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pandoc-3.12.1: src/Text/Pandoc/Writers/OpenDocument.hs

{-# LANGUAGE FlexibleContexts  #-}
{-# LANGUAGE LambdaCase        #-}
{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE PatternGuards     #-}
{- |
   Module      : Text.Pandoc.Writers.OpenDocument
   Copyright   : Copyright (C) 2008-2020 Andrea Rossato and John MacFarlane
   License     : GNU GPL, version 2 or above

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

Conversion of 'Pandoc' documents to OpenDocument XML.
-}
module Text.Pandoc.Writers.OpenDocument ( writeOpenDocument ) where
import Control.Monad (unless, liftM, when)
import Control.Monad.State.Strict ( StateT(..), modify, gets, lift )
import Data.Char (chr, isDigit)
import Data.List (sortOn, sortBy)
import qualified Data.List as L
import qualified Data.Map as Map
import Data.Ord (comparing, Down (Down))
import qualified Data.Set as Set
import Data.Text (Text)
import qualified Data.Text as T
import Text.Collate.Lang (Lang (..), parseLang)
import Text.Pandoc.Class.PandocMonad (PandocMonad, report)
import Text.Pandoc.Translations (translateTerm)
import Text.Pandoc.Definition
import qualified Text.Pandoc.Builder as B
import Text.Pandoc.Logging
import Text.Pandoc.Options
import Text.DocLayout hiding (link)
import Text.Pandoc.Shared (linesToPara, tshow, blocksToInlines)
import Text.Pandoc.Templates (renderTemplate)
import qualified Text.Pandoc.Translations as Term (Term(Figure, Table))
import Text.Pandoc.Walk
import Text.Pandoc.Writers.Math
import Text.Pandoc.Writers.Shared
import qualified Text.Pandoc.Writers.AnnotatedTable as Ann
import Text.Pandoc.XML
import Text.Printf (printf)
import Text.Pandoc.Highlighting (highlight)
import Skylighting (FormatOptions(..), SourceLine, Token)

-- | Auxiliary function to convert Plain block to Para.
plainToPara :: Block -> Block
plainToPara (Plain x) = Para x
plainToPara x         = x

-- Names of predefined styles in the reference.odt; see data/odt/styles.xml.
defaultBulletListStyleName, defaultNumberedListStyleName :: Text
defaultBulletListStyleName   = "List_20_1"
defaultNumberedListStyleName = "Numbering_20_1"

bulletItemStyleName, bulletItemTightStyleName,
  numberItemStyleName, numberItemTightStyleName :: Text
bulletItemStyleName      = "List_20_Bullet"
bulletItemTightStyleName = "List_20_Bullet_20_Tight"
numberItemStyleName      = "List_20_Number"
numberItemTightStyleName = "List_20_Number_20_Tight"

-- | Predefined inline style names for single-style spans.
wellKnownTextStyle :: Set.Set TextStyle -> Maybe Text
wellKnownTextStyle s = case Set.toList s of
  [Italic] -> Just "Emphasis"
  [Bold]   -> Just "Strong_20_Emphasis"
  [Strike] -> Just "Strikeout"
  [Sub]    -> Just "Subscript"
  [Sup]    -> Just "Superscript"
  [Pre]    -> Just "Source_20_Text"
  _        -> Nothing

--
-- OpenDocument writer
--

type OD m = StateT WriterState m

data ReferenceType
  = HeaderRef
  | TableRef
  | FigureRef

data Direction = LTR | RTL
  deriving (Show, Eq, Ord)

data WriterState =
    WriterState { stNoteCount      :: Int
                , stTableStyles    :: [Doc Text]
                , stTableStyleCount :: Int
                , stParaStyles     :: [Doc Text]
                , stParaStyleCount :: Int
                , stParaStyleCache :: Map.Map ([(Text,Text)],[(Text,Text)]) Text
                  -- ^ cache of automatic paragraph styles, keyed on
                  -- (style attributes, paragraph properties)
                , stListOverrides  :: Map.Map (ListNumberStyle,ListNumberDelim)
                                        (Text, Doc Text)
                , stTextStyles     :: Map.Map (Set.Set TextStyle)
                                        (Int, Doc Text)
                  -- ^ automatic text styles, with the number that
                  -- makes up the style's @Tn@ name
                , stTextStyleAttr  :: Set.Set TextStyle
                , stIndentPara     :: Int
                , stInDefinition   :: Bool
                , stFirstPara      :: Bool
                , stImageId        :: Int
                , stTableCaptionId :: Int
                , stImageCaptionId :: Int
                , stIdentTypes     :: Map.Map Text ReferenceType
                , stDirection      :: Maybe Direction
                  -- ^ active writing mode
                }

defaultWriterState :: WriterState
defaultWriterState =
    WriterState { stNoteCount      = 0
                , stTableStyles    = []
                , stTableStyleCount = 0
                , stParaStyles     = []
                , stParaStyleCount = 0
                , stParaStyleCache = Map.empty
                , stListOverrides  = Map.empty
                , stTextStyles     = Map.empty
                , stTextStyleAttr  = Set.empty
                , stIndentPara     = 0
                , stInDefinition   = False
                , stFirstPara      = False
                , stImageId        = 1
                , stTableCaptionId = 1
                , stImageCaptionId = 1
                , stIdentTypes     = Map.empty
                , stDirection      = Nothing
                }

addTableStyle :: PandocMonad m => Doc Text -> OD m ()
addTableStyle i = modify $ \s ->
  s { stTableStyles = i : stTableStyles s
    , stTableStyleCount = stTableStyleCount s + 1 }

addParaStyle :: PandocMonad m => Doc Text -> OD m ()
addParaStyle i = modify $ \s ->
  s { stParaStyles = i : stParaStyles s
    , stParaStyleCount = stParaStyleCount s + 1 }

addTextStyle :: PandocMonad m
             => Set.Set TextStyle -> (Int, Doc Text) -> OD m ()
addTextStyle attrs i = modify $ \s ->
  s { stTextStyles = Map.insert attrs i (stTextStyles s) }

increaseIndent :: PandocMonad m => OD m ()
increaseIndent = modify $ \s -> s { stIndentPara = 1 + stIndentPara s }

resetIndent :: PandocMonad m => OD m ()
resetIndent = modify $ \s -> s { stIndentPara = stIndentPara s - 1 }

setInDefinitionList :: PandocMonad m => Bool -> OD m ()
setInDefinitionList b = modify $  \s -> s { stInDefinition = b }

