module FMP.File (
      Parameters(..),
      fileExists, clearFile, getParameters
      ) where

import System.IO

data Parameters               =  Parameters{  mpBin           :: String,
                                              funcmpBin,
                                              funcmpRTS       :: String,
                                              defaultDX,
                                              defaultDY,
                                              textDX,
                                              textDY          :: Double,
                                              newmp           :: Bool,
                                              prolog,
                                              epilog          :: String}
                                 deriving (Eq, Read, Show)

stdParameters                 :: Parameters
stdParameters                 =  Parameters{  mpBin           = "virmp",
                                              funcmpBin       = "FuncMP",
                                              funcmpRTS       = "+RTS -H10m -RTS",    ---
                                              defaultDX       = 3,
                                              defaultDY       = 3,
                                              textDX          = 2,
                                              textDY          = 2,
                                              newmp           = False,
                                              prolog          = prolog',
                                              epilog          = "\\end"}


-- Existiert die Datei |file|, f"uhre |t| aus, sonst |f|.

fileExists                    :: String -> IO a -> (IOError -> IO a) -> IO a
fileExists file t f           =  catch (openFile file ReadMode
                                        >>= \h1 -> hClose h1
                                        >> t)
                                       f

-- L"osche eine Datei

clearFile                     :: String -> IO a -> (IOError -> IO a) -> IO a
clearFile file t f            =  catch (openFile file WriteMode
                                        >>= \h1 -> hClose h1
                                        >> t)
                                       f

getParameters                 :: IO Parameters
getParameters                 =  fileExists "fmp.ini"
                                      (readFile "fmp.ini"
                                       >>= \p-> let tok = tokens p
                                                in
                                                return (scanParameters tok stdParameters))
                                      (\_ -> return stdParameters)

tokens                        :: String -> [String]
tokens t                      =  if null a
                                      then []
                                      else a:tokens b
              where (a,b)     =  head (lex t)

changeParameters              :: Parameters -> String -> String -> Parameters
changeParameters p "prolog" c =  p{ prolog    = read c }
changeParameters p "epilog" c =  p{ epilog    = read c }
changeParameters p "mp_bin" c =  p{ mpBin     = read c }
changeParameters p "defaultDX" c
                              =  p{ defaultDX = read c }
changeParameters p "defaultDY" c
                              =  p{ defaultDY = read c }
changeParameters p "textDX" c =  p{ textDX    = read c }
changeParameters p "textDY" c =  p{ textDY    = read c }
changeParameters p "newmp" c  =  p{ newmp     = read c }
changeParameters p  "funcmp_rts" c
                              =  p{ funcmpRTS = read c }
changeParameters p  "funcmp_bin" c
                              =  p{ funcmpBin = read c }
changeParameters p _ _        =  p

scanParameters                :: [String] -> Parameters -> Parameters
scanParameters [] a           =  a
scanParameters (a:b:c:r) p    =  if b == "="
                                  then scanParameters r (changeParameters p a c)
                                  else scanParameters (b:c:r) p

prolog'                       :: String
prolog'                       =  "verbatimtex\n\
                                 \\\documentclass[11pt]{report}\n\
                                 \\\begin{document}\n\
                                 \etex\n\n\
                                 \input boxes\n\
                                 \input FuncMP"