    {-# LANGUAGE NoImplicitPrelude #-}
    {-# LANGUAGE OverloadedStrings #-}
    {-
    Copyright (C) 2010-2015 Puneeth Chaganti <punchagan@gmail.com>
                  2010-2018 John MacFarlane <jgm@berkeley.edu>
                  2016-2018 Albert Krewinkel <tarleb+pandoc@moltkeplatz.de>

    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.Org
      Copyright    : © 2010-2015 Puneeth Chaganti <punchagan@gmail.com>
                       2010-2018 John MacFarlane <jgm@berkeley.edu>
                       2016-2018 Albert Krewinkel <tarleb+pandoc@moltkeplatz.de>
       License     : GNU GPL, version 2 or above

       Maintainer  : Albert Krewinkel <tarleb+pandoc@moltkeplatz.de>
       Stability   : alpha
       Portability : portable

    Conversion of 'Pandoc' documents to Emacs Org-Mode.

    Org-Mode:  <http://orgmode.org>
    -}
    module Text.Pandoc.Writers.Org (writeOrg) where
    import Prelude
    import Control.Monad.State.Strict
    import Data.Char (isAlphaNum, toLower)
    import Data.List (intersect, intersperse, isPrefixOf, partition, transpose)
    import Data.Text (Text)
    import Text.Pandoc.Class (PandocMonad, report)
    import Text.Pandoc.Definition
    import Text.Pandoc.Logging
    import Text.Pandoc.Options
    import Text.Pandoc.Pretty
    import Text.Pandoc.Shared
    import Text.Pandoc.Templates (renderTemplate')
    import Text.Pandoc.Writers.Shared

    data WriterState =
      WriterState { stNotes   :: [[Block]]
                  , stHasMath :: Bool
                  , stOptions :: WriterOptions
                  }

    type Org = StateT WriterState

    -- | Convert Pandoc to Org.
    writeOrg :: PandocMonad m => WriterOptions -> Pandoc -> m Text
    writeOrg opts document = do
      let st = WriterState { stNotes = [],
                             stHasMath = False,
                             stOptions = opts }
      evalStateT (pandocToOrg document) st

    -- | Return Org representation of document.
    pandocToOrg :: PandocMonad m => Pandoc -> Org m Text
    pandocToOrg (Pandoc meta blocks) = do
      opts <- gets stOptions
      let colwidth = if writerWrapText opts == WrapAuto
                        then Just $ writerColumns opts
                        else Nothing
      let render' :: Doc -> Text
          render' = render colwidth
      metadata <- metaToJSON opts
                   (fmap render' . blockListToOrg)
                   (fmap render' . inlineListToOrg)
                   meta
      body <- blockListToOrg blocks
      notes <- gets (reverse . stNotes) >>= notesToOrg
      hasMath <- gets stHasMath
      let main = render colwidth . foldl ($+$) empty $ [body, notes]
      let context = defField "body" main
                  . defField "math" hasMath
                  $ metadata
      case writerTemplate opts of
           Nothing  -> return main
           Just tpl -> renderTemplate' tpl context

    -- | Return Org representation of notes.
    notesToOrg :: PandocMonad m => [[Block]] -> Org m Doc
    notesToOrg notes =
      vsep <$> zipWithM noteToOrg [1..] notes

    -- | Return Org representation of a note.
    noteToOrg :: PandocMonad m => Int -> [Block] -> Org m Doc
    noteToOrg num note = do
      contents <- blockListToOrg note
      let marker = "[fn:" ++ show num ++ "] "
      return $ hang (length marker) (text marker) contents

    -- | Escape special characters for Org.
    escapeString :: String -> String
    escapeString = escapeStringUsing $
                   [ ('\x2014',"---")
                   , ('\x2013',"--")
                   , ('\x2019',"'")
                   , ('\x2026',"...")
                   ]

    isRawFormat :: Format -> Bool
    isRawFormat f =
      f == Format "latex" || f == Format "tex" || f == Format "org"