setFirstPara :: PandocMonad m => OD m ()
setFirstPara =  modify $  \s -> s { stFirstPara = True }

inParagraphTags :: PandocMonad m => Doc Text -> OD m (Doc Text)
inParagraphTags d = do
  b <- gets stFirstPara
  sty <- if b
         then do modify $ \st -> st { stFirstPara = False }
                 return "First_20_paragraph"
         else    return "Text_20_body"
  sty' <- dirStyleFor sty
  return $ inTags False "text:p" [("text:style-name", sty')] d

inParagraphTagsWithStyle :: Text -> Doc Text -> Doc Text
inParagraphTagsWithStyle sty = inTags False "text:p" [("text:style-name", sty)]

inSpanTags :: Text -> Doc Text -> Doc Text
inSpanTags s = inTags False "text:span" [("text:style-name",s)]

withAlteredTextStyles :: PandocMonad m
                       => (Set.Set TextStyle -> Set.Set TextStyle) -> OD m a -> OD m a
withAlteredTextStyles f action = do
  oldTextStyleAttr <- gets stTextStyleAttr
  modify $ \st -> st{ stTextStyleAttr = f oldTextStyleAttr }
  res <- action
  modify $ \st -> st{ stTextStyleAttr = oldTextStyleAttr }
  return res

withTextStyle :: PandocMonad m => TextStyle -> OD m a -> OD m a
withTextStyle s = withAlteredTextStyles (Set.insert s)

withDirection :: PandocMonad m => Maybe Direction -> OD m a -> OD m a
withDirection mbdir action = do
  olddir <- gets stDirection
  modify $ \st -> st{ stDirection = mbdir }
  res <- action
  modify $ \st -> st{ stDirection = olddir }
  return res

-- | Apply the writing direction from a @dir@ attribute, if present.
withDirFromAttr :: PandocMonad m => Attr -> OD m a -> OD m a
withDirFromAttr (_,_,kvs) action =
  case lookup "dir" kvs of
    Just "rtl" -> withDirection (Just RTL) action
    Just "ltr" -> withDirection (Just LTR) action
    _          -> action

inTextStyle :: PandocMonad m => Doc Text -> OD m (Doc Text)
inTextStyle d = do
  at <- gets stTextStyleAttr
  if Set.null at
     then return d
     else case wellKnownTextStyle at of
       Just styleName -> return $
         inTags False "text:span" [("text:style-name", styleName)] d
       Nothing -> do
         styles <- gets stTextStyles
         case Map.lookup at styles of
              Just (num, _) -> return $
                inTags False "text:span"
                  [("text:style-name", textStyleName num)] d
              Nothing -> do
                let num = Map.size styles + 1
                    styleName = textStyleName num
                addTextStyle at (num,
                       inTags False "style:style"
                         [("style:name", styleName)
                         ,("style:family", "text")]
                         $ selfClosingTag "style:text-properties"
                            (sortOn fst . Map.toList
                                  $ L.foldl' textStyleAttr mempty (Set.toList at)))
                return $ inTags False
                    "text:span" [("text:style-name",styleName)] d

-- | Name of the @n@th automatic text style.
textStyleName :: Int -> Text
textStyleName num = "T" <> tshow num

formulaStyles :: [Doc Text]
formulaStyles = [formulaStyle InlineMath, formulaStyle DisplayMath]

formulaStyle :: MathType -> Doc Text
formulaStyle mt = inTags False "style:style"
  [("style:name", if mt == InlineMath then "fr1" else "fr2")
  ,("style:family", "graphic")
  ,("style:parent-style-name", "Formula")]
  $ selfClosingTag "style:graphic-properties" $ if mt == InlineMath then
                                                  [("style:vertical-pos", "middle")
                                                  ,("style:vertical-rel", "text")]
                                                else
                                                  [("style:vertical-pos",   "middle")
                                                  ,("style:vertical-rel",   "text")
                                                  ,("style:horizontal-pos", "center")
                                                  ,("style:horizontal-rel", "paragraph-content")
                                                  ,("style:wrap",           "none")]

inBookmarkTags :: Text -> Doc Text -> Doc Text
inBookmarkTags ident d =
  selfClosingTag "text:bookmark-start" [ ("text:name", ident) ]
  <> d <>
  selfClosingTag "text:bookmark-end" [ ("text:name", ident) ]

selfClosingBookmark :: Text -> Doc Text
selfClosingBookmark ident =
  selfClosingTag "text:bookmark" [("text:name", ident)]

inHeaderTags :: PandocMonad m => Int -> Text -> Doc Text -> OD m (Doc Text)
inHeaderTags i ident d = do
  sty <- dirStyleFor ("Heading_20_" <> tshow i)
  return $ inTags False "text:h" [ ("text:style-name", sty)
                                 , ("text:outline-level", tshow i)]
         $ if T.null ident
              then d
              else inBookmarkTags ident d

inQuotes :: QuoteType -> Doc Text -> Doc Text
inQuotes SingleQuote s = char '\8216' <> s <> char '\8217'
inQuotes DoubleQuote s = char '\8220' <> s <> char '\8221'

handleSpaces :: Text -> Doc Text
handleSpaces s = case T.uncons s of
  Just (' ', _) -> genTag s
  Just ('\t',x) -> tabTag <> rm x
  _             -> rm s
  where
    tabTag = selfClosingTag "text:tab" []
    -- collapse a run of spaces into a single <text:s>
    genTag t = let (spaces, t') = T.span (== ' ') t
               in  tag (T.length spaces) <> rm t'
    tag 0  = empty
    tag n  = selfClosingTag "text:s" [("text:c", tshow n)]
    -- emit text verbatim up to the next space or tab; a lone space is
    -- kept literal and any further ones become a <text:s>
    rm t = let (chunk, t') = T.break (\c -> c == ' ' || c == '\t') t
               pre = if T.null chunk then empty else literal chunk
           in  case T.uncons t' of
                 Just (' ', xs) -> pre <> char ' ' <> genTag xs
                 Just (_  , xs) -> pre <> tabTag <> genTag xs
                 Nothing        -> pre

