{-# LANGUAGE OverloadedStrings #-}
{-
Copyright (C) 2007-2015 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.ConTeXt
   Copyright   : Copyright (C) 2007-2015 John MacFarlane
   License     : GNU GPL, version 2 or above

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

Conversion of 'Pandoc' format into ConTeXt.
-}
module Text.Pandoc.Writers.ConTeXt ( writeConTeXt ) where
import Text.Pandoc.Definition
import Text.Pandoc.Shared
import Text.Pandoc.Writers.Shared
import Text.Pandoc.Options
import Text.Pandoc.Walk (query)
import Text.Printf ( printf )
import Data.List ( intercalate, intersperse )
import Data.Char ( ord )
import Data.Maybe ( catMaybes )
import Control.Monad.State
import Text.Pandoc.Pretty
import Text.Pandoc.ImageSize
import Text.Pandoc.Templates ( renderTemplate' )
import Network.URI ( isURI, unEscapeString )

data WriterState =
  WriterState { stNextRef          :: Int  -- number of next URL reference
              , stOrderedListLevel :: Int  -- level of ordered list
              , stOptions          :: WriterOptions -- writer options
              }

orderedListStyles :: [Char]
orderedListStyles = cycle "narg"

-- | Convert Pandoc to ConTeXt.
writeConTeXt :: WriterOptions -> Pandoc -> String
writeConTeXt options document =
  let defaultWriterState = WriterState { stNextRef = 1
                                       , stOrderedListLevel = 0
                                       , stOptions = options
                                       }
  in evalState (pandocToConTeXt options document) defaultWriterState

pandocToConTeXt :: WriterOptions -> Pandoc -> State WriterState String
pandocToConTeXt options (Pandoc meta blocks) = do
  let colwidth = if writerWrapText options == WrapAuto
                    then Just $ writerColumns options
                    else Nothing
  metadata <- metaToJSON options
              (fmap (render colwidth) . blockListToConTeXt)
              (fmap (render colwidth) . inlineListToConTeXt)
              meta
  body <- mapM (elementToConTeXt options) $ hierarchicalize blocks
  let main = (render colwidth . vcat) body
  let layoutFromMargins = intercalate [','] $ catMaybes $
                              map (\(x,y) ->
                                ((x ++ "=") ++) <$> getField y metadata)
                              [("leftmargin","margin-left")
                              ,("rightmargin","margin-right")
                              ,("top","margin-top")
                              ,("bottom","margin-bottom")
                              ]
  let context =   defField "toc" (writerTableOfContents options)
                $ defField "placelist" (intercalate ("," :: String) $
                     take (writerTOCDepth options +
                           if writerTopLevelDivision options < Section
                           then 0
                           else 1)
                       ["chapter","section","subsection","subsubsection",
                        "subsubsubsection","subsubsubsubsection"])
                $ defField "body" main
                $ defField "layout" layoutFromMargins
                $ defField "number-sections" (writerNumberSections options)
                $ metadata
  let context' =  defField "context-lang" (maybe "" (fromBcp47 . splitBy (=='-')) $
                    getField "lang" context)
                $ defField "context-dir" (toContextDir $ getField "dir" context)
                $ context
  return $ if writerStandalone options
              then renderTemplate' (writerTemplate options) context'
              else main

toContextDir :: Maybe String -> String
toContextDir (Just "rtl") = "r2l"
toContextDir (Just "ltr") = "l2r"
toContextDir _            = ""

-- | escape things as needed for ConTeXt
escapeCharForConTeXt :: WriterOptions -> Char -> String
escapeCharForConTeXt opts ch =
 let ligatures = writerTeXLigatures opts in
 case ch of
    '{'    -> "\\{"
    '}'    -> "\\}"
    '\\'   -> "\\letterbackslash{}"
    '$'    -> "\\$"
    '|'    -> "\\letterbar{}"
    '%'    -> "\\letterpercent{}"
    '~'    -> "\\lettertilde{}"
    '#'    -> "\\#"
    '['    -> "{[}"
    ']'    -> "{]}"
    '\160' -> "~"
    '\x2014' | ligatures -> "---"
    '\x2013' | ligatures -> "--"
    '\x2019' | ligatures -> "'"
    '\x2026' -> "\\ldots{}"
    x      -> [x]

