{-# LANGUAGE OverloadedStrings #-}
{-
Copyright (C) 2006-2015 John MacFarlane <jgm@berkeley.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.RST
   Copyright   : Copyright (C) 2006-2015 John MacFarlane
   License     : GNU GPL, version 2 or above

   Maintainer  : John MacFarlane <jgm@berkeley.edu>
   Stability   : alpha
   Portability : portable

Conversion of 'Pandoc' documents to reStructuredText.

reStructuredText:  <http://docutils.sourceforge.net/rst.html>
-}
module Text.Pandoc.Writers.RST ( writeRST ) where
import Control.Monad.State
import Data.Char (isSpace, toLower)
import Data.List (intersperse, isPrefixOf, stripPrefix, transpose)
import Data.Maybe (fromMaybe)
import Network.URI (isURI)
import Text.Pandoc.Builder (deleteMeta)
import Text.Pandoc.Class (PandocMonad)
import Text.Pandoc.Definition
import Text.Pandoc.ImageSize
import Text.Pandoc.Options
import Text.Pandoc.Pretty
import Text.Pandoc.Shared
import Text.Pandoc.Templates (renderTemplate')
import Text.Pandoc.Writers.Shared

type Refs = [([Inline], Target)]

data WriterState =
  WriterState { stNotes       :: [[Block]]
              , stLinks       :: Refs
              , stImages      :: [([Inline], (Attr, String, String, Maybe String))]
              , stHasMath     :: Bool
              , stHasRawTeX   :: Bool
              , stOptions     :: WriterOptions
              , stTopLevel    :: Bool
              }

-- | Convert Pandoc to RST.
writeRST :: PandocMonad m => WriterOptions -> Pandoc -> m String
writeRST opts document = return $
  let st = WriterState { stNotes = [], stLinks = [],
                         stImages = [], stHasMath = False,
                         stHasRawTeX = False, stOptions = opts,
                         stTopLevel = True}
  in evalState (pandocToRST document) st

-- | Return RST representation of document.
pandocToRST :: Pandoc -> State WriterState String
pandocToRST (Pandoc meta blocks) = do
  opts <- gets stOptions
  let colwidth = if writerWrapText opts == WrapAuto
                    then Just $ writerColumns opts
                    else Nothing
  let subtit = case lookupMeta "subtitle" meta of
                    Just (MetaBlocks [Plain xs]) -> xs
                    _                            -> []
  title <- titleToRST (docTitle meta) subtit
  metadata <- metaToJSON opts
                (fmap (render colwidth) . blockListToRST)
                (fmap (trimr . render colwidth) . inlineListToRST)
                $ deleteMeta "title" $ deleteMeta "subtitle" meta
  body <- blockListToRST' True $ case writerTemplate opts of
                                      Just _  -> normalizeHeadings 1 blocks
                                      Nothing -> blocks
  notes <- gets (reverse . stNotes) >>= notesToRST
  -- note that the notes may contain refs, so we do them first
  refs <- gets (reverse . stLinks) >>= refsToRST
  pics <- gets (reverse . stImages) >>= pictRefsToRST
  hasMath <- gets stHasMath
  rawTeX <- gets stHasRawTeX
  let main = render colwidth $ foldl ($+$) empty $ [body, notes, refs, pics]
  let context = defField "body" main
              $ defField "toc" (writerTableOfContents opts)
              $ defField "toc-depth" (show $ writerTOCDepth opts)
              $ defField "math" hasMath
              $ defField "title" (render Nothing title :: String)
              $ defField "math" hasMath
              $ defField "rawtex" rawTeX
              $ metadata
  case writerTemplate opts of
       Nothing  -> return main
       Just tpl -> return $ renderTemplate' tpl context
  where
    normalizeHeadings lev (Header l a i:bs) =
      Header lev a i:normalizeHeadings (lev+1) cont ++ normalizeHeadings lev bs'
      where (cont,bs') = break (headerLtEq l) bs
            headerLtEq level (Header l' _ _) = l' <= level
            headerLtEq _ _                   = False
    normalizeHeadings lev (b:bs) = b:normalizeHeadings lev bs
    normalizeHeadings _   []     = []

