#!/usr/bin/runhaskell

\begin{code}
{-# OPTIONS -fwarn-unused-imports #-}
module Main where

import Distribution.PackageDescription (PackageDescription(..))
import Distribution.Simple.Setup ( BuildFlags(..), buildVerbosity, fromFlagOrDefault )
import Distribution.Simple ( defaultMainWithHooks, simpleUserHooks, UserHooks(..) )
import Distribution.Simple.LocalBuildInfo ( LocalBuildInfo(..) )
import Distribution.Simple.Program
import Distribution.Verbosity ( normal )

import System.FilePath ((</>))
import Control.Exception ( try )
import System.Directory (removeFile)
import Data.Char (isDigit)

main :: IO ()
main = defaultMainWithHooks simpleUserHooks { postBuild = myPostBuild,
                                              postClean = myPostClean,
                                              copyHook  = myCopy,
                                              instHook  = myInstall }

-- hack to turn cpp-style '# 27 "GenericTemplate.hs"' into
-- '{-# LINE 27 "GenericTemplate.hs" #-}'.
mungeLinePragma line = case symbols line of
 syms | Just prag <- getLinePrag syms  -> prag
 -- Also convert old-style CVS lines, no idea why we do this...
 ("--":"$":"Id":":":_) -> filter (/='$') line
 (     "$":"Id":":":_) -> filter (/='$') line
 _ -> line

getLinePrag :: [String] -> Maybe String
getLinePrag ("#" : n : string : rest)
  | length rest <= 1   -- clang puts an extra field
  , length string >= 2 && head string == '"' && last string == '"'
  , all isDigit n
  = Just $ "{-# LINE " ++ n ++ " " ++ string ++ " #-}"
getLinePrag other = Nothing

symbols :: String -> [String]
symbols cs = case lex cs of
              (sym, cs'):_ | not (null sym) -> sym : symbols cs'
              _ -> []

myPostBuild _ flags _ lbi = do
  let runProgram p = rawSystemProgramConf (fromFlagOrDefault normal (buildVerbosity flags))
                                          p
                                          (withPrograms lbi)
      cpp_template src dst opts = do
        let tmp = dst ++ ".tmp"
        runProgram ghcProgram (["-o", tmp, "-E", "-cpp", "templates" </> src] ++ opts)
        writeFile dst . unlines . map mungeLinePragma . lines =<< readFile tmp
        removeFile tmp

  sequence_ ([ cpp_template "GenericTemplate.hs" dst opts | (dst,opts) <- templates ] ++
             [ cpp_template "GLR_Base.hs"       dst opts | (dst,opts) <- glr_base_templates ] ++
             [ cpp_template "GLR_Lib.hs"        dst opts | (dst,opts) <- glr_templates ])

myPostClean _ _ _ _ = mapM_ (try' . removeFile) all_template_files
  where try' :: IO a -> IO (Either IOError a)
        try' = try

myInstall pkg_descr lbi hooks flags =
  instHook simpleUserHooks pkg_descr' lbi hooks flags
  where pkg_descr' = pkg_descr {
          dataFiles = dataFiles pkg_descr ++ all_template_files
        }

myCopy pkg_descr lbi hooks copy_flags =
  copyHook simpleUserHooks pkg_descr' lbi hooks copy_flags
  where pkg_descr' = pkg_descr {
          dataFiles = dataFiles pkg_descr ++ all_template_files
        }

all_template_files :: [FilePath]
all_template_files = map fst (templates ++ glr_base_templates ++ glr_templates)

templates :: [(FilePath,[String])]
templates = [
  ("HappyTemplate"                      , []),
  ("HappyTemplate-ghc"                  , ["-DHAPPY_GHC"]),
  ("HappyTemplate-coerce"               , ["-DHAPPY_GHC","-DHAPPY_COERCE"]),
  ("HappyTemplate-arrays"               , ["-DHAPPY_ARRAY"]),
  ("HappyTemplate-arrays-ghc"           , ["-DHAPPY_ARRAY","-DHAPPY_GHC"]),
  ("HappyTemplate-arrays-coerce"        , ["-DHAPPY_ARRAY","-DHAPPY_GHC","-DHAPPY_COERCE"]),
  ("HappyTemplate-arrays-debug"         , ["-DHAPPY_ARRAY","-DHAPPY_DEBUG"]),
  ("HappyTemplate-arrays-ghc-debug"     , ["-DHAPPY_ARRAY","-DHAPPY_GHC","-DHAPPY_DEBUG"]),
  ("HappyTemplate-arrays-coerce-debug"  , ["-DHAPPY_ARRAY","-DHAPPY_GHC","-DHAPPY_COERCE","-DHAPPY_DEBUG"])
 ]

glr_base_templates :: [(FilePath,[String])]
glr_base_templates = [
  ("GLR_Base"           , [])
 ]

glr_templates :: [(FilePath,[String])]
glr_templates = [
  ("GLR_Lib"            , []),
  ("GLR_Lib-ghc"        , ["-DHAPPY_GHC"]),
  ("GLR_Lib-ghc-debug"  , ["-DHAPPY_GHC", "-DHAPPY_DEBUG"])
 ]

\end{code}