-- | Definitions for creation of S5 powerpoint-like HTML.
-- (See <http://meyerweb.com/eric/tools/s5/>.)
module Text.Pandoc.Writers.S5 (
                -- * Strings
                s5Javascript,
                s5CSS,
                s5Links,
                -- * Functions
                writeS5,
                insertS5Structure
                ) where
import Text.Pandoc.Shared ( joinWithSep, WriterOptions )
import Text.Pandoc.Writers.HTML ( writeHtml )
import Text.Pandoc.Definition

s5Javascript :: String
s5Javascript = "<script type=\"text/javascript\">\n@slides.js@</script>\n" 

s5CoreCSS :: String
s5CoreCSS = "@s5-core.css@"

s5FramingCSS :: String
s5FramingCSS = "@framing.css@"

s5PrettyCSS :: String
s5PrettyCSS = "@pretty.css@"

s5OperaCSS :: String
s5OperaCSS = "@opera.css@"

s5OutlineCSS :: String
s5OutlineCSS = "@outline.css@"

s5PrintCSS :: String
s5PrintCSS = "@print.css@"

s5CSS :: String
s5CSS = "<style type=\"text/css\" media=\"projection\" id=\"slideProj\">\n" ++ s5CoreCSS ++ "\n" ++ s5FramingCSS ++ "\n" ++ s5PrettyCSS ++ "\n</style>\n<style type=\"text/css\" media=\"projection\" id=\"operaFix\">\n" ++ s5OperaCSS ++ "\n</style>\n<style type=\"text/css\" media=\"screen\" id=\"outlineStyle\">\n" ++ s5OutlineCSS ++ "\n</style>\n<style type=\"text/css\" media=\"print\" id=\"slidePrint\">\n" ++ s5PrintCSS ++ "\n</style>\n"

s5Links :: String
s5Links = "<!-- style sheet links -->\n<link rel=\"stylesheet\" href=\"ui/default/slides.css\" type=\"text/css\" media=\"projection\" id=\"slideProj\" />\n<link rel=\"stylesheet\" href=\"ui/default/outline.css\" type=\"text/css\" media=\"screen\" id=\"outlineStyle\" />\n<link rel=\"stylesheet\" href=\"ui/default/print.css\" type=\"text/css\" media=\"print\" id=\"slidePrint\" />\n<link rel=\"stylesheet\" href=\"ui/default/opera.css\" type=\"text/css\" media=\"projection\" id=\"operaFix\" />\n<!-- S5 JS -->\n<script src=\"ui/default/slides.js\" type=\"text/javascript\"></script>\n"

-- | Converts 'Pandoc' to an S5 HTML presentation.
writeS5 :: WriterOptions -> Pandoc -> String
writeS5 options = writeHtml options . insertS5Structure

-- | Inserts HTML needed for an S5 presentation (e.g. around slides).
layoutDiv :: [Inline]  -- ^ Title of document (for header or footer)
          -> String    -- ^ Date of document (for header or footer)
          -> [Block]   -- ^ List of block elements returned
layoutDiv title date = [(RawHtml "<div class=\"layout\">\n<div id=\"controls\"></div>\n<div id=\"currentSlide\"></div>\n<div id=\"header\"></div>\n<div id=\"footer\">\n"), (Header 1 [Str date]), (Header 2 title), (RawHtml "</div>\n</div>\n")]

presentationStart = (RawHtml "<div class=\"presentation\">\n\n")

presentationEnd = (RawHtml "</div>\n")

slideStart = (RawHtml "<div class=\"slide\">\n")

slideEnd = (RawHtml "</div>\n") 

-- | Returns 'True' if block is a Header 1.
isH1 :: Block -> Bool
isH1 (Header 1 _) = True
isH1 _ = False 

-- | Insert HTML around sections to make individual slides.
insertSlides :: Bool -> [Block] -> [Block]
insertSlides beginning blocks = 
    let (beforeHead, rest) = break isH1 blocks in
    if (null rest) then 
        if beginning then
            beforeHead 
        else
            beforeHead ++ [slideEnd]
    else
        if beginning then
            beforeHead ++ slideStart:(head rest):(insertSlides False (tail rest))
        else
            beforeHead ++ slideEnd:slideStart:(head rest):(insertSlides False (tail rest)) 

-- | Insert blocks into 'Pandoc' for slide structure.
insertS5Structure :: Pandoc -> Pandoc
insertS5Structure (Pandoc meta []) = Pandoc meta []
insertS5Structure (Pandoc (Meta title authors date) blocks) = 
    let slides = insertSlides True blocks 
        firstSlide = if (not (null title)) then [slideStart, (Header 1 title), (Header 3 [Str (joinWithSep ", " authors)]), (Header 4 [Str date]), slideEnd] else [] in
    let newBlocks = (layoutDiv title date) ++ presentationStart:firstSlide ++ slides ++ [presentationEnd] in
    Pandoc (Meta title authors date) newBlocks