    {-
    Copyright (C) 2007-2010 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.Man
       Copyright   : Copyright (C) 2007-2010 John MacFarlane
       License     : GNU GPL, version 2 or above

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

    Conversion of 'Pandoc' documents to groff man page format.

    -}
    module Text.Pandoc.Writers.Man ( writeMan) where
    import Text.Pandoc.Definition
    import Text.Pandoc.Templates
    import Text.Pandoc.Shared
    import Text.Pandoc.Writers.Shared
    import Text.Pandoc.Options
    import Text.Pandoc.Readers.TeXMath
    import Text.Printf ( printf )
    import Data.List ( isPrefixOf, intersperse, intercalate )
    import Text.Pandoc.Pretty
    import Text.Pandoc.Builder (deleteMeta)
    import Control.Monad.State
    import Data.Char ( isDigit )

    type Notes = [[Block]]
    data WriterState = WriterState { stNotes  :: Notes
                                   , stHasTables :: Bool }

    -- | Convert Pandoc to Man.
    writeMan :: WriterOptions -> Pandoc -> String
    writeMan opts document = evalState (pandocToMan opts document) (WriterState [] False)

    -- | Return groff man representation of document.
    pandocToMan :: WriterOptions -> Pandoc -> State WriterState String
    pandocToMan opts (Pandoc meta blocks) = do
      let colwidth = if writerWrapText opts
                        then Just $ writerColumns opts
                        else Nothing
      let render' = render colwidth
      titleText <- inlineListToMan opts $ docTitle meta
      let title' = render' titleText
      let setFieldsFromTitle =
           case break (== ' ') title' of
               (cmdName, rest) -> case reverse cmdName of
                                       (')':d:'(':xs) | isDigit d ->
                                         defField "title" (reverse xs) .
                                         defField "section" [d] .
                                         case splitBy (=='|') rest of
                                              (ft:hds) ->
                                                defField "footer" (trim ft) .
                                                defField "header"
                                                   (trim $ concat hds)
                                              [] -> id
                                       _  -> defField "title" title'
      metadata <- metaToJSON opts
                  (fmap (render colwidth) . blockListToMan opts)
                  (fmap (render colwidth) . inlineListToMan opts)
                  $ deleteMeta "title" meta
      body <- blockListToMan opts blocks
      notes <- liftM stNotes get
      notes' <- notesToMan opts (reverse notes)
      let main = render' $ body $$ notes' $$ text ""
      hasTables <- liftM stHasTables get
      let context = defField "body" main
                  $ setFieldsFromTitle
                  $ defField "has-tables" hasTables
                  $ metadata
      if writerStandalone opts
         then return $ renderTemplate' (writerTemplate opts) context
         else return main

    -- | Return man representation of notes.
    notesToMan :: WriterOptions -> [[Block]] -> State WriterState Doc
    notesToMan opts notes =
      if null notes
         then return empty
         else mapM (\(num, note) -> noteToMan opts num note) (zip [1..] notes) >>=
              return . (text ".SH NOTES" $$) . vcat

    -- | Return man representation of a note.
    noteToMan :: WriterOptions -> Int -> [Block] -> State WriterState Doc
    noteToMan opts num note = do
      contents <- blockListToMan opts note
      let marker = cr <> text ".SS " <> brackets (text (show num))
      return $ marker $$ contents

    -- | Association list of characters to escape.
    manEscapes :: [(Char, String)]
    manEscapes = [ ('\160', "\\ ")
                 , ('\'', "\\[aq]")
                 , ('’', "'")
                 , ('\x2014', "\\[em]")
                 , ('\x2013', "\\[en]")
                 , ('\x2026', "\\&...")
                 ] ++ backslashEscapes "-@\\"

    -- | Escape special characters for Man.
    escapeString :: String -> String
    escapeString = escapeStringUsing manEscapes

    -- | Escape a literal (code) section for Man.
    escapeCode :: String -> String
    escapeCode = concat . intersperse "\n" . map escapeLine . lines  where
      escapeLine codeline =
        case escapeStringUsing (manEscapes ++ backslashEscapes "\t ") codeline of
          a@('.':_) -> "\\&" ++ a
          b       -> b

    -- We split inline lists into sentences, and print one sentence per
    -- line.  groff/troff treats the line-ending period differently.
    -- See http://code.google.com/p/pandoc/issues/detail?id=148.

