    {-
    Copyright (C) 2009 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
    -}

    {- Functions for exporting wiki pages in various formats.
    -}

    module Network.Gitit.Export ( exportFormats ) where
    import Control.Exception (throwIO)
    import Text.Pandoc hiding (HTMLMathMethod(..), getDataFileName)
    import qualified Text.Pandoc as Pandoc
    import Text.Pandoc.PDF (makePDF)
    import Text.Pandoc.SelfContained as SelfContained
    import qualified Text.Pandoc.UTF8 as UTF8
    import Network.Gitit.Server
    import Network.Gitit.Framework (pathForPage)
    import Network.Gitit.State (getConfig)
    import Network.Gitit.Types
    import Network.Gitit.Cache (cacheContents, lookupCache)
    import Control.Monad.Trans (liftIO)
    import Control.Monad (unless)
    import Text.XHtml (noHtml)
    import qualified Data.ByteString as B
    import qualified Data.ByteString.Lazy as L
    import System.FilePath ((</>), takeDirectory)
    import System.Directory (doesFileExist)
    import Text.HTML.SanitizeXSS
    import Text.Pandoc.Writers.RTF (writeRTF)
    import Data.ByteString.Lazy (fromStrict)
    import Data.Text (Text)
    import qualified Data.Text as T
    import Data.Text.Encoding (encodeUtf8)
    import Data.List (isPrefixOf)
    import Skylighting (styleToCss, pygments)
    import Paths_gitit (getDataFileName)

    defaultRespOptions :: WriterOptions
    defaultRespOptions = def { writerHighlightStyle = Just pygments }

    respondX :: String -> String -> String
              -> (WriterOptions -> Pandoc -> PandocIO L.ByteString)
              -> WriterOptions -> String -> Pandoc -> Handler
    respondX templ mimetype ext fn opts page doc = do
      cfg <- getConfig
      doc' <- if ext `elem` ["odt","pdf","beamer","epub","docx","rtf"]
                 then fixURLs page doc
                 else return doc
      doc'' <- liftIO $ runIO $ do
            setUserDataDir $ pandocUserData cfg
            template <- getDefaultTemplate templ
            fn opts{ writerTemplate = Just template } doc'
      either (liftIO . throwIO)
             (ok . setContentType mimetype .
               (if null ext then id else setFilename (page ++ "." ++ ext)) .
                toResponseBS B.empty)
             doc''

    respondS :: String -> String -> String -> (WriterOptions -> Pandoc -> PandocIO Text)
              -> WriterOptions -> String -> Pandoc -> Handler
    respondS templ mimetype ext fn =
      respondX templ mimetype ext (\o d -> fromStrict . encodeUtf8 <$> fn o d)

    respondSlides :: String -> (WriterOptions -> Pandoc -> PandocIO Text) -> String -> Pandoc -> Handler
    respondSlides templ fn page doc = do
        cfg <- getConfig
        let math = case mathMethod cfg of
                       MathML       -> Pandoc.MathML
                       WebTeX u     -> Pandoc.WebTeX u
                       _            -> Pandoc.PlainMath
        let opts' = defaultRespOptions { writerIncremental = True
                                       , writerHTMLMathMethod = math}
        -- We sanitize the body only, to protect against XSS attacks.
        -- (Sanitizing the whole HTML page would strip out javascript
        -- needed for the slides.)  We then pass the body into the
        -- slide template using the 'body' variable.
        Pandoc meta blocks <- fixURLs page doc
        docOrError <- liftIO $ runIO $ do
              setUserDataDir $ pandocUserData cfg
              body' <- writeHtml5String opts' (Pandoc meta blocks) -- just body
              let body'' = T.unpack
                           $ (if xssSanitize cfg then sanitizeBalance else id)
                           $ body'
              variables' <- if mathMethod cfg == MathML
                              then do
                                  s <- readDataFile "MathMLinHTML.js"
                                  return [("mathml-script", UTF8.toString s)]
                              else return []
              template <- getDefaultTemplate templ
              dzcore <- if templ == "dzslides"
                          then do
                            dztempl <- readDataFile $ "dzslides" </> "template.html"
                            return $ unlines
                                $ dropWhile (not . isPrefixOf "<!-- {{{{ dzslides core")
                                $ lines $ UTF8.toString dztempl
                          else return ""
              let opts'' = opts'{
                                 writerVariables =
                                   ("body",body''):("dzslides-core",dzcore):("highlighting-css",pygmentsCss):variables'
                                ,writerTemplate = Just template }
              h <- fn opts'' (Pandoc meta [])
              makeSelfContained (T.unpack h)
        either (liftIO . throwIO)
               (ok . setContentType "text/html;charset=UTF-8" .
                 (setFilename (page ++ ".html")) .
                 toResponseBS B.empty . UTF8.fromStringLazy)
               docOrError

    respondLaTeX :: String -> Pandoc -> Handler
    respondLaTeX = respondS "latex" "application/x-latex" "tex"
      writeLaTeX defaultRespOptions

    respondConTeXt :: String -> Pandoc -> Handler
    respondConTeXt = respondS "context" "application/x-context" "tex"
      writeConTeXt defaultRespOptions

    respondRTF :: String -> Pandoc -> Handler
    respondRTF = respondX "rtf" "application/rtf" "rtf"
      (\o d -> L.fromStrict . UTF8.fromText <$> writeRTF o d) defaultRespOptions

    respondRST :: String -> Pandoc -> Handler
    respondRST = respondS "rst" "text/plain; charset=utf-8" ""
      writeRST defaultRespOptions{writerReferenceLinks = True}

    respondMarkdown :: String -> Pandoc -> Handler
    respondMarkdown = respondS "markdown" "text/plain; charset=utf-8" ""
      writeMarkdown defaultRespOptions{writerReferenceLinks = True}

    respondCommonMark :: String -> Pandoc -> Handler
    respondCommonMark = respondS "commonmark" "text/plain; charset=utf-8" ""
      writeCommonMark defaultRespOptions{writerReferenceLinks = True}

    respondPlain :: String -> Pandoc -> Handler
    respondPlain = respondS "plain" "text/plain; charset=utf-8" ""
      writePlain defaultRespOptions

    respondMan :: String -> Pandoc -> Handler
    respondMan = respondS "man" "text/plain; charset=utf-8" ""
      writeMan defaultRespOptions

    respondTexinfo :: String -> Pandoc -> Handler
    respondTexinfo = respondS "texinfo" "application/x-texinfo" "texi"
      writeTexinfo defaultRespOptions

    respondDocbook :: String -> Pandoc -> Handler
    respondDocbook = respondS "docbook" "application/docbook+xml" "xml"
      writeDocbook5 defaultRespOptions

    respondOrg :: String -> Pandoc -> Handler
    respondOrg = respondS "org" "text/plain; charset=utf-8" ""
      writeOrg defaultRespOptions

    respondICML :: String -> Pandoc -> Handler
    respondICML = respondX "icml" "application/xml; charset=utf-8" ""
                  (\o d -> L.fromStrict . UTF8.fromText <$> writeICML o d)
                             defaultRespOptions

    respondTextile :: String -> Pandoc -> Handler
    respondTextile = respondS "textile" "text/plain; charset=utf-8" ""
      writeTextile defaultRespOptions

    respondAsciiDoc :: String -> Pandoc -> Handler
    respondAsciiDoc = respondS "asciidoc" "text/plain; charset=utf-8" ""
      writeAsciiDoc defaultRespOptions

    respondMediaWiki :: String -> Pandoc -> Handler
    respondMediaWiki = respondS "mediawiki" "text/plain; charset=utf-8" ""
      writeMediaWiki defaultRespOptions

    respondODT :: String -> Pandoc -> Handler
    respondODT = respondX "opendocument" "application/vnd.oasis.opendocument.text"
                  "odt" writeODT defaultRespOptions

    respondEPUB :: String -> Pandoc -> Handler
    respondEPUB = respondX "html" "application/epub+zip" "epub" writeEPUB3
                   defaultRespOptions

    respondDocx :: String -> Pandoc -> Handler
    respondDocx = respondX "native"
      "application/vnd.openxmlformats-officedocument.wordprocessingml.document"
      "docx" writeDocx defaultRespOptions

    respondPDF :: Bool -> String -> Pandoc -> Handler
    respondPDF useBeamer page old_pndc = fixURLs page old_pndc >>= \pndc -> do
      cfg <- getConfig
      unless (pdfExport cfg) $ error "PDF export disabled"
      let cacheName = pathForPage page (defaultExtension cfg) ++ ".export.pdf"
      cached <- if useCache cfg
                   then lookupCache cacheName
                   else return Nothing
      pdf' <- case cached of
                Just (_modtime, bs) -> return $ Right $ L.fromChunks [bs]
                Nothing -> do
                  let toc = tableOfContents cfg
                  res <- liftIO $ runIO $ do
                    setUserDataDir $ pandocUserData cfg
                    setInputFiles [baseUrl cfg]
                    template <- getDefaultTemplate $ if useBeamer then "beamer" else "latex"
                    makePDF "pdflatex" [] (if useBeamer then writeBeamer else writeLaTeX)
                      defaultRespOptions{ writerTemplate = Just template
                                        , writerTableOfContents = toc } pndc
                  either (liftIO . throwIO) return res

      case pdf' of
           Left logOutput' -> simpleErrorHandler ("PDF creation failed:\n"
                               ++ UTF8.toStringLazy logOutput')
           Right pdfBS -> do
                  case cached of
                    Nothing ->
                         cacheContents cacheName $ B.concat . L.toChunks $ pdfBS
                    _ -> return ()
                  ok $ setContentType "application/pdf" $ setFilename (page ++ ".pdf") $
                            (toResponse noHtml) {rsBody = pdfBS}

    -- | When we create a PDF or ODT from a Gitit page, we need to fix the URLs of any
    -- images on the page. Those URLs will often be relative to the staticDir, but the
    -- PDF or ODT processor only understands paths relative to the working directory.
    --
    -- Because the working directory will not in general be the root of the gitit instance
    -- at the time the Pandoc is fed to e.g. pdflatex, this function replaces the URLs of
    -- images in the staticDir with their correct absolute file path.
    fixURLs :: String -> Pandoc -> GititServerPart Pandoc
    fixURLs page pndc = do
        cfg <- getConfig
        defaultStatic <- liftIO $ getDataFileName $ "data" </> "static"

        let static = staticDir cfg
        let repoPath = repositoryPath cfg

        let go (Image attr ils (url, title)) = do
               fixedURL <- fixURL url
               return $ Image attr ils (fixedURL, title)
            go x                        = return x

            fixURL ('/':url) = resolve url
            fixURL url       = resolve $ takeDirectory page </> url

            resolve p = do
               sp <- doesFileExist $ static </> p
               dsp <- doesFileExist $ defaultStatic </> p
               return (if sp then static </> p
                       else (if dsp then defaultStatic </> p
                             else repoPath </> p))
        liftIO $ bottomUpM go pndc

    exportFormats :: Config -> [(String, String -> Pandoc -> Handler)]
    exportFormats cfg = if pdfExport cfg
                           then ("PDF", respondPDF False) :
                                ("Beamer", respondPDF True) :
                                rest
                           else rest
       where rest = [ ("LaTeX",     respondLaTeX)     -- (description, writer)
                    , ("ConTeXt",   respondConTeXt)
                    , ("Texinfo",   respondTexinfo)
                    , ("reST",      respondRST)
                    , ("Markdown",  respondMarkdown)
                    , ("CommonMark",respondCommonMark)
                    , ("Plain text",respondPlain)
                    , ("MediaWiki", respondMediaWiki)
                    , ("Org-mode",  respondOrg)
                    , ("ICML",      respondICML)
                    , ("Textile",   respondTextile)
                    , ("AsciiDoc",  respondAsciiDoc)
                    , ("Man page",  respondMan)
                    , ("DocBook",   respondDocbook)
                    , ("DZSlides",  respondSlides "dzslides" writeDZSlides)
                    , ("Slidy",     respondSlides "slidy" writeSlidy)
                    , ("S5",        respondSlides "s5" writeS5)
                    , ("EPUB",      respondEPUB)
                    , ("ODT",       respondODT)
                    , ("DOCX",      respondDocx)
                    , ("RTF",       respondRTF) ]

    pygmentsCss :: String
    pygmentsCss = styleToCss pygments