-- | Escape string for ConTeXt
stringToConTeXt :: WriterOptions -> String -> String
stringToConTeXt opts = concatMap (escapeCharForConTeXt opts)

-- | Sanitize labels
toLabel :: String -> String
toLabel z = concatMap go z
 where go x
         | elem x ("\\#[]\",{}%()|=" :: String) = "ux" ++ printf "%x" (ord x)
         | otherwise = [x]

-- | Convert Elements to ConTeXt
elementToConTeXt :: WriterOptions -> Element -> State WriterState Doc
elementToConTeXt _ (Blk block) = blockToConTeXt block
elementToConTeXt opts (Sec level _ attr title' elements) = do
  header' <- sectionHeader attr level title'
  innerContents <- mapM (elementToConTeXt opts) elements
  return $ vcat (header' : innerContents)

-- | Convert Pandoc block element to ConTeXt.
blockToConTeXt :: Block
               -> State WriterState Doc
blockToConTeXt Null = return empty
blockToConTeXt (Plain lst) = inlineListToConTeXt lst
-- title beginning with fig: indicates that the image is a figure
blockToConTeXt (Para [Image attr txt (src,'f':'i':'g':':':_)]) = do
  capt <- inlineListToConTeXt txt
  img  <- inlineToConTeXt (Image attr txt (src, ""))
  let (ident, _, _) = attr
      label = if null ident
                 then empty
                 else "[]" <> brackets (text $ toLabel ident)
  return $ blankline $$ "\\placefigure" <> label <> braces capt <> img <> blankline
blockToConTeXt (Para lst) = do
  contents <- inlineListToConTeXt lst
  return $ contents <> blankline
blockToConTeXt (LineBlock lns) = do
  doclines <- nowrap . vcat <$> mapM inlineListToConTeXt lns
  return $ "\\startlines" $$ doclines $$ "\\stoplines" <> blankline
blockToConTeXt (BlockQuote lst) = do
  contents <- blockListToConTeXt lst
  return $ "\\startblockquote" $$ nest 0 contents $$ "\\stopblockquote" <> blankline
blockToConTeXt (CodeBlock _ str) =
  return $ flush ("\\starttyping" <> cr <> text str <> cr <> "\\stoptyping") $$ blankline
  -- blankline because \stoptyping can't have anything after it, inc. '}'
blockToConTeXt (RawBlock "context" str) = return $ text str <> blankline
blockToConTeXt (RawBlock _ _ ) = return empty
blockToConTeXt (Div (ident,_,kvs) bs) = do
  let align dir txt = "\\startalignment[" <> dir <> "]" $$ txt $$ "\\stopalignment"
  let wrapRef txt = if null ident
                       then txt
                       else ("\\reference" <> brackets (text $ toLabel ident) <>
                              braces empty <> "%") $$ txt
      wrapDir = case lookup "dir" kvs of
                  Just "rtl" -> align "righttoleft"
                  Just "ltr" -> align "lefttoright"
                  _          -> id
      wrapLang txt = case lookup "lang" kvs of
                       Just lng -> "\\start\\language["
                                     <> text (fromBcp47' lng) <> "]" $$ txt $$ "\\stop"
                       Nothing  -> txt
      wrapBlank txt = blankline <> txt <> blankline
  fmap (wrapBlank . wrapLang . wrapDir . wrapRef) $ blockListToConTeXt bs
blockToConTeXt (BulletList lst) = do
  contents <- mapM listItemToConTeXt lst
  return $ ("\\startitemize" <> if isTightList lst
                                   then brackets "packed"
                                   else empty) $$
    vcat contents $$ text "\\stopitemize" <> blankline
blockToConTeXt (OrderedList (start, style', delim) lst) = do
    st <- get
    let level = stOrderedListLevel st
    put $ st {stOrderedListLevel = level + 1}
    contents <- mapM listItemToConTeXt lst
    put $ st {stOrderedListLevel = level}
    let start' = if start == 1 then "" else "start=" ++ show start
    let delim' = case delim of
                        DefaultDelim -> ""
                        Period       -> "stopper=."
                        OneParen     -> "stopper=)"
                        TwoParens    -> "left=(,stopper=)"
    let width = maximum $ map length $ take (length contents)
                          (orderedListMarkers (start, style', delim))
    let width' = (toEnum width + 1) / 2
    let width'' = if width' > (1.5 :: Double)
                     then "width=" ++ show width' ++ "em"
                     else ""
    let specs2Items = filter (not . null) [start', delim', width'']
    let specs2 = if null specs2Items
                    then ""
                    else "[" ++ intercalate "," specs2Items ++ "]"
    let style'' = '[': (case style' of
                          DefaultStyle -> orderedListStyles !! level
                          Decimal      -> 'n'
                          Example      -> 'n'
                          LowerRoman   -> 'r'
                          UpperRoman   -> 'R'
                          LowerAlpha   -> 'a'
                          UpperAlpha   -> 'A') :
                       if isTightList lst then ",packed]" else "]"
    let specs = style'' ++ specs2
    return $ "\\startitemize" <> text specs $$ vcat contents $$
             "\\stopitemize" <> blankline
blockToConTeXt (DefinitionList lst) =
  liftM vcat $ mapM defListItemToConTeXt lst
blockToConTeXt HorizontalRule = return $ "\\thinrule" <> blankline
-- If this is ever executed, provide a default for the reference identifier.
blockToConTeXt (Header level attr lst) = sectionHeader attr level lst
blockToConTeXt (Table caption aligns widths heads rows) = do
    let colDescriptor colWidth alignment = (case alignment of
                                               AlignLeft    -> 'l'
                                               AlignRight   -> 'r'
                                               AlignCenter  -> 'c'
                                               AlignDefault -> 'l'):
           if colWidth == 0
              then "|"
              else ("p(" ++ printf "%.2f" colWidth ++ "\\textwidth)|")
    let colDescriptors = "|" ++ (concat $
                                 zipWith colDescriptor widths aligns)
    headers <- if all null heads
                  then return empty
                  else liftM ($$ "\\HL") $ tableRowToConTeXt heads
    captionText <- inlineListToConTeXt caption
    rows' <- mapM tableRowToConTeXt rows
    return $ "\\placetable" <> (if null caption
                                   then brackets "none"
                                   else empty)
                            <> braces captionText $$
             "\\starttable" <> brackets (text colDescriptors) $$
             "\\HL" $$ headers $$
             vcat rows' $$ "\\HL" $$ "\\stoptable" <> blankline