-- | Convert Pandoc document to string in OpenDocument format.
writeOpenDocument :: PandocMonad m => WriterOptions -> Pandoc -> m Text
writeOpenDocument opts (Pandoc meta blocks) = do
  setupTranslations meta
  let colwidth = if writerWrapText opts == WrapAuto
                    then Just $ writerColumns opts
                    else Nothing
  -- The abstract is the one template field that takes block-level
  -- content, so it is rendered separately; everything else in the
  -- metadata goes in a context where only inlines are allowed.
  let abstractBlocks = case lookupMetaBlocks "abstract" meta of
                         [] -> []
                         xs -> [Div ("",[],[("custom-style","Abstract")]) xs]
  let meta' = B.deleteMeta "abstract" meta
  -- Set the default writing direction from the "dir" metadata field;
  -- in its absence, a right-to-left main language implies RTL.
  let mbDir = case lookupMetaString "dir" meta of
                "rtl" -> Just RTL
                "ltr" -> Nothing
                _     -> case getLang opts meta of
                           Just l | Right lang <- parseLang l
                                  , isRTLLang lang -> Just RTL
                           _ -> Nothing
  ((body, abstract, metadata),s) <- flip runStateT
        defaultWriterState{ stDirection = mbDir } $ do
           let collectBlockIdent (Header _ attr _)      = identRef HeaderRef attr
               collectBlockIdent (Figure attr _ _ )     = identRef FigureRef attr
               collectBlockIdent (Table attr _ _ _ _ _) = identRef TableRef attr
               collectBlockIdent _                      = []
               identRef ty (ident,_,_)
                 | T.null ident = []
                 | otherwise    = [(ident, ty)]
           -- only needed to resolve cross references
           when (isEnabled Ext_xrefs_name opts ||
                 isEnabled Ext_xrefs_number opts) $
             modify $ \s -> s{ stIdentTypes =
                                 Map.fromListWith (\_ old -> old)
                                   (query collectBlockIdent blocks) }
           m <- metaToContext opts
                  (inlinesToOpenDocument opts . blocksToInlines)
                  (fmap chomp . inlinesToOpenDocument opts)
                  meta'
           a <- blocksToOpenDocument opts abstractBlocks
           b <- blocksToOpenDocument opts blocks
           return (b, a, m)
  -- 'styles' is reversed below, so the text styles are put in
  -- descending order here to come out as T1, T2, ..., T10
  let styles   = stTableStyles s ++ stParaStyles s ++ formulaStyles ++
                     map snd (sortBy (comparing (Down . fst)) (
                        Map.elems (stTextStyles s)))
  let listStyles  = map snd (Map.elems (stListOverrides s))
  let automaticStyles = vcat $ reverse styles ++ listStyles
  let context = defField "body" body
              . defField "toc" (writerTableOfContents opts)
              . defField "toc-depth" (tshow $ writerTOCDepth opts)
              . defField "automatic-styles" automaticStyles
              . (if null abstractBlocks
                    then id
                    else defField "abstract" abstract)
              $ metadata
  return $ render colwidth $
    case writerTemplate opts of
       Nothing  -> body
       Just tpl -> renderTemplate tpl context

withParagraphStyle :: PandocMonad m
                   => WriterOptions -> Text -> [Block] -> OD m (Doc Text)
withParagraphStyle o s bs = do
  s' <- dirStyleFor s
  -- 'Plain' is treated like 'Para' so that the requested style is not
  -- lost (e.g. for metadata fields, figure bodies, or tight list items)
  let go (b:bs')
        | Para  l <- b = cont bs' =<< styled l
        | Plain l <- b = cont bs' =<< styled l
        | otherwise    = cont bs' =<< blockToOpenDocument o b
      go [] = return empty
      cont bs' i = (<>) i <$> go bs'
      styled l = inParagraphTagsWithStyle s' <$> inlinesToOpenDocument o l
  go bs

inPreformattedTags :: [Doc Text] -> Doc Text
inPreformattedTags s =
  inParagraphTagsWithStyle "Preformatted_20_Text" $ hcat s

-- | Get the list-style name to use for an ordered list with the given
-- numbering style and delimiter, registering an override automatic style
-- if needed.  Lists with default style/delimiter use the predefined
-- @Numbering_20_1@ style and no override is generated.
orderedListStyleName :: PandocMonad m
                     => ListNumberStyle -> ListNumberDelim -> OD m Text
orderedListStyleName ns nd
  | (ns == DefaultStyle || ns == Decimal) &&
    (nd == DefaultDelim || nd == Period) =
      return defaultNumberedListStyleName
  | otherwise = do
      overrides <- gets stListOverrides
      case Map.lookup (ns, nd) overrides of
        Just (name, _) -> return name
        Nothing -> do
          let name = "Pandoc_5f_Numbering_5f_" <>
                       tshow (Map.size overrides + 1)
              doc = inTags True "text:list-style"
                      [("style:name", name)]
                      (vcat (map (orderedListLevel ns nd) [1..10]))
          modify $ \s -> s { stListOverrides =
                               Map.insert (ns, nd) (name, doc)
                                          (stListOverrides s) }
          return name

orderedListLevel :: ListNumberStyle -> ListNumberDelim -> Int -> Doc Text
orderedListLevel ns nd lvl =
    let suffix = case nd of
                   OneParen  -> [("style:num-suffix", ")")]
                   TwoParens -> [("style:num-prefix", "(")
                                ,("style:num-suffix", ")")]
                   _         -> [("style:num-suffix", ".")]
        format = case ns of
                   UpperAlpha -> "A"
                   LowerAlpha -> "a"
                   UpperRoman -> "I"
                   LowerRoman -> "i"
                   _          -> "1"
    in inTags True "text:list-level-style-number"
              ([ ("text:level"      , tshow lvl)
               , ("text:style-name" , "Numbering_20_Symbols")
               , ("style:num-format", format)
               ] ++ suffix)
              (selfClosingTag "style:list-level-properties"
                 [ ("text:space-before",
                      T.pack (printf "%.4fin" (0.1972 * fromIntegral (lvl - 1) :: Double)))
                 , ("text:min-label-width", "0.1965in")
                 , ("text:min-label-distance", "0.1in")
                 ])

orderedListToOpenDocument :: PandocMonad m
                          => WriterOptions -> Text -> [[Block]]
                          -> OD m (Doc Text)
orderedListToOpenDocument o paraName bs =
    vcat . map (inTagsIndented "text:list-item") <$>
    mapM (orderedItemToOpenDocument o paraName . map plainToPara) bs

orderedItemToOpenDocument :: PandocMonad m
                          => WriterOptions -> Text -> [Block]
                          -> OD m (Doc Text)
orderedItemToOpenDocument  o paraName bs = vcat <$> mapM go bs
 where go (OrderedList a l) = orderedList a l
       go (Para          l) = do
         sty <- dirStyleFor paraName
         inParagraphTagsWithStyle sty <$> inlinesToOpenDocument o l
       go b                 = blockToOpenDocument o b
       orderedList a@(_,ns,nd) l = do
         lstName <- orderedListStyleName ns nd
         let pn = if isTightList l then numberItemTightStyleName
                                   else numberItemStyleName
         let listAttrs = ("text:style-name", lstName) : startValueAttr a
         inTags True "text:list" listAttrs <$>
           orderedListToOpenDocument o pn l

