aboutsummaryrefslogtreecommitdiff
path: root/src/Text/Pandoc/Writers/Powerpoint/Presentation.hs
blob: 495675aaddeac3341f2b579004ebc029c203feba (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
{-# LANGUAGE PatternGuards #-}

{-
Copyright (C) 2017-2018 Jesse Rosenthal <jrosenthal@jhu.edu>

This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
-}

{- |
   Module      : Text.Pandoc.Writers.Powerpoint.Presentation
   Copyright   : Copyright (C) 2017-2018 Jesse Rosenthal
   License     : GNU GPL, version 2 or above

   Maintainer  : Jesse Rosenthal <jrosenthal@jhu.edu>
   Stability   : alpha
   Portability : portable

Definition of Presentation datatype, modeling a MS Powerpoint (pptx)
document, and functions for converting a Pandoc document to
Presentation.
-}

module Text.Pandoc.Writers.Powerpoint.Presentation ( documentToPresentation
                                                   , Presentation(..)
                                                   , Slide(..)
                                                   , Layout(..)
                                                   , Notes(..)
                                                   , SlideId(..)
                                                   , Shape(..)
                                                   , Graphic(..)
                                                   , BulletType(..)
                                                   , Algnment(..)
                                                   , Paragraph(..)
                                                   , ParaElem(..)
                                                   , ParaProps(..)
                                                   , RunProps(..)
                                                   , TableProps(..)
                                                   , Strikethrough(..)
                                                   , Capitals(..)
                                                   , PicProps(..)
                                                   , URL
                                                   , TeXString(..)
                                                   , LinkTarget(..)
                                                   ) where


import Control.Monad.Reader
import Control.Monad.State
import Data.List (intercalate)
import Data.Default
import Text.Pandoc.Definition
import Text.Pandoc.ImageSize
import Text.Pandoc.Slides (getSlideLevel)
import Text.Pandoc.Options
import Text.Pandoc.Logging
import Text.Pandoc.Walk
import qualified Text.Pandoc.Shared as Shared -- so we don't overlap "Element"
import Text.Pandoc.Writers.Shared (metaValueToInlines)
import qualified Data.Map as M
import qualified Data.Set as S
import Data.Maybe (maybeToList)

data WriterEnv = WriterEnv { envMetadata :: Meta
                           , envRunProps :: RunProps
                           , envParaProps :: ParaProps
                           , envSlideLevel :: Int
                           , envOpts :: WriterOptions
                           , envSlideHasHeader :: Bool
                           , envInList :: Bool
                           , envInNoteSlide :: Bool
                           , envCurSlideId :: SlideId
                           }
                 deriving (Show)

instance Default WriterEnv where
  def = WriterEnv { envMetadata = mempty
                  , envRunProps = def
                  , envParaProps = def
                  , envSlideLevel = 2
                  , envOpts = def
                  , envSlideHasHeader = False
                  , envInList = False
                  , envInNoteSlide = False
                  , envCurSlideId = SlideId "Default"
                  }


data WriterState = WriterState { stNoteIds :: M.Map Int [Block]
                               -- associate anchors with slide id
                               , stAnchorMap :: M.Map String SlideId
                               , stSlideIdSet :: S.Set SlideId
                               , stLog :: [LogMessage]

                               } deriving (Show, Eq)

instance Default WriterState where
  def = WriterState { stNoteIds = mempty
                    , stAnchorMap = mempty
                    -- we reserve this s
                    , stSlideIdSet = reservedSlideIds
                    , stLog = []
                    }

metadataSlideId :: SlideId
metadataSlideId = SlideId "Metadata"

tocSlideId :: SlideId
tocSlideId = SlideId "TOC"

endNotesSlideId :: SlideId
endNotesSlideId = SlideId "EndNotes"

reservedSlideIds :: S.Set SlideId
reservedSlideIds = S.fromList [ metadataSlideId
                              , tocSlideId
                              , endNotesSlideId
                              ]

uniqueSlideId' :: Integer -> S.Set SlideId -> String -> SlideId
uniqueSlideId' n idSet s =
  let s' = if n == 0 then s else (s ++ "-" ++ show n)
  in if SlideId s' `S.member` idSet
     then uniqueSlideId' (n+1) idSet s
     else SlideId s'

uniqueSlideId :: S.Set SlideId -> String -> SlideId
uniqueSlideId = uniqueSlideId' 0

runUniqueSlideId :: String -> Pres SlideId
runUniqueSlideId s = do
  idSet <- gets stSlideIdSet
  let sldId = uniqueSlideId idSet s
  modify $ \st -> st{stSlideIdSet = S.insert sldId idSet}
  return sldId

addLogMessage :: LogMessage -> Pres ()
addLogMessage msg = modify $ \st -> st{stLog = msg : (stLog st)}

type Pres = ReaderT WriterEnv (State WriterState)

runPres :: WriterEnv -> WriterState -> Pres a -> (a, [LogMessage])
runPres env st p = (pres, reverse $ stLog finalSt)
  where (pres, finalSt) = runState (runReaderT p env) st