-- | Return RST representation of reference key table.
refsToRST :: Refs -> State WriterState Doc
refsToRST refs = mapM keyToRST refs >>= return . vcat

-- | Return RST representation of a reference key.
keyToRST :: ([Inline], (String, String))
         -> State WriterState Doc
keyToRST (label, (src, _)) = do
  label' <- inlineListToRST label
  let label'' = if ':' `elem` ((render Nothing label') :: String)
                   then char '`' <> label' <> char '`'
                   else label'
  return $ nowrap $ ".. _" <> label'' <> ": " <> text src

-- | Return RST representation of notes.
notesToRST :: [[Block]] -> State WriterState Doc
notesToRST notes =
  mapM (\(num, note) -> noteToRST num note) (zip [1..] notes) >>=
  return . vsep

-- | Return RST representation of a note.
noteToRST :: Int -> [Block] -> State WriterState Doc
noteToRST num note = do
  contents <- blockListToRST note
  let marker = ".. [" <> text (show num) <> "]"
  return $ nowrap $ marker $$ nest 3 contents

-- | Return RST representation of picture reference table.
pictRefsToRST :: [([Inline], (Attr, String, String, Maybe String))]
              -> State WriterState Doc
pictRefsToRST refs = mapM pictToRST refs >>= return . vcat

-- | Return RST representation of a picture substitution reference.
pictToRST :: ([Inline], (Attr, String, String, Maybe String))
          -> State WriterState Doc
pictToRST (label, (attr, src, _, mbtarget)) = do
  label' <- inlineListToRST label
  dims   <- imageDimsToRST attr
  let (_, cls, _) = attr
      classes = if null cls
                   then empty
                   else ":class: " <> text (unwords cls)
  return $ nowrap
         $ ".. |" <> label' <> "| image:: " <> text src $$ hang 3 empty (classes $$ dims)
         $$ case mbtarget of
                 Nothing -> empty
                 Just t  -> "   :target: " <> text t

-- | Escape special characters for RST.
escapeString :: WriterOptions -> String -> String
escapeString _  [] = []
escapeString opts (c:cs) =
  case c of
       _ | c `elem` ['\\','`','*','_','|'] -> '\\':c:escapeString opts cs
       '\'' | isEnabled Ext_smart opts -> '\\':'\'':escapeString opts cs
       '"' | isEnabled Ext_smart opts -> '\\':'"':escapeString opts cs
       '-' | isEnabled Ext_smart opts ->
              case cs of
                   '-':_ -> '\\':'-':escapeString opts cs
                   _     -> '-':escapeString opts cs
       '.' | isEnabled Ext_smart opts ->
              case cs of
                   '.':'.':rest -> '\\':'.':'.':'.':escapeString opts rest
                   _            -> '.':escapeString opts cs
       _ -> c : escapeString opts cs

titleToRST :: [Inline] -> [Inline] -> State WriterState Doc
titleToRST [] _ = return empty
titleToRST tit subtit = do
  title <- inlineListToRST tit
  subtitle <- inlineListToRST subtit
  return $ bordered title '=' $$ bordered subtitle '-'

bordered :: Doc -> Char -> Doc
bordered contents c =
  if len > 0
     then border $$ contents $$ border
     else empty
   where len = offset contents
         border = text (replicate len c)