-- | Generate a @text:start-value@ attribute when the start value is not 1.
startValueAttr :: ListAttributes -> [(Text, Text)]
startValueAttr (s,_,_) | s /= 1 = [("text:start-value", tshow s)]
startValueAttr _                = []

isTightList :: [[Block]] -> Bool
isTightList []          = False
isTightList (b:_)
    | Plain {} : _ <- b = True
    | otherwise         = False

bulletListToOpenDocument :: PandocMonad m
                         => WriterOptions -> [[Block]] -> OD m (Doc Text)
bulletListToOpenDocument o b = do
  let pn = if isTightList b then bulletItemTightStyleName
                            else bulletItemStyleName
  is <- listItemsToOpenDocument pn o b
  return $ inTags True "text:list"
             [("text:style-name", defaultBulletListStyleName)] is

listItemsToOpenDocument :: PandocMonad m
                        => Text -> WriterOptions -> [[Block]] -> OD m (Doc Text)
listItemsToOpenDocument s o is =
    vcat . map (inTagsIndented "text:list-item") <$> mapM (withParagraphStyle o s . map plainToPara) is

deflistItemToOpenDocument :: PandocMonad m
                          => WriterOptions -> ([Inline],[[Block]]) -> OD m (Doc Text)
deflistItemToOpenDocument o (t,d) = do
  let ts = if isTightList d
           then "Definition_20_Term_20_Tight"       else "Definition_20_Term"
      ds = if isTightList d
           then "Definition_20_Definition_20_Tight" else "Definition_20_Definition"
  t' <- withParagraphStyle o ts [Para t]
  d' <- liftM vcat $ mapM (withParagraphStyle o ds . map plainToPara) d
  return $ t' $$ d'

inBlockQuote :: PandocMonad m
             => WriterOptions -> Text -> [Block] -> OD m (Doc Text)
inBlockQuote  o sty (b:bs)
    | BlockQuote l <- b = do increaseIndent
                             ni <- paraStyle
                                   [("style:parent-style-name","Quotations")]
                             inner <- inBlockQuote o ni (map plainToPara l)
                             resetIndent
                             go inner
    | Para       l <- b = go =<< inParagraphTagsWithStyle sty <$> inlinesToOpenDocument o l
    | otherwise         = go =<< blockToOpenDocument o b
    where go  block  = ($$) block <$> inBlockQuote o sty bs
inBlockQuote     _ _ [] = return empty

-- | Convert a list of Pandoc blocks to OpenDocument.
blocksToOpenDocument :: PandocMonad m => WriterOptions -> [Block] -> OD m (Doc Text)
blocksToOpenDocument o b = vcat <$> mapM (blockToOpenDocument o) b

-- | Convert a Pandoc block element to OpenDocument.
blockToOpenDocument :: PandocMonad m => WriterOptions -> Block -> OD m (Doc Text)
blockToOpenDocument o = \case
    Plain          b -> if null b
                        then return empty
                        else inParagraphTags =<< inlinesToOpenDocument o b
    Para           b -> if null b &&
                           not (isEnabled Ext_empty_paragraphs o)
                        then return empty
                        else inParagraphTags =<< inlinesToOpenDocument o b
    LineBlock      b -> blockToOpenDocument o $ linesToPara b
    Div attr xs      -> mkDiv attr xs
    Header     i (ident,_,_) b -> do
      setFirstPara
      inHeaderTags i ident =<< inlinesToOpenDocument o b
    BlockQuote     b -> setFirstPara >> mkBlockQuote b
    DefinitionList b -> setFirstPara >> defList b
    BulletList     b -> setFirstPara >> bulletListToOpenDocument o b
    OrderedList  a b -> setFirstPara >> orderedList a b
    CodeBlock attrs s -> do
      setFirstPara
      let highlighted =
            case highlight (writerSyntaxMap o) formatOpenDocument attrs s of
                Right h  -> return $ flush . vcat $ map (inTags True "text:p"
                                          [("text:style-name",
                                            "Preformatted_20_Text")] . hcat) h
                Left msg -> do
                  unless (T.null msg) $ report $ CouldNotHighlight msg
                  unhighlighted s
      case writerHighlightMethod o of
        Skylighting {} -> highlighted
        DefaultHighlighting -> highlighted
        _ -> unhighlighted s
    Table a bc s th tb tf -> setFirstPara >>
                              table o (Ann.toTable a bc s th tb tf)
    HorizontalRule   -> setFirstPara >> return (selfClosingTag "text:p"
                         [ ("text:style-name", "Horizontal_20_Line") ])
    b@(RawBlock f s) -> if f == Format "opendocument"
                        then return $ literal s
                        else empty <$ report (BlockNotRendered b)
    Figure a capt b  -> figure o a capt b
    where
      defList       b = do setInDefinitionList True
                           r <- vcat  <$> mapM (deflistItemToOpenDocument o) b
                           setInDefinitionList False
                           return r
      unhighlighted s = pure $ flush . vcat $
            (map ((inPreformattedTags . (:[])) . preformatted) (T.lines s))
      mkDiv    attr s = do
        let (ident,_,kvs) = attr
            i = withDirFromAttr attr $ withLangFromAttr attr $
                case lookup "custom-style" kvs of
                  Just sty -> withParagraphStyle o sty s
                  _        -> blocksToOpenDocument o s
            mkBookmarkedDiv = inTags False "text:section" [("text:name", ident)]
        if T.null ident
          then i
          else fmap mkBookmarkedDiv i
      mkBlockQuote  b = do sty <- paraStyle
                                    [("style:parent-style-name","Quotations")]
                           inBlockQuote o sty (map plainToPara b)
      orderedList a@(_,ns,nd) b = do
        lstName <- orderedListStyleName ns nd
        let pn = if isTightList b then numberItemTightStyleName
                                  else numberItemStyleName
        let listAttrs = ("text:style-name", lstName) : startValueAttr a
        inTags True "text:list" listAttrs <$>
          orderedListToOpenDocument o pn b
      table :: PandocMonad m => WriterOptions -> Ann.Table -> OD m (Doc Text)
      table opts
          (Ann.Table (ident, _, _) (Caption _ c) colspecs thead tbodies tfoot) = do
        tn <- gets stTableStyleCount
        pn <- gets stParaStyleCount
        let  genIds      = map colLetters [0..]
             name        = "Table" <> tshow (tn + 1)
             (aligns, mwidths) = unzip colspecs
             fromWidth (ColWidth w) | w > 0 = w
             fromWidth _                    = 0
             widths = map fromWidth mwidths
             textWidth   = sum widths
             columnIds   = zip genIds widths
             mkColumn  n = selfClosingTag "table:table-column" [("table:style-name", name <> "." <> fst n)]
             columns     = map mkColumn columnIds
             paraHStyles = paraTableStyles "Heading"  pn aligns
             paraStyles  = paraTableStyles "Contents" (pn + length (newPara paraHStyles)) aligns
             newPara     = map snd . filter (not . isEmpty . snd)
        addTableStyle $ tableStyle tn textWidth columnIds
        mapM_ addParaStyle . newPara $ paraHStyles ++ paraStyles
        captionDoc <- if null c
                      then return empty
                      else inlinesToOpenDocument o (blocksToInlines c) >>=
                             if isEnabled Ext_native_numbering o
                                then numberedTableCaption ident
                                else unNumberedCaption "TableCaption"
        th <- colHeadsToOpenDocument o (map fst paraHStyles) thead
        tr <- mapM (tableBodyToOpenDocument o (map fst paraHStyles) (map fst paraStyles)) tbodies
        tf <- tableFootToOpenDocument o (map fst paraStyles) tfoot
        let tableDoc = inTags True "table:table" [
                            ("table:name"      , name)
                          , ("table:style-name", name)
                          ] (vcat columns $$ th $$ vcat tr $$ tf)
        return $
          case writerTableCaptionPosition opts of
            CaptionAbove -> captionDoc $$ tableDoc
            CaptionBelow -> tableDoc $$ captionDoc
      figure opts (ident, _, _) (Caption _ longcapt) body =
        case blocksToInlines longcapt of
          [] ->
            withParagraphStyle o "Figure" body
          caption -> do
            imageDoc <- withParagraphStyle o "FigureWithCaption" body
            captionDoc <- inlinesToOpenDocument o caption >>=
                          if isEnabled Ext_native_numbering o
                          then numberedFigureCaption ident
                          else unNumberedCaption "FigureCaption"
            return $
              case writerFigureCaptionPosition opts of
                CaptionAbove -> captionDoc $$ imageDoc
                CaptionBelow -> imageDoc $$ captionDoc