-- GHC 7.8 will still complain about concat <$> mapM unless we specify
-- Functor. We can get rid of this when we stop supporting GHC 7.8.
concatMapM        :: (Monad m) => (a -> m [b]) -> [a] -> m [b]
concatMapM f xs   =  liftM concat (mapM f xs)

type Pixels = Integer

data Presentation = Presentation [Slide]
  deriving (Show)


data Slide = Slide { slideId :: SlideId
                   , slideLayout :: Layout
                   , slideNotes :: (Maybe Notes)
                   } deriving (Show, Eq)

newtype SlideId = SlideId String
  deriving (Show, Eq, Ord)

-- In theory you could have anything on a notes slide but it seems
-- designed mainly for one textbox, so we'll just put in the contents
-- of that textbox, to avoid other shapes that won't work as well.
newtype Notes = Notes [Paragraph]
  deriving (Show, Eq)

data Layout = MetadataSlide { metadataSlideTitle :: [ParaElem]
                            , metadataSlideSubtitle :: [ParaElem]
                            , metadataSlideAuthors :: [[ParaElem]]
                            , metadataSlideDate :: [ParaElem]
                            }
           | TitleSlide { titleSlideHeader :: [ParaElem]}
           | ContentSlide { contentSlideHeader :: [ParaElem]
                          , contentSlideContent :: [Shape]
                          }
           | TwoColumnSlide { twoColumnSlideHeader :: [ParaElem]
                            , twoColumnSlideLeft   :: [Shape]
                            , twoColumnSlideRight  :: [Shape]
                            }
           deriving (Show, Eq)

data Shape = Pic PicProps FilePath [ParaElem]
           | GraphicFrame [Graphic] [ParaElem]
           | TextBox [Paragraph]
  deriving (Show, Eq)

type Cell = [Paragraph]

data TableProps = TableProps { tblPrFirstRow :: Bool
                             , tblPrBandRow :: Bool
                             } deriving (Show, Eq)

data Graphic = Tbl TableProps [Cell] [[Cell]]
  deriving (Show, Eq)


data Paragraph = Paragraph { paraProps :: ParaProps
                           , paraElems  :: [ParaElem]
                           } deriving (Show, Eq)


data BulletType = Bullet
                | AutoNumbering ListAttributes
  deriving (Show, Eq)

data Algnment = AlgnLeft | AlgnRight | AlgnCenter
  deriving (Show, Eq)

data ParaProps = ParaProps { pPropMarginLeft :: Maybe Pixels
                           , pPropMarginRight :: Maybe Pixels
                           , pPropLevel :: Int
                           , pPropBullet :: Maybe BulletType
                           , pPropAlign :: Maybe Algnment
                           , pPropSpaceBefore :: Maybe Pixels
                           } deriving (Show, Eq)

instance Default ParaProps where
  def = ParaProps { pPropMarginLeft = Just 0
                  , pPropMarginRight = Just 0
                  , pPropLevel = 0
                  , pPropBullet = Nothing
                  , pPropAlign = Nothing
                  , pPropSpaceBefore = Nothing
                  }

newtype TeXString = TeXString {unTeXString :: String}
  deriving (Eq, Show)

data ParaElem = Break
              | Run RunProps String
              -- It would be more elegant to have native TeXMath
              -- Expressions here, but this allows us to use
              -- `convertmath` from T.P.Writers.Math. Will perhaps
              -- revisit in the future.
              | MathElem MathType TeXString
              deriving (Show, Eq)

data Strikethrough = NoStrike | SingleStrike | DoubleStrike
  deriving (Show, Eq)

data Capitals = NoCapitals | SmallCapitals | AllCapitals
  deriving (Show, Eq)

type URL = String

data LinkTarget = ExternalTarget (URL, String)
                | InternalTarget SlideId
                deriving (Show, Eq)