-- | Convert Pandoc block element to RST.
blockToRST :: Block         -- ^ Block element
           -> State WriterState Doc
blockToRST Null = return empty
blockToRST (Div attr bs) = do
  contents <- blockListToRST bs
  let startTag = ".. raw:: html" $+$ nest 3 (tagWithAttrs "div" attr)
  let endTag = ".. raw:: html" $+$ nest 3 "</div>"
  return $ blankline <> startTag $+$ contents $+$ endTag $$ blankline
blockToRST (Plain inlines) = inlineListToRST inlines
-- title beginning with fig: indicates that the image is a figure
blockToRST (Para [Image attr txt (src,'f':'i':'g':':':tit)]) = do
  capt <- inlineListToRST txt
  dims <- imageDimsToRST attr
  let fig = "figure:: " <> text src
      alt = ":alt: " <> if null tit then capt else text tit
      (_,cls,_) = attr
      classes = if null cls
                   then empty
                   else ":figclass: " <> text (unwords cls)
  return $ hang 3 ".. " (fig $$ alt $$ classes $$ dims $+$ capt) $$ blankline
blockToRST (Para inlines)
  | LineBreak `elem` inlines = do -- use line block if LineBreaks
      linesToLineBlock $ splitBy (==LineBreak) inlines
  | otherwise = do
      contents <- inlineListToRST inlines
      return $ contents <> blankline
blockToRST (LineBlock lns) =
  linesToLineBlock lns
blockToRST (RawBlock f@(Format f') str)
  | f == "rst" = return $ text str
  | otherwise  = return $ blankline <> ".. raw:: " <>
                    text (map toLower f') $+$
                    (nest 3 $ text str) $$ blankline
blockToRST HorizontalRule =
  return $ blankline $$ "--------------" $$ blankline
blockToRST (Header level (name,classes,_) inlines) = do
  contents <- inlineListToRST inlines
  isTopLevel <- gets stTopLevel
  if isTopLevel
    then do
          let headerChar = if level > 5 then ' ' else "=-~^'" !! (level - 1)
          let border = text $ replicate (offset contents) headerChar
          return $ nowrap $ contents $$ border $$ blankline
    else do
          let rub     = "rubric:: " <> contents
          let name' | null name    = empty
                    | otherwise    = ":name: " <> text name
          let cls   | null classes = empty
                    | otherwise    = ":class: " <> text (unwords classes)
          return $ nowrap $ hang 3 ".. " (rub $$ name' $$ cls) $$ blankline
blockToRST (CodeBlock (_,classes,kvs) str) = do
  opts <- gets stOptions
  let tabstop = writerTabStop opts
  let startnum = maybe "" (\x -> " " <> text x) $ lookup "startFrom" kvs
  let numberlines = if "numberLines" `elem` classes
                       then "   :number-lines:" <> startnum
                       else empty
  if "haskell" `elem` classes && "literate" `elem` classes &&
                  isEnabled Ext_literate_haskell opts
     then return $ prefixed "> " (text str) $$ blankline
     else return $
          (case [c | c <- classes,
                     c `notElem` ["sourceCode","literate","numberLines"]] of
             []       -> "::"
             (lang:_) -> (".. code:: " <> text lang) $$ numberlines)
          $+$ nest tabstop (text str) $$ blankline
blockToRST (BlockQuote blocks) = do
  tabstop <- gets $ writerTabStop . stOptions
  contents <- blockListToRST blocks
  return $ (nest tabstop contents) <> blankline
blockToRST (Table caption _ widths headers rows) =  do
  caption' <- inlineListToRST caption
  headers' <- mapM blockListToRST headers
  rawRows <- mapM (mapM blockListToRST) rows
  -- let isSimpleCell [Plain _] = True
  --     isSimpleCell [Para _]  = True
  --     isSimpleCell []        = True
  --     isSimpleCell _         = False
  -- let isSimple = all (==0) widths && all (all isSimpleCell) rows
  let numChars = maximum . map offset
  opts <- gets stOptions
  let widthsInChars =
       if all (== 0) widths
          then map ((+2) . numChars) $ transpose (headers' : rawRows)
          else map (floor . (fromIntegral (writerColumns opts) *)) widths
  let hpipeBlocks blocks = hcat [beg, middle, end]
        where h      = height (hcat blocks)
              sep'   = lblock 3 $ vcat (map text $ replicate h " | ")
              beg    = lblock 2 $ vcat (map text $ replicate h "| ")
              end    = lblock 2 $ vcat (map text $ replicate h " |")
              middle = hcat $ intersperse sep' blocks
  let makeRow = hpipeBlocks . zipWith lblock widthsInChars
  let head' = makeRow headers'
  let rows' = map makeRow rawRows
  let border ch = char '+' <> char ch <>
                  (hcat $ intersperse (char ch <> char '+' <> char ch) $
                          map (\l -> text $ replicate l ch) widthsInChars) <>
                  char ch <> char '+'
  let body = vcat $ intersperse (border '-') rows'
  let head'' = if all null headers
                  then empty
                  else head' $$ border '='
  let tbl = border '-' $$ head'' $$ body $$ border '-'
  return $ if null caption
              then tbl $$ blankline
              else (".. table:: " <> caption') $$ blankline $$ nest 3 tbl $$
                   blankline
blockToRST (BulletList items) = do
  contents <- mapM bulletListItemToRST items
  -- ensure that sublists have preceding blank line
  return $ blankline $$ chomp (vcat contents) $$ blankline
blockToRST (OrderedList (start, style', delim) items) = do
  let markers = if start == 1 && style' == DefaultStyle && delim == DefaultDelim
                   then take (length items) $ repeat "#."
                   else take (length items) $ orderedListMarkers
                                              (start, style', delim)
  let maxMarkerLength = maximum $ map length markers
  let markers' = map (\m -> let s = maxMarkerLength - length m
                            in  m ++ replicate s ' ') markers
  contents <- mapM (\(item, num) -> orderedListItemToRST item num) $
              zip markers' items
  -- ensure that sublists have preceding blank line
  return $ blankline $$ chomp (vcat contents) $$ blankline
blockToRST (DefinitionList items) = do
  contents <- mapM definitionListItemToRST items
  -- ensure that sublists have preceding blank line
  return $ blankline $$ chomp (vcat contents) $$ blankline