numberedTableCaption :: PandocMonad m => Text -> Doc Text -> OD m (Doc Text)
numberedTableCaption ident caption = do
    id' <- gets stTableCaptionId
    modify (\st -> st{ stTableCaptionId = id' + 1 })
    capterm <- translateTerm Term.Table
    sty <- dirStyleFor "TableCaption"
    return $ numberedCaption sty capterm "Table" id' ident caption

numberedFigureCaption :: PandocMonad m => Text -> Doc Text -> OD m (Doc Text)
numberedFigureCaption ident caption = do
    id' <- gets stImageCaptionId
    modify (\st -> st{ stImageCaptionId = id' + 1 })
    capterm <- translateTerm Term.Figure
    sty <- dirStyleFor "FigureCaption"
    return $ numberedCaption sty capterm  "Illustration" id' ident caption

numberedCaption :: Text -> Text -> Text -> Int -> Text -> Doc Text -> Doc Text
numberedCaption style term name num ident caption =
    let t = literal term
        r = num - 1
        ident' = case ident of
          "" -> "ref" <> name <> tshow r
          _ -> ident
        s = inTags False "text:sequence" [ ("text:ref-name", ident'),
                                           ("text:name", name),
                                           ("text:formula", "ooow:" <> name <> "+1"),
                                           ("style:num-format", "1") ] $ text $ show num
        c = text ": "
    in inParagraphTagsWithStyle style $ hcat [ t, text " ", s, c, caption ]

unNumberedCaption :: PandocMonad m => Text -> Doc Text -> OD m (Doc Text)
unNumberedCaption style caption = do
  sty <- dirStyleFor style
  return $ inParagraphTagsWithStyle sty caption

colHeadsToOpenDocument :: PandocMonad m
                       => WriterOptions -> [Text] -> Ann.TableHead
                       -> OD m (Doc Text)
colHeadsToOpenDocument o ns (Ann.TableHead _ hs) =
  case hs of
    [] -> return empty
    xs -> inTagsIndented "table:table-header-rows" <$>
      tableHeaderRowsToOpenDocument o ns "TableHeaderRowCell" xs

tableHeaderRowsToOpenDocument :: PandocMonad m
                              => WriterOptions -> [Text] -> Text -> [Ann.HeaderRow]
                              -> OD m (Doc Text)
tableHeaderRowsToOpenDocument o ns s headerRows =
  vcat <$> mapM headerRowToOpenDocument headerRows
  where
    headerRowToOpenDocument (Ann.HeaderRow _ _ c) =
      inTagsIndented "table:table-row" .
      vcat <$> mapM (tableItemToOpenDocument o s) (zip ns c)

tableBodyToOpenDocument:: PandocMonad m
                       => WriterOptions -> [Text] -> [Text] -> Ann.TableBody
                       -> OD m (Doc Text)
tableBodyToOpenDocument o headns bodyns tb = do
    let (Ann.TableBody _ _ hs r) = tb
    tableRowHeaders <- tableHeaderRowsToOpenDocument o headns "TableRowCell" hs
    tableRows <- mapM (tableRowToOpenDocument o headns bodyns) r
    return $ tableRowHeaders $$ vcat tableRows

tableFootToOpenDocument :: PandocMonad m
                        => WriterOptions -> [Text] -> Ann.TableFoot
                        -> OD m (Doc Text)
tableFootToOpenDocument o ns (Ann.TableFoot _ r) =
  tableHeaderRowsToOpenDocument o ns "TableRowCell" r

tableRowToOpenDocument :: PandocMonad m
                       => WriterOptions -> [Text] -> [Text] -> Ann.BodyRow
                       -> OD m (Doc Text)

