aboutsummaryrefslogtreecommitdiff
path: root/src/Text/Pandoc/Readers/Org/Inlines.hs
blob: 103dfc86a28c0bff3fcc2e3e05a0cb114421e80a (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
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
{-# LANGUAGE NoImplicitPrelude #-}
{-# LANGUAGE OverloadedStrings #-}
{- |
   Module      : Text.Pandoc.Readers.Org.Inlines
   Copyright   : Copyright (C) 2014-2019 Albert Krewinkel
   License     : GNU GPL, version 2 or above

   Maintainer  : Albert Krewinkel <tarleb+pandoc@moltkeplatz.de>

Parsers for Org-mode inline elements.
-}
module Text.Pandoc.Readers.Org.Inlines
  ( inline
  , inlines
  , addToNotesTable
  , linkTarget
  ) where

import Prelude
import Text.Pandoc.Readers.Org.BlockStarts (endOfBlock, noteMarker)
import Text.Pandoc.Readers.Org.ParserState
import Text.Pandoc.Readers.Org.Parsing
import Text.Pandoc.Readers.Org.Shared (cleanLinkText, isImageFilename,
                                       originalLang, translateLang, exportsCode)

import Text.Pandoc.Builder (Inlines)
import qualified Text.Pandoc.Builder as B
import Text.Pandoc.Class (PandocMonad)
import Text.Pandoc.Definition
import Text.Pandoc.Options
import Text.Pandoc.Readers.LaTeX (inlineCommand, rawLaTeXInline)
import Text.Pandoc.Shared (underlineSpan)
import Text.TeXMath (DisplayType (..), readTeX, writePandoc)
import qualified Text.TeXMath.Readers.MathML.EntityMap as MathMLEntityMap

import Control.Monad (guard, mplus, mzero, unless, void, when)
import Control.Monad.Trans (lift)
import Data.Char (isAlphaNum, isSpace)
import Data.List (intersperse)
import qualified Data.Map as M
import Data.Text (Text)
import qualified Data.Text as T

--
-- Functions acting on the parser state
--
recordAnchorId :: PandocMonad m => Text -> OrgParser m ()
recordAnchorId i = updateState $ \s ->
  s{ orgStateAnchorIds = i : orgStateAnchorIds s }

pushToInlineCharStack :: PandocMonad m => Char -> OrgParser m ()
pushToInlineCharStack c = updateState $ \s ->
  s{ orgStateEmphasisCharStack = c:orgStateEmphasisCharStack s }

popInlineCharStack :: PandocMonad m => OrgParser m ()
popInlineCharStack = updateState $ \s ->
  s{ orgStateEmphasisCharStack = drop 1 . orgStateEmphasisCharStack $ s }

surroundingEmphasisChar :: PandocMonad m => OrgParser m [Char]
surroundingEmphasisChar =
  take 1 . drop 1 . orgStateEmphasisCharStack <$> getState

startEmphasisNewlinesCounting :: PandocMonad m => Int -> OrgParser m ()
startEmphasisNewlinesCounting maxNewlines = updateState $ \s ->
  s{ orgStateEmphasisNewlines = Just maxNewlines }

decEmphasisNewlinesCount :: PandocMonad m => OrgParser m ()
decEmphasisNewlinesCount = updateState $ \s ->
  s{ orgStateEmphasisNewlines = (\n -> n - 1) <$> orgStateEmphasisNewlines s }

newlinesCountWithinLimits :: PandocMonad m => OrgParser m Bool
newlinesCountWithinLimits = do
  st <- getState
  return $ ((< 0) <$> orgStateEmphasisNewlines st) /= Just True

resetEmphasisNewlines :: PandocMonad m => OrgParser m ()
resetEmphasisNewlines = updateState $ \s ->
  s{ orgStateEmphasisNewlines = Nothing }

addToNotesTable :: PandocMonad m => OrgNoteRecord -> OrgParser m ()
addToNotesTable note = do
  oldnotes <- orgStateNotes' <$> getState
  updateState $ \s -> s{ orgStateNotes' = note:oldnotes }

-- | Parse a single Org-mode inline element
inline :: PandocMonad m => OrgParser m (F Inlines)
inline =
  choice [ whitespace
         , linebreak
         , cite
         , footnote
         , linkOrImage
         , anchor
         , inlineCodeBlock
         , str
         , endline
         , emphasizedText
         , code
         , math
         , displayMath
         , verbatim
         , subscript
         , superscript
         , inlineLaTeX
         , exportSnippet
         , macro
         , smart
         , symbol
         ] <* (guard =<< newlinesCountWithinLimits)
  <?> "inline"

-- | Read the rest of the input as inlines.
inlines :: PandocMonad m => OrgParser m (F Inlines)
inlines = trimInlinesF . mconcat <$> many1 inline

