aboutsummaryrefslogtreecommitdiff
path: root/src/Text/Pandoc/Citeproc.hs
blob: 9649c697167b2dc6c93ffbd993071fdaa96efa5a (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
{-# LANGUAGE ScopedTypeVariables #-}
{-# LANGUAGE FlexibleContexts #-}
{-# LANGUAGE StrictData #-}
{-# LANGUAGE MultiParamTypeClasses #-}
{-# LANGUAGE FlexibleInstances #-}
{-# LANGUAGE OverloadedStrings #-}
module Text.Pandoc.Citeproc
  ( processCitations,
    getReferences,
    getStyle
  )
where

import Citeproc
import Citeproc.Pandoc ()
import Text.Pandoc.Citeproc.Locator (parseLocator)
import Text.Pandoc.Citeproc.CslJson (cslJsonToReferences)
import Text.Pandoc.Citeproc.BibTeX (readBibtexString, Variant(..))
import Text.Pandoc.Citeproc.MetaValue (metaValueToReference, metaValueToText)
import Text.Pandoc.Readers.Markdown (yamlToRefs)
import Text.Pandoc.Class (setResourcePath, getResourcePath, getUserDataDir)
import qualified Text.Pandoc.BCP47 as BCP47
import Data.ByteString (ByteString)
import qualified Data.ByteString.Lazy as L
import Text.Pandoc.Definition as Pandoc
import Text.Pandoc.Walk
import Text.Pandoc.Builder as B
import Text.Pandoc (PandocMonad(..), PandocError(..),
                    readDataFile, ReaderOptions(..), pandocExtensions,
                    report, LogMessage(..), fetchItem)
import Text.Pandoc.Shared (stringify, ordNub, blocksToInlines, tshow)
import qualified Text.Pandoc.UTF8 as UTF8
import Data.Aeson (eitherDecode)
import Data.Default
import Data.Ord ()
import qualified Data.Map as M
import qualified Data.Set as Set
import Data.Char (isPunctuation, isUpper)
import Data.Text (Text)
import qualified Data.Text as T
import Control.Monad.State
import qualified Data.Sequence as Seq
import qualified Data.Foldable as Foldable
import System.FilePath
import Control.Applicative
import Control.Monad.Except
import Data.Maybe (mapMaybe, fromMaybe)
import Safe (lastMay, initSafe)
-- import Debug.Trace as Trace (trace, traceShowId)


processCitations  :: PandocMonad m => Pandoc -> m Pandoc
processCitations (Pandoc meta bs) = do
  style <- getStyle (Pandoc meta bs)

  mblang <- getLang meta
  let locale = Citeproc.mergeLocales mblang style

  refs <- getReferences (Just locale) (Pandoc meta bs)

  let otherIdsMap = foldr (\ref m ->
                             case T.words . extractText <$>
                                  M.lookup "other-ids"
                                      (referenceVariables ref) of
                                Nothing  -> m
                                Just ids -> foldr
                                  (\id' ->
                                    M.insert id' (referenceId ref)) m ids)
                          M.empty refs
  let meta' = deleteMeta "nocite" meta
  let citations = getCitations locale otherIdsMap $ Pandoc meta' bs


  let linkCites = maybe False truish $ lookupMeta "link-citations" meta
  let opts = defaultCiteprocOptions{ linkCitations = linkCites }
  let result = Citeproc.citeproc opts style (localeLanguage locale)
                  refs citations
  mapM_ (report . CiteprocWarning) (resultWarnings result)
  let sopts = styleOptions style
  let classes = "references" : -- TODO remove this or keep for compatibility?
                "csl-bib-body" :
                ["hanging-indent" | styleHangingIndent sopts]
  let refkvs = (case styleEntrySpacing sopts of
                   Just es | es > 0 -> (("entry-spacing",T.pack $ show es):)
                   _ -> id) .
               (case styleLineSpacing sopts of
                   Just ls | ls > 1 -> (("line-spacing",T.pack $ show ls):)
                   _ -> id) $ []
  let bibs = mconcat $ map (\(ident, out) ->
                     B.divWith ("ref-" <> ident,["csl-entry"],[]) . B.para .
                       walk (convertQuotes locale) .  insertSpace $ out)
                      (resultBibliography result)
  let moveNotes = maybe True truish $
                        lookupMeta "notes-after-punctuation" meta
  let cits = map (walk fixLinks . walk (convertQuotes locale)) $
               resultCitations result