tableRowToOpenDocument o headns bodyns r =
    let (Ann.BodyRow _ _ rowheaders cs) = r
    in inTagsIndented "table:table-row" . vcat <$>
    mapM (tableItemToOpenDocument o "TableRowCell")
        ((zip headns rowheaders) ++ (zip (drop (length rowheaders) bodyns) cs))

colspanAttrib :: ColSpan -> [(Text, Text)]
colspanAttrib cs =
  case cs of
    ColSpan 1 -> mempty
    ColSpan n -> [("table:number-columns-spanned", tshow n)]

rowspanAttrib :: RowSpan -> [(Text, Text)]
rowspanAttrib rs =
  case rs of
    RowSpan 1 -> mempty
    RowSpan n -> [("table:number-rows-spanned", tshow n)]

alignAttrib :: Alignment -> [(Text,Text)]
alignAttrib a = case a of
  AlignRight  -> ("fo:text-align","end") : style
  AlignCenter -> ("fo:text-align","center") : style
  _ -> []
  where
    style = [("style:justify-single-word","false")]

tableItemToOpenDocument :: PandocMonad m
                        => WriterOptions -> Text -> (Text,Ann.Cell)
                        -> OD m (Doc Text)
tableItemToOpenDocument o s (n,c) = do
  let (Ann.Cell _colspecs _colnum (Cell _ align rs cs i) ) = c
      csa = colspanAttrib cs
      rsa = rowspanAttrib rs
      aa = alignAttrib align
      a = [ ("table:style-name" , s )
          , ("office:value-type", "string" ) ] ++ csa ++ rsa
  itemParaStyle <- paraStyleFromParent n aa
  inTags True "table:table-cell" a <$>
    withParagraphStyle o itemParaStyle (map plainToPara i)

-- | Convert a list of inline elements to OpenDocument.
inlinesToOpenDocument :: PandocMonad m => WriterOptions -> [Inline] -> OD m (Doc Text)
inlinesToOpenDocument o l = hcat <$> toChunks o l

toChunks :: PandocMonad m => WriterOptions -> [Inline] -> OD m [Doc Text]
toChunks _ [] = return []
toChunks o (x : xs)
  | isChunkable x = do
        contents <- (inTextStyle . hcat) =<<
                     mapM (inlineToOpenDocument o) (x:ys)
        rest <- toChunks o zs
        return (contents : rest)
  | otherwise     = do
        contents <- inlineToOpenDocument o x
        rest <- toChunks o xs
        return (contents : rest)
  where (ys, zs) = span isChunkable xs

isChunkable :: Inline -> Bool
isChunkable (Str _)   = True
isChunkable Space     = True
isChunkable SoftBreak = True
isChunkable _         = False

-- | Convert an inline element to OpenDocument.
inlineToOpenDocument :: PandocMonad m => WriterOptions -> Inline -> OD m (Doc Text)
inlineToOpenDocument o ils
  = case ils of
    Space         -> return space
    SoftBreak
     | writerWrapText o == WrapPreserve
                  -> return $ preformatted "\n"
     | otherwise  -> return space
    Span ("", ["mark"], []) xs ->
      inTags False "text:span" [("text:style-name","Highlighted")] <$>
        inlinesToOpenDocument o xs
    Span attr xs  -> mkSpan attr xs
    LineBreak     -> return $ selfClosingTag "text:line-break" []
    Str         s -> return $ handleSpaces $ escapeStringForXML s
    Emph        l -> withTextStyle Italic $ inlinesToOpenDocument o l
    Underline   l -> withTextStyle Under  $ inlinesToOpenDocument o l
    Strong      l -> withTextStyle Bold   $ inlinesToOpenDocument o l
    Strikeout   l -> withTextStyle Strike $ inlinesToOpenDocument o l
    Superscript l -> withTextStyle Sup    $ inlinesToOpenDocument o l
    Subscript   l -> withTextStyle Sub    $ inlinesToOpenDocument o l
    SmallCaps   l -> withTextStyle SmallC $ inlinesToOpenDocument o l
    Quoted    t l -> inQuotes t <$> inlinesToOpenDocument o l
    Code      attrs s ->
      let highlighted =
            case highlight (writerSyntaxMap o) formatOpenDocument attrs s of
                Right h  -> inlinedCode $ mconcat $ mconcat h
                Left msg -> do
                  unless (T.null msg) $ report $ CouldNotHighlight msg
                  unhighlighted s
      in case writerHighlightMethod o of
           Skylighting {} -> highlighted
           DefaultHighlighting -> highlighted
           _ -> unhighlighted s
    Math      t s -> lift (texMathToInlines t s) >>=
                         inlinesToOpenDocument o
    Cite      _ l -> inlinesToOpenDocument o l
    RawInline f s -> if f == Format "opendocument"
                       then return $ literal s
                       else do
                         report $ InlineNotRendered ils
                         return empty
    Link _ l (s,t) -> do
      identTypes <- gets stIdentTypes
      mkLink o identTypes s t <$> inlinesToOpenDocument o l
    Image attr _ (s,t) -> mkImg attr s t
    Note        l  -> mkNote l
    where
      unhighlighted s = inlinedCode $ preformatted s
      inlinedCode s = return $ inTags False "text:span"
                                 [("text:style-name", "Source_20_Text")] s
      mkImg (_, _, kvs) s _ = do
               id' <- gets stImageId
               modify (\st -> st{ stImageId = id' + 1 })
               let getDims [] = []
                   getDims (("width", w) :xs) = ("svg:width", w)  : getDims xs
                   getDims (("rel-width", w):xs) = ("style:rel-width", w) : getDims xs
                   getDims (("height", h):xs) = ("svg:height", h) : getDims xs
                   getDims (("rel-height", w):xs) = ("style:rel-height", w) : getDims xs
                   getDims (_:xs) =                             getDims xs
               -- Image is an Inline: anchor the frame as a character so
               -- it flows with the text.  Without an explicit anchor,
               -- consumers default to paragraph anchoring and float the
               -- frame beside the following text.
               return $ inTags False "draw:frame"
                        (("draw:name", "img" <> tshow id')
                         : ("text:anchor-type", "as-char")
                         : getDims kvs) $
                     selfClosingTag "draw:image" [ ("xlink:href"   , s       )
                                                 , ("xlink:type"   , "simple")
                                                 , ("xlink:show"   , "embed" )
                                                 , ("xlink:actuate", "onLoad")]
      mkSpan attr xs =  do
        let (ident,_,kvs) = attr
            i = maybe id (\sty ->
                           fmap (inTags False "text:span"
                                  [ ("text:style-name", sty) ]))
                  (lookup "custom-style" kvs) .
                 withLangFromAttr attr $ inlinesToOpenDocument o xs
            mkBookmarkedSpan b =
              if isEmpty b
                then selfClosingBookmark ident
                else inBookmarkTags ident b
        if T.null ident
          then i
          else fmap mkBookmarkedSpan i
      mkNote     l = do
        n <- gets stNoteCount
        -- bump the counter before rendering the body, so that a note
        -- nested inside this one does not reuse the same text:id
        modify $ \st -> st{ stNoteCount = n + 1 }
        let footNote t = inTags False "text:note"
                         [ ("text:id"        , "ftn" <> tshow n)
                         , ("text:note-class", "footnote"     )] $
                         inTagsSimple "text:note-citation" (text . show $ n + 1) <>
                         inTagsSimple "text:note-body" t
        footNote <$> withAlteredTextStyles (const mempty)
                       (withParagraphStyle o "Footnote" l)