    -- | Returns the first sentence in a list of inlines, and the rest.
    breakSentence :: [Inline] -> ([Inline], [Inline])
    breakSentence [] = ([],[])
    breakSentence xs =
      let isSentenceEndInline (Str ys@(_:_)) | last ys == '.' = True
          isSentenceEndInline (Str ys@(_:_)) | last ys == '?' = True
          isSentenceEndInline (LineBreak) = True
          isSentenceEndInline _         = False
          (as, bs) = break isSentenceEndInline xs
      in  case bs of
               []             -> (as, [])
               [c]            -> (as ++ [c], [])
               (c:Space:cs)   -> (as ++ [c], cs)
               (Str ".":Str (')':ys):cs) -> (as ++ [Str ".", Str (')':ys)], cs)
               (x@(Str ('.':')':_)):cs) -> (as ++ [x], cs)
               (LineBreak:x@(Str ('.':_)):cs) -> (as ++[LineBreak], x:cs)
               (c:cs)         -> (as ++ [c] ++ ds, es)
                  where (ds, es) = breakSentence cs

    -- | Split a list of inlines into sentences.
    splitSentences :: [Inline] -> [[Inline]]
    splitSentences xs =
      let (sent, rest) = breakSentence xs
      in  if null rest then [sent] else sent : splitSentences rest

    -- | Convert Pandoc block element to man.
    blockToMan :: WriterOptions -- ^ Options
                    -> Block         -- ^ Block element
                    -> State WriterState Doc
    blockToMan _ Null = return empty
    blockToMan opts (Div _ bs) = blockListToMan opts bs
    blockToMan opts (Plain inlines) =
      liftM vcat $ mapM (inlineListToMan opts) $ splitSentences inlines
    blockToMan opts (Para inlines) = do
      contents <- liftM vcat $ mapM (inlineListToMan opts) $
        splitSentences inlines
      return $ text ".PP" $$ contents
    blockToMan _ (RawBlock f str)
      | f == Format "man" = return $ text str
      | otherwise         = return empty
    blockToMan _ HorizontalRule = return $ text ".PP" $$ text "   *   *   *   *   *"
    blockToMan opts (Header level _ inlines) = do
      contents <- inlineListToMan opts inlines
      let heading = case level of
                      1 -> ".SH "
                      _ -> ".SS "
      return $ text heading <> contents
    blockToMan _ (CodeBlock _ str) = return $
      text ".IP" $$
      text ".nf" $$
      text "\\f[C]" $$
      text (escapeCode str) $$
      text "\\f[]" $$
      text ".fi"
    blockToMan opts (BlockQuote blocks) = do
      contents <- blockListToMan opts blocks
      return $ text ".RS" $$ contents $$ text ".RE"
    blockToMan opts (Table caption alignments widths headers rows) =
      let aligncode AlignLeft    = "l"
          aligncode AlignRight   = "r"
          aligncode AlignCenter  = "c"
          aligncode AlignDefault = "l"
      in do
      caption' <- inlineListToMan opts caption
      modify $ \st -> st{ stHasTables = True }
      let iwidths = if all (== 0) widths
                       then repeat ""
                       else map (printf "w(%0.1fn)" . (70 *)) widths
      -- 78n default width - 8n indent = 70n
      let coldescriptions = text $ intercalate " "
                            (zipWith (\align width -> aligncode align ++ width)
                            alignments iwidths) ++ "."
      colheadings <- mapM (blockListToMan opts) headers
      let makeRow cols = text "T{" $$
                         (vcat $ intersperse (text "T}@T{") cols) $$
                         text "T}"
      let colheadings' = if all null headers
                            then empty
                            else makeRow colheadings $$ char '_'
      body <- mapM (\row -> do
                             cols <- mapM (blockListToMan opts) row
                             return $ makeRow cols) rows
      return $ text ".PP" $$ caption' $$
               text ".TS" $$ text "tab(@);" $$ coldescriptions $$
               colheadings' $$ vcat body $$ text ".TE"