-- | Convert bullet list item (list of blocks) to RST.
bulletListItemToRST :: [Block] -> State WriterState Doc
bulletListItemToRST items = do
  contents <- blockListToRST items
  return $ hang 3 "-  " $ contents <> cr

-- | Convert ordered list item (a list of blocks) to RST.
orderedListItemToRST :: String   -- ^ marker for list item
                     -> [Block]  -- ^ list item (list of blocks)
                     -> State WriterState Doc
orderedListItemToRST marker items = do
  contents <- blockListToRST items
  let marker' = marker ++ " "
  return $ hang (length marker') (text marker') $ contents <> cr

-- | Convert defintion list item (label, list of blocks) to RST.
definitionListItemToRST :: ([Inline], [[Block]]) -> State WriterState Doc
definitionListItemToRST (label, defs) = do
  label' <- inlineListToRST label
  contents <- liftM vcat $ mapM blockListToRST defs
  tabstop <- gets $ writerTabStop . stOptions
  return $ label' $$ nest tabstop (nestle contents <> cr)

-- | Format a list of lines as line block.
linesToLineBlock :: [[Inline]] -> State WriterState Doc
linesToLineBlock inlineLines = do
  lns <- mapM inlineListToRST inlineLines
  return $ (vcat $ map (hang 2 (text "| ")) lns) <> blankline

-- | Convert list of Pandoc block elements to RST.
blockListToRST' :: Bool
                -> [Block]       -- ^ List of block elements
                -> State WriterState Doc
blockListToRST' topLevel blocks = do
  tl <- gets stTopLevel
  modify (\s->s{stTopLevel=topLevel})
  res <- vcat `fmap` mapM blockToRST blocks
  modify (\s->s{stTopLevel=tl})
  return res

blockListToRST :: [Block]       -- ^ List of block elements
               -> State WriterState Doc
blockListToRST = blockListToRST' False

