{-# LANGUAGE CPP                 #-}
{-# LANGUAGE NoImplicitPrelude   #-}
{-# LANGUAGE ScopedTypeVariables #-}
module Main where
import           Prelude
import           Control.Applicative              (many, (<|>))
import           Control.Exception                as E
import           Control.Monad
import           Data.Aeson.Encode.Pretty         (Config (..), Indent (Spaces),
                                                   NumberFormat (Generic),
                                                   defConfig, encodePretty')
import           Data.Attoparsec.ByteString.Char8 as Attoparsec
import qualified Data.ByteString                  as B
import qualified Data.ByteString.Char8            as B8
import qualified Data.ByteString.Lazy             as BL
import           Data.Char                        (chr, toLower)
import           Data.List                        (group, sort)
import qualified Data.Text                        as T
import           Data.Text.Encoding               (encodeUtf8)
import           Data.Version                     (showVersion)
import           Data.Yaml.Builder                (toByteString)
import           Paths_pandoc_citeproc            (version)
import           System.Console.GetOpt
import           System.Environment               (getArgs)
import           System.Exit
import           System.FilePath                  (takeExtension)
import           System.IO
import           Text.CSL.Data                    (getLicense, getManPage)
import           Text.CSL.Exception
import           Text.CSL.Input.Bibutils          (BibFormat (..),
                                                   readBiblioString)
import           Text.CSL.Pandoc                  (processCites')
import           Text.CSL.Reference               (Literal (..),
                                                   Reference (refId))
import           Text.Pandoc.JSON                 hiding (Format)
import qualified Text.Pandoc.UTF8                 as UTF8
import           Text.Pandoc.Walk

main :: IO ()
main = do
  argv <- getArgs
  let (flags, args, errs) = getOpt Permute options argv
  let header = "Usage: pandoc-citeproc [options] [file..]"
  unless (null errs) $ do
    UTF8.hPutStrLn stderr $ usageInfo (unlines $ errs ++ [header]) options
    exitWith $ ExitFailure 1
  when (Version `elem` flags) $ do
    UTF8.putStrLn $ "pandoc-citeproc " ++ showVersion version
    exitSuccess
  when (Help `elem` flags) $ do
    UTF8.putStrLn $ usageInfo header options
    exitSuccess
  when (Man `elem` flags) $ do
    getManPage >>= BL.putStr
    exitSuccess
  when (License `elem` flags) $ do
    getLicense >>= BL.putStr
    exitSuccess

  E.handle
    (\(e :: CiteprocException) -> do
        UTF8.hPutStrLn stderr $ renderError e
        exitWith (ExitFailure 1)) $
    if Bib2YAML `elem` flags || Bib2JSON `elem` flags
       then do
         let mbformat = case [f | Format f <- flags] of
                             [x] -> readFormat x
                             _   -> Nothing
         bibformat <- case mbformat <|>
                           msum (map formatFromExtension args) of
                           Just f   -> return f
                           Nothing  -> do
                              UTF8.hPutStrLn stderr $ usageInfo
                                ("Unknown format\n" ++ header) options
                              exitWith $ ExitFailure 3
         bibstring <- case args of
                           [] -> UTF8.getContents
                           xs -> mconcat <$> mapM UTF8.readFile xs
         readBiblioString (const True) bibformat bibstring >>=
           warnDuplicateKeys >>=
           if Bib2YAML `elem` flags
              then outputYamlBlock .
                   B8.intercalate (B.singleton 10) .
                   map (unescapeTags . toByteString . (:[]))
              else B8.putStrLn . unescapeUnicode . B.concat . BL.toChunks .
                encodePretty' defConfig{ confIndent = Spaces 2
                                       , confCompare = compare
                                       , confNumFormat = Generic }
       else toJSONFilter doCites

formatFromExtension :: FilePath -> Maybe BibFormat
formatFromExtension = readFormat . dropWhile (=='.') . takeExtension

