module Exercise04 where
import Text.ParserCombinators.ReadP
    ( ReadP, char, many1, skipSpaces, readP_to_S, satisfy, string, munch1, (<++), eof, skipMany)

{-WETT-}
skipTagsandPlainText :: ReadP ()
skipTagsandPlainText = skipMany $ parseTag <++ parsePlain

parseTag :: ReadP String
parseTag = do
    _ <- char '<'
    str <- many1 $ satisfy (`notElem` "<>/ ")
    skipSpaces
    _ <- char '>'
    skipTagsandPlainText
    _ <- string $ "</" ++ str
    skipSpaces
    string ">"

parsePlain :: ReadP String
parsePlain = munch1 (`notElem` "<>")

xmlLightParser :: ReadP ()
xmlLightParser = do
    skipTagsandPlainText
    eof

xmlLight :: String -> Bool
xmlLight = not . (null . readP_to_S xmlLightParser)
{-TTEW-}