data RunProps = RunProps { rPropBold :: Bool
                         , rPropItalics :: Bool
                         , rStrikethrough :: Maybe Strikethrough
                         , rBaseline :: Maybe Int
                         , rCap :: Maybe Capitals
                         , rLink :: Maybe LinkTarget
                         , rPropCode :: Bool
                         , rPropBlockQuote :: Bool
                         , rPropForceSize :: Maybe Pixels
                         } deriving (Show, Eq)

instance Default RunProps where
  def = RunProps { rPropBold = False
                 , rPropItalics = False
                 , rStrikethrough = Nothing
                 , rBaseline = Nothing
                 , rCap = Nothing
                 , rLink = Nothing
                 , rPropCode = False
                 , rPropBlockQuote = False
                 , rPropForceSize = Nothing
                 }

data PicProps = PicProps { picPropLink :: Maybe LinkTarget
                         , picWidth    :: Maybe Dimension
                         , picHeight   :: Maybe Dimension
                         } deriving (Show, Eq)

instance Default PicProps where
  def = PicProps { picPropLink = Nothing
                 , picWidth = Nothing
                 , picHeight = Nothing
                 }

--------------------------------------------------

inlinesToParElems :: [Inline] -> Pres [ParaElem]
inlinesToParElems ils = concatMapM inlineToParElems ils

inlineToParElems :: Inline -> Pres [ParaElem]
inlineToParElems (Str s) = do
  pr <- asks envRunProps
  return [Run pr s]
inlineToParElems (Emph ils) =
  local (\r -> r{envRunProps = (envRunProps r){rPropItalics=True}}) $
  inlinesToParElems ils
inlineToParElems (Strong ils) =
  local (\r -> r{envRunProps = (envRunProps r){rPropBold=True}}) $
  inlinesToParElems ils
inlineToParElems (Strikeout ils) =
  local (\r -> r{envRunProps = (envRunProps r){rStrikethrough=Just SingleStrike}}) $
  inlinesToParElems ils
inlineToParElems (Superscript ils) =
  local (\r -> r{envRunProps = (envRunProps r){rBaseline=Just 30000}}) $
  inlinesToParElems ils
inlineToParElems (Subscript ils) =
  local (\r -> r{envRunProps = (envRunProps r){rBaseline=Just (-25000)}}) $
  inlinesToParElems ils
inlineToParElems (SmallCaps ils) =
  local (\r -> r{envRunProps = (envRunProps r){rCap = Just SmallCapitals}}) $
  inlinesToParElems ils
inlineToParElems Space = inlineToParElems (Str " ")
inlineToParElems SoftBreak = inlineToParElems (Str " ")
inlineToParElems LineBreak = return [Break]
inlineToParElems (Link _ ils (url, title)) = do
  local (\r ->r{envRunProps = (envRunProps r){rLink = Just $ ExternalTarget (url, title)}}) $
    inlinesToParElems ils
inlineToParElems (Code _ str) = do
  local (\r ->r{envRunProps = (envRunProps r){rPropCode = True}}) $
    inlineToParElems $ Str str
inlineToParElems (Math mathtype str) =
  return [MathElem mathtype (TeXString str)]
inlineToParElems (Note blks) = do
  notes <- gets stNoteIds
  let maxNoteId = case M.keys notes of
        [] -> 0
        lst -> maximum lst
      curNoteId = maxNoteId + 1
  modify $ \st -> st { stNoteIds = M.insert curNoteId blks notes }
  local (\env -> env{envRunProps = (envRunProps env){rLink = Just $ InternalTarget endNotesSlideId}}) $
    inlineToParElems $ Superscript [Str $ show curNoteId]
inlineToParElems (Span _ ils) = concatMapM inlineToParElems ils
inlineToParElems (RawInline _ _) = return []
inlineToParElems _ = return []

isListType :: Block -> Bool
isListType (OrderedList _ _) = True
isListType (BulletList _) = True
isListType (DefinitionList _) = True
isListType _ = False

registerAnchorId :: String -> Pres ()
registerAnchorId anchor = do
  anchorMap <- gets stAnchorMap
  sldId <- asks envCurSlideId
  unless (null anchor) $
    modify $ \st -> st {stAnchorMap = M.insert anchor sldId anchorMap}