-- treat these as potentially non-text when parsing inline:
specialChars :: [Char]
specialChars = "\"$'()*+-,./:;<=>@[\\]^_{|}~"


whitespace :: PandocMonad m => OrgParser m (F Inlines)
whitespace = pure B.space <$ skipMany1 spaceChar
                          <* updateLastPreCharPos
                          <* updateLastForbiddenCharPos
             <?> "whitespace"

linebreak :: PandocMonad m => OrgParser m (F Inlines)
linebreak = try $ pure B.linebreak <$ string "\\\\" <* skipSpaces <* newline

str :: PandocMonad m => OrgParser m (F Inlines)
str = return . B.str <$> many1Char (noneOf $ specialChars ++ "\n\r ")
      <* updateLastStrPos

-- | An endline character that can be treated as a space, not a structural
-- break.  This should reflect the values of the Emacs variable
-- @org-element-pagaraph-separate@.
endline :: PandocMonad m => OrgParser m (F Inlines)
endline = try $ do
  newline
  notFollowedBy' endOfBlock
  decEmphasisNewlinesCount
  guard =<< newlinesCountWithinLimits
  updateLastPreCharPos
  useHardBreaks <- exportPreserveBreaks . orgStateExportSettings <$> getState
  returnF (if useHardBreaks then B.linebreak else B.softbreak)


--
-- Citations
--

-- The state of citations is a bit confusing due to the lack of an official
-- syntax and multiple syntaxes coexisting.  The pandocOrgCite syntax was the
-- first to be implemented here and is almost identical to Markdown's citation
-- syntax.  The org-ref package is in wide use to handle citations, but the
-- syntax is a bit limiting and not quite as simple to write.  The
-- semi-official Org-mode citation syntax is based on John MacFarlane's Pandoc
-- sytax and Org-oriented enhancements contributed by Richard Lawrence and
-- others.  It's dubbed Berkeley syntax due the place of activity of its main
-- contributors.  All this should be consolidated once an official Org-mode
-- citation syntax has emerged.

cite :: PandocMonad m => OrgParser m (F Inlines)
cite = try $ berkeleyCite <|> do
  guardEnabled Ext_citations
  (cs, raw) <- withRaw $ choice
               [ pandocOrgCite
               , orgRefCite
               , berkeleyTextualCite
               ]
  return $ flip B.cite (B.text raw) <$> cs

-- | A citation in Pandoc Org-mode style (@[prefix \@citekey suffix]@).
pandocOrgCite :: PandocMonad m => OrgParser m (F [Citation])
pandocOrgCite = try $
  char '[' *> skipSpaces *> citeList <* skipSpaces <* char ']'

orgRefCite :: PandocMonad m => OrgParser m (F [Citation])
orgRefCite = try $ choice
  [ normalOrgRefCite
  , fmap (:[]) <$> linkLikeOrgRefCite
  ]

normalOrgRefCite :: PandocMonad m => OrgParser m (F [Citation])
normalOrgRefCite = try $ do
  mode <- orgRefCiteMode
  firstCitation <- orgRefCiteList mode
  moreCitations <- many (try $ char ',' *> orgRefCiteList mode)
  return . sequence $ firstCitation : moreCitations
 where
  -- | A list of org-ref style citation keys, parsed as citation of the given
  -- citation mode.
  orgRefCiteList :: PandocMonad m => CitationMode -> OrgParser m (F Citation)
  orgRefCiteList citeMode = try $ do
    key <- orgRefCiteKey
    returnF Citation
     { citationId      = key
     , citationPrefix  = mempty
     , citationSuffix  = mempty
     , citationMode    = citeMode
     , citationNoteNum = 0
     , citationHash    = 0
     }

-- | Read an Berkeley-style Org-mode citation.  Berkeley citation style was
-- develop and adjusted to Org-mode style by John MacFarlane and Richard
-- Lawrence, respectively, both philosophers at UC Berkeley.
berkeleyCite :: PandocMonad m => OrgParser m (F Inlines)
berkeleyCite = try $ do
  bcl <- berkeleyCitationList
  return $ do
    parens <- berkeleyCiteParens <$> bcl
    prefix <- berkeleyCiteCommonPrefix <$> bcl
    suffix <- berkeleyCiteCommonSuffix <$> bcl
    citationList <- berkeleyCiteCitations <$> bcl
    return $
      if parens
      then toCite
           . maybe id (alterFirst . prependPrefix) prefix
           . maybe id (alterLast . appendSuffix) suffix
           $ citationList
      else maybe mempty (<> " ") prefix
             <> toListOfCites (map toInTextMode citationList)
             <> maybe mempty (", " <>) suffix
 where
   toCite :: [Citation] -> Inlines
   toCite cs = B.cite cs mempty

