{-# OPTIONS_GHC -fno-warn-orphans #-}
module Hakyll.TeX.BibTeX
    ( bibtexCompiler
    , compileBibtex
    , BibTeX
    ) where

import Prolog

import Data.List qualified as L
import Hakyll
import Text.BibTeX.Entry qualified as B
import Text.BibTeX.Format qualified as B
import Text.BibTeX.Parse qualified as B
import Text.Parsec qualified as P
import Text.Parsec.Error qualified as P

type BibTeX = B.T

deriving instance Generic B.T
instance Binary B.T

instance Writable B.T where
    write p = write p . B.entry

instance Writable [B.T] where
    write p = write p . fold . L.intersperse "\n" . fmap B.entry


compileBibtex :: (StringConv s String) => Item s -> Compiler (Item [B.T])
compileBibtex (Item i b) = either (throwError . fmap P.messageString . P.errorMessages) (pure . Item i) $ P.parse p (show i) (toSL b)
    where
        p = B.skippingLeadingSpace $ B.file <* P.eof

bibtexCompiler :: Compiler (Item [B.T])
bibtexCompiler = getResourceBody >>= compileBibtex