{-# LANGUAGE OverloadedStrings #-}
{- |
   Module      : Text.Pandoc.Writers.Texinfo
   Copyright   : Copyright (C) 2008-2021 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 Control.Monad.Except (throwError)
import Control.Monad.State.Strict
import Data.Char (chr, ord, isAlphaNum)
import Data.List (maximumBy, transpose, foldl')
import Data.List.NonEmpty (nonEmpty)
import Data.Ord (comparing)
import qualified Data.Set as Set
import Data.Text (Text)
import qualified Data.Text as T
import Network.URI (unEscapeString)
import System.FilePath
import Text.Pandoc.Class.PandocMonad (PandocMonad, report)
import Text.Pandoc.Definition
import Text.Pandoc.Error
import Text.Pandoc.ImageSize
import Text.Pandoc.Logging
import Text.Pandoc.Options
import Text.DocLayout
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 Text -- 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
  metadata <- metaToContext options
              blockListToTexinfo
              (fmap chomp .inlineListToTexinfo)
              meta
  body <- blockListToTexinfo blocks
  st <- get
  let context = defField "body" body
              $ defField "toc" (writerTableOfContents options)
              $ defField "titlepage" titlePage
              $ defField "strikeout" (stStrikeout st) metadata
  return $ render colwidth $
    case writerTemplate options of
       Nothing  -> body
       Just tpl -> renderTemplate tpl context

-- | Escape things as needed for Texinfo.
stringToTexinfo :: Text -> Text
stringToTexinfo t
  | T.all isAlphaNum t = t
  | otherwise = T.concatMap escChar t
  where escChar '{'      = "@{"
        escChar '}'      = "@}"
        escChar '@'      = "@@"
        escChar '\160'   = "@ "
        escChar '\x2014' = "---"
        escChar '\x2013' = "--"
        escChar '\x2026' = "@dots{}"
        escChar '\x2019' = "'"
        escChar c        = T.singleton c

escapeCommas :: PandocMonad m => TI m (Doc Text) -> TI m (Doc Text)
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 :: Text -> Doc Text -> Doc Text
inCmd cmd contents = char '@' <> literal cmd <> braces contents

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

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 (SimpleFigure attr txt (src, 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 (literal str) $$
         text "@end verbatim" <> blankline

blockToTexinfo b@(RawBlock f str)
  | f == "texinfo" = return $ literal str
  | f == "latex" || f == "tex" =
                      return $ text "@tex" $$ literal str $$ 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 (ident,_,_) lst)
  | level < 1 || level > 4 = blockToTexinfo (Para lst)
  | otherwise = do
    node <- inlineListForNode lst
    txt <- inlineListToTexinfo lst
    idsUsed <- gets stIdentifiers
    opts <- gets stOptions
    let id' = if T.null ident
                 then uniqueIdent (writerExtensions opts) lst idsUsed
                 else ident
    modify $ \st -> st{ stIdentifiers = Set.insert id' idsUsed }
    sec <- seccmd level
    return $ if (level > 0) && (level <= 4)
                then blankline <> text "@node " <> node $$
                     literal sec <> txt $$
                     text "@anchor" <> braces (literal $ "#" <> id')
                else txt
    where
      seccmd :: PandocMonad m => Int -> TI m Text
      seccmd 1 = return "@chapter "
      seccmd 2 = return "@section "
      seccmd 3 = return "@subsection "
      seccmd 4 = return "@subsubsection "
      seccmd _ = throwError $ PandocSomeError "illegal seccmd level"

blockToTexinfo (Table _ blkCapt specs thead tbody tfoot) = do
  let (caption, aligns, widths, heads, rows) = toLegacyTable blkCapt specs thead tbody tfoot
  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 (fmap (T.unpack . render Nothing . hcat) .
                           mapM blockToTexinfo)) $
                        transpose $ heads : rows
            return $ concatMap
                ((\x -> "{"++x++"} ") .
                        maybe "" (maximumBy (comparing length)) . nonEmpty)
                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 Text)
tableHeadToTexinfo = tableAnyRowToTexinfo "@headitem "

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

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

alignedBlock :: PandocMonad m
             => Alignment
             -> [Block]
             -> TI m (Doc Text)
-- 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 Text)
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 Text)
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 Text)
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 Text)
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 Text)
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 Text)
inlineListForNode = return . literal . stringToTexinfo .
                    T.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 Text)

inlineToTexinfo (Span _ lst) =
  inlineListToTexinfo lst

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

-- Underline isn't supported, fall back to Emph
inlineToTexinfo (Underline lst) =
  inlineToTexinfo (Emph 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 $ literal $ "@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 $ literal (stringToTexinfo str)
inlineToTexinfo (Math _ str) = return $ inCmd "math" $ literal str
inlineToTexinfo il@(RawInline f str)
  | f == "latex" || f == "tex" =
                      return $ text "@tex" $$ literal str $$ text "@end tex"
  | f == "texinfo" =  return $ literal 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, _))
  | Just ('#', _) <- T.uncons src = do
      contents <- escapeCommas $ inlineListToTexinfo txt
      return $ text "@ref" <>
        braces (literal (stringToTexinfo src) <> text "," <> contents)
  | otherwise = case txt of
      [Str x] | escapeURI x == src ->  -- autolink
                  return $ literal $ "@url{" <> x <> "}"
      _ -> do
        contents <- escapeCommas $ inlineListToTexinfo txt
        let src1 = stringToTexinfo src
        return $ literal ("@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)           -> tshow d
                      Nothing            -> ""
  return $ literal ("@image{" <> base <> "," <> showDim Width <> "," <> showDim Height <> ",")
           <> content <> text "," <> literal (ext <> "}")
  where
    ext     = T.drop 1 $ T.pack $ takeExtension source'
    base    = T.pack $ dropExtension source'
    source' = if isURI source
              then T.unpack source
              else unEscapeString $ T.unpack source

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