  let fixQuotes = case localePunctuationInQuote locale of
                    Just True ->
                      B.toList . movePunctuationInsideQuotes .  B.fromList
                    _ -> id

  let metanocites = lookupMeta "nocite" meta
  let Pandoc meta'' bs' =
         maybe id (setMeta "nocite") metanocites .
         walk (map capitalizeNoteCitation .
                fixQuotes .  mvPunct moveNotes locale) .
         walk deNote .
         evalState (walkM insertResolvedCitations $ Pandoc meta' bs)
         $ cits
  return $ Pandoc meta''
         $ insertRefs refkvs classes meta''
            (walk fixLinks $ B.toList bibs) bs'

-- | Retrieve the CSL style specified by the csl or citation-style
-- metadata field in a pandoc document, or the default CSL style
-- if none is specified.  Retrieve the parent style
-- if the style is a dependent style.  Add abbreviations defined
-- in an abbreviation file if one has been specified.
getStyle :: PandocMonad m => Pandoc -> m (Style Inlines)
getStyle (Pandoc meta _) = do
  let cslfile = (lookupMeta "csl" meta <|> lookupMeta "citation-style" meta)
                >>= metaValueToText

  let getFile defaultExtension fp = do
        oldRp <- getResourcePath
        mbUdd <- getUserDataDir
        setResourcePath $ oldRp ++ maybe []
                                   (\u -> [u <> "/csl",
                                           u <> "/csl/dependent"]) mbUdd
        let fp' = if T.any (=='.') fp || "data:" `T.isPrefixOf` fp
                     then fp
                     else fp <> defaultExtension
        (result, _) <- fetchItem fp'
        setResourcePath oldRp
        return result

  let getCslDefault = readDataFile "default.csl"

  cslContents <- UTF8.toText <$> maybe getCslDefault (getFile ".csl") cslfile

  let abbrevFile = lookupMeta "citation-abbreviations" meta >>= metaValueToText

  mbAbbrevs <- case abbrevFile of
                 Nothing -> return Nothing
                 Just fp -> do
                   rawAbbr <- getFile ".json" fp
                   case eitherDecode (L.fromStrict rawAbbr) of
                     Left err -> throwError $ PandocCiteprocError $
                                 CiteprocParseError $
                                 "Could not parse abbreviations file " <> fp
                                 <> "\n" <> T.pack err
                     Right abbr -> return $ Just abbr

  let getParentStyle url = do
        -- first, try to retrieve the style locally, then use HTTP.
        let basename = T.takeWhileEnd (/='/') url
        UTF8.toText <$>
          catchError (getFile ".csl" basename) (\_ -> fst <$> fetchItem url)

  styleRes <- Citeproc.parseStyle getParentStyle cslContents
  case styleRes of
     Left err    -> throwError $ PandocAppError $ prettyCiteprocError err
     Right style -> return style{ styleAbbreviations = mbAbbrevs }


-- Retrieve citeproc lang based on metadata.
getLang :: PandocMonad m => Meta -> m (Maybe Lang)
getLang meta = maybe (return Nothing) bcp47LangToIETF
                 ((lookupMeta "lang" meta <|> lookupMeta "locale" meta) >>=
                   metaValueToText)

-- | Get references defined inline in the metadata and via an external
-- bibliography.  Only references that are actually cited in the document
-- (either with a genuine citation or with `nocite`) are returned.
-- URL variables are converted to links.
getReferences :: PandocMonad m
              => Maybe Locale -> Pandoc -> m [Reference Inlines]
getReferences mblocale (Pandoc meta bs) = do
  locale <- case mblocale of
                Just l  -> return l
                Nothing -> do
                  mblang <- getLang meta
                  case mblang of
                    Just lang -> return $ either mempty id $ getLocale lang
                    Nothing   -> return mempty

  let getCiteId (Cite cs _) = Set.fromList $ map B.citationId cs
      getCiteId _ = mempty
  let metanocites = lookupMeta "nocite" meta
  let nocites = maybe mempty (query getCiteId) metanocites
  let citeIds = query getCiteId (Pandoc meta bs)
  let idpred = if "*" `Set.member` nocites
                  then const True
                  else (`Set.member` citeIds)
  let inlineRefs = case lookupMeta "references" meta of
                    Just (MetaList rs) -> mapMaybe metaValueToReference rs
                    _                  -> []
  externalRefs <- case lookupMeta "bibliography" meta of
                    Just (MetaList xs) ->
                      mconcat <$>
                        mapM (getRefsFromBib locale idpred)
                          (mapMaybe metaValueToText xs)
                    Just x ->
                      case metaValueToText x of
                        Just fp -> getRefsFromBib locale idpred fp
                        Nothing -> return []
                    Nothing -> return []
  return $ map (linkifyVariables . legacyDateRanges)
               (externalRefs ++ inlineRefs)
            -- note that inlineRefs can override externalRefs