   toListOfCites :: [Citation] -> Inlines
   toListOfCites = mconcat . intersperse ", " . map (\c -> B.cite [c] mempty)

   toInTextMode :: Citation -> Citation
   toInTextMode c = c { citationMode = AuthorInText }

   alterFirst, alterLast :: (a -> a) -> [a] -> [a]
   alterFirst _ []     = []
   alterFirst f (c:cs) = f c : cs
   alterLast  f = reverse . alterFirst f . reverse

   prependPrefix, appendSuffix :: Inlines -> Citation -> Citation
   prependPrefix pre c = c { citationPrefix = B.toList pre <> citationPrefix c }
   appendSuffix  suf c = c { citationSuffix = citationSuffix c <> B.toList suf }

data BerkeleyCitationList = BerkeleyCitationList
  { berkeleyCiteParens       :: Bool
  , berkeleyCiteCommonPrefix :: Maybe Inlines
  , berkeleyCiteCommonSuffix :: Maybe Inlines
  , berkeleyCiteCitations    :: [Citation]
  }
berkeleyCitationList :: PandocMonad m => OrgParser m (F BerkeleyCitationList)
berkeleyCitationList = try $ do
  char '['
  parens <- choice [ False <$ berkeleyBareTag, True <$ berkeleyParensTag ]
  char ':'
  skipSpaces
  commonPrefix <- optionMaybe (try $ citationListPart <* char ';')
  citations    <- citeList
  commonSuffix <- optionMaybe (try citationListPart)
  char ']'
  return (BerkeleyCitationList parens
    <$> sequence commonPrefix
    <*> sequence commonSuffix
    <*> citations)
 where
   citationListPart :: PandocMonad m => OrgParser m (F Inlines)
   citationListPart = fmap (trimInlinesF . mconcat) . try . many1 $ do
     notFollowedBy' citeKey
     notFollowedBy (oneOf ";]")
     inline

berkeleyBareTag :: PandocMonad m => OrgParser m ()
berkeleyBareTag = try $ void berkeleyBareTag'

berkeleyParensTag :: PandocMonad m => OrgParser m ()
berkeleyParensTag = try . void $ enclosedByPair1 '(' ')' berkeleyBareTag'

berkeleyBareTag' :: PandocMonad m => OrgParser m ()
berkeleyBareTag' = try $ void (string "cite")

berkeleyTextualCite :: PandocMonad m => OrgParser m (F [Citation])
berkeleyTextualCite = try $ do
  (suppressAuthor, key) <- citeKey
  returnF . return $ Citation
    { citationId      = key
    , citationPrefix  = mempty
    , citationSuffix  = mempty
    , citationMode    = if suppressAuthor then SuppressAuthor else AuthorInText
    , citationNoteNum = 0
    , citationHash    = 0
    }

-- The following is what a Berkeley-style bracketed textual citation parser
-- would look like.  However, as these citations are a subset of Pandoc's Org
-- citation style, this isn't used.
-- berkeleyBracketedTextualCite :: PandocMonad m => OrgParser m (F [Citation])
-- berkeleyBracketedTextualCite = try . (fmap head) $
--   enclosedByPair1 '[' ']' berkeleyTextualCite

-- | Read a link-like org-ref style citation.  The citation includes pre and
-- post text.  However, multiple citations are not possible due to limitations
-- in the syntax.
linkLikeOrgRefCite :: PandocMonad m => OrgParser m (F Citation)
linkLikeOrgRefCite = try $ do
  _    <- string "[["
  mode <- orgRefCiteMode
  key  <- orgRefCiteKey
  _    <- string "]["
  pre  <- trimInlinesF . mconcat <$> manyTill inline (try $ string "::")
  spc  <- option False (True <$ spaceChar)
  suf  <- trimInlinesF . mconcat <$> manyTill inline (try $ string "]]")
  return $ do
    pre' <- pre
    suf' <- suf
    return Citation
      { citationId      = key
      , citationPrefix  = B.toList pre'
      , citationSuffix  = B.toList (if spc then B.space <> suf' else suf')
      , citationMode    = mode
      , citationNoteNum = 0
      , citationHash    = 0
      }

-- | Read a citation key.  The characters allowed in citation keys are taken
-- from the `org-ref-cite-re` variable in `org-ref.el`.
orgRefCiteKey :: PandocMonad m => OrgParser m Text
orgRefCiteKey =
  let citeKeySpecialChars = "-_:\\./," :: String
      isCiteKeySpecialChar c = c `elem` citeKeySpecialChars
      isCiteKeyChar c = isAlphaNum c || isCiteKeySpecialChar c
      endOfCitation = try $ do
        many $ satisfy isCiteKeySpecialChar
        satisfy $ not . isCiteKeyChar
  in try $ satisfy isCiteKeyChar `many1TillChar` lookAhead endOfCitation


