import System.IO
import System.Environment
import Data.Char
import System.Directory

main = do
 fileList <- listDirectory "."
 let texFiles = reverseElts (getTexFiles (reverseElts fileList))
 convertAndWrite texFiles

data Mode = Search | Command | Comment

convertTex :: String -> Mode -> String

convertTex ('%':bs) Search = "<comment>%" ++ convertTex bs Comment
convertTex ['\n'] Comment = "</comment>"
convertTex ('\n':bs) Comment = "</comment><br>\n" ++ convertTex bs Search
convertTex (b:bs) Comment = (b:convertTex bs Comment)
convertTex [] Comment = "</comment>"

convertTex (b:bs) Search
 | b == '{' || b == '}' || b == '[' || b == ']' = "<brace>" ++ [b] ++ "</brace>" ++ convertTex bs Search
convertTex ['\n'] Search = []
convertTex ('\n':b) Search = "<br>\n" ++ convertTex b Search

convertTex ('\\':'d':'o':'c':'u':'m':'e':'n':'t':'c':'l':'a':'s':'s':b) Search = "<dc>\\documentclass</dc>" ++ convertTex b Search
convertTex ('\\':'b':'e':'g':'i':'n':b) Search = "<env>\\begin</env>" ++ convertTex b Search
convertTex ('\\':'u':'s':'e':'p':'a':'c':'k':'a':'g':'e':b) Search = "<preamb>\\usepackage</preamb>" ++ convertTex b Search
convertTex ('\\':'e':'n':'d':b) Search = "<env>\\end</env>" ++ convertTex b Search

convertTex ('\\':bs) Search = "<texcommand>\\" ++ convertTex bs Command
convertTex (b:bs) Search = (b:convertTex bs Search)
convertTex (b:bs) Command
 | isLetter b = (b:convertTex bs Command) 
 | otherwise = "</texcommand>" ++ convertTex (b:bs) Search

convertTex [] Command = "</texcommand>"
convertTex [] Search = []

reverseElts :: [String] -> [String]
reverseElts (a:as) = ((reverse a):reverseElts as)
reverseElts [] = []

getTexFiles :: [String] -> [String]
getTexFiles (('x':'e':'t':'.':as):b) = (as:getTexFiles b)
getTexFiles (b:bs) = getTexFiles bs
getTexFiles [] = []

convertAndWrite :: [String] -> IO()
convertAndWrite [] = do return()
convertAndWrite (a:as) = do
 tex <- readFile (a ++ ".tex")
 writeFile (a ++ ".conv") (convertTex tex Search)
 convertAndWrite as