readFormat :: String -> Maybe BibFormat
readFormat = go . map toLower
  where go "biblatex"   = Just BibLatex
        go "bib"        = Just BibLatex
        go "bibtex"     = Just Bibtex
        go "json"       = Just Json
        go "yaml"       = Just Yaml
#ifdef USE_BIBUTILS
        go "ris"        = Just Ris
        go "endnote"    = Just Endnote
        go "enl"        = Just Endnote
        go "endnotexml" = Just EndnotXml
        go "xml"        = Just EndnotXml
        go "wos"        = Just Isi
        go "isi"        = Just Isi
        go "medline"    = Just Medline
        go "copac"      = Just Copac
        go "mods"       = Just Mods
#endif
        go _            = Nothing


doCites :: Pandoc -> IO Pandoc
doCites doc = do
  doc' <- processCites' doc
  let warnings = query findWarnings doc'
  mapM_ (UTF8.hPutStrLn stderr) warnings
  return doc'

findWarnings :: Inline -> [String]
findWarnings (Span (_,["citeproc-not-found"],[("data-reference-id",ref)]) _) =
  ["pandoc-citeproc: reference " ++ ref ++ " not found" | ref /= "*"]
findWarnings (Span (_,["citeproc-no-output"],_) _) =
  ["pandoc-citeproc: reference with no printed form"]
findWarnings _ = []

data Option =
      Help
    | Man
    | License
    | Version
    | Convert
    | Format String
    | Bib2YAML
    | Bib2JSON
  deriving (Ord, Eq, Show)

options :: [OptDescr Option]
options =
  [ Option ['h'] ["help"] (NoArg Help) "show usage information"
  , Option [] ["man"] (NoArg Man) "print man page to stdout"
  , Option [] ["license"] (NoArg License) "print license to stdout"
  , Option ['V'] ["version"] (NoArg Version) "show program version"
  , Option ['y'] ["bib2yaml"] (NoArg Bib2YAML) "convert bibliography to YAML"
  , Option ['j'] ["bib2json"] (NoArg Bib2JSON) "convert bibliography to JSON"
  , Option ['f'] ["format"] (ReqArg Format "FORMAT") "bibliography format"
  ]

warnDuplicateKeys :: [Reference] -> IO [Reference]
warnDuplicateKeys refs = mapM_ warnDup dupKeys >> return refs
  where warnDup k = UTF8.hPutStrLn stderr $ "biblio2yaml: duplicate key " ++ k
        allKeys   = map (unLiteral . refId) refs
        dupKeys   = [x | (x:_:_) <- group (sort allKeys)]

outputYamlBlock :: B.ByteString -> IO ()
outputYamlBlock contents = do
  UTF8.putStrLn "---\nreferences:"
  B.putStr contents
  UTF8.putStrLn "..."

-- turn
-- id: ! "\u043F\u0443\u043D\u043A\u04423"
-- into
-- id: пункт3
unescapeTags :: B.ByteString -> B.ByteString
unescapeTags bs = case parseOnly (many $ tag <|> other) bs of
                       Left e  -> error e
                       Right r -> B.concat r

unescapeUnicode :: B.ByteString -> B.ByteString
unescapeUnicode bs = case parseOnly (many other) bs of
                       Left e  -> error e
                       Right r -> B.concat r

tag :: Attoparsec.Parser B.ByteString
tag = do
  _ <- string $ B8.pack ": ! "
  c <- char '\'' <|> char '"'
  cs <- manyTill (escaped c <|> other) (char c)
  return $ B8.pack ": " <> B8.singleton c <> B.concat cs <> B8.singleton c

escaped :: Char -> Attoparsec.Parser B.ByteString
escaped c = string $ B8.pack ['\\',c]

other :: Attoparsec.Parser B.ByteString
other = uchar <|> Attoparsec.takeWhile1 notspecial <|> regchar
  where notspecial = not . inClass ":!\\\"'"

uchar :: Attoparsec.Parser B.ByteString
uchar = do
  _ <- char '\\'
  num <- (2 <$ char 'x') <|> (4 <$ char 'u') <|> (8 <$ char 'U')
  cs <- count num $ satisfy $ inClass "0-9a-fA-F"
  let n = read ('0':'x':cs)
  return $ encodeUtf8 $ T.pack [chr n]

regchar :: Attoparsec.Parser B.ByteString
regchar = B8.singleton <$> anyChar