-- Currently hardcoded, until I figure out how to make it dynamic.
blockQuoteSize :: Pixels
blockQuoteSize = 20

noteSize :: Pixels
noteSize = 18

blockToParagraphs :: Block -> Pres [Paragraph]
blockToParagraphs (Plain ils) = do
  parElems <- inlinesToParElems ils
  pProps <- asks envParaProps
  return [Paragraph pProps parElems]
blockToParagraphs (Para ils) = do
  parElems <- inlinesToParElems ils
  pProps <- asks envParaProps
  return [Paragraph pProps parElems]
blockToParagraphs (LineBlock ilsList) = do
  parElems <- inlinesToParElems $ intercalate [LineBreak] ilsList
  pProps <- asks envParaProps
  return [Paragraph pProps parElems]
-- TODO: work out the attributes
blockToParagraphs (CodeBlock attr str) =
  local (\r -> r{envParaProps = def{pPropMarginLeft = Just 100}}) $
  blockToParagraphs $ Para [Code attr str]
-- We can't yet do incremental lists, but we should render a
-- (BlockQuote List) as a list to maintain compatibility with other
-- formats.
blockToParagraphs (BlockQuote (blk : blks)) | isListType blk = do
  ps  <- blockToParagraphs blk
  ps' <- blockToParagraphs $ BlockQuote blks
  return $ ps ++ ps'
blockToParagraphs (BlockQuote blks) =
  local (\r -> r{ envParaProps = (envParaProps r){pPropMarginLeft = Just 100}
                , envRunProps = (envRunProps r){rPropForceSize = Just blockQuoteSize}})$
  concatMapM blockToParagraphs blks
-- TODO: work out the format
blockToParagraphs (RawBlock _ _) = return []
blockToParagraphs (Header _ (ident, _, _) ils) = do
  -- Note that this function only deals with content blocks, so it
  -- will only touch headers that are above the current slide level --
  -- slides at or below the slidelevel will be taken care of by
  -- `blocksToSlide'`. We have the register anchors in both of them.
  registerAnchorId ident
  -- we set the subeader to bold
  parElems <- local (\e->e{envRunProps = (envRunProps e){rPropBold=True}}) $
              inlinesToParElems ils
  -- and give it a bit of space before it.
  return [Paragraph def{pPropSpaceBefore = Just 30} parElems]
blockToParagraphs (BulletList blksLst) = do
  pProps <- asks envParaProps
  let lvl = pPropLevel pProps
  local (\env -> env{ envInList = True
                    , envParaProps = pProps{ pPropLevel = lvl + 1
                                           , pPropBullet = Just Bullet
                                           , pPropMarginLeft = Nothing
                                           }}) $
    concatMapM multiParBullet blksLst
blockToParagraphs (OrderedList listAttr blksLst) = do
  pProps <- asks envParaProps
  let lvl = pPropLevel pProps
  local (\env -> env{ envInList = True
                    , envParaProps = pProps{ pPropLevel = lvl + 1
                                           , pPropBullet = Just (AutoNumbering listAttr)
                                           , pPropMarginLeft = Nothing
                                           }}) $
    concatMapM multiParBullet blksLst
blockToParagraphs (DefinitionList entries) = do
  let go :: ([Inline], [[Block]]) -> Pres [Paragraph]
      go (ils, blksLst) = do
        term <-blockToParagraphs $ Para [Strong ils]
        -- For now, we'll treat each definition term as a
        -- blockquote. We can extend this further later.
        definition <- concatMapM (blockToParagraphs . BlockQuote) blksLst
        return $ term ++ definition
  concatMapM go entries
blockToParagraphs (Div (_, ("notes" : []), _) _) = return []
blockToParagraphs (Div _ blks)  = concatMapM blockToParagraphs blks
blockToParagraphs blk = do
  addLogMessage $ BlockNotRendered blk
  return []

-- Make sure the bullet env gets turned off after the first para.
multiParBullet :: [Block] -> Pres [Paragraph]
multiParBullet [] = return []
multiParBullet (b:bs) = do
  pProps <- asks envParaProps
  p <- blockToParagraphs b
  ps <- local (\env -> env{envParaProps = pProps{pPropBullet = Nothing}}) $
    concatMapM blockToParagraphs bs
  return $ p ++ ps

cellToParagraphs :: Alignment -> TableCell -> Pres [Paragraph]
cellToParagraphs algn tblCell = do
  paras <- mapM (blockToParagraphs) tblCell
  let alignment = case algn of
        AlignLeft -> Just AlgnLeft
        AlignRight -> Just AlgnRight
        AlignCenter -> Just AlgnCenter
        AlignDefault -> Nothing
      paras' = map (map (\p -> p{paraProps = (paraProps p){pPropAlign = alignment}})) paras
  return $ concat paras'