-- | Convert list of Pandoc inline elements to RST.
inlineListToRST :: [Inline] -> State WriterState Doc
inlineListToRST lst =
  mapM inlineToRST (removeSpaceAfterDisplayMath $ insertBS lst) >>=
    return . hcat
  where -- remove spaces after displaymath, as they screw up indentation:
        removeSpaceAfterDisplayMath (Math DisplayMath x : zs) =
              Math DisplayMath x : dropWhile (==Space) zs
        removeSpaceAfterDisplayMath (x:xs) = x : removeSpaceAfterDisplayMath xs
        removeSpaceAfterDisplayMath [] = []
        insertBS :: [Inline] -> [Inline] -- insert '\ ' where needed
        insertBS (x:y:z:zs)
          | isComplex y && (surroundComplex x z) =
              x : y : insertBS (z : zs)
        insertBS (x:y:zs)
          | isComplex x && not (okAfterComplex y) =
              x : RawInline "rst" "\\ " : insertBS (y : zs)
          | isComplex y && not (okBeforeComplex x) =
              x : RawInline "rst" "\\ " : insertBS (y : zs)
          | otherwise =
              x : insertBS (y : zs)
        insertBS (x:ys) = x : insertBS ys
        insertBS [] = []
        surroundComplex :: Inline -> Inline -> Bool
        surroundComplex (Str s@(_:_)) (Str s'@(_:_)) =
          case (last s, head s') of
             ('\'','\'') -> True
             ('"','"')   -> True
             ('<','>')   -> True
             ('[',']')   -> True
             ('{','}')   -> True
             _           -> False
        surroundComplex _ _ = False
        okAfterComplex :: Inline -> Bool
        okAfterComplex Space = True
        okAfterComplex SoftBreak = True
        okAfterComplex LineBreak = True
        okAfterComplex (Str (c:_)) = isSpace c || c `elem` ("-.,:;!?\\/'\")]}>–—" :: String)
        okAfterComplex _ = False
        okBeforeComplex :: Inline -> Bool
        okBeforeComplex Space = True
        okBeforeComplex SoftBreak = True
        okBeforeComplex LineBreak = True
        okBeforeComplex (Str (c:_)) = isSpace c || c `elem` ("-:/'\"<([{–—" :: String)
        okBeforeComplex _ = False
        isComplex :: Inline -> Bool
        isComplex (Emph _)        = True
        isComplex (Strong _)      = True
        isComplex (SmallCaps _)   = True
        isComplex (Strikeout _)   = True
        isComplex (Superscript _) = True
        isComplex (Subscript _)   = True
        isComplex (Link _ _ _)    = True
        isComplex (Image _ _ _)   = True
        isComplex (Code _ _)      = True
        isComplex (Math _ _)      = True
        isComplex (Cite _ (x:_))  = isComplex x
        isComplex (Span _ (x:_))  = isComplex x
        isComplex _               = False

