    {-# LANGUAGE NoImplicitPrelude #-}
    {-# LANGUAGE OverloadedStrings #-}
    {-
    Copyright (C) 2008-2018 John MacFarlane
                  2012 Peter Wang

    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.Texinfo
       Copyright   : Copyright (C) 2008-2018 John MacFarlane
                                   2012 Peter Wang
       License     : GNU GPL, version 2 or above

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

    Conversion of 'Pandoc' format into Texinfo.
    -}
    module Text.Pandoc.Writers.Texinfo ( writeTexinfo ) where
    import Prelude
    import Control.Monad.Except (throwError)
    import Control.Monad.State.Strict
    import Data.Char (chr, ord)
    import Data.List (maximumBy, transpose)
    import Data.Ord (comparing)
    import qualified Data.Set as Set
    import Data.Text (Text)
    import Network.URI (unEscapeString)
    import System.FilePath
    import Text.Pandoc.Class (PandocMonad, report)
    import Text.Pandoc.Definition
    import Text.Pandoc.Error
    import Text.Pandoc.ImageSize
    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
    import Text.Printf (printf)

    data WriterState =
      WriterState { stStrikeout   :: Bool  -- document contains strikeout
                  , stEscapeComma :: Bool -- in a context where we need @comma
                  , stIdentifiers :: Set.Set String -- header ids used already
                  , stOptions     :: WriterOptions -- writer options
                  }

    {- TODO:
     - internal cross references a la HTML
     - generated .texi files don't work when run through texi2dvi
     -}

    type TI m = StateT WriterState m

    -- | Convert Pandoc to Texinfo.
    writeTexinfo :: PandocMonad m => WriterOptions -> Pandoc -> m Text
    writeTexinfo options document =
      evalStateT (pandocToTexinfo options $ wrapTop document)
      WriterState { stStrikeout = False, stEscapeComma = False,
                    stIdentifiers = Set.empty, stOptions = options}

    -- | Add a "Top" node around the document, needed by Texinfo.
    wrapTop :: Pandoc -> Pandoc
    wrapTop (Pandoc meta blocks) =
      Pandoc meta (Header 0 nullAttr (docTitle meta) : blocks)

    pandocToTexinfo :: PandocMonad m => WriterOptions -> Pandoc -> TI m Text
    pandocToTexinfo options (Pandoc meta blocks) = do
      let titlePage = not $ all null
                          $ docTitle meta : docDate meta : docAuthors meta
      let colwidth = if writerWrapText options == WrapAuto
                        then Just $ writerColumns options
                        else Nothing
      let render' :: Doc -> Text
          render' = render colwidth
      metadata <- metaToJSON options
                  (fmap render' . blockListToTexinfo)
                  (fmap render' . inlineListToTexinfo)
                  meta
      main <- blockListToTexinfo blocks
      st <- get
      let body = render colwidth main
      let context = defField "body" body
                  $ defField "toc" (writerTableOfContents options)
                  $ defField "titlepage" titlePage
                  $
            defField "strikeout" (stStrikeout st) metadata
      case writerTemplate options of
           Nothing  -> return body
           Just tpl -> renderTemplate' tpl context

    -- | Escape things as needed for Texinfo.
    stringToTexinfo :: String -> String
    stringToTexinfo = escapeStringUsing texinfoEscapes
      where texinfoEscapes = [ ('{', "@{")
                             , ('}', "@}")
                             , ('@', "@@")
                             , ('\160', "@ ")
                             , ('\x2014', "---")
                             , ('\x2013', "--")
                             , ('\x2026', "@dots{}")
                             , ('\x2019', "'")
                             ]

    escapeCommas :: PandocMonad m => TI m Doc -> TI m Doc
    escapeCommas parser = do
      oldEscapeComma <- gets stEscapeComma
      modify $ \st -> st{ stEscapeComma = True }
      res <- parser
      modify $ \st -> st{ stEscapeComma = oldEscapeComma }
      return res

    -- | Puts contents into Texinfo command.
    inCmd :: String -> Doc -> Doc
    inCmd cmd contents = char '@' <> text cmd <> braces contents