formatOpenDocument :: FormatOptions -> [SourceLine] -> [[Doc Text]]
formatOpenDocument _fmtOpts = map (map toHlTok)
toHlTok :: Token -> Doc Text
toHlTok (toktype,tok) =
  inTags False "text:span" [("text:style-name", T.pack $ show toktype)] $ preformatted tok

preformatted :: Text -> Doc Text
preformatted s = handleSpaces $ escapeStringForXML s

mkLink :: WriterOptions -> Map.Map Text ReferenceType -> Text -> Text
       -> Doc Text -> Doc Text
mkLink o identTypes s t d =
  let d' = inSpanTags "Definition" d
      ref refType format ident       = inTags False refType
                                       [ ("text:reference-format", format ),
                                         ("text:ref-name", ident) ]
      inlineSpace                    = selfClosingTag "text:s" []
      bookmarkRef                    = ref "text:bookmark-ref"
      bookmarkRefNumber ident        = bookmarkRef "number" ident mempty
      bookmarkRefName ident          = bookmarkRef "text" ident d
      bookmarkRefNameNumber ident    = bookmarkRefNumber ident <> inlineSpace <> bookmarkRefName ident
      bookmarkRef'
        | isEnabled Ext_xrefs_number o && isEnabled Ext_xrefs_name o = bookmarkRefNameNumber
        | isEnabled Ext_xrefs_name o                                 = bookmarkRefName
        | otherwise                                                  = bookmarkRefNumber
      sequenceRef                    = ref "text:sequence-ref"
      sequenceRefNumber ident        = sequenceRef "value" ident mempty
      sequenceRefName ident          = sequenceRef "caption" ident d
      sequenceRefNameNumber ident    = sequenceRefNumber ident <> inlineSpace <> sequenceRefName ident
      sequenceRef'
        | isEnabled Ext_xrefs_number o && isEnabled Ext_xrefs_name o = sequenceRefNameNumber
        | isEnabled Ext_xrefs_name o                                 = sequenceRefName
        | otherwise                                                  = sequenceRefNumber
      link = inTags False "text:a" [ ("xlink:type" , "simple")
                                          , ("xlink:href" , s       )
                                          , ("office:name", t       )
                                          ] d'
      linkOrReference = case T.uncons s of
                          Just ('#', ident) ->
                            case Map.lookup ident identTypes of
                              Just HeaderRef -> bookmarkRef' ident
                              Just TableRef  -> sequenceRef' ident
                              Just FigureRef -> sequenceRef' ident
                              Nothing        -> link
                          _ -> link
      in if isEnabled Ext_xrefs_name o || isEnabled Ext_xrefs_number o
            then linkOrReference
            else link

-- | Spreadsheet-style column names (@A@, @B@, ..., @Z@, @AA@, @AB@, ...).
-- Plain @chr@ arithmetic would run past @Z@ into characters like @[@
-- and @\\@, which are not legal in a @style:name@.
colLetters :: Int -> Text
colLetters n
  | n < 26    = T.singleton (chr (65 + n))
  | otherwise = colLetters (n `div` 26 - 1) <> T.singleton (chr (65 + n `mod` 26))

tableStyle :: Int -> Double -> [(Text,Double)] -> Doc Text
tableStyle num textWidth wcs =
    let tableId        = "Table" <> tshow (num + 1)
        tableWidthAttr :: [(Text,Text)]
        tableWidthAttr
          | textWidth <= 1 && textWidth > 0 = [("style:rel-width",
                                                T.pack (show (round (textWidth * 100) :: Int) <> "%"))]
          | otherwise    = []
        table          = inTags True "style:style"
                         [("style:name", tableId)
                         ,("style:family", "table")] $
                         selfClosingTag "style:table-properties"
                         (("table:align", "center") : tableWidthAttr)
        colStyle (c,0) = selfClosingTag "style:style"
                         [ ("style:name"  , tableId <> "." <> c)
                         , ("style:family", "table-column"       )]
        colStyle (c,w) = inTags True "style:style"
                         [ ("style:name"  , tableId <> "." <> c)
                         , ("style:family", "table-column"       )] $
                         selfClosingTag "style:table-column-properties"
                         [("style:rel-column-width", T.pack $ printf "%d*" (floor $ w * 65535 :: Integer))]
        headerRowCellStyle = inTags True "style:style"
                         [ ("style:name"  , "TableHeaderRowCell")
                         , ("style:family", "table-cell"    )] $
                         selfClosingTag "style:table-cell-properties"
                         [ ("fo:border", "none")]
        rowCellStyle = inTags True "style:style"
                         [ ("style:name"  , "TableRowCell")
                         , ("style:family", "table-cell"    )] $
                         selfClosingTag "style:table-cell-properties"
                         [ ("fo:border", "none")]
        cellStyles = if num == 0
                     then headerRowCellStyle $$ rowCellStyle
                     else empty
        columnStyles   = map colStyle wcs
    in cellStyles $$ table $$ vcat columnStyles