-- If we have a span.csl-left-margin followed by span.csl-right-inline,
-- we insert a space. This ensures that they will be separated by a space,
-- even in formats that don't have special handling for the display spans.
insertSpace :: Inlines -> Inlines
insertSpace ils =
  case Seq.viewl (unMany ils) of
    (Span ("",["csl-left-margin"],[]) xs) Seq.:< rest ->
      case Seq.lookup 0 rest of
        Just (Span ("",["csl-right-inline"],[]) _) ->
          Many $
            Span ("",["csl-left-margin"],[]) (xs ++ case lastMay xs of
                                                      Just Space -> []
                                                      _          -> [Space])
            Seq.<| rest
        _ -> ils
    _ -> ils

getRefsFromBib :: PandocMonad m
               => Locale -> (Text -> Bool) -> Text -> m [Reference Inlines]
getRefsFromBib locale idpred fp = do
  (raw, _) <- fetchItem fp
  case formatFromExtension (T.unpack fp) of
    Just f -> getRefs locale f idpred (Just fp) raw
    Nothing -> throwError $ PandocAppError $
                 "Could not determine bibliography format for " <> fp

getRefs :: PandocMonad m
        => Locale
        -> BibFormat
        -> (Text -> Bool)
        -> Maybe Text
        -> ByteString
        -> m [Reference Inlines]
getRefs locale format idpred mbfp raw = do
  let err' = throwError .
             PandocBibliographyError (fromMaybe mempty mbfp)
  case format of
    Format_bibtex ->
      either (err' . tshow) return .
        readBibtexString Bibtex locale idpred . UTF8.toText $ raw
    Format_biblatex ->
      either (err' . tshow) return .
        readBibtexString Biblatex locale idpred . UTF8.toText $ raw
    Format_json ->
      either (err' . T.pack)
             (return . filter (idpred . unItemId . referenceId)) .
        cslJsonToReferences $ raw
    Format_yaml -> do
      rs <- yamlToRefs idpred
              def{ readerExtensions = pandocExtensions }
              (T.unpack <$> mbfp)
              (L.fromStrict raw)
      return $ mapMaybe metaValueToReference rs

-- localized quotes
convertQuotes :: Locale -> Inline -> Inline
convertQuotes locale (Quoted qt ils) =
  case (M.lookup openterm terms, M.lookup closeterm terms) of
    (Just ((_,oq):_), Just ((_,cq):_)) ->
         Span ("",[],[]) (Str oq : ils ++ [Str cq])
    _ -> Quoted qt ils
  where
   terms = localeTerms locale
   openterm = case qt of
                DoubleQuote -> "open-quote"
                SingleQuote -> "open-inner-quote"
   closeterm = case qt of
                 DoubleQuote -> "close-quote"
                 SingleQuote -> "close-inner-quote"
convertQuotes _ x = x

-- assumes we walk in same order as query
insertResolvedCitations :: Inline -> State [Inlines] Inline
insertResolvedCitations (Cite cs ils) = do
  resolved <- get
  case resolved of
    [] -> return (Cite cs ils)
    (x:xs) -> do
      put xs
      return $ Cite cs (B.toList x)
insertResolvedCitations x = return x

getCitations :: Locale
             -> M.Map Text ItemId
             -> Pandoc
             -> [Citeproc.Citation Inlines]
getCitations locale otherIdsMap = Foldable.toList . query getCitation
 where
  getCitation (Cite cs _fallback) = Seq.singleton $
    Citeproc.Citation { Citeproc.citationId = Nothing
                      , Citeproc.citationNoteNumber =
                          case cs of
                            []    -> Nothing
                            (Pandoc.Citation{ Pandoc.citationNoteNum = n }:
                               _) | n > 0     -> Just n
                                  | otherwise -> Nothing
                      , Citeproc.citationItems =
                           fromPandocCitations locale otherIdsMap cs
                      }
  getCitation _ = mempty