    blockToMan opts (BulletList items) = do
      contents <- mapM (bulletListItemToMan opts) items
      return (vcat contents)
    blockToMan opts (OrderedList attribs items) = do
      let markers = take (length items) $ orderedListMarkers attribs
      let indent = 1 + (maximum $ map length markers)
      contents <- mapM (\(num, item) -> orderedListItemToMan opts num indent item) $
                  zip markers items
      return (vcat contents)
    blockToMan opts (DefinitionList items) = do
      contents <- mapM (definitionListItemToMan opts) items
      return (vcat contents)

    -- | Convert bullet list item (list of blocks) to man.
    bulletListItemToMan :: WriterOptions -> [Block] -> State WriterState Doc
    bulletListItemToMan _ [] = return empty
    bulletListItemToMan opts ((Para first):rest) =
      bulletListItemToMan opts ((Plain first):rest)
    bulletListItemToMan opts ((Plain first):rest) = do
      first' <- blockToMan opts (Plain first)
      rest' <- blockListToMan opts rest
      let first'' = text ".IP \\[bu] 2" $$ first'
      let rest''  = if null rest
                       then empty
                       else text ".RS 2" $$ rest' $$ text ".RE"
      return (first'' $$ rest'')
    bulletListItemToMan opts (first:rest) = do
      first' <- blockToMan opts first
      rest' <- blockListToMan opts rest
      return $ text "\\[bu] .RS 2" $$ first' $$ rest' $$ text ".RE"

    -- | Convert ordered list item (a list of blocks) to man.
    orderedListItemToMan :: WriterOptions -- ^ options
                              -> String   -- ^ order marker for list item
                              -> Int      -- ^ number of spaces to indent
                              -> [Block]  -- ^ list item (list of blocks)
                              -> State WriterState Doc
    orderedListItemToMan _ _ _ [] = return empty
    orderedListItemToMan opts num indent ((Para first):rest) =
      orderedListItemToMan opts num indent ((Plain first):rest)
    orderedListItemToMan opts num indent (first:rest) = do
      first' <- blockToMan opts first
      rest' <- blockListToMan opts rest
      let num' = printf ("%" ++ show (indent - 1) ++ "s") num
      let first'' = text (".IP \"" ++ num' ++ "\" " ++ show indent) $$ first'
      let rest''  = if null rest
                       then empty
                       else text ".RS 4" $$ rest' $$ text ".RE"
      return $ first'' $$ rest''

    -- | Convert definition list item (label, list of blocks) to man.
    definitionListItemToMan :: WriterOptions
                                 -> ([Inline],[[Block]])
                                 -> State WriterState Doc
    definitionListItemToMan opts (label, defs) = do
      labelText <- inlineListToMan opts label
      contents <- if null defs
                     then return empty
                     else liftM vcat $ forM defs $ \blocks -> do
                            let (first, rest) = case blocks of
                                  ((Para x):y) -> (Plain x,y)
                                  (x:y)        -> (x,y)
                                  []           -> error "blocks is null"
                            rest' <- liftM vcat $
                                      mapM (\item -> blockToMan opts item) rest
                            first' <- blockToMan opts first
                            return $ first' $$ text ".RS" $$ rest' $$ text ".RE"
      return $ text ".TP" $$ text ".B " <> labelText $$ contents

    -- | Convert list of Pandoc block elements to man.
    blockListToMan :: WriterOptions -- ^ Options
                        -> [Block]       -- ^ List of block elements
                        -> State WriterState Doc
    blockListToMan opts blocks =
      mapM (blockToMan opts) blocks >>= (return . vcat)

