{-|
Module      : Gargantext.Text.Parsers.RIS
Description : 
Copyright   : (c) CNRS, 2017-Present
License     : AGPL + CECILL v3
Maintainer  : team@gargantext.org
Stability   : experimental
Portability : POSIX


RIS is a standardized tag format developed by Research Information
Systems, Incorporated (the format name refers to the company) to enable
citation programs to exchange data.

[More](https://en.wikipedia.org/wiki/RIS_(file_format))

-}

{-# LANGUAGE NoImplicitPrelude #-}
{-# LANGUAGE OverloadedStrings #-}

module Gargantext.Text.Parsers.RIS (parser, withField, fieldWith, lines) where

import Data.List (lookup)
import Control.Applicative
import Data.Attoparsec.ByteString (Parser, try, takeTill, take, many1)
import Data.Attoparsec.ByteString.Char8 (isEndOfLine)
import Data.ByteString (ByteString, concat)
import Data.Monoid ((<>))
import Gargantext.Prelude hiding (takeWhile, take)
import qualified Data.List as DL
-------------------------------------------------------------

parser :: Parser [[(ByteString, ByteString)]]
parser = do
    n  <- notice "TY  -"
    ns <- many1 (notice "\nTY  -")
    pure $ [n] <> ns

notice :: Parser ByteString -> Parser [(ByteString, ByteString)]
notice s = start *> many (fieldWith field)  <* end
    where
      field :: Parser ByteString
      field = "\n" *> take 2 <* "  - "

      start :: Parser ByteString
      start = s *> takeTill isEndOfLine

      end :: Parser ByteString
      end =  "\nER  -" *> takeTill isEndOfLine


fieldWith :: Parser ByteString -> Parser (ByteString, ByteString)
fieldWith n = do
    name  <- n
    txt   <- takeTill isEndOfLine
    txts  <- try lines
    let txts' = case DL.length txts > 0 of
            True  -> txts
            False -> []
    pure (name, concat ([txt] <> txts'))


lines :: Parser [ByteString]
lines = many line
    where
        line :: Parser ByteString
        line = "\n " *> takeTill isEndOfLine

-------------------------------------------------------------
withField :: ByteString -> (ByteString -> [(ByteString, ByteString)])
       -> [(ByteString, ByteString)] -> [(ByteString, ByteString)]
withField k f m = m <> ( maybe [] f (lookup k m) )