: FilePath,
      install :: Bool
   }

deflt :: T
deflt =
   Cons {
      help = False,
      llvmConfigPath = "llvm-config",
      installPath = "/usr/local/lib/pkgconfig/llvm.pc",
      install = False
   }


options :: [OptDescr (T -> Exc.Exceptional String T)]
options =
   Option ['h'] ["help"]
      (NoArg (\flags -> return $ flags{help = True}))
      "show options" :
   Option [] ["llvm-config"]
      (ReqArg (\str flags -> return $ flags{llvmConfigPath = str}) "PATH")
      (printf "path of llvm-config executable (default %s)" $
       llvmConfigPath deflt) :
   Option [] ["install"]
      (NoArg (\flags -> return $ flags{install = True}))
      (printf "install config file at standard location (default %s)" $
       installPath deflt) :
   []


get :: Exc.ExceptionalT String IO T
get = do
   argv <- MT.lift Env.getArgs
   let (opts, args, errors) =
          getOpt RequireOrder options argv
   when (not (null errors)) $ Exc.throwT $ concat $ errors
   when (not (null args)) $ Exc.throwT $
      "I have no usage for the arguments " ++ show args
   flags <-
      Exc.ExceptionalT $ return $
         foldl (>>=) (return deflt) opts
   when (help flags)
      (MT.lift $
       Env.getProgName >>= \programName ->
       putStrLn
          (usageInfo ("Usage: " ++ programName ++
                      " [OPTIONS]") options) >>
       exitSuccess)
   return flags