fromPandocCitations :: Locale
                    -> M.Map Text ItemId
                    -> [Pandoc.Citation]
                    -> [CitationItem Inlines]
fromPandocCitations locale otherIdsMap = concatMap go
 where
  go c =
    let (loclab, suffix) = parseLocator locale (citationSuffix c)
        (mblab, mbloc) = case loclab of
                           Just (loc, lab) -> (Just loc, Just lab)
                           Nothing         -> (Nothing, Nothing)
        cit = CitationItem
               { citationItemId = fromMaybe
                   (ItemId $ Pandoc.citationId c)
                   (M.lookup (Pandoc.citationId c) otherIdsMap)
               , citationItemLabel = mblab
               , citationItemLocator = mbloc
               , citationItemType = NormalCite
               , citationItemPrefix = case citationPrefix c of
                                        [] -> Nothing
                                        ils -> Just $ B.fromList ils <>
                                                      B.space
               , citationItemSuffix = case suffix of
                                        [] -> Nothing
                                        ils -> Just $ B.fromList ils
               }
     in if Pandoc.citationId c == "*"
           then []
           else
             case citationMode c of
                  AuthorInText   -> [ cit{ citationItemType = AuthorOnly
                                         , citationItemSuffix = Nothing }
                                    , cit{ citationItemType =
                                              Citeproc.SuppressAuthor
                                         , citationItemPrefix = Nothing } ]
                  NormalCitation -> [ cit ]
                  Pandoc.SuppressAuthor
                                 -> [ cit{ citationItemType =
                                              Citeproc.SuppressAuthor } ]



data BibFormat =
    Format_biblatex
  | Format_bibtex
  | Format_json
  | Format_yaml
  deriving (Show, Eq, Ord)

formatFromExtension :: FilePath -> Maybe BibFormat
formatFromExtension fp = case dropWhile (== '.') $ takeExtension fp of
                           "biblatex" -> Just Format_biblatex
                           "bibtex"   -> Just Format_bibtex
                           "bib"      -> Just Format_biblatex
                           "json"     -> Just Format_json
                           "yaml"     -> Just Format_yaml
                           _          -> Nothing


isNote :: Inline -> Bool
isNote (Note _)          = True
isNote (Cite _ [Note _]) = True
 -- the following allows citation styles that are "in-text" but use superscript
 -- references to be treated as if they are "notes" for the purposes of moving
 -- the citations after trailing punctuation (see <https://github.com/jgm/pandoc-citeproc/issues/382>):
isNote (Cite _ [Superscript _]) = True
isNote _                 = False

isSpacy :: Inline -> Bool
isSpacy Space     = True
isSpacy SoftBreak = True
isSpacy _         = False


mvPunct :: Bool -> Locale -> [Inline] -> [Inline]
mvPunct moveNotes locale (x : xs)
  | isSpacy x = x : mvPunct moveNotes locale xs
-- 'x [^1],' -> 'x,[^1]'
mvPunct moveNotes locale (q : s : x : ys)
  | isSpacy s
  , isNote x
  = let spunct = T.takeWhile isPunctuation $ stringify ys
    in  if moveNotes
           then if T.null spunct
                   then q : x : mvPunct moveNotes locale ys
                   else q : Str spunct : x : mvPunct moveNotes locale
                        (B.toList
                          (dropTextWhile isPunctuation (B.fromList ys)))
           else q : x : mvPunct moveNotes locale ys
-- 'x[^1],' -> 'x,[^1]'
mvPunct moveNotes locale (Cite cs ils : ys)
   | not (null ils)
   , isNote (last ils)
   , startWithPunct ys
   , moveNotes
   = let s = stringify ys
         spunct = T.takeWhile isPunctuation s
     in  Cite cs (init ils
                  ++ [Str spunct | not (endWithPunct False (init ils))]
                  ++ [last ils]) :
         mvPunct moveNotes locale
           (B.toList (dropTextWhile isPunctuation (B.fromList ys)))
mvPunct moveNotes locale (s : x : ys) | isSpacy s, isNote x =
  x : mvPunct moveNotes locale ys
mvPunct moveNotes locale (s : x@(Cite _ (Superscript _ : _)) : ys)
  | isSpacy s = x : mvPunct moveNotes locale ys
mvPunct moveNotes locale (Cite cs ils : Str "." : ys)
  | "." `T.isSuffixOf` (stringify ils)
  = Cite cs ils : mvPunct moveNotes locale ys
mvPunct moveNotes locale (x:xs) = x : mvPunct moveNotes locale xs
mvPunct _ _ [] = []