    -- | Convert Pandoc block element to Texinfo.
    blockToTexinfo :: PandocMonad m
                   => Block     -- ^ Block to convert
                   -> TI m Doc

    blockToTexinfo Null = return empty

    blockToTexinfo (Div _ bs) = blockListToTexinfo bs

    blockToTexinfo (Plain lst) =
      inlineListToTexinfo lst

    -- title beginning with fig: indicates that the image is a figure
    blockToTexinfo (Para [Image attr txt (src,'f':'i':'g':':':tit)]) = do
      capt <- if null txt
                 then return empty
                 else (\c -> text "@caption" <> braces c) `fmap`
                        inlineListToTexinfo txt
      img  <- inlineToTexinfo (Image attr txt (src,tit))
      return $ text "@float" $$ img $$ capt $$ text "@end float"

    blockToTexinfo (Para lst) =
      inlineListToTexinfo lst    -- this is handled differently from Plain in blockListToTexinfo

    blockToTexinfo (LineBlock lns) =
      blockToTexinfo $ linesToPara lns

    blockToTexinfo (BlockQuote lst) = do
      contents <- blockListToTexinfo lst
      return $ text "@quotation" $$
               contents $$
               text "@end quotation"

    blockToTexinfo (CodeBlock _ str) =
      return $ blankline $$
             text "@verbatim" $$
             flush (text str) $$
             text "@end verbatim" <> blankline

    blockToTexinfo b@(RawBlock f str)
      | f == "texinfo" = return $ text str
      | f == "latex" || f == "tex" =
                          return $ text "@tex" $$ text str $$ text "@end tex"
      | otherwise      = do
          report $ BlockNotRendered b
          return empty

    blockToTexinfo (BulletList lst) = do
      items <- mapM listItemToTexinfo lst
      return $ text "@itemize" $$
               vcat items $$
               text "@end itemize" <> blankline

    blockToTexinfo (OrderedList (start, numstyle, _) lst) = do
      items <- mapM listItemToTexinfo lst
      return $ text "@enumerate " <> exemplar $$
               vcat items $$
               text "@end enumerate" <> blankline
      where
        exemplar = case numstyle of
                    DefaultStyle -> decimal
                    Decimal      -> decimal
                    Example      -> decimal
                    UpperRoman   -> decimal   -- Roman numerals not supported
                    LowerRoman   -> decimal
                    UpperAlpha   -> upperAlpha
                    LowerAlpha   -> lowerAlpha
        decimal = if start == 1
                     then empty
                     else text (show start)
        upperAlpha = text [chr $ ord 'A' + start - 1]
        lowerAlpha = text [chr $ ord 'a' + start - 1]

    blockToTexinfo (DefinitionList lst) = do
      items <- mapM defListItemToTexinfo lst
      return $ text "@table @asis" $$
               vcat items $$
               text "@end table" <> blankline

    blockToTexinfo HorizontalRule =
        -- XXX can't get the equivalent from LaTeX.hs to work
        return $ text "@iftex" $$
                 text "@bigskip@hrule@bigskip" $$
                 text "@end iftex" $$
                 text "@ifnottex" $$
                 text (replicate 72 '-') $$
                 text "@end ifnottex"

    blockToTexinfo (Header 0 _ lst) = do
      txt <- if null lst
                then return $ text "Top"
                else inlineListToTexinfo lst
      return $ text "@node Top" $$
               text "@top " <> txt <> blankline

    blockToTexinfo (Header level _ lst)
      | level < 1 || level > 4 = blockToTexinfo (Para lst)
      | otherwise = do
        node <- inlineListForNode lst
        txt <- inlineListToTexinfo lst
        idsUsed <- gets stIdentifiers
        opts <- gets stOptions
        let id' = uniqueIdent (writerExtensions opts) lst idsUsed
        modify $ \st -> st{ stIdentifiers = Set.insert id' idsUsed }
        sec <- seccmd level
        return $ if (level > 0) && (level <= 4)
                    then blankline <> text "@node " <> node $$
                         text sec <> txt $$
                         text "@anchor" <> braces (text $ '#':id')
                    else txt
        where
          seccmd :: PandocMonad m => Int -> TI m String
          seccmd 1 = return "@chapter "
          seccmd 2 = return "@section "
          seccmd 3 = return "@subsection "
          seccmd 4 = return "@subsubsection "
          seccmd _ = throwError $ PandocSomeError "illegal seccmd level"

    blockToTexinfo (Table caption aligns widths heads rows) = do
      headers <- if all null heads
                    then return empty
                    else tableHeadToTexinfo aligns heads
      captionText <- inlineListToTexinfo caption
      rowsText <- mapM (tableRowToTexinfo aligns) rows
      colDescriptors <-
        if all (== 0) widths
           then do -- use longest entry instead of column widths
                cols <- mapM (mapM (liftM (render Nothing . hcat) . mapM blockToTexinfo)) $
                            transpose $ heads : rows
                return $ concatMap ((\x -> "{"++x++"} ") .  maximumBy (comparing length)) cols
           else return $ "@columnfractions " ++ concatMap (printf "%.2f ") widths
      let tableBody = text ("@multitable " ++ colDescriptors) $$
                      headers $$
                      vcat rowsText $$
                      text "@end multitable"
      return $ if isEmpty captionText
                  then tableBody <> blankline
                  else text "@float" $$
                       tableBody $$
                       inCmd "caption" captionText $$
                       text "@end float"