-- | Supported citation types.  Only a small subset of org-ref types is
-- supported for now.  TODO: rewrite this, use LaTeX reader as template.
orgRefCiteMode :: PandocMonad m => OrgParser m CitationMode
orgRefCiteMode =
  choice $ map (\(s, mode) -> mode <$ try (string s <* char ':'))
    [ ("cite", AuthorInText)
    , ("citep", NormalCitation)
    , ("citep*", NormalCitation)
    , ("citet", AuthorInText)
    , ("citet*", AuthorInText)
    , ("citeyear", SuppressAuthor)
    ]

citeList :: PandocMonad m => OrgParser m (F [Citation])
citeList = sequence <$> sepEndBy1 citation (try $ char ';' *> skipSpaces)

citation :: PandocMonad m => OrgParser m (F Citation)
citation = try $ do
  pref <- prefix
  (suppress_author, key) <- citeKey
  suff <- suffix
  return $ do
    x <- pref
    y <- suff
    return Citation
      { citationId      = key
      , citationPrefix  = B.toList x
      , citationSuffix  = B.toList y
      , citationMode    = if suppress_author
                          then SuppressAuthor
                          else NormalCitation
      , citationNoteNum = 0
      , citationHash    = 0
      }
 where
   prefix = trimInlinesF . mconcat <$>
            manyTill inline (char ']' <|> (']' <$ lookAhead citeKey))
   suffix = try $ do
     hasSpace <- option False (notFollowedBy nonspaceChar >> return True)
     skipSpaces
     rest <- trimInlinesF . mconcat <$>
             many (notFollowedBy (oneOf ";]") *> inline)
     return $ if hasSpace
              then (B.space <>) <$> rest
              else rest

footnote :: PandocMonad m => OrgParser m (F Inlines)
footnote = try $ inlineNote <|> referencedNote

inlineNote :: PandocMonad m => OrgParser m (F Inlines)
inlineNote = try $ do
  string "[fn:"
  ref <- manyChar alphaNum
  char ':'
  note <- fmap B.para . trimInlinesF . mconcat <$> many1Till inline (char ']')
  unless (T.null ref) $
       addToNotesTable ("fn:" <> ref, note)
  return $ B.note <$> note

referencedNote :: PandocMonad m => OrgParser m (F Inlines)
referencedNote = try $ do
  ref <- noteMarker
  return $ do
    notes <- asksF orgStateNotes'
    case lookup ref notes of
      Nothing   -> return . B.str $ "[" <> ref <> "]"
      Just contents  -> do
        st <- askF
        let contents' = runF contents st{ orgStateNotes' = [] }
        return $ B.note contents'

linkOrImage :: PandocMonad m => OrgParser m (F Inlines)
linkOrImage = explicitOrImageLink
              <|> selflinkOrImage
              <|> angleLink
              <|> plainLink
              <?> "link or image"

explicitOrImageLink :: PandocMonad m => OrgParser m (F Inlines)
explicitOrImageLink = try $ do
  char '['
  srcF   <- applyCustomLinkFormat =<< possiblyEmptyLinkTarget
  descr  <- enclosedRaw (char '[') (char ']')
  titleF <- parseFromString (mconcat <$> many inline) descr
  char ']'
  return $ do
    src <- srcF
    title <- titleF
    case cleanLinkText descr of
      Just imgSrc | isImageFilename imgSrc ->
        return . B.link src "" $ B.image imgSrc mempty mempty
      _ ->
        linkToInlinesF src title

selflinkOrImage :: PandocMonad m => OrgParser m (F Inlines)
selflinkOrImage = try $ do
  target <- char '[' *> linkTarget <* char ']'
  case cleanLinkText target of
    Nothing        -> case T.uncons target of
                        Just ('#', _) -> returnF $ B.link target "" (B.str target)
                        _             -> return $ internalLink target (B.str target)
    Just nonDocTgt -> if isImageFilename nonDocTgt
                      then returnF $ B.image nonDocTgt "" ""
                      else returnF $ B.link nonDocTgt "" (B.str target)

plainLink :: PandocMonad m => OrgParser m (F Inlines)
plainLink = try $ do
  (orig, src) <- uri
  returnF $ B.link src "" (B.str orig)

angleLink :: PandocMonad m => OrgParser m (F Inlines)
angleLink = try $ do
  char '<'
  link <- plainLink
  char '>'
  return link

linkTarget :: PandocMonad m => OrgParser m Text
linkTarget = T.pack <$> enclosedByPair1 '[' ']' (noneOf "\n\r[]")

possiblyEmptyLinkTarget :: PandocMonad m => OrgParser m Text
possiblyEmptyLinkTarget = try linkTarget <|> ("" <$ string "[]")

applyCustomLinkFormat :: Text -> OrgParser m (F Text)
applyCustomLinkFormat link = do
  let (linkType, rest) = T.break (== ':') link
  return $ do
    formatter <- M.lookup linkType <$> asksF orgStateLinkFormatters
    return $ maybe link ($ T.drop 1 rest) formatter