-- move https://doi.org etc. prefix inside link text (#6723):
fixLinks :: [Inline] -> [Inline]
fixLinks (Str t : Link attr [Str u1] (u2,tit) : xs)
  | t <> u1 == u2
  = Link attr [Str (t <> u1)] (u2,tit) : fixLinks xs
fixLinks (x:xs) = x : fixLinks xs
fixLinks [] = []


endWithPunct :: Bool -> [Inline] -> Bool
endWithPunct _ [] = False
endWithPunct onlyFinal xs@(_:_) =
  case reverse (T.unpack $ stringify xs) of
       []                       -> True
       -- covers .), .", etc.:
       (d:c:_) | isPunctuation d
                 && not onlyFinal
                 && isEndPunct c -> True
       (c:_) | isEndPunct c      -> True
             | otherwise         -> False
  where isEndPunct c = c `elem` (".,;:!?" :: String)



startWithPunct :: [Inline] -> Bool
startWithPunct ils =
  case T.uncons (stringify ils) of
    Just (c,_) -> c `elem` (".,;:!?" :: [Char])
    Nothing -> False

truish :: MetaValue -> Bool
truish (MetaBool t) = t
truish (MetaString s) = isYesValue (T.toLower s)
truish (MetaInlines ils) = isYesValue (T.toLower (stringify ils))
truish (MetaBlocks [Plain ils]) = isYesValue (T.toLower (stringify ils))
truish _ = False

isYesValue :: Text -> Bool
isYesValue "t" = True
isYesValue "true" = True
isYesValue "yes" = True
isYesValue _ = False

-- if document contains a Div with id="refs", insert
-- references as its contents.  Otherwise, insert references
-- at the end of the document in a Div with id="refs"
insertRefs :: [(Text,Text)] -> [Text] -> Meta -> [Block] -> [Block] -> [Block]
insertRefs _ _ _  []   bs = bs
insertRefs refkvs refclasses meta refs bs =
  if isRefRemove meta
     then bs
     else case runState (walkM go bs) False of
               (bs', True) -> bs'
               (_, False)
                 -> case refTitle meta of
                      Nothing ->
                        case reverse bs of
                          Header lev (id',classes,kvs) ys : xs ->
                            reverse xs ++
                            [Header lev (id',addUnNumbered classes,kvs) ys,
                             Div ("refs",refclasses,refkvs) refs]
                          _ -> bs ++ [refDiv]
                      Just ils -> bs ++
                        [Header 1 ("bibliography", ["unnumbered"], []) ils,
                         refDiv]
  where
   refDiv = Div ("refs", refclasses, refkvs) refs
   addUnNumbered cs = "unnumbered" : [c | c <- cs, c /= "unnumbered"]
   go :: Block -> State Bool Block
   go (Div ("refs",cs,kvs) xs) = do
     put True
     -- refHeader isn't used if you have an explicit references div
     let cs' = ordNub $ cs ++ refclasses
     return $ Div ("refs",cs',kvs) (xs ++ refs)
   go x = return x

refTitle :: Meta -> Maybe [Inline]
refTitle meta =
  case lookupMeta "reference-section-title" meta of
    Just (MetaString s)           -> Just [Str s]
    Just (MetaInlines ils)        -> Just ils
    Just (MetaBlocks [Plain ils]) -> Just ils
    Just (MetaBlocks [Para ils])  -> Just ils
    _                             -> Nothing

isRefRemove :: Meta -> Bool
isRefRemove meta =
  maybe False truish $ lookupMeta "suppress-bibliography" meta

legacyDateRanges :: Reference Inlines -> Reference Inlines
legacyDateRanges ref =
  ref{ referenceVariables = M.map go $ referenceVariables ref }
 where
  go (DateVal d)
    | null (dateParts d)
    , Just lit <- dateLiteral d
    = case T.splitOn "_" lit of
        [x,y] -> case Citeproc.rawDateEDTF (x <> "/" <> y) of
                   Just d' -> DateVal d'
                   Nothing -> DateVal d
        _ -> DateVal d
  go x = x