    -- | Convert Pandoc block element to Org.
    blockToOrg :: PandocMonad m
               => Block         -- ^ Block element
               -> Org m Doc
    blockToOrg Null = return empty
    blockToOrg (Div (_,classes@(cls:_),kvs) bs) | "drawer" `elem` classes = do
      contents <- blockListToOrg bs
      let drawerNameTag = ":" <> text cls <> ":"
      let keys = vcat $ map (\(k,v) ->
                           ":" <> text k <> ":"
                           <> space <> text v) kvs
      let drawerEndTag = text ":END:"
      return $ drawerNameTag $$ cr $$ keys $$
               blankline $$ contents $$
               blankline $$ drawerEndTag $$
               blankline
    blockToOrg (Div (ident, classes, kv) bs) = do
      contents <- blockListToOrg bs
      -- if one class looks like the name of a greater block then output as such:
      -- The ID, if present, is added via the #+NAME keyword; other classes and
      -- key-value pairs are kept as #+ATTR_HTML attributes.
      let isGreaterBlockClass = (`elem` ["center", "quote"]) . map toLower
          (blockTypeCand, classes') = partition isGreaterBlockClass classes
      return $ case blockTypeCand of
        (blockType:classes'') ->
          blankline $$ attrHtml (ident, classes'' <> classes', kv) $$
          "#+BEGIN_" <> text blockType $$ contents $$
          "#+END_" <> text blockType $$ blankline
        _                     ->
          -- fallback with id: add id as an anchor if present, discard classes and
          -- key-value pairs, unwrap the content.
          let contents' = if not (null ident)
                          then "<<" <> text ident <> ">>" $$ contents
                          else contents
          in blankline $$ contents' $$ blankline
    blockToOrg (Plain inlines) = inlineListToOrg inlines
    -- title beginning with fig: indicates that the image is a figure
    blockToOrg (Para [Image attr txt (src,'f':'i':'g':':':tit)]) = do
      capt <- if null txt
                 then return empty
                 else ("#+CAPTION: " <>) `fmap` inlineListToOrg txt
      img <- inlineToOrg (Image attr txt (src,tit))
      return $ capt $$ img $$ blankline
    blockToOrg (Para inlines) = do
      contents <- inlineListToOrg inlines
      return $ contents <> blankline
    blockToOrg (LineBlock lns) = do
      let splitStanza [] = []
          splitStanza xs = case break (== mempty) xs of
            (l, [])  -> [l]
            (l, _:r) -> l : splitStanza r
      let joinWithLinefeeds  = nowrap . mconcat . intersperse cr
      let joinWithBlankLines = mconcat . intersperse blankline
      let prettifyStanza ls  = joinWithLinefeeds <$> mapM inlineListToOrg ls
      contents <- joinWithBlankLines <$> mapM prettifyStanza (splitStanza lns)
      return $ blankline $$ "#+BEGIN_VERSE" $$
               nest 2 contents $$ "#+END_VERSE" <> blankline
    blockToOrg (RawBlock "html" str) =
      return $ blankline $$ "#+BEGIN_HTML" $$
               nest 2 (text str) $$ "#+END_HTML" $$ blankline
    blockToOrg b@(RawBlock f str)
      | isRawFormat f = return $ text str
      | otherwise     = do
          report $ BlockNotRendered b
          return empty
    blockToOrg HorizontalRule = return $ blankline $$ "--------------" $$ blankline
    blockToOrg (Header level attr inlines) = do
      contents <- inlineListToOrg inlines
      let headerStr = text $ if level > 999 then " " else replicate level '*'
      let drawerStr = if attr == nullAttr
                      then empty
                      else cr <> nest (level + 1) (propertiesDrawer attr)
      return $ headerStr <> " " <> contents <> drawerStr <> blankline
    blockToOrg (CodeBlock (_,classes,_) str) = do
      opts <- gets stOptions
      let tabstop = writerTabStop opts
      let at = map pandocLangToOrg classes `intersect` orgLangIdentifiers
      let (beg, end) = case at of
                          []    -> ("#+BEGIN_EXAMPLE", "#+END_EXAMPLE")
                          (x:_) -> ("#+BEGIN_SRC " ++ x, "#+END_SRC")
      return $ text beg $$ nest tabstop (text str) $$ text end $$ blankline
    blockToOrg (BlockQuote blocks) = do
      contents <- blockListToOrg blocks
      return $ blankline $$ "#+BEGIN_QUOTE" $$
               nest 2 contents $$ "#+END_QUOTE" $$ blankline
    blockToOrg (Table caption' _ _ headers rows) =  do
      caption'' <- inlineListToOrg caption'
      let caption = if null caption'
                       then empty
                       else "#+CAPTION: " <> caption''
      headers' <- mapM blockListToOrg headers
      rawRows <- mapM (mapM blockListToOrg) rows
      let numChars = maximum . map offset
      -- FIXME: width is not being used.
      let widthsInChars =
           map ((+2) . numChars) $ transpose (headers' : rawRows)
      -- FIXME: Org doesn't allow blocks with height more than 1.
      let hpipeBlocks blocks = hcat [beg, middle, end]
            where h      = maximum (1 : map height blocks)
                  sep'   = lblock 3 $ vcat (replicate h (text " | "))
                  beg    = lblock 2 $ vcat (replicate h (text "| "))
                  end    = lblock 2 $ vcat (replicate h (text " |"))
                  middle = hcat $ intersperse sep' blocks
      let makeRow = hpipeBlocks . zipWith lblock widthsInChars
      let head' = makeRow headers'
      rows' <- mapM (\row -> do cols <- mapM blockListToOrg row
                                return $ makeRow cols) rows
      let border ch = char '|' <> char ch <>
                      (hcat . intersperse (char ch <> char '+' <> char ch) $
                              map (\l -> text $ replicate l ch) widthsInChars) <>
                      char ch <> char '|'
      let body = vcat rows'
      let head'' = if all null headers
                      then empty
                      else head' $$ border '-'
      return $ head'' $$ body $$ caption $$ blankline
    blockToOrg (BulletList items) = do
      contents <- mapM bulletListItemToOrg items
      -- ensure that sublists have preceding blank line
      return $ blankline $+$ vcat contents $$ blankline
    blockToOrg (OrderedList (start, _, delim) items) = do
      let delim' = case delim of
                        TwoParens -> OneParen
                        x         -> x
      let markers = take (length items) $ orderedListMarkers
                                          (start, Decimal, delim')
      let maxMarkerLength = maximum $ map length markers
      let markers' = map (\m -> let s = maxMarkerLength - length m
                                in  m ++ replicate s ' ') markers
      contents <- zipWithM orderedListItemToOrg markers' items
      -- ensure that sublists have preceding blank line
      return $ blankline $$ vcat contents $$ blankline
    blockToOrg (DefinitionList items) = do
      contents <- mapM definitionListItemToOrg items
      return $ vcat contents $$ blankline