-- | Generate (or reuse) a paragraph style with the given attributes.
-- When the only attribute is @style:parent-style-name@ and no
-- indent/tight overrides are active, the parent name is returned
-- directly (no @Pn@ automatic style is created), so that the
-- predefined style passes through unchanged.
paraStyle :: PandocMonad m => [(Text,Text)] -> OD m Text
paraStyle attrs = do
  i  <- (*) (0.5 :: Double) . fromIntegral <$> gets stIndentPara
  b  <- gets stInDefinition
  dirAttrs <- getDirAttrs
  let indentVal = flip (<>) "in" . tshow $ if b then max 0.5 i else i
      indent    = if i /= 0 || b
                      then [ ("fo:margin-left"         , indentVal)
                           , ("fo:margin-right"        , "0in"    )
                           , ("fo:text-indent"         , "0in"    )
                           , ("style:auto-text-indent" , "false"  )]
                      else []
      attributes = indent <> dirAttrs
  case (attributes, attrs) of
    ([], [("style:parent-style-name", parent)]) -> return parent
    _ -> mkParaStyle attrs attributes

paraStyleFromParent :: PandocMonad m => Text -> [(Text,Text)] -> OD m Text
paraStyleFromParent parent attrs = do
  dirAttrs <- getDirAttrs
  let attrs' = attrs <> dirAttrs
  if null attrs'
     then return parent
     else mkParaStyle [("style:parent-style-name", parent)] attrs'

-- | Create an automatic paragraph style with the given @style:style@
-- attributes and @style:paragraph-properties@, reusing an identical
-- style if one has already been created.
mkParaStyle :: PandocMonad m => [(Text,Text)] -> [(Text,Text)] -> OD m Text
mkParaStyle attrs props = do
  cache <- gets stParaStyleCache
  case Map.lookup (attrs, props) cache of
    Just name -> return name
    Nothing -> do
      name <- ("P" <>) . tshow . (+ 1) <$> gets stParaStyleCount
      let styleAttr = ("style:name"  , name)
                    : ("style:family", "paragraph")
                    : attrs
          paraProps = if null props
                         then mempty
                         else selfClosingTag
                                 "style:paragraph-properties" props
      addParaStyle $ inTags True "style:style" styleAttr paraProps
      modify $ \st -> st{ stParaStyleCache =
                            Map.insert (attrs, props) name
                                       (stParaStyleCache st) }
      return name

getDirAttrs :: PandocMonad m => OD m [(Text, Text)]
getDirAttrs = do
  wm <- gets stDirection
  pure $
    case wm of
      Nothing -> []
      Just RTL -> [("style:writing-mode", "rl-tb"),
                        ("fo:text-align", "right")]
      Just LTR -> [("style:writing-mode", "lr-tb"),
                        ("fo:text-align", "left")]

-- | Adjust a named paragraph style for the current writing direction.
-- When a direction is active, an automatic style derived from the
-- given style with the appropriate @style:writing-mode@ is created.
-- With no direction active the name passes through unchanged, as do
-- automatic style names (@P1@, @P2@, ...), since automatic styles are
-- always created with the current direction included.
dirStyleFor :: PandocMonad m => Text -> OD m Text
dirStyleFor parent
  | isAutoStyleName parent = return parent
  | otherwise              = paraStyleFromParent parent []
  where
    isAutoStyleName t = case T.uncons t of
      Just ('P', ds) -> not (T.null ds) && T.all isDigit ds
      _              -> False

paraTableStyles :: Text -> Int -> [Alignment] -> [(Text, Doc Text)]
paraTableStyles _ _ [] = []
paraTableStyles t s (a:xs)
    | AlignRight  <- a = (         pName s, res s "end"   ) : paraTableStyles t (s + 1) xs
    | AlignCenter <- a = (         pName s, res s "center") : paraTableStyles t (s + 1) xs
    | otherwise        = ("Table_20_" <> t, empty         ) : paraTableStyles t  s      xs
    where pName sn = "P" <> tshow (sn + 1)
          res sn x = inTags True "style:style"
                     [ ("style:name"             , pName sn        )
                     , ("style:family"           , "paragraph"     )
                     , ("style:parent-style-name", "Table_20_" <> t)] $
                     selfClosingTag "style:paragraph-properties"
                     [ ("fo:text-align", x)
                     , ("style:justify-single-word", "false")]

data TextStyle = Italic
               | Bold
               | Under
               | Strike
               | Sub
               | Sup
               | SmallC
               | Pre
               | Language Lang
               deriving ( Eq,Ord )

textStyleAttr :: Map.Map Text Text
              -> TextStyle
              -> Map.Map Text Text
textStyleAttr m = \case
  Italic -> Map.insert "fo:font-style" "italic" .
                Map.insert "style:font-style-asian" "italic" .
                Map.insert "style:font-style-complex" "italic" $ m
  Bold   -> Map.insert "fo:font-weight" "bold" .
                Map.insert "style:font-weight-asian" "bold" .
                Map.insert "style:font-weight-complex" "bold" $ m
  Under  -> Map.insert "style:text-underline-style" "solid" .
                Map.insert "style:text-underline-width" "auto" .
                Map.insert "style:text-underline-color" "font-color" $ m
  Strike -> Map.insert "style:text-line-through-style" "solid" m
  Sub    -> Map.insert "style:text-position" "sub 58%" m
  Sup    -> Map.insert "style:text-position" "super 58%" m
  SmallC -> Map.insert "fo:font-variant" "small-caps" m
  Pre    -> Map.insert "style:font-name" "Courier New" .
            Map.insert "style:font-name-asian" "Courier New" .
            Map.insert "style:font-name-complex" "Courier New" $ m
  Language lang -> addLanguage lang m

addLanguage :: Lang -> Map.Map Text Text -> Map.Map Text Text
addLanguage lang
  | isRTLLang lang =
     Map.insert "style:language-complex" (langLanguage lang) .
     maybe id (Map.insert "style:country-complex") (langRegion lang)
  | otherwise =
     Map.insert "fo:language" (langLanguage lang) .
     maybe id (Map.insert "fo:country") (langRegion lang)

-- | Returns True if the language is conventionally written right-to-left.
isRTLLang :: Lang -> Bool
isRTLLang Lang{ langLanguage = l } =
  l `elem` ["ar", "he", "fa", "ur", "sd", "ckb", "yi", "dv"]

withLangFromAttr :: PandocMonad m => Attr -> OD m a -> OD m a
withLangFromAttr (_,_,kvs) action =
  case lookup "lang" kvs of
       Nothing -> action
       Just l  ->
         case parseLang l of
              Right lang -> withTextStyle (Language lang) action
              Left _ -> do
                report $ InvalidLang l
                action