From 8c13c60d65b648d2723c048f176eccd61e245ad6 Mon Sep 17 00:00:00 2001
From: Sean Whitton <spwhitton@spwhitton.name>
Date: Sat, 26 Sep 2015 21:17:25 -0700
Subject: script generalised beyond just hardcoded LaTeX

---
 src/pandoc-citeproc-preamble.hs | 63 +++++++++++++++++++++++++++--------------
 1 file changed, 41 insertions(+), 22 deletions(-)

(limited to 'src')

diff --git a/src/pandoc-citeproc-preamble.hs b/src/pandoc-citeproc-preamble.hs
index 1bfa2f8..df75ed5 100644
--- a/src/pandoc-citeproc-preamble.hs
+++ b/src/pandoc-citeproc-preamble.hs
@@ -1,28 +1,47 @@
+import           Data.List        (isPrefixOf)
+import           System.Directory (doesFileExist)
+import           System.FilePath  ((<.>), (</>))
+import           System.Process   (readProcess)
 import           Text.Pandoc.JSON
 
-preamble = [ RawBlock (Format "latex") "\\section*{References}"
-           , Para [ RawInline (Format "tex") "\\setlength{\\parindent}{-0.2in}"
-                  , Space
-                  , RawInline (Format "tex") "\\singlespacing"
-                  , Space
-                  , RawInline (Format "tex") "\\small"
-                  , Space
-                  , RawInline (Format "tex") "\\setlength{\\leftskip}{0.2in}"
-                  , Space
-                  , RawInline (Format "tex") "\\setlength{\\parskip}{8pt}"
-                  , Space
-                  , RawInline (Format "tex") "\\vspace*{-0.4in}"
-                  , Space
-                  , RawInline (Format "tex") "\\noindent"
-                  ]
-           ]
-
-insertPreamble :: [Block] -> [Block]
-insertPreamble = foldr step []
+insertPreamble :: Block -> [Block] -> [Block]
+insertPreamble preamble = foldr step []
   where
-    step refs@(Div (_, ["references"], _) _) xs = preamble ++ refs : xs
+    step refs@(Div (_, ["references"], _) _) xs = preamble : refs : xs
     step x xs = x:xs
 
-main = toJSONFilter preamble
+doPreamble :: Maybe Format -> Pandoc -> IO Pandoc
+doPreamble maybeFormat input@(Pandoc meta blocks) =
+    findPreambleFile format meta
+    >>= maybe (return input)
+    (\file -> do
+          ls <- readFile file
+          return $ Pandoc meta (insertPreamble (lsBlock ls) blocks))
+  where
+    lsBlock ls = RawBlock format ls
+    format = maybe (Format "latex") id maybeFormat
+
+findPreambleFile    :: Format -> Meta -> IO (Maybe FilePath)
+findPreambleFile (Format format) meta =
+    case lookupMeta "citeproc-preamble" meta >>= toPath of
+        metadataPreamble@(Just _) -> return metadataPreamble
+        Nothing                   -> tryDatadir
   where
-    preamble (Pandoc meta blocks) = Pandoc meta (insertPreamble blocks)
+    defaultPreamble = (</> "citeproc-preamble" </> "default" <.> format)
+                      <$> getPandocDatadir
+    tryDatadir      = defaultPreamble >>= doesFileExist >>= \exists ->
+        if exists then Just <$> defaultPreamble else return Nothing
+
+getPandocDatadir :: IO FilePath
+getPandocDatadir =
+    drop (length prefix) . head . filter (prefix `isPrefixOf`) . lines
+    <$> readProcess "pandoc" ["--version"] ""
+  where
+    prefix = "Default user data directory: "
+
+toPath                :: MetaValue -> Maybe String
+toPath (MetaString s) = Just s
+toPath _              = Nothing
+
+main :: IO ()
+main = toJSONFilter doPreamble
-- 
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