import System.Cmd (system)
import System.FilePath ((</>))
import Control.Monad (when, unless)
import Distribution.Simple
import Distribution.Simple.LocalBuildInfo
import Distribution.PackageDescription
import Distribution.Simple.InstallDirs (CopyDest(..))
import Distribution.Simple.LocalBuildInfo (absoluteInstallDirs, InstallDirs(..))

main = defaultMainWithHooks simpleUserHooks { postInst = myPostInst }
  where myPostInst _ _ pkgdesc buildinfo = do 
          let dirs  = absoluteInstallDirs pkgdesc buildinfo NoCopyDest
              lhc   = bindir dirs </> "lhc"
              confargs = unwords ["--lhc", "--with-lhc="++lhc, "--prefix="++show (prefix (installDirTemplates buildinfo))]
              lpkgdesc = localPkgDescr buildinfo
              exes     = executables lpkgdesc
              sanity   = any (\(Executable s _ _) -> s == "lhc") exes
          unless sanity $ fail "No lhc executale found - this probably shouldn't happen"
          let lhcexe   = head $ filter (\(Executable s _ _) -> s == "lhc") exes
              binfo    = buildInfo lhcexe
              customF  = customFieldsBI binfo
          when (withBase customF) $ installLhcPkg confargs "base"
        withBase = any $ \(x,y) -> x == "x-build-base" && y == "True"
        installLhcPkgs cf  = mapM_ (installLhcPkg cf)
        installLhcPkg cf n = do 
            putStrLn $ "\n[installing "++n++" package for lhc]\n"
            let x = unwords ["cd","lib" </> n
                            ,"&&","runghc Setup configure",cf
                            ,"&&","runghc Setup build"
                            ,"&&","runghc Setup install"]
            putStrLn $ x
            system x
            return ()