rowToParagraphs :: [Alignment] -> [TableCell] -> Pres [[Paragraph]]
rowToParagraphs algns tblCells = do
  -- We have to make sure we have the right number of alignments
  let pairs = zip (algns ++ repeat AlignDefault) tblCells
  mapM (\(a, tc) -> cellToParagraphs a tc) pairs

withAttr :: Attr -> Shape -> Shape
withAttr attr (Pic picPr url caption) =
  let picPr' = picPr { picWidth = dimension Width attr
                     , picHeight = dimension Height attr
                     }
  in
    Pic picPr' url caption
withAttr _ sp = sp

blockToShape :: Block -> Pres Shape
blockToShape (Plain (il:_)) | Image attr ils (url, _) <- il =
      (withAttr attr . Pic def url) <$> (inlinesToParElems ils)
blockToShape (Para (il:_))  | Image attr ils (url, _) <- il =
      (withAttr attr . Pic def url) <$> (inlinesToParElems ils)
blockToShape (Plain (il:_)) | Link _ (il':_) target <- il
                            , Image attr ils (url, _) <- il' =
      (withAttr attr . Pic def {picPropLink = Just $ ExternalTarget target} url) <$>
      (inlinesToParElems ils)
blockToShape (Para (il:_))  | Link _ (il':_) target <- il
                            , Image attr ils (url, _) <- il' =
      (withAttr attr . Pic def{picPropLink = Just $ ExternalTarget target} url) <$>
      (inlinesToParElems ils)
blockToShape (Table caption algn _ hdrCells rows) = do
  caption' <- inlinesToParElems caption
  hdrCells' <- rowToParagraphs algn hdrCells
  rows' <- mapM (rowToParagraphs algn) rows
  let tblPr = if null hdrCells
              then TableProps { tblPrFirstRow = False
                              , tblPrBandRow = True
                              }
              else TableProps { tblPrFirstRow = True
                              , tblPrBandRow = True
                              }

  return $ GraphicFrame [Tbl tblPr hdrCells' rows'] caption'
blockToShape blk = do paras <- blockToParagraphs blk
                      let paras' = map (\par -> par{paraElems = combineParaElems $ paraElems par}) paras
                      return $ TextBox paras'

combineShapes :: [Shape] -> [Shape]
combineShapes [] = []
combineShapes (s : []) = [s]
combineShapes (pic@(Pic _ _ _) : ss) = pic : combineShapes ss
combineShapes ((TextBox []) : ss) = combineShapes ss
combineShapes (s : TextBox [] : ss) = combineShapes (s : ss)
combineShapes ((TextBox (p:ps)) : (TextBox (p':ps')) : ss) =
  combineShapes $ TextBox ((p:ps) ++ (p':ps')) : ss
combineShapes (s:ss) = s : combineShapes ss

blocksToShapes :: [Block] -> Pres [Shape]
blocksToShapes blks = combineShapes <$> mapM blockToShape blks

isImage :: Inline -> Bool
isImage (Image _ _ _) = True
isImage (Link _ ((Image _ _ _) : _) _) = True
isImage _ = False

splitBlocks' :: [Block] -> [[Block]] -> [Block] -> Pres [[Block]]
splitBlocks' cur acc [] = return $ acc ++ (if null cur then [] else [cur])
splitBlocks' cur acc (HorizontalRule : blks) =
  splitBlocks' [] (acc ++ (if null cur then [] else [cur])) blks
splitBlocks' cur acc (h@(Header n _ _) : blks) = do
  slideLevel <- asks envSlideLevel
  case compare n slideLevel of
    LT -> splitBlocks' [] (acc ++ (if null cur then [] else [cur]) ++ [[h]]) blks
    EQ -> splitBlocks' [h] (acc ++ (if null cur then [] else [cur])) blks
    GT -> splitBlocks' (cur ++ [h]) acc blks
-- `blockToParagraphs` treats Plain and Para the same, so we can save
-- some code duplication by treating them the same here.
splitBlocks' cur acc ((Plain ils) : blks) = splitBlocks' cur acc ((Para ils) : blks)
splitBlocks' cur acc ((Para (il:ils)) : blks) | isImage il = do
  slideLevel <- asks envSlideLevel
  case cur of
    (Header n _ _) : [] | n == slideLevel ->
                            splitBlocks' []
                            (acc ++ [cur ++ [Para [il]]])
                            (if null ils then blks else (Para ils) : blks)
    _ -> splitBlocks' []
         (acc ++ (if null cur then [] else [cur]) ++ [[Para [il]]])
         (if null ils then blks else (Para ils) : blks)
splitBlocks' cur acc (tbl@(Table _ _ _ _ _) : blks) = do
  slideLevel <- asks envSlideLevel
  case cur of
    (Header n _ _) : [] | n == slideLevel ->
                            splitBlocks' [] (acc ++ [cur ++ [tbl]]) blks
    _ ->  splitBlocks' [] (acc ++ (if null cur then [] else [cur]) ++ [[tbl]]) blks
splitBlocks' cur acc (d@(Div (_, classes, _) _): blks) | "columns" `elem` classes =  do
  slideLevel <- asks envSlideLevel
  case cur of
    (Header n _ _) : [] | n == slideLevel ->
                            splitBlocks' [] (acc ++ [cur ++ [d]]) blks
    _ ->  splitBlocks' [] (acc ++ (if null cur then [] else [cur]) ++ [[d]]) blks
splitBlocks' cur acc (blk : blks) = splitBlocks' (cur ++ [blk]) acc blks

