{-# LANGUAGE CPP, ForeignFunctionInterface, GeneralizedNewtypeDeriving,
    DeriveGeneric, DeriveDataTypeable, FlexibleContexts #-}

module CMark (
    commonmarkToHtml
  , commonmarkToXml
  , commonmarkToMan
  , commonmarkToLaTeX
  , commonmarkToNode
  , nodeToHtml
  , nodeToXml
  , nodeToMan
  , nodeToLaTeX
  , nodeToCommonmark
  , optSourcePos
  , optNormalize
  , optHardBreaks
  , optSmart
  , optSafe
  , optUnsafe
  , Node(..)
  , NodeType(..)
  , PosInfo(..)
  , DelimType(..)
  , ListType(..)
  , ListAttributes(..)
  , Url
  , Title
  , Level
  , Info
  , CMarkOption
  ) where

import Foreign
import Foreign.C.Types
import Foreign.C.String (CString)
import qualified System.IO.Unsafe as Unsafe
import Data.Maybe (fromMaybe)
import GHC.Generics (Generic)
import Data.Data (Data)
import Data.Typeable (Typeable)
import Data.Text (Text, empty, snoc)
import qualified Data.Text.Foreign as TF
import Data.ByteString.Unsafe (unsafePackMallocCString)
import Data.Text.Encoding (decodeUtf8)
import Control.Applicative ((<$>), (<*>))

#include <cmark.h>

-- | Convert CommonMark formatted text to Html, using cmark's
-- built-in renderer.
commonmarkToHtml :: [CMarkOption] -> Text -> Text
commonmarkToHtml opts = commonmarkToX render_html opts Nothing
  where render_html n o _ = c_cmark_render_html n o

-- | Convert CommonMark formatted text to CommonMark XML, using cmark's
-- built-in renderer.
commonmarkToXml :: [CMarkOption] -> Text -> Text
commonmarkToXml opts = commonmarkToX render_xml opts Nothing
  where render_xml n o _ = c_cmark_render_xml n o

-- | Convert CommonMark formatted text to groff man, using cmark's
-- built-in renderer.
commonmarkToMan :: [CMarkOption] -> Maybe Int -> Text -> Text
commonmarkToMan = commonmarkToX c_cmark_render_man

-- | Convert CommonMark formatted text to latex, using cmark's
-- built-in renderer.
commonmarkToLaTeX :: [CMarkOption] -> Maybe Int -> Text -> Text
commonmarkToLaTeX = commonmarkToX c_cmark_render_latex

-- | Convert CommonMark formatted text to a structured 'Node' tree,
-- which can be transformed or rendered using Haskell code.
commonmarkToNode :: [CMarkOption] -> Text -> Node
commonmarkToNode opts s = Unsafe.unsafePerformIO $ do
  nptr <- TF.withCStringLen s $! \(ptr, len) ->
             c_cmark_parse_document ptr len (combineOptions opts)
  fptr <- newForeignPtr c_cmark_node_free nptr
  withForeignPtr fptr toNode

nodeToHtml :: [CMarkOption] -> Node -> Text
nodeToHtml opts = nodeToX render_html opts Nothing
  where render_html n o _ = c_cmark_render_html n o

nodeToXml :: [CMarkOption] -> Node -> Text
nodeToXml opts = nodeToX render_xml opts Nothing
  where render_xml n o _ = c_cmark_render_xml n o

nodeToMan :: [CMarkOption] -> Maybe Int -> Node -> Text
nodeToMan = nodeToX c_cmark_render_man

nodeToLaTeX :: [CMarkOption] -> Maybe Int -> Node -> Text
nodeToLaTeX = nodeToX c_cmark_render_latex

nodeToCommonmark :: [CMarkOption] -> Maybe Int -> Node -> Text
nodeToCommonmark = nodeToX c_cmark_render_commonmark

type Renderer = NodePtr -> CInt -> Int -> IO CString

nodeToX :: Renderer -> [CMarkOption] -> Maybe Int -> Node -> Text
nodeToX renderer opts mbWidth node = Unsafe.unsafePerformIO $ do
  nptr <- fromNode node
  fptr <- newForeignPtr c_cmark_node_free nptr
  withForeignPtr fptr $ \ptr -> do
    cstr <- renderer ptr (combineOptions opts) (fromMaybe 0 mbWidth)
    decodeUtf8 <$> unsafePackMallocCString cstr

commonmarkToX :: Renderer
              -> [CMarkOption]
              -> Maybe Int
              -> Text
              -> Text
commonmarkToX renderer opts mbWidth s = Unsafe.unsafePerformIO $
  TF.withCStringLen s $ \(ptr, len) -> do
    let opts' = combineOptions opts
    nptr <- c_cmark_parse_document ptr len opts'
    fptr <- newForeignPtr c_cmark_node_free nptr
    withForeignPtr fptr $ \p -> do
      str <- renderer p opts' (fromMaybe 0 mbWidth)
      decodeUtf8 <$> unsafePackMallocCString str

type NodePtr = Ptr ()

data Node = Node (Maybe PosInfo) NodeType [Node]
     deriving (Show, Read, Eq, Ord, Typeable, Data, Generic)

data DelimType =
    PERIOD_DELIM
  | PAREN_DELIM
  deriving (Show, Read, Eq, Ord, Typeable, Data, Generic)

data ListType =
    BULLET_LIST
  | ORDERED_LIST
  deriving (Show, Read, Eq, Ord, Typeable, Data, Generic)

data ListAttributes = ListAttributes{
    listType     :: ListType
  , listTight    :: Bool
  , listStart    :: Int
  , listDelim    :: DelimType
  } deriving (Show, Read, Eq, Ord, Typeable, Data, Generic)

type Url = Text

type Title = Text

type Level = Int

type Info = Text

type OnEnter = Text

type OnExit = Text

data NodeType =
    DOCUMENT
  | THEMATIC_BREAK
  | PARAGRAPH
  | BLOCK_QUOTE
  | HTML_BLOCK Text
  | CUSTOM_BLOCK OnEnter OnