{-
Copyright (C) 2006 John MacFarlane <jgm at berkeley dot 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.LaTeX
   Copyright   : Copyright (C) 2006 John MacFarlane
   License     : GNU GPL, version 2 or above 

   Maintainer  : John MacFarlane <jgm at berkeley dot edu>
   Stability   : alpha 
   Portability : portable

Conversion of 'Pandoc' format into LaTeX.
-}
module Text.Pandoc.Writers.LaTeX ( 
                                  writeLaTeX 
                                 ) where
import Text.Pandoc.Definition
import Text.Pandoc.Shared
import List ( (\\) )

-- | Convert Pandoc to LaTeX.
writeLaTeX :: WriterOptions -> Pandoc -> String
writeLaTeX options (Pandoc meta blocks) = 
  let notes = filter isNoteBlock blocks in -- assumes all notes at outer level
  let body = (writerIncludeBefore options) ++ 
             (concatMap (blockToLaTeX notes) 
                        (replaceReferenceLinks blocks)) ++ 
             (writerIncludeAfter options) in
  let head = if writerStandalone options
                then latexHeader notes options meta
                else "" in
  let foot = if writerStandalone options then "\n\\end{document}\n" else "" in
  head ++ body ++ foot

-- | Insert bibliographic information into LaTeX header.
latexHeader ::  [Block] -- ^ List of note blocks to use in resolving note refs
            -> WriterOptions -- ^ Options, including LaTeX header
            -> Meta          -- ^ Meta with bibliographic information
            -> String
latexHeader notes options (Meta title authors date) =
  let titletext = if null title
                     then "" 
                     else "\\title{" ++ inlineListToLaTeX notes title ++ "}\n"
      authorstext = if null authors
                       then "" 
                       else "\\author{" ++ (joinWithSep "\\\\" 
                            (map stringToLaTeX authors)) ++ "}\n"
      datetext = if date == ""
                    then "" 
                    else "\\date{" ++ stringToLaTeX date ++ "}\n"
      maketitle = if null title then "" else "\\maketitle\n" 
      secnumline = if (writerNumberSections options)
                      then "" 
                      else "\\setcounter{secnumdepth}{0}\n" 
      header     = writerHeader options in
  header ++ secnumline ++ titletext ++ authorstext ++ datetext ++ 
  "\\begin{document}\n" ++ maketitle

-- escape things as needed for LaTeX (also ldots, dashes, quotes, etc.) 

escapeBrackets  = backslashEscape "{}"
escapeSpecial   = backslashEscape "$%&~_#"

escapeBackslash = gsub "\\\\" "\\\\textbackslash{}" 
fixBackslash    = gsub "\\\\textbackslash\\\\\\{\\\\\\}" "\\\\textbackslash{}"
escapeHat       = gsub "\\^" "\\\\^{}"
escapeBar       = gsub "\\|" "\\\\textbar{}"
escapeLt        = gsub "<" "\\\\textless{}"
escapeGt        = gsub ">" "\\\\textgreater{}"

-- | Escape string for LaTeX
stringToLaTeX :: String -> String
stringToLaTeX = escapeGt . escapeLt . escapeBar . escapeHat . 
                escapeSpecial . fixBackslash . escapeBrackets . 
                escapeBackslash 

-- | Remove all code elements from list of inline elements
-- (because it's illegal to have a \\verb inside a command argument)
deVerb :: [Inline] -> [Inline]
deVerb [] = []
deVerb ((Code str):rest) = (Str str):(deVerb rest)
deVerb (other:rest) = other:(deVerb rest)