-- | Take a link and return a function which produces new inlines when given
-- description inlines.
linkToInlinesF :: Text -> Inlines -> F Inlines
linkToInlinesF linkStr =
  case T.uncons linkStr of
    Nothing       -> pure . B.link mempty ""       -- wiki link (empty by convention)
    Just ('#', _) -> pure . B.link linkStr ""      -- document-local fraction
    _             -> case cleanLinkText linkStr of
      Just extTgt -> return . B.link extTgt ""
      Nothing     -> internalLink linkStr  -- other internal link

internalLink :: Text -> Inlines -> F Inlines
internalLink link title = do
  anchorB <- (link `elem`) <$> asksF orgStateAnchorIds
  if anchorB
    then return $ B.link ("#" <> link) "" title
    else return $ B.emph title

-- | Parse an anchor like @<<anchor-id>>@ and return an empty span with
-- @anchor-id@ set as id.  Legal anchors in org-mode are defined through
-- @org-target-regexp@, which is fairly liberal.  Since no link is created if
-- @anchor-id@ contains spaces, we are more restrictive in what is accepted as
-- an anchor.

anchor :: PandocMonad m => OrgParser m (F Inlines)
anchor =  try $ do
  anchorId <- parseAnchor
  recordAnchorId anchorId
  returnF $ B.spanWith (solidify anchorId, [], []) mempty
 where
       parseAnchor = string "<<"
                     *> many1Char (noneOf "\t\n\r<>\"' ")
                     <* string ">>"
                     <* skipSpaces

-- | Replace every char but [a-zA-Z0-9_.-:] with a hyphen '-'.  This mirrors
-- the org function @org-export-solidify-link-text@.

solidify :: Text -> Text
solidify = T.map replaceSpecialChar
 where replaceSpecialChar c
           | isAlphaNum c    = c
           | c `elem` ("_.-:" :: String) = c
           | otherwise       = '-'

-- | Parses an inline code block and marks it as an babel block.
inlineCodeBlock :: PandocMonad m => OrgParser m (F Inlines)
inlineCodeBlock = try $ do
  string "src_"
  lang <- many1Char orgArgWordChar
  opts <- option [] $ enclosedByPair '[' ']' inlineBlockOption
  inlineCode <- T.pack <$> enclosedByPair1 '{' '}' (noneOf "\n\r")
  let attrClasses = [translateLang lang]
  let attrKeyVal  = originalLang lang <> opts
  let codeInlineBlck = B.codeWith ("", attrClasses, attrKeyVal) inlineCode
  returnF $ if exportsCode opts then codeInlineBlck else mempty
 where
   inlineBlockOption :: PandocMonad m => OrgParser m (Text, Text)
   inlineBlockOption = try $ do
     argKey <- orgArgKey
     paramValue <- option "yes" orgInlineParamValue
     return (argKey, paramValue)

   orgInlineParamValue :: PandocMonad m => OrgParser m Text
   orgInlineParamValue = try $
     skipSpaces
       *> notFollowedBy (char ':')
       *> many1Char (noneOf "\t\n\r ]")
       <* skipSpaces


emphasizedText :: PandocMonad m => OrgParser m (F Inlines)
emphasizedText = do
  state <- getState
  guard . exportEmphasizedText . orgStateExportSettings $ state
  try $ choice
    [ emph
    , strong
    , strikeout
    , underline
    ]

enclosedByPair :: PandocMonad m
               => Char          -- ^ opening char
               -> Char          -- ^ closing char
               -> OrgParser m a   -- ^ parser
               -> OrgParser m [a]
enclosedByPair s e p = char s *> manyTill p (char e)

enclosedByPair1 :: PandocMonad m
               => Char          -- ^ opening char
               -> Char          -- ^ closing char
               -> OrgParser m a   -- ^ parser
               -> OrgParser m [a]
enclosedByPair1 s e p = char s *> many1Till p (char e)

emph      :: PandocMonad m => OrgParser m (F Inlines)
emph      = fmap B.emph         <$> emphasisBetween '/'

strong    :: PandocMonad m => OrgParser m (F Inlines)
strong    = fmap B.strong       <$> emphasisBetween '*'

strikeout :: PandocMonad m => OrgParser m (F Inlines)
strikeout = fmap B.strikeout    <$> emphasisBetween '+'

underline :: PandocMonad m => OrgParser m (F Inlines)
underline = fmap underlineSpan  <$> emphasisBetween '_'

