{-# LANGUAGE PatternGuards #-}
{-
Copyright (C) 2008 Andrea Rossato <andrea.rossato@ing.unitn.it>

This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
-}

{- |
   Module      : Text.Pandoc.Biblio
   Copyright   : Copyright (C) 2008 Andrea Rossato
   License     : GNU GPL, version 2 or above

   Maintainer  : Andrea Rossato <andrea.rossato@ing.unitn.it>
   Stability   : alpha
   Portability : portable
-}

module Text.Pandoc.Biblio ( processBiblio ) where

import Control.Monad ( when )
import Data.List
import Text.CSL
import Text.Pandoc.Definition

-- | Process a 'Pandoc' document by adding citations formatted
-- according to a CSL style, using 'citeproc' from citeproc-hs.
processBiblio :: String -> [Reference] -> Pandoc -> IO Pandoc
processBiblio cf r p
    = if null r then return p
      else do
        when (null cf) $ error "Missing the needed citation style file"
        csl  <- readCSLFile cf
        let groups     = queryWith getCite p
            result     = citeproc csl r groups
            cits_map   = zip groups (citations result)
            biblioList = map (read . renderPandoc' csl) (bibliography result)
            Pandoc m b = processWith (processCite csl cits_map) p
        return $ Pandoc m $ b ++ biblioList

-- | Substitute 'Cite' elements with formatted citations.
processCite :: Style -> [([Target],[FormattedOutput])] -> Inline -> Inline
processCite s cs il
    | Cite t _ <- il = Cite t (process t)
    | otherwise      = il
    where
      process t = case elemIndex t (map fst cs) of
                    Just i -> read . renderPandoc s $ snd (cs !! i)
                    Nothing -> [Str ("Error processing " ++ show t)]

-- | Retrieve all citations from a 'Pandoc' docuument. To be used with
-- 'queryWith'.
getCite :: Inline -> [[(String,String)]]
getCite i | Cite t _ <- i = [t]
          | otherwise     = []