-- | Convert Pandoc block element to LaTeX.
blockToLaTeX :: [Block]   -- ^ List of note blocks to use in resolving note refs
             -> Block     -- ^ Block to convert
             -> String 
blockToLaTeX notes Blank = "\n" 
blockToLaTeX notes Null = ""
blockToLaTeX notes (Plain lst) = inlineListToLaTeX notes lst ++ "\n"
blockToLaTeX notes (Para lst) = (inlineListToLaTeX notes lst) ++ "\n\n"
blockToLaTeX notes (BlockQuote lst) = "\\begin{quote}\n" ++ 
    (concatMap (blockToLaTeX notes) lst) ++ "\\end{quote}\n"
blockToLaTeX notes (Note ref lst) = ""
blockToLaTeX notes (Key _ _) = ""
blockToLaTeX notes (CodeBlock str) = "\\begin{verbatim}\n" ++ str ++ 
    "\n\\end{verbatim}\n"
blockToLaTeX notes (RawHtml str) = ""
blockToLaTeX notes (BulletList lst) = "\\begin{itemize}\n" ++ 
    (concatMap (listItemToLaTeX notes) lst) ++ "\\end{itemize}\n"
blockToLaTeX notes (OrderedList lst) = "\\begin{enumerate}\n" ++ 
    (concatMap (listItemToLaTeX notes) lst) ++ "\\end{enumerate}\n"
blockToLaTeX notes HorizontalRule = 
    "\\begin{center}\\rule{3in}{0.4pt}\\end{center}\n\n"
blockToLaTeX notes (Header level lst) = 
    if (level > 0) && (level <= 3)
       then "\\" ++ (concat (replicate (level - 1) "sub")) ++ "section{" ++ 
            (inlineListToLaTeX notes (deVerb lst)) ++ "}\n\n"
       else (inlineListToLaTeX notes lst) ++ "\n\n"
listItemToLaTeX notes list = "\\item " ++ 
    (concatMap (blockToLaTeX notes) list) 

-- | Convert list of inline elements to LaTeX.
inlineListToLaTeX :: [Block]   -- ^ List of note blocks to use in resolving note refs
                  -> [Inline]  -- ^ Inlines to convert
                  -> String
inlineListToLaTeX notes lst = 
  concatMap (inlineToLaTeX notes) lst

-- | Convert inline element to LaTeX
inlineToLaTeX :: [Block]   -- ^ List of note blocks to use in resolving note refs
              -> Inline    -- ^ Inline to convert
              -> String
inlineToLaTeX notes (Emph lst) = "\\emph{" ++ 
    (inlineListToLaTeX notes (deVerb lst)) ++ "}"
inlineToLaTeX notes (Strong lst) = "\\textbf{" ++ 
    (inlineListToLaTeX notes (deVerb lst)) ++ "}"
inlineToLaTeX notes (Code str) = "\\verb" ++ [chr] ++ stuffing ++ [chr]
                     where stuffing = str 
                           chr      = ((enumFromTo '!' '~') \\ stuffing) !! 0
inlineToLaTeX notes (Quoted SingleQuote lst) =
  "`" ++ inlineListToLaTeX notes lst ++ "'"
inlineToLaTeX notes (Quoted DoubleQuote lst) =
  "``" ++ inlineListToLaTeX notes lst ++ "''"
inlineToLaTeX notes Apostrophe = "'"
inlineToLaTeX notes EmDash = "---"
inlineToLaTeX notes EnDash = "--"
inlineToLaTeX notes Ellipses = "\\ldots{}"
inlineToLaTeX notes (Str str) = stringToLaTeX str
inlineToLaTeX notes (TeX str) = str
inlineToLaTeX notes (HtmlInline str) = ""
inlineToLaTeX notes (LineBreak) = "\\\\\n"
inlineToLaTeX notes Space = " "
inlineToLaTeX notes (Link text (Src src tit)) = 
    "\\href{" ++ src ++ "}{" ++ (inlineListToLaTeX notes (deVerb text)) ++ "}"
inlineToLaTeX notes (Link text (Ref ref)) = "[" ++ 
    (inlineListToLaTeX notes text) ++ "][" ++ (inlineListToLaTeX notes ref) ++
    "]"  -- this is what markdown does, for better or worse
inlineToLaTeX notes (Image alternate (Src source tit)) = 
    "\\includegraphics{" ++ source ++ "}" 
inlineToLaTeX notes (Image alternate (Ref ref)) = 
    "![" ++ (inlineListToLaTeX notes alternate) ++ "][" ++ 
    (inlineListToLaTeX notes ref) ++ "]"
inlineToLaTeX [] (NoteRef ref) = ""
inlineToLaTeX ((Note firstref firstblocks):rest) (NoteRef ref) = 
    if (firstref == ref)
       then "\\footnote{" ++ (stripTrailingNewlines 
            (concatMap (blockToLaTeX rest) firstblocks))  ++ "}"
       else inlineToLaTeX rest (NoteRef ref)