verbatim  :: PandocMonad m => OrgParser m (F Inlines)
verbatim  = return . B.code     <$> verbatimBetween '='

code      :: PandocMonad m => OrgParser m (F Inlines)
code      = return . B.code     <$> verbatimBetween '~'

subscript   :: PandocMonad m => OrgParser m (F Inlines)
subscript   = fmap B.subscript   <$> try (char '_' *> subOrSuperExpr)

superscript :: PandocMonad m => OrgParser m (F Inlines)
superscript = fmap B.superscript <$> try (char '^' *> subOrSuperExpr)

math      :: PandocMonad m => OrgParser m (F Inlines)
math      = return . B.math      <$> choice [ math1CharBetween '$'
                                            , mathTextBetween '$'
                                            , rawMathBetween "\\(" "\\)"
                                            ]

displayMath :: PandocMonad m => OrgParser m (F Inlines)
displayMath = return . B.displayMath <$> choice [ rawMathBetween "\\[" "\\]"
                                                , rawMathBetween "$$"  "$$"
                                                ]

updatePositions :: PandocMonad m
                => Char
                -> OrgParser m Char
updatePositions c = do
  st <- getState
  let emphasisPreChars = orgStateEmphasisPreChars st
  when (c `elem` emphasisPreChars) updateLastPreCharPos
  when (c `elem` emphasisForbiddenBorderChars) updateLastForbiddenCharPos
  return c

symbol :: PandocMonad m => OrgParser m (F Inlines)
symbol = return . B.str . T.singleton <$> (oneOf specialChars >>= updatePositions)

emphasisBetween :: PandocMonad m
                => Char
                -> OrgParser m (F Inlines)
emphasisBetween c = try $ do
  startEmphasisNewlinesCounting emphasisAllowedNewlines
  res <- enclosedInlines (emphasisStart c) (emphasisEnd c)
  isTopLevelEmphasis <- null . orgStateEmphasisCharStack <$> getState
  when isTopLevelEmphasis
       resetEmphasisNewlines
  return res

verbatimBetween :: PandocMonad m
                => Char
                -> OrgParser m Text
verbatimBetween c = try $
  emphasisStart c *>
  many1TillNOrLessNewlines 1 verbatimChar (emphasisEnd c)
 where
   verbatimChar = noneOf "\n\r" >>= updatePositions

-- | Parses a raw string delimited by @c@ using Org's math rules
mathTextBetween :: PandocMonad m
                  => Char
                  -> OrgParser m Text
mathTextBetween c = try $ do
  mathStart c
  body <- many1TillNOrLessNewlines mathAllowedNewlines
                                   (noneOf (c:"\n\r"))
                                   (lookAhead $ mathEnd c)
  final <- mathEnd c
  return $ T.snoc body final

-- | Parse a single character between @c@ using math rules
math1CharBetween :: PandocMonad m
                 => Char
                -> OrgParser m Text
math1CharBetween c = try $ do
  char c
  res <- noneOf $ c:mathForbiddenBorderChars
  char c
  eof <|> () <$ lookAhead (oneOf mathPostChars)
  return $ T.singleton res

rawMathBetween :: PandocMonad m
               => Text
               -> Text
               -> OrgParser m Text
rawMathBetween s e = try $ textStr s *> manyTillChar anyChar (try $ textStr e)

-- | Parses the start (opening character) of emphasis
emphasisStart :: PandocMonad m => Char -> OrgParser m Char
emphasisStart c = try $ do
  guard =<< afterEmphasisPreChar
  guard =<< notAfterString
  char c
  lookAhead (noneOf emphasisForbiddenBorderChars)
  pushToInlineCharStack c
  -- nested inlines are allowed, so mark this position as one which might be
  -- followed by another inline.
  updateLastPreCharPos
  return c

-- | Parses the closing character of emphasis
emphasisEnd :: PandocMonad m => Char -> OrgParser m Char
emphasisEnd c = try $ do
  guard =<< notAfterForbiddenBorderChar
  char c
  eof <|> () <$ lookAhead acceptablePostChars
  updateLastStrPos
  popInlineCharStack
  return c
 where
  acceptablePostChars = do
    emphasisPostChars <- orgStateEmphasisPostChars <$> getState
    surroundingEmphasisChar >>= \x -> oneOf (x ++ emphasisPostChars)

mathStart :: PandocMonad m => Char -> OrgParser m Char
mathStart c = try $
  char c <* notFollowedBy' (oneOf (c:mathForbiddenBorderChars))

mathEnd :: PandocMonad m => Char -> OrgParser m Char
mathEnd c = try $ do
  res <- noneOf (c:mathForbiddenBorderChars)
  char c
  eof <|> () <$ lookAhead (oneOf mathPostChars)
  return res


enclosedInlines :: (PandocMonad m, Show b) => OrgParser m a
                -> OrgParser m b
                -> OrgParser m (F Inlines)
enclosedInlines start end = try $
  trimInlinesF . mconcat <$> enclosed start end inline

enclosedRaw :: (PandocMonad m, Show b) => OrgParser m a
            -> OrgParser m b
            -> OrgParser m Text
enclosedRaw start end = try $
  start *> (onSingleLine <|> spanningTwoLines)
 where onSingleLine = try $ many1TillChar (noneOf "\n\r") end
       spanningTwoLines = try $
         anyLine >>= \f -> mappend (f <> " ") <$> onSingleLine