    tableHeadToTexinfo :: PandocMonad m
                       => [Alignment]
                       -> [[Block]]
                       -> TI m Doc
    tableHeadToTexinfo = tableAnyRowToTexinfo "@headitem "

    tableRowToTexinfo :: PandocMonad m
                      => [Alignment]
                      -> [[Block]]
                      -> TI m Doc
    tableRowToTexinfo = tableAnyRowToTexinfo "@item "

    tableAnyRowToTexinfo :: PandocMonad m
                         => String
                         -> [Alignment]
                         -> [[Block]]
                         -> TI m Doc
    tableAnyRowToTexinfo itemtype aligns cols =
      zipWithM alignedBlock aligns cols >>=
      return . (text itemtype $$) . foldl (\row item -> row $$
      (if isEmpty row then empty else text " @tab ") <> item) empty

    alignedBlock :: PandocMonad m
                 => Alignment
                 -> [Block]
                 -> TI m Doc
    -- XXX @flushleft and @flushright text won't get word wrapped.  Since word
    -- wrapping is more important than alignment, we ignore the alignment.
    alignedBlock _ = blockListToTexinfo
    {-
    alignedBlock AlignLeft col = do
      b <- blockListToTexinfo col
      return $ text "@flushleft" $$ b $$ text "@end flushleft"
    alignedBlock AlignRight col = do
      b <- blockListToTexinfo col
      return $ text "@flushright" $$ b $$ text "@end flushright"
    alignedBlock _ col = blockListToTexinfo col
    -}

    -- | Convert Pandoc block elements to Texinfo.
    blockListToTexinfo :: PandocMonad m
                       => [Block]
                       -> TI m Doc
    blockListToTexinfo [] = return empty
    blockListToTexinfo (x:xs) = do
      x' <- blockToTexinfo x
      case x of
        Header level _ _ -> do
          -- We need need to insert a menu for this node.
          let (before, after) = break isHeaderBlock xs
          before' <- blockListToTexinfo before
          let menu = if level < 4
                        then collectNodes (level + 1) after
                        else []
          lines' <- mapM makeMenuLine menu
          let menu' = if null lines'
                        then empty
                        else blankline $$
                             text "@menu" $$
                             vcat lines' $$
                             text "@end menu"
          after' <- blockListToTexinfo after
          return $ x' $$ before' $$ menu' $$ after'
        Para _ -> do
          xs' <- blockListToTexinfo xs
          case xs of
               (CodeBlock _ _:_) -> return $ x' $$ xs'
               _                 -> return $ x' $+$ xs'
        _ -> do
          xs' <- blockListToTexinfo xs
          return $ x' $$ xs'

    collectNodes :: Int -> [Block] -> [Block]
    collectNodes _ [] = []
    collectNodes level (x:xs) =
      case x of
        (Header hl _ _) | hl < level -> []
                        | hl == level -> x : collectNodes level xs
                        | otherwise -> collectNodes level xs
        _ ->
          collectNodes level xs

    makeMenuLine :: PandocMonad m
                 => Block
                 -> TI m Doc
    makeMenuLine (Header _ _ lst) = do
      txt <- inlineListForNode lst
      return $ text "* " <> txt <> text "::"
    makeMenuLine _ = throwError $ PandocSomeError "makeMenuLine called with non-Header block"

    listItemToTexinfo :: PandocMonad m
                      => [Block]
                      -> TI m Doc
    listItemToTexinfo lst = do
      contents <- blockListToTexinfo lst
      let spacer = case reverse lst of
                        (Para{}:_) -> blankline
                        _          -> empty
      return $ text "@item" $$ contents <> spacer

    defListItemToTexinfo :: PandocMonad m
                         => ([Inline], [[Block]])
                         -> TI m Doc
    defListItemToTexinfo (term, defs) = do
        term' <- inlineListToTexinfo term
        let defToTexinfo bs = do d <- blockListToTexinfo bs
                                 case reverse bs of
                                      (Para{}:_) -> return $ d <> blankline
                                      _          -> return d
        defs' <- mapM defToTexinfo defs
        return $ text "@item " <> term' $+$ vcat defs'

