{-# Language ForeignFunctionInterface #-}

module Text.Sundown.Renderers.Html
       ( renderHtml
       , noHtmlModes
       , allHtmlModes
       , smartypants
       , HtmlRenderMode (..)
       ) where

import Foreign.Marshal
import Foreign.Ptr
import Foreign.Storable

import System.IO.Unsafe

import Data.ByteString (ByteString)
import qualified Data.ByteString as BS
import Data.Maybe (fromMaybe)

import Text.Sundown.Markdown.Foreign
import Text.Sundown.Buffer.Foreign
import Text.Sundown.Renderers.Html.Foreign

defaultMaxNesting :: Int
defaultMaxNesting = 16

-- | Parses a 'ByteString' containing the markdown, returns the Html
-- code.
{-# NOINLINE renderHtml #-}
renderHtml :: ByteString
           -> Extensions
           -> HtmlRenderMode
           -> Maybe Int -- ^ The maximum nesting of the HTML. If Nothing, a default value (16)
                       -- will be used.
           -> ByteString
renderHtml input exts mode maxNestingM =
  unsafePerformIO $
  alloca $ \callbacks ->
  alloca $ \options -> do
    -- Allocate buffers
    ob <- c_bufnew 64
    ib <- c_bufnew . fromIntegral . BS.length $ input

    -- Put the input content into the buffer
    c_bufputs ib input

    -- Do the markdown
    c_sdhtml_renderer callbacks options mode

    let maxNesting = fromIntegral $ fromMaybe defaultMaxNesting maxNestingM
    markdown <- c_sd_markdown_new exts maxNesting callbacks (castPtr options)

    Buffer {bufData = cs, bufSize = size} <- peek ib
    c_sd_markdown_render ob cs size markdown

    c_sd_markdown_free markdown

    -- Get the result
    output <- peek ob >>= getBufferData

    c_bufrelease ib
    c_bufrelease ob

    return output

-- | All the 'HtmlRenderMode' disabled
noHtmlModes :: HtmlRenderMode
noHtmlModes = HtmlRenderMode False False False False False False False False False False

-- | All the 'HtmlRenderMode' enabled
allHtmlModes :: HtmlRenderMode
allHtmlModes = HtmlRenderMode True True True True True True True True True True

-- | Converts punctuation in Html entities,
-- <http://daringfireball.net/projects/smartypants/>
{-# NOINLINE smartypants #-}
smartypants :: ByteString -> ByteString
smartypants input =
  unsafePerformIO $ do
    ob <- c_bufnew 64
    ib <- c_bufnew $ fromInteger . toInteger $ BS.length input

    c_bufputs ib input

    Buffer {bufData = cs, bufSize = size} <- peek ib
    c_sdhtml_smartypants ob cs size

    output <- peek ob >>= getBufferData

    c_bufrelease ib
    c_bufrelease ob

    return output