tableRowToConTeXt :: [[Block]] -> State WriterState Doc
tableRowToConTeXt cols = do
  cols' <- mapM blockListToConTeXt cols
  return $ (vcat (map ("\\NC " <>) cols')) $$ "\\NC\\AR"

listItemToConTeXt :: [Block] -> State WriterState Doc
listItemToConTeXt list = blockListToConTeXt list >>=
  return . ("\\item" $$) . (nest 2)

defListItemToConTeXt :: ([Inline], [[Block]]) -> State WriterState Doc
defListItemToConTeXt (term, defs) = do
  term' <- inlineListToConTeXt term
  def'  <- liftM vsep $ mapM blockListToConTeXt defs
  return $ "\\startdescription" <> braces term' $$ nest 2 def' $$
           "\\stopdescription" <> blankline

-- | Convert list of block elements to ConTeXt.
blockListToConTeXt :: [Block] -> State WriterState Doc
blockListToConTeXt lst = liftM vcat $ mapM blockToConTeXt lst

-- | Convert list of inline elements to ConTeXt.
inlineListToConTeXt :: [Inline]  -- ^ Inlines to convert
                    -> State WriterState Doc
inlineListToConTeXt lst = liftM hcat $ mapM inlineToConTeXt $ addStruts lst
  -- We add a \strut after a line break that precedes a space,
  -- or the space gets swallowed
  where addStruts (LineBreak : s : xs) | isSpacey s =
           LineBreak : RawInline (Format "context") "\\strut " : s :
             addStruts xs
        addStruts (x:xs) = x : addStruts xs
        addStruts [] = []
        isSpacey Space = True
        isSpacey (Str ('\160':_)) = True
        isSpacey _ = False

-- | Convert inline element to ConTeXt
inlineToConTeXt :: Inline    -- ^ Inline to convert
                -> State WriterState Doc
inlineToConTeXt (Emph lst) = do
  contents <- inlineListToConTeXt lst
  return $ braces $ "\\em " <> contents
inlineToConTeXt (Strong lst) = do
  contents <- inlineListToConTeXt lst
  return $ braces $ "\\bf " <> contents
inlineToConTeXt (Strikeout lst) = do
  contents <- inlineListToConTeXt lst
  return $ "\\overstrikes" <> braces contents
inlineToConTeXt (Superscript lst) = do
  contents <- inlineListToConTeXt lst
  return $ "\\high" <> braces contents
inlineToConTeXt (Subscript lst) = do
  contents <- inlineListToConTeXt lst
  return $ "\\low" <> braces contents
inlineToConTeXt (SmallCaps lst) = do
  contents <- inlineListToConTeXt lst
  return $ braces $ "\\sc " <> contents
inlineToConTeXt (Code _ str) | not ('{' `elem` str || '}' `elem` str) =
  return $ "\\type" <> braces (text str)
inlineToConTeXt (Code _ str) = do
  opts <- gets stOptions
  return $ "\\mono" <> braces (text $ stringToConTeXt opts str)
inlineToConTeXt (Quoted SingleQuote lst) = do
  contents <- inlineListToConTeXt lst
  return $ "\\quote" <> braces contents
inlineToConTeXt (Quoted DoubleQuote lst) = do
  contents <- inlineListToConTeXt lst
  return $ "\\quotation" <> braces contents
inlineToConTeXt (Cite _ lst) = inlineListToConTeXt lst
inlineToConTeXt (Str str) = do
  opts <- gets stOptions
  return $ text $ stringToConTeXt opts str
inlineToConTeXt (Math InlineMath str) =
  return $ char '$' <> text str <> char '$'
inlineToConTeXt (Math DisplayMath str) =
  return $ text "\\startformula "  <> text str <> text " \\stopformula" <> space
inlineToConTeXt (RawInline "context" str) = return $ text str
inlineToConTeXt (RawInline "tex" str) = return $ text str
inlineToConTeXt (RawInline _ _) = return empty
inlineToConTeXt (LineBreak) = return $ text "\\crlf" <> cr
inlineToConTeXt SoftBreak = do
  wrapText <- gets (writerWrapText . stOptions)
  return $ case wrapText of
               WrapAuto     -> space
               WrapNone     -> space
               WrapPreserve -> cr
inlineToConTeXt Space = return space
-- Handle HTML-like internal document references to sections
inlineToConTeXt (Link _ txt (('#' : ref), _)) = do
  opts <- gets stOptions
  contents <-  inlineListToConTeXt txt
  let ref' = toLabel $ stringToConTeXt opts ref
  return $ text "\\goto"
           <> braces contents
           <> brackets (text ref')

inlineToConTeXt (Link _ txt (src, _)) = do
  let isAutolink = txt == [Str (unEscapeString src)]
  st <- get
  let next = stNextRef st
  put $ st {stNextRef = next + 1}
  let ref = "url" ++ show next
  contents <-  inlineListToConTeXt txt
  return $ "\\useURL"
           <> brackets (text ref)
           <> brackets (text $ escapeStringUsing [('#',"\\#"),('%',"\\%")] src)
           <> (if isAutolink
                  then empty
                  else brackets empty <> brackets contents)
           <> "\\from"
           <> brackets (text ref)
inlineToConTeXt (Image attr@(_,cls,_) _ (src, _)) = do
  opts <- gets stOptions
  let showDim dir = let d = text (show dir) <> "="
                    in case (dimension dir attr) of
                         Just (Pixel a)   ->
                           [d <> text (showInInch opts (Pixel a)) <> "in"]
                         Just (Percent a) ->
                           [d <> text (showFl (a / 100)) <> "\\textwidth"]
                         Just dim         ->
                           [d <> text (show dim)]
                         Nothing          ->
                           []
      dimList = showDim Width ++ showDim Height
      dims = if null dimList
                then empty
                else brackets $ cat (intersperse "," dimList)
      clas = if null cls
                then empty
                else brackets $ text $ toLabel $ head cls
      src' = if isURI src
                then src
                else unEscapeString src
  return $ braces $ "\\externalfigure" <> brackets (text src') <> dims <> clas
inlineToConTeXt (Note contents) = do
  contents' <- blockListToConTeXt contents
  let codeBlock x@(CodeBlock _ _) = [x]
      codeBlock _ = []
  let codeBlocks = query codeBlock contents
  return $ if null codeBlocks
              then text "\\footnote{" <> nest 2 contents' <> char '}'
              else text "\\startbuffer " <> nest 2 contents' <>
                   text "\\stopbuffer\\footnote{\\getbuffer}"
inlineToConTeXt (Span (_,_,kvs) ils) = do
  let wrapDir txt = case lookup "dir" kvs of
                      Just "rtl" -> braces $ "\\righttoleft " <> txt
                      Just "ltr" -> braces $ "\\lefttoright " <> txt
                      _          -> txt
      wrapLang txt = case lookup "lang" kvs of
                       Just lng -> "\\start\\language[" <> text (fromBcp47' lng)
                                      <> "]" <> txt <> "\\stop "
                       Nothing -> txt
  fmap (wrapLang . wrapDir) $ inlineListToConTeXt ils

-- | Craft the section header, inserting the section reference, if supplied.
sectionHeader :: Attr
              -> Int
              -> [Inline]
              -> State WriterState Doc
sectionHeader (ident,classes,_) hdrLevel lst = do
  contents <- inlineListToConTeXt lst
  st <- get
  let opts = stOptions st
  let level' = case writerTopLevelDivision opts of
                 Part    -> hdrLevel - 2
                 Chapter -> hdrLevel - 1
                 Section -> hdrLevel
  let ident' = toLabel ident
  let (section, chapter) = if "unnumbered" `elem` classes
                              then (text "subject", text "title")
                              else (text "section", text "chapter")
  return $ case level' of
             -1                   -> text "\\part" <> braces contents
             0                    -> char '\\' <> chapter <> braces contents
             n | n >= 1 && n <= 5 -> char '\\'
                                     <> text (concat (replicate (n - 1) "sub"))
                                     <> section
                                     <> (if (not . null) ident'
                                         then brackets (text ident')
                                         else empty)
                                     <> braces contents
                                     <> blankline
             _                    -> contents <> blankline

fromBcp47' :: String -> String
fromBcp47' = fromBcp47 . splitBy (=='-')

-- Takes a list of the constituents of a BCP 47 language code
-- and irons out ConTeXt's exceptions
-- https://tools.ietf.org/html/bcp47#section-2.1
-- http://wiki.contextgarden.net/Language_Codes
fromBcp47 :: [String] -> String
fromBcp47 []              = ""
fromBcp47 ("ar":"SY":_)   = "ar-sy"
fromBcp47 ("ar":"IQ":_)   = "ar-iq"
fromBcp47 ("ar":"JO":_)   = "ar-jo"
fromBcp47 ("ar":"LB":_)   = "ar-lb"
fromBcp47 ("ar":"DZ":_)   = "ar-dz"
fromBcp47 ("ar":"MA":_)   = "ar-ma"
fromBcp47 ("de":"1901":_) = "deo"
fromBcp47 ("de":"DE":_)   = "de-de"
fromBcp47 ("de":"AT":_)   = "de-at"
fromBcp47 ("de":"CH":_)   = "de-ch"
fromBcp47 ("el":"poly":_) = "agr"
fromBcp47 ("en":"US":_)   = "en-us"
fromBcp47 ("en":"GB":_)   = "en-gb"
fromBcp47 ("grc":_)       = "agr"
fromBcp47 x               = fromIso $ head x
  where
    fromIso "el" = "gr"
    fromIso "eu" = "ba"
    fromIso "he" = "il"
    fromIso "jp" = "ja"
    fromIso "uk" = "ua"
    fromIso "vi" = "vn"
    fromIso "zh" = "cn"
    fromIso l    = l