    -- | Convert list of Pandoc inline elements to man.
    inlineListToMan :: WriterOptions -> [Inline] -> State WriterState Doc
    -- if list starts with ., insert a zero-width character \& so it
    -- won't be interpreted as markup if it falls at the beginning of a line.
    inlineListToMan opts lst@(Str ('.':_) : _) = mapM (inlineToMan opts) lst >>=
      (return . (text "\\&" <>)  . hcat)
    inlineListToMan opts lst = mapM (inlineToMan opts) lst >>= (return . hcat)

    -- | Convert Pandoc inline element to man.
    inlineToMan :: WriterOptions -> Inline -> State WriterState Doc
    inlineToMan opts (Span _ ils) = inlineListToMan opts ils
    inlineToMan opts (Emph lst) = do
      contents <- inlineListToMan opts lst
      return $ text "\\f[I]" <> contents <> text "\\f[]"
    inlineToMan opts (Strong lst) = do
      contents <- inlineListToMan opts lst
      return $ text "\\f[B]" <> contents <> text "\\f[]"
    inlineToMan opts (Strikeout lst) = do
      contents <- inlineListToMan opts lst
      return $ text "[STRIKEOUT:" <> contents <> char ']'
    inlineToMan opts (Superscript lst) = do
      contents <- inlineListToMan opts lst
      return $ char '^' <> contents <> char '^'
    inlineToMan opts (Subscript lst) = do
      contents <- inlineListToMan opts lst
      return $ char '~' <> contents <> char '~'
    inlineToMan opts (SmallCaps lst) = inlineListToMan opts lst -- not supported
    inlineToMan opts (Quoted SingleQuote lst) = do
      contents <- inlineListToMan opts lst
      return $ char '`' <> contents <> char '\''
    inlineToMan opts (Quoted DoubleQuote lst) = do
      contents <- inlineListToMan opts lst
      return $ text "\\[lq]" <> contents <> text "\\[rq]"
    inlineToMan opts (Cite _ lst) =
      inlineListToMan opts lst
    inlineToMan _ (Code _ str) =
      return $ text $ "\\f[C]" ++ escapeCode str ++ "\\f[]"
    inlineToMan _ (Str str) = return $ text $ escapeString str
    inlineToMan opts (Math InlineMath str) =
      inlineListToMan opts $ readTeXMath' InlineMath str
    inlineToMan opts (Math DisplayMath str) = do
      contents <- inlineListToMan opts $ readTeXMath' DisplayMath str
      return $ cr <> text ".RS" $$ contents $$ text ".RE"
    inlineToMan _ (RawInline f str)
      | f == Format "man" = return $ text str
      | otherwise         = return empty
    inlineToMan _ (LineBreak) = return $
      cr <> text ".PD 0" $$ text ".P" $$ text ".PD" <> cr
    inlineToMan _ Space = return space
    inlineToMan opts (Link txt (src, _)) = do
      linktext <- inlineListToMan opts txt
      let srcSuffix = if isPrefixOf "mailto:" src then drop 7 src else src
      return $ case txt of
               [Str s]
                 | escapeURI s == srcSuffix ->
                                     char '<' <> text srcSuffix <> char '>'
               _                  -> linktext <> text " (" <> text src <> char ')'
    inlineToMan opts (Image alternate (source, tit)) = do
      let txt = if (null alternate) || (alternate == [Str ""]) ||
                   (alternate == [Str source]) -- to prevent autolinks
                   then [Str "image"]
                   else alternate
      linkPart <- inlineToMan opts (Link txt (source, tit))
      return $ char '[' <> text "IMAGE: " <> linkPart <> char ']'
    inlineToMan _ (Note contents) = do
      -- add to notes in state
      modify $ \st -> st{ stNotes = contents : stNotes st }
      notes <- liftM stNotes get
      let ref = show $ (length notes)
      return $ char '[' <> text ref <> char ']'