    -- | Convert bullet list item (list of blocks) to Org.
    bulletListItemToOrg :: PandocMonad m => [Block] -> Org m Doc
    bulletListItemToOrg items = do
      contents <- blockListToOrg items
      return $ hang 2 "- " (contents <> cr)

    -- | Convert ordered list item (a list of blocks) to Org.
    orderedListItemToOrg :: PandocMonad m
                         => String   -- ^ marker for list item
                         -> [Block]  -- ^ list item (list of blocks)
                         -> Org m Doc
    orderedListItemToOrg marker items = do
      contents <- blockListToOrg items
      return $ hang (length marker + 1) (text marker <> space) (contents <> cr)

    -- | Convert definition list item (label, list of blocks) to Org.
    definitionListItemToOrg :: PandocMonad m
                            => ([Inline], [[Block]]) -> Org m Doc
    definitionListItemToOrg (label, defs) = do
      label' <- inlineListToOrg label
      contents <- vcat <$> mapM blockListToOrg defs
      return . hang 2 "- " $ label' <> " :: " <> (contents <> cr)

    -- | Convert list of key/value pairs to Org :PROPERTIES: drawer.
    propertiesDrawer :: Attr -> Doc
    propertiesDrawer (ident, classes, kv) =
      let
        drawerStart = text ":PROPERTIES:"
        drawerEnd   = text ":END:"
        kv'  = if classes == mempty then kv  else ("CLASS", unwords classes):kv
        kv'' = if ident == mempty   then kv' else ("CUSTOM_ID", ident):kv'
        properties = vcat $ map kvToOrgProperty kv''
      in
        drawerStart <> cr <> properties <> cr <> drawerEnd
     where
       kvToOrgProperty :: (String, String) -> Doc
       kvToOrgProperty (key, value) =
         text ":" <> text key <> text ": " <> text value <> cr

    attrHtml :: Attr -> Doc
    attrHtml (""   , []     , []) = mempty
    attrHtml (ident, classes, kvs) =
      let
        name = if null ident then mempty else "#+NAME: " <> text ident <> cr
        keyword = "#+ATTR_HTML"
        classKv = ("class", unwords classes)
        kvStrings = map (\(k,v) -> ":" <> k <> " " <> v) (classKv:kvs)
      in name <> keyword <> ": " <> text (unwords kvStrings) <> cr

    -- | Convert list of Pandoc block elements to Org.
    blockListToOrg :: PandocMonad m
                   => [Block]       -- ^ List of block elements
                   -> Org m Doc
    blockListToOrg blocks = vcat <$> mapM blockToOrg blocks

    -- | Convert list of Pandoc inline elements to Org.
    inlineListToOrg :: PandocMonad m
                    => [Inline]
                    -> Org m Doc
    inlineListToOrg lst = hcat <$> mapM inlineToOrg (fixMarkers lst)
      where fixMarkers [] = []  -- prevent note refs and list markers from wrapping, see #4171
            fixMarkers (Space : x : rest) | shouldFix x =
              Str " " : x : fixMarkers rest
            fixMarkers (SoftBreak : x : rest) | shouldFix x =
              Str " " : x : fixMarkers rest
            fixMarkers (x : rest) = x : fixMarkers rest

            shouldFix Note{} = True -- Prevent footnotes
            shouldFix (Str "-") = True -- Prevent bullet list items
            -- TODO: prevent ordered list items
            shouldFix _ = False

    -- | Convert Pandoc inline element to Org.
    inlineToOrg :: PandocMonad m => Inline -> Org m Doc
    inlineToOrg (Span (uid, [], []) []) =
      return $ "<<" <> text uid <> ">>"
    inlineToOrg (Span _ lst) =
      inlineListToOrg lst
    inlineToOrg (Emph lst) = do
      contents <- inlineListToOrg lst
      return $ "/" <> contents <> "/"
    inlineToOrg (Strong lst) = do
      contents <- inlineListToOrg lst
      return $ "*" <> contents <> "*"
    inlineToOrg (Strikeout lst) = do
      contents <- inlineListToOrg lst
      return $ "+" <> contents <> "+"
    inlineToOrg (Superscript lst) = do
      contents <- inlineListToOrg lst
      return $ "^{" <> contents <> "}"
    inlineToOrg (Subscript lst) = do
      contents <- inlineListToOrg lst
      return $ "_{" <> contents <> "}"
    inlineToOrg (SmallCaps lst) = inlineListToOrg lst
    inlineToOrg (Quoted SingleQuote lst) = do
      contents <- inlineListToOrg lst
      return $ "'" <> contents <> "'"
    inlineToOrg (Quoted DoubleQuote lst) = do
      contents <- inlineListToOrg lst
      return $ "\"" <> contents <> "\""
    inlineToOrg (Cite _  lst) = inlineListToOrg lst
    inlineToOrg (Code _ str) = return $ "=" <> text str <> "="
    inlineToOrg (Str str) = return . text $ escapeString str
    inlineToOrg (Math t str) = do
      modify $ \st -> st{ stHasMath = True }
      return $ if t == InlineMath
                  then "$" <> text str <> "$"
                  else "$$" <> text str <> "$$"
    inlineToOrg il@(RawInline f str)
      | isRawFormat f = return $ text str
      | otherwise     = do
          report $ InlineNotRendered il
          return empty
    inlineToOrg LineBreak = return (text "\\\\" <> cr)
    inlineToOrg Space = return space
    inlineToOrg SoftBreak = do
      wrapText <- gets (writerWrapText . stOptions)
      case wrapText of
           WrapPreserve -> return cr
           WrapAuto     -> return space
           WrapNone     -> return space
    inlineToOrg (Link _ txt (src, _)) =
      case txt of
            [Str x] | escapeURI x == src ->  -- autolink
                 return $ "[[" <> text (orgPath x) <> "]]"
            _ -> do contents <- inlineListToOrg txt
                    return $ "[[" <> text (orgPath src) <> "][" <> contents <> "]]"
    inlineToOrg (Image _ _ (source, _)) =
      return $ "[[" <> text (orgPath source) <> "]]"
    inlineToOrg (Note contents) = do
      -- add to notes in state
      notes <- gets stNotes
      modify $ \st -> st { stNotes = contents:notes }
      let ref = show $ length notes + 1
      return $ "[fn:" <> text ref <> "]"

    orgPath :: String -> String
    orgPath src =
      case src of
        []      -> mempty         -- wiki link
        ('#':_) -> src            -- internal link
        _       | isUrl src      -> src
        _       | isFilePath src -> src
        _       -> "file:" <> src
     where
       isFilePath :: String -> Bool
       isFilePath cs = any (`isPrefixOf` cs) ["/", "./", "../", "file:"]

       isUrl :: String -> Bool
       isUrl cs =
         let (scheme, path) = break (== ':') cs
         in all (\c -> isAlphaNum c || c `elem` (".-"::String)) scheme
              && not (null path)

    -- | Translate from pandoc's programming language identifiers to those used by
    -- org-mode.
    pandocLangToOrg :: String -> String
    pandocLangToOrg cs =
      case cs of
        "c"          -> "C"
        "cpp"        -> "C++"
        "commonlisp" -> "lisp"
        "r"          -> "R"
        "bash"       -> "sh"
        _            -> cs

    -- | List of language identifiers recognized by org-mode.
    orgLangIdentifiers :: [String]
    orgLangIdentifiers =
      [ "asymptote", "awk", "C", "C++", "clojure", "css", "d", "ditaa", "dot"
      , "calc", "emacs-lisp", "fortran", "gnuplot", "haskell", "java", "js"
      , "latex", "ledger", "lisp", "lilypond", "matlab", "mscgen", "ocaml"
      , "octave", "org", "oz", "perl", "plantuml", "processing", "python", "R"
      , "ruby", "sass", "scheme", "screen", "sed", "sh", "sql", "sqlite"
      ]