-- | Like many1Till, but parses at most @n+1@ lines.  @p@ must not consume
--   newlines.
many1TillNOrLessNewlines :: PandocMonad m => Int
                         -> OrgParser m Char
                         -> OrgParser m a
                         -> OrgParser m Text
many1TillNOrLessNewlines n p end = try $
  nMoreLines (Just n) mempty >>= oneOrMore
 where
   nMoreLines Nothing  cs = return cs
   nMoreLines (Just 0) cs = try $ (cs ++) <$> finalLine
   nMoreLines k        cs = try $ (final k cs <|> rest k cs)
                                  >>= uncurry nMoreLines
   final _ cs = (\x -> (Nothing,      cs ++ x)) <$> try finalLine
   rest  m cs = (\x -> (minus1 <$> m, cs ++ x ++ "\n")) <$> try (manyTill p newline)
   finalLine = try $ manyTill p end
   minus1 k = k - 1
   oneOrMore cs = T.pack cs <$ guard (not $ null cs)

-- Org allows customization of the way it reads emphasis.  We use the defaults
-- here (see, e.g., the Emacs Lisp variable `org-emphasis-regexp-components`
-- for details).

-- | Chars not allowed at the (inner) border of emphasis
emphasisForbiddenBorderChars :: [Char]
emphasisForbiddenBorderChars = "\t\n\r "

-- | The maximum number of newlines within
emphasisAllowedNewlines :: Int
emphasisAllowedNewlines = 1

-- LaTeX-style math: see `org-latex-regexps` for details

-- | Chars allowed after an inline ($...$) math statement
mathPostChars :: [Char]
mathPostChars = "\t\n \"'),-.:;?"

-- | Chars not allowed at the (inner) border of math
mathForbiddenBorderChars :: [Char]
mathForbiddenBorderChars = "\t\n\r ,;.$"

-- | Maximum number of newlines in an inline math statement
mathAllowedNewlines :: Int
mathAllowedNewlines = 2

-- | Whether we are right behind a char allowed before emphasis
afterEmphasisPreChar :: PandocMonad m => OrgParser m Bool
afterEmphasisPreChar = do
  pos <- getPosition
  lastPrePos <- orgStateLastPreCharPos <$> getState
  return $ maybe True (== pos) lastPrePos

-- | Whether the parser is right after a forbidden border char
notAfterForbiddenBorderChar :: PandocMonad m => OrgParser m Bool
notAfterForbiddenBorderChar = do
  pos <- getPosition
  lastFBCPos <- orgStateLastForbiddenCharPos <$> getState
  return $ lastFBCPos /= Just pos

-- | Read a sub- or superscript expression
subOrSuperExpr :: PandocMonad m => OrgParser m (F Inlines)
subOrSuperExpr = try $
  simpleSubOrSuperText <|>
  (choice [ charsInBalanced '{' '}' (noneOf "\n\r")
          , enclosing ('(', ')') <$> charsInBalanced '(' ')' (noneOf "\n\r")
          ] >>= parseFromString (mconcat <$> many inline))
 where enclosing (left, right) s = T.cons left $ T.snoc s right

simpleSubOrSuperText :: PandocMonad m => OrgParser m (F Inlines)
simpleSubOrSuperText = try $ do
  state <- getState
  guard . exportSubSuperscripts . orgStateExportSettings $ state
  return . B.str <$>
    choice [ textStr "*"
           , mappend <$> option "" (T.singleton <$> oneOf "+-")
                     <*> many1Char alphaNum
           ]

inlineLaTeX :: PandocMonad m => OrgParser m (F Inlines)
inlineLaTeX = try $ do
  cmd <- inlineLaTeXCommand
  ils <- (lift . lift) $ parseAsInlineLaTeX cmd
  maybe mzero returnF $
     parseAsMathMLSym cmd `mplus` parseAsMath cmd `mplus` ils
 where
   parseAsMath :: Text -> Maybe Inlines
   parseAsMath cs = B.fromList <$> texMathToPandoc cs

