module Main (main) where
import System(getArgs)

server = "news.studfb.unibw-muenchen.de"
port = "119"

prefix  = "#!/usr/local/bin/expect\n"++
          "spawn /usr/bin/telnet "++server++' ':port++"\n"++
          "expect 200\n"++
          "send \"POST\\r\"\n"++
          "expect 340\n"
postfix = "\n"++
          "send \"\\r\"\n"++
          "send \".\\r\"\n"++
          "expect 240\n"++
          "send \"q\\r\"\n"


main = getArgs >>= runMain

runMain :: [String] -> IO ()
runMain args = 
  do
    let source = args!!0
    let destination = source++".sh" 
    c<-readFile source 
    let text = prefix ++ (unlines.walkThrough.lines $ c) ++ postfix
    writeFile destination text 

walkThrough::[String]->[String]
walkThrough [] = []
walkThrough (x:xs) | x=="" = map (\x->"send \""++tagSpecialChars x++"\\r\"") (x:xs)
                   | startsWith x "From:" || startsWith x "Newsgroups:" || startsWith x "Subject:" = 
                        ("send \""++handle x++"\\r\""):walkThrough xs
                   | otherwise = walkThrough xs --omit other headers

startsWith x [] = True
startsWith (x:xs) (y:ys) | x == y = startsWith xs ys
                         | otherwise = False

--unfortunately there are some problems with signatures, they are not accepted
--will look at the protocol spec later
tagSpecialChars ('-':'-':xs) = []
--a point represents end of message -> must not occur in the message
tagSpecialChars (".") = ("..")
tagSpecialChars xs = handle xs
--probably some special cases are still missing

--tag brackets
handle [] = []
handle ('[':xs) = "\\["++handle xs
handle (']':xs) = "\\]"++handle xs
handle ('\"':xs) = "\\\""++handle xs
handle (x:xs) = x:handle xs