-- An utility to split a source Haskell file
-- generated by hsffig into smaller parts as guided
-- by the special comments found in the file.

module Main where

import Prelude hiding (putStrLn, readFile)
import Data.List
import System.Directory
import System.FilePath
import System.Environment.UTF8
import System.IO (openFile, IOMode(..), hClose)
import System.IO.UTF8
import Control.Monad
import Maybe

import Data.SplitBounds

main = do
       args <- getArgs
       case args of
         [] -> usage
         other -> splitModule $ head args

-- Print the usage information.

usage = putStrLn "Usage: splitter filename"

-- Do the actual module split. The file name is expected
-- to be in the form [path/]MODULENAME[.suffix]. Path will be preserved.
-- Suffix will be replaced with .hs. Names of modules will be derived from
-- MODULENAME and be treated relativeky to the current directory.

splitModule fn = do

-- Open the file

  src <- (readFile fn)

  let srcln = lines src 

  procLines Nothing "" srcln

  return ()

-- Line-by-line processor.

procLines _ _ [] = return ()

procLines handle fnpath (l:ls) = do
  let derivefn  app = fnpath </> app' <.> "hs" where
                app' = concat $ intersperse "/" $ parts (== '.') app
      skipline = do procLines handle fnpath ls
                    return ()
      startfile app = do let path = derivefn app
                             dir = fst $ splitFileName path
                         createDirectoryIfMissing True dir
                         handle' <- openFile path WriteMode
                         procLines (Just handle') fnpath ls
                         return ()
      endfile = do when (handle /= Nothing) $ hClose (fromJust handle)
                   procLines Nothing fnpath ls
                   return ()
      nextline = do when (handle /= Nothing) $ hPutStrLn (fromJust handle) l
                    procLines handle fnpath ls
                    return ()
  case l of
    _ | l == splitOpen -> skipline                    -- these comments
    _ | l == splitClose -> skipline                   -- are removed
    _ | (takeWhile (/= '/') l) == splitBegin -> startfile $ drop 1 $ dropWhile (/= '/') l
    _ | l == splitEnd -> endfile
    other -> nextline
  return ()