   parseAsInlineLaTeX :: PandocMonad m => Text -> m (Maybe Inlines)
   parseAsInlineLaTeX cs = maybeRight <$> runParserT inlineCommand state "" cs

   parseAsMathMLSym :: Text -> Maybe Inlines
   parseAsMathMLSym cs = B.str <$> MathMLEntityMap.getUnicode (clean cs)
    -- drop initial backslash and any trailing "{}"
    where clean = T.dropWhileEnd (`elem` ("{}" :: String)) . T.drop 1

   state :: ParserState
   state = def{ stateOptions = def{ readerExtensions =
                    enableExtension Ext_raw_tex (readerExtensions def) } }

   texMathToPandoc :: Text -> Maybe [Inline]
   texMathToPandoc cs = maybeRight (readTeX cs) >>= writePandoc DisplayInline

maybeRight :: Either a b -> Maybe b
maybeRight = either (const Nothing) Just

inlineLaTeXCommand :: PandocMonad m => OrgParser m Text
inlineLaTeXCommand = try $ do
  rest <- getInput
  st <- getState
  parsed <- (lift . lift) $ runParserT rawLaTeXInline st "source" rest
  case parsed of
    Right cs -> do
      -- drop any trailing whitespace, those are not be part of the command as
      -- far as org mode is concerned.
      let cmdNoSpc = T.dropWhileEnd isSpace cs
      let len = T.length cmdNoSpc
      count len anyChar
      return cmdNoSpc
    _ -> mzero

exportSnippet :: PandocMonad m => OrgParser m (F Inlines)
exportSnippet = try $ do
  string "@@"
  format <- many1TillChar (alphaNum <|> char '-') (char ':')
  snippet <- manyTillChar anyChar (try $ string "@@")
  returnF $ B.rawInline format snippet

macro :: PandocMonad m => OrgParser m (F Inlines)
macro = try $ do
  recursionDepth <- orgStateMacroDepth <$> getState
  guard $ recursionDepth < 15
  string "{{{"
  name <- manyChar alphaNum
  args <- ([] <$ string "}}}")
          <|> char '(' *> argument `sepBy` char ',' <* eoa
  expander <- lookupMacro name <$> getState
  case expander of
    Nothing -> mzero
    Just fn -> do
      updateState $ \s -> s { orgStateMacroDepth = recursionDepth + 1 }
      res <- parseFromString (mconcat <$> many inline) $ fn args
      updateState $ \s -> s { orgStateMacroDepth = recursionDepth }
      return res
 where
  argument = manyChar $ notFollowedBy eoa *> noneOf ","
  eoa = string ")}}}"

smart :: PandocMonad m => OrgParser m (F Inlines)
smart = choice [doubleQuoted, singleQuoted, orgApostrophe, orgDash, orgEllipses]
  where
    orgDash = do
      guardOrSmartEnabled =<< getExportSetting exportSpecialStrings
      pure <$> dash <* updatePositions '-'
    orgEllipses = do
      guardOrSmartEnabled =<< getExportSetting exportSpecialStrings
      pure <$> ellipses <* updatePositions '.'
    orgApostrophe = do
      guardEnabled Ext_smart
      (char '\'' <|> char '\8217') <* updateLastPreCharPos
                                   <* updateLastForbiddenCharPos
      returnF (B.str "\x2019")

guardOrSmartEnabled :: PandocMonad m => Bool -> OrgParser m ()
guardOrSmartEnabled b = do
  smartExtension <- extensionEnabled Ext_smart <$> getOption readerExtensions
  guard (b || smartExtension)

singleQuoted :: PandocMonad m => OrgParser m (F Inlines)
singleQuoted = try $ do
  guardOrSmartEnabled =<< getExportSetting exportSmartQuotes
  singleQuoteStart
  updatePositions '\''
  withQuoteContext InSingleQuote $
    fmap B.singleQuoted . trimInlinesF . mconcat <$>
      many1Till inline (singleQuoteEnd <* updatePositions '\'')

-- doubleQuoted will handle regular double-quoted sections, as well
-- as dialogues with an open double-quote without a close double-quote
-- in the same paragraph.
doubleQuoted :: PandocMonad m => OrgParser m (F Inlines)
doubleQuoted = try $ do
  guardOrSmartEnabled =<< getExportSetting exportSmartQuotes
  doubleQuoteStart
  updatePositions '"'
  contents <- mconcat <$> many (try $ notFollowedBy doubleQuoteEnd >> inline)
  let doubleQuotedContent = withQuoteContext InDoubleQuote $ do
        doubleQuoteEnd
        updateLastForbiddenCharPos
        return . fmap B.doubleQuoted . trimInlinesF $ contents
  let leftQuoteAndContent = return $ pure (B.str "\8220") <> contents
  doubleQuotedContent <|> leftQuoteAndContent