linkifyVariables :: Reference Inlines -> Reference Inlines
linkifyVariables ref =
  ref{ referenceVariables = M.mapWithKey go $ referenceVariables ref }
 where
  go "URL" x    = tolink "https://" x
  go "DOI" x    = tolink "https://doi.org/" (fixShortDOI x)
  go "ISBN" x   = tolink "https://worldcat.org/isbn/" x
  go "PMID" x   = tolink "https://www.ncbi.nlm.nih.gov/pubmed/" x
  go "PMCID" x  = tolink "https://www.ncbi.nlm.nih.gov/pmc/articles/" x
  go _ x        = x
  fixShortDOI x = let x' = extractText x
                  in  if "10/" `T.isPrefixOf` x'
                         then TextVal $ T.drop 3 x'
                              -- see http://shortdoi.org
                         else TextVal x'
  tolink pref x = let x' = extractText x
                      x'' = if "://" `T.isInfixOf` x'
                               then x'
                               else pref <> x'
                  in  if T.null x'
                         then x
                         else FancyVal (B.link x'' "" (B.str x'))

extractText :: Val Inlines -> Text
extractText (TextVal x)  = x
extractText (FancyVal x) = toText x
extractText (NumVal n)   = T.pack (show n)
extractText _            = mempty

capitalizeNoteCitation :: Inline -> Inline
capitalizeNoteCitation (Cite cs [Note [Para ils]]) =
  Cite cs
  [Note [Para $ B.toList $ addTextCase Nothing CapitalizeFirst
              $ B.fromList ils]]
capitalizeNoteCitation x = x

deNote :: [Inline] -> [Inline]
deNote [] = []
deNote (Note bs:rest) =
  Note (walk go bs) : deNote rest
 where
  go [] = []
  go (Cite (c:cs) ils : zs)
    | citationMode c == AuthorInText
      = Cite (c:cs) (concatMap (noteAfterComma (needsPeriod zs)) ils) : go zs
    | otherwise
      = Cite (c:cs) (concatMap noteInParens ils) : go zs
  go (x:xs) = x : go xs
  needsPeriod [] = True
  needsPeriod (Str t:_) = case T.uncons t of
                            Nothing    -> False
                            Just (c,_) -> isUpper c
  needsPeriod (Space:zs) = needsPeriod zs
  needsPeriod _ = False
  noteInParens (Note bs')
       = Space : Str "(" :
         removeFinalPeriod (blocksToInlines bs') ++ [Str ")"]
  noteInParens x = [x]
  noteAfterComma needsPer (Note bs')
       = Str "," : Space :
         (if needsPer
             then id
             else removeFinalPeriod) (blocksToInlines bs')
  noteAfterComma _ x = [x]
deNote (x:xs) = x : deNote xs

-- Note: we can't use dropTextWhileEnd indiscriminately,
-- because this would remove the final period on abbreviations like Ibid.
-- But it turns out that when the note citation ends with Ibid.
-- (or Ed. etc.), the last inline will be Str "" as a result of
-- the punctuation-fixing mechanism that removes the double '.'.
removeFinalPeriod :: [Inline] -> [Inline]
removeFinalPeriod ils =
  case lastMay ils of
    Just (Span attr ils')
      -> initSafe ils ++ [Span attr (removeFinalPeriod ils')]
    Just (Emph ils')
      -> initSafe ils ++ [Emph (removeFinalPeriod ils')]
    Just (Strong ils')
      -> initSafe ils ++ [Strong (removeFinalPeriod ils')]
    Just (SmallCaps ils')
      -> initSafe ils ++ [SmallCaps (removeFinalPeriod ils')]
    Just (Str t)
      | T.takeEnd 1 t == "." -> initSafe ils ++ [Str (T.dropEnd 1 t)]
      | isRightQuote (T.takeEnd 1 t)
        -> removeFinalPeriod
             (initSafe ils ++ [Str tInit | not (T.null tInit)]) ++ [Str tEnd]
             where
               tEnd  = T.takeEnd 1 t
               tInit = T.dropEnd 1 t
    _ -> ils
 where
  isRightQuote "\8221" = True
  isRightQuote "\8217" = True
  isRightQuote "\187"  = True
  isRightQuote _       = False

bcp47LangToIETF :: PandocMonad m => Text -> m (Maybe Lang)
bcp47LangToIETF bcplang =
  case BCP47.parseBCP47 bcplang of
    Left _ -> do
      report $ InvalidLang bcplang
      return Nothing
    Right lang ->
      return $ Just
             $ Lang (BCP47.langLanguage lang)
                    (if T.null (BCP47.langRegion lang)
                        then Nothing
                        else Just (BCP47.langRegion lang))