    -- | Convert list of inline elements to Texinfo.
    inlineListToTexinfo :: PandocMonad m
                        => [Inline]  -- ^ Inlines to convert
                        -> TI m Doc
    inlineListToTexinfo lst = hcat <$> mapM inlineToTexinfo lst

    -- | Convert list of inline elements to Texinfo acceptable for a node name.
    inlineListForNode :: PandocMonad m
                      => [Inline]  -- ^ Inlines to convert
                      -> TI m Doc
    inlineListForNode = return . text . stringToTexinfo .
                        filter (not . disallowedInNode) . stringify

    -- periods, commas, colons, and parentheses are disallowed in node names
    disallowedInNode :: Char -> Bool
    disallowedInNode c = c `elem` (".,:()" :: String)

    -- | Convert inline element to Texinfo
    inlineToTexinfo :: PandocMonad m
                    => Inline    -- ^ Inline to convert
                    -> TI m Doc

    inlineToTexinfo (Span _ lst) =
      inlineListToTexinfo lst

    inlineToTexinfo (Emph lst) =
      inCmd "emph" <$> inlineListToTexinfo lst

    inlineToTexinfo (Strong lst) =
      inCmd "strong" <$> inlineListToTexinfo lst

    inlineToTexinfo (Strikeout lst) = do
      modify $ \st -> st{ stStrikeout = True }
      contents <- inlineListToTexinfo lst
      return $ text "@textstrikeout{" <> contents <> text "}"

    inlineToTexinfo (Superscript lst) = do
      contents <- inlineListToTexinfo lst
      return $ text "@sup{" <> contents <> char '}'

    inlineToTexinfo (Subscript lst) = do
      contents <- inlineListToTexinfo lst
      return $ text "@sub{" <> contents <> char '}'

    inlineToTexinfo (SmallCaps lst) =
      inCmd "sc" <$> inlineListToTexinfo lst

    inlineToTexinfo (Code _ str) =
      return $ text $ "@code{" ++ stringToTexinfo str ++ "}"

    inlineToTexinfo (Quoted SingleQuote lst) = do
      contents <- inlineListToTexinfo lst
      return $ char '`' <> contents <> char '\''

    inlineToTexinfo (Quoted DoubleQuote lst) = do
      contents <- inlineListToTexinfo lst
      return $ text "``" <> contents <> text "''"

    inlineToTexinfo (Cite _ lst) =
      inlineListToTexinfo lst
    inlineToTexinfo (Str str) = return $ text (stringToTexinfo str)
    inlineToTexinfo (Math _ str) = return $ inCmd "math" $ text str
    inlineToTexinfo il@(RawInline f str)
      | f == "latex" || f == "tex" =
                          return $ text "@tex" $$ text str $$ text "@end tex"
      | f == "texinfo" =  return $ text str
      | otherwise      =  do
          report $ InlineNotRendered il
          return empty
    inlineToTexinfo LineBreak = return $ text "@*" <> cr
    inlineToTexinfo SoftBreak = do
      wrapText <- gets (writerWrapText . stOptions)
      case wrapText of
          WrapAuto     -> return space
          WrapNone     -> return space
          WrapPreserve -> return cr
    inlineToTexinfo Space = return space

    inlineToTexinfo (Link _ txt (src@('#':_), _)) = do
      contents <- escapeCommas $ inlineListToTexinfo txt
      return $ text "@ref" <>
               braces (text (stringToTexinfo src) <> text "," <> contents)
    inlineToTexinfo (Link _ txt (src, _)) =
      case txt of
            [Str x] | escapeURI x == src ->  -- autolink
                 return $ text $ "@url{" ++ x ++ "}"
            _ -> do contents <- escapeCommas $ inlineListToTexinfo txt
                    let src1 = stringToTexinfo src
                    return $ text ("@uref{" ++ src1 ++ ",") <> contents <>
                             char '}'

    inlineToTexinfo (Image attr alternate (source, _)) = do
      content <- escapeCommas $ inlineListToTexinfo alternate
      opts <- gets stOptions
      let showDim dim = case dimension dim attr of
                          (Just (Pixel a))   -> showInInch opts (Pixel a) ++ "in"
                          (Just (Percent _)) -> ""
                          (Just d)           -> show d
                          Nothing            -> ""
      return $ text ("@image{" ++ base ++ ',':(showDim Width) ++ ',':(showDim Height) ++ ",")
               <> content <> text "," <> text (ext ++ "}")
      where
        ext     = drop 1 $ takeExtension source'
        base    = dropExtension source'
        source' = if isURI source
                     then source
                     else unEscapeString source

    inlineToTexinfo (Note contents) = do
      contents' <- blockListToTexinfo contents
      return $ text "@footnote" <> braces contents'