module Rakka.Wiki.Parser
    ( wikiPage
    )
    where

import           Rakka.Wiki
import           Text.ParserCombinators.Parsec


wikiPage :: Parser WikiPage
wikiPage = do xs <- many wikiElement
              eof
              return xs


wikiElement :: Parser WikiElement
wikiElement = ( try (blockElement >>= return . Block)
                <|>
                try (inlineElement >>= return . Inline)
              )


blockElement :: Parser BlockElement
blockElement = ( try header
                 <|>
                 try emptyLine
               )


header :: Parser BlockElement
header = foldr (<|>) pzero (map (try . header') [1..5])
    where
      header' :: Int -> Parser BlockElement
      header' n = do count n (char '=')
                     notFollowedBy (char '=')
                     ws
                     x  <- notFollowedBy (char '=') >> anyChar
                     xs <- manyTill anyChar (try $ ws >> (count n (char '=')))
                     ws
                     eol
                     return (Header n (x:xs))


emptyLine :: Parser BlockElement
emptyLine = newline >> return EmptyLine


inlineElement :: Parser InlineElement
inlineElement = text


text :: Parser InlineElement
text = do xs <- many1 (noneOf symbols)
          nl <- option "" (count 1 newline)
          return $ Text (xs ++ nl)


symbols :: [Char]
symbols = "\n"


-- white space
ws :: Parser String
ws = many (oneOf " \t")

-- end of line
eol :: Parser ()
eol = ( (newline >> return ())
        <|>
        eof
      )