-- | Convert Pandoc inline element to RST.
inlineToRST :: Inline -> State WriterState Doc
inlineToRST (Span _ ils) = inlineListToRST ils
inlineToRST (Emph lst) = do
  contents <- inlineListToRST lst
  return $ "*" <> contents <> "*"
inlineToRST (Strong lst) = do
  contents <- inlineListToRST lst
  return $ "**" <> contents <> "**"
inlineToRST (Strikeout lst) = do
  contents <- inlineListToRST lst
  return $ "[STRIKEOUT:" <> contents <> "]"
inlineToRST (Superscript lst) = do
  contents <- inlineListToRST lst
  return $ ":sup:`" <> contents <> "`"
inlineToRST (Subscript lst) = do
  contents <- inlineListToRST lst
  return $ ":sub:`" <> contents <> "`"
inlineToRST (SmallCaps lst) = inlineListToRST lst
inlineToRST (Quoted SingleQuote lst) = do
  contents <- inlineListToRST lst
  opts <- gets stOptions
  if isEnabled Ext_smart opts
     then return $ "'" <> contents <> "'"
     else return $ "‘" <> contents <> "’"
inlineToRST (Quoted DoubleQuote lst) = do
  contents <- inlineListToRST lst
  opts <- gets stOptions
  if isEnabled Ext_smart opts
     then return $ "\"" <> contents <> "\""
     else return $ "“" <> contents <> "”"
inlineToRST (Cite _  lst) =
  inlineListToRST lst
inlineToRST (Code _ str) =
  -- we trim the string because the delimiters must adjoin a
  -- non-space character; see #3496
  return $ "``" <> text (trim str) <> "``"
inlineToRST (Str str) = do
  opts <- gets stOptions
  return $ text $
    (if isEnabled Ext_smart opts
        then unsmartify opts
        else id) $ escapeString opts str
inlineToRST (Math t str) = do
  modify $ \st -> st{ stHasMath = True }
  return $ if t == InlineMath
              then ":math:`" <> text str <> "`"
              else if '\n' `elem` str
                   then blankline $$ ".. math::" $$
                        blankline $$ nest 3 (text str) $$ blankline
                   else blankline $$ (".. math:: " <> text str) $$ blankline
inlineToRST (RawInline f x)
  | f == "rst" = return $ text x
  | f == "latex" || f == "tex" = do
      modify $ \st -> st{ stHasRawTeX = True }
      return $ ":raw-latex:`" <> text x <> "`"
  | otherwise  = return empty
inlineToRST (LineBreak) = return cr -- there's no line break in RST (see Para)
inlineToRST Space = return space
inlineToRST SoftBreak = do
  wrapText <- gets $ writerWrapText . stOptions
  case wrapText of
        WrapPreserve -> return cr
        WrapAuto     -> return space
        WrapNone     -> return space
-- autolink
inlineToRST (Link _ [Str str] (src, _))
  | isURI src &&
    if "mailto:" `isPrefixOf` src
       then src == escapeURI ("mailto:" ++ str)
       else src == escapeURI str = do
  let srcSuffix = fromMaybe src (stripPrefix "mailto:" src)
  return $ text srcSuffix
inlineToRST (Link _ [Image attr alt (imgsrc,imgtit)] (src, _tit)) = do
  label <- registerImage attr alt (imgsrc,imgtit) (Just src)
  return $ "|" <> label <> "|"
inlineToRST (Link _ txt (src, tit)) = do
  useReferenceLinks <- gets $ writerReferenceLinks . stOptions
  linktext <- inlineListToRST $ normalizeSpaces txt
  if useReferenceLinks
    then do refs <- gets stLinks
            case lookup txt refs of
                 Just (src',tit') ->
                   if src == src' && tit == tit'
                      then return $ "`" <> linktext <> "`_"
                      else do -- duplicate label, use non-reference link
                        return $ "`" <> linktext <> " <" <> text src <> ">`__"
                 Nothing -> do
                   modify $ \st -> st { stLinks = (txt,(src,tit)):refs }
                   return $ "`" <> linktext <> "`_"
    else return $ "`" <> linktext <> " <" <> text src <> ">`__"
inlineToRST (Image attr alternate (source, tit)) = do
  label <- registerImage attr alternate (source,tit) Nothing
  return $ "|" <> label <> "|"
inlineToRST (Note contents) = do
  -- add to notes in state
  notes <- gets stNotes
  modify $ \st -> st { stNotes = contents:notes }
  let ref = show $ (length notes) + 1
  return $ " [" <> text ref <> "]_"

registerImage :: Attr -> [Inline] -> Target -> Maybe String -> State WriterState Doc
registerImage attr alt (src,tit) mbtarget = do
  pics <- gets stImages
  txt <- case lookup alt pics of
               Just (a,s,t,mbt) | (a,s,t,mbt) == (attr,src,tit,mbtarget)
                 -> return alt
               _ -> do
                 let alt' = if null alt || alt == [Str ""]
                               then [Str $ "image" ++ show (length pics)]
                               else alt
                 modify $ \st -> st { stImages =
                        (alt', (attr,src,tit, mbtarget)):stImages st }
                 return alt'
  inlineListToRST txt

imageDimsToRST :: Attr -> State WriterState Doc
imageDimsToRST attr = do
  let (ident, _, _) = attr
      name = if null ident
                then empty
                else ":name: " <> text ident
      showDim dir = let cols d = ":" <> text (show dir) <> ": " <> text (show d)
                    in  case (dimension dir attr) of
                          Just (Percent a) ->
                            case dir of
                              Height -> empty
                              Width  -> cols (Percent a)
                          Just dim -> cols dim
                          Nothing  -> empty
  return $ cr <> name $$ showDim Width $$ showDim Height