splitBlocks :: [Block] -> Pres [[Block]]
splitBlocks = splitBlocks' [] []

blocksToSlide' :: Int -> [Block] -> Pres Slide
blocksToSlide' lvl ((Header n (ident, _, _) ils) : blks)
  | n < lvl = do
      registerAnchorId ident
      sldId <- asks envCurSlideId
      hdr <- inlinesToParElems ils
      return $ Slide sldId (TitleSlide {titleSlideHeader = hdr}) Nothing
  | n == lvl = do
      registerAnchorId ident
      hdr <- inlinesToParElems ils
      -- Now get the slide without the header, and then add the header
      -- in.
      slide <- blocksToSlide' lvl blks
      let layout = case slideLayout slide of
            ContentSlide _ cont          -> ContentSlide hdr cont
            TwoColumnSlide _ contL contR -> TwoColumnSlide hdr contL contR
            layout'                     -> layout'
      return $ slide{slideLayout = layout}
blocksToSlide' _ (blk : blks)
  | Div (_, classes, _) divBlks <- blk
  , "columns" `elem` classes
  , (Div (_, clsL, _) blksL) : (Div (_, clsR, _) blksR) : remaining <- divBlks
  , "column" `elem` clsL, "column" `elem` clsR = do
      unless (null blks)
        (mapM (addLogMessage . BlockNotRendered) blks >> return ())
      unless (null remaining)
        (mapM (addLogMessage . BlockNotRendered) remaining >> return ())
      mbSplitBlksL <- splitBlocks blksL
      mbSplitBlksR <- splitBlocks blksR
      let blksL' = case mbSplitBlksL of
            bs : _ -> bs
            []     -> []
      let blksR' = case mbSplitBlksR of
            bs : _ -> bs
            []     -> []
      shapesL <- blocksToShapes blksL'
      shapesR <- blocksToShapes blksR'
      sldId <- asks envCurSlideId
      return $ Slide
        sldId
        TwoColumnSlide { twoColumnSlideHeader = []
                       , twoColumnSlideLeft = shapesL
                       , twoColumnSlideRight = shapesR
                       }
        Nothing
blocksToSlide' _ (blk : blks) = do
      inNoteSlide <- asks envInNoteSlide
      shapes <- if inNoteSlide
                then forceFontSize noteSize $ blocksToShapes (blk : blks)
                else blocksToShapes (blk : blks)
      sldId <- asks envCurSlideId
      return $
        Slide
        sldId
        ContentSlide { contentSlideHeader = []
                     , contentSlideContent = shapes
                     }
        Nothing
blocksToSlide' _ [] = do
  sldId <- asks envCurSlideId
  return $
    Slide
    sldId
    ContentSlide { contentSlideHeader = []
                 , contentSlideContent = []
                 }
    Nothing

blocksToSlide :: [Block] -> Pres Slide
blocksToSlide blks = do
  slideLevel <- asks envSlideLevel
  blocksToSlide' slideLevel blks

makeNoteEntry :: Int -> [Block] -> [Block]
makeNoteEntry n blks =
  let enum = Str (show n ++ ".")
  in
    case blks of
      (Para ils : blks') -> (Para $ enum : Space : ils) : blks'
      _ -> (Para [enum]) : blks

forceFontSize :: Pixels -> Pres a -> Pres a
forceFontSize px x = do
  rpr <- asks envRunProps
  local (\r -> r {envRunProps = rpr{rPropForceSize = Just px}}) x

-- We leave these as blocks because we will want to include them in
-- the TOC.
makeEndNotesSlideBlocks :: Pres [Block]
makeEndNotesSlideBlocks = do
  noteIds <- gets stNoteIds
  slideLevel <- asks envSlideLevel
  meta <- asks envMetadata
  -- Get identifiers so we can give the notes section a unique ident.
  anchorSet <- M.keysSet <$> gets stAnchorMap
  if M.null noteIds
    then return []
    else do let title = case lookupMeta "notes-title" meta of
                  Just val -> metaValueToInlines val
                  Nothing  -> [Str "Notes"]
                ident = Shared.uniqueIdent title anchorSet
                hdr = Header slideLevel (ident, [], []) title
            blks <- return $
                    concatMap (\(n, bs) -> makeNoteEntry n bs) $
                    M.toList noteIds
            return $ hdr : blks

getMetaSlide :: Pres (Maybe Slide)
getMetaSlide  = do
  meta <- asks envMetadata
  title <- inlinesToParElems $ docTitle meta
  subtitle <- inlinesToParElems $
    case lookupMeta "subtitle" meta of
      Just (MetaString s)           -> [Str s]
      Just (MetaInlines ils)        -> ils
      Just (MetaBlocks [Plain ils]) -> ils
      Just (MetaBlocks [Para ils])  -> ils
      _                             -> []
  authors <- mapM inlinesToParElems $ docAuthors meta
  date <- inlinesToParElems $ docDate meta
  if null title && null subtitle && null authors && null date
    then return Nothing
    else return $
         Just $
         Slide
         metadataSlideId
         MetadataSlide { metadataSlideTitle = title
                       , metadataSlideSubtitle = subtitle
                       , metadataSlideAuthors = authors
                       , metadataSlideDate = date
                       }
         Nothing

-- adapted from the markdown writer
elementToListItem :: Shared.Element -> Pres [Block]
elementToListItem (Shared.Sec lev _nums (ident,_,_) headerText subsecs) = do
  opts <- asks envOpts
  let headerLink = if null ident
                   then walk Shared.deNote headerText
                   else [Link nullAttr (walk Shared.deNote headerText)
                          ('#':ident, "")]
  listContents <- if null subsecs || lev >= writerTOCDepth opts
                  then return []
                  else mapM elementToListItem subsecs
  return [Plain headerLink, BulletList listContents]
elementToListItem (Shared.Blk _) = return []

makeTOCSlide :: [Block] -> Pres Slide
makeTOCSlide blks = local (\env -> env{envCurSlideId = tocSlideId}) $ do
  contents <- BulletList <$> mapM elementToListItem (Shared.hierarchicalize blks)
  meta <- asks envMetadata
  slideLevel <- asks envSlideLevel
  let tocTitle = case lookupMeta "toc-title" meta of
                   Just val -> metaValueToInlines val
                   Nothing  -> [Str "Table of Contents"]
      hdr = Header slideLevel nullAttr tocTitle
  sld <- blocksToSlide [hdr, contents]
  return sld

combineParaElems' :: Maybe ParaElem -> [ParaElem] -> [ParaElem]
combineParaElems' mbPElem [] = maybeToList mbPElem
combineParaElems' Nothing (pElem : pElems) =
  combineParaElems' (Just pElem) pElems
combineParaElems' (Just pElem') (pElem : pElems)
  | Run rPr' s' <- pElem'
  , Run rPr s <- pElem
  , rPr == rPr' =
    combineParaElems' (Just $ Run rPr' $ s' ++ s) pElems
  | otherwise =
    pElem' : combineParaElems' (Just pElem) pElems

combineParaElems :: [ParaElem] -> [ParaElem]
combineParaElems = combineParaElems' Nothing

applyToParagraph :: Monad m => (ParaElem -> m ParaElem) -> Paragraph -> m Paragraph
applyToParagraph f para = do
  paraElems' <- mapM f $ paraElems para
  return $ para {paraElems = paraElems'}

applyToShape :: Monad m => (ParaElem -> m ParaElem) -> Shape -> m Shape
applyToShape f (Pic pPr fp pes) = do
  pes' <- mapM f pes
  return $ Pic pPr fp pes'
applyToShape f (GraphicFrame gfx pes) = do
  pes' <- mapM f pes
  return $ GraphicFrame gfx pes'
applyToShape f (TextBox paras) = do
  paras' <- mapM (applyToParagraph f) paras
  return $ TextBox paras'

applyToLayout :: Monad m => (ParaElem -> m ParaElem) -> Layout -> m Layout
applyToLayout f (MetadataSlide title subtitle authors date) = do
  title' <- mapM f title
  subtitle' <- mapM f subtitle
  authors' <- mapM (mapM f) authors
  date' <- mapM f date
  return $ MetadataSlide title' subtitle' authors' date'
applyToLayout f (TitleSlide title) = do
  title' <- mapM f title
  return $ TitleSlide title'
applyToLayout f (ContentSlide hdr content) = do
  hdr' <- mapM f hdr
  content' <- mapM (applyToShape f) content
  return $ ContentSlide hdr' content'
applyToLayout f (TwoColumnSlide hdr contentL contentR) = do
  hdr' <- mapM f hdr
  contentL' <- mapM (applyToShape f) contentL
  contentR' <- mapM (applyToShape f) contentR
  return $ TwoColumnSlide hdr' contentL' contentR'

applyToSlide :: Monad m => (ParaElem -> m ParaElem) -> Slide -> m Slide
applyToSlide f slide = do
  layout' <- applyToLayout f $ slideLayout slide
  mbNotes' <- case slideNotes slide of
                Just (Notes notes) -> (Just . Notes) <$>
                                      mapM (applyToParagraph f) notes
                Nothing -> return Nothing
  return slide{slideLayout = layout', slideNotes = mbNotes'}

replaceAnchor :: ParaElem -> Pres ParaElem
replaceAnchor (Run rProps s)
  | Just (ExternalTarget ('#':anchor, _)) <- rLink rProps = do
      anchorMap <- gets stAnchorMap
      -- If the anchor is not in the anchormap, we just remove the
      -- link.
      let rProps' = case M.lookup anchor anchorMap of
                      Just n  -> rProps{rLink = Just $ InternalTarget n}
                      Nothing -> rProps{rLink = Nothing}
      return $ Run rProps' s
replaceAnchor pe = return pe

blocksToPresentation :: [Block] -> Pres Presentation
blocksToPresentation blks = do
  opts <- asks envOpts
  metadataslides <- maybeToList <$> getMetaSlide
  -- As far as I can tell, if we want to have a variable-length toc in
  -- the future, we'll have to make it twice. Once to get the length,
  -- and a second time to include the notes slide. We can't make the
  -- notes slide before the body slides because we need to know if
  -- there are notes, and we can't make either before the toc slide,
  -- because we need to know its length to get slide numbers right.
  --
  -- For now, though, since the TOC slide is only length 1, if it
  -- exists, we'll just get the length, and then come back to make the
  -- slide later
  blksLst <- splitBlocks blks
  bodySlideIds <- mapM
                  (\n -> runUniqueSlideId $ "BodySlide" ++ show n)
                  (take (length blksLst) [1..] :: [Integer])
  bodyslides <- mapM
                (\(bs, ident) ->
                    local (\st -> st{envCurSlideId = ident}) (blocksToSlide bs))
                (zip blksLst bodySlideIds)
  endNotesSlideBlocks <- makeEndNotesSlideBlocks
  -- now we come back and make the real toc...
  tocSlides <- if writerTableOfContents opts
               then do toc <- makeTOCSlide $ blks ++ endNotesSlideBlocks
                       return [toc]
               else return []
  -- ... and the notes slide. We test to see if the blocks are empty,
  -- because we don't want to make an empty slide.
  endNotesSlides <- if null endNotesSlideBlocks
                    then return []
                    else do endNotesSlide <- local
                              (\env -> env { envCurSlideId = endNotesSlideId
                                           , envInNoteSlide = True
                                           })
                              (blocksToSlide $ endNotesSlideBlocks)
                            return [endNotesSlide]

  let slides = metadataslides ++ tocSlides ++ bodyslides ++ endNotesSlides
  slides' <- mapM (applyToSlide replaceAnchor) slides
  return $ Presentation slides'

documentToPresentation :: WriterOptions
                       -> Pandoc
                       -> (Presentation, [LogMessage])
documentToPresentation opts (Pandoc meta blks) = do
  let env = def { envOpts = opts
                , envMetadata = meta
                , envSlideLevel = case writerSlideLevel opts of
                                    Just lvl -> lvl
                                    Nothing  -> getSlideLevel blks
                }
  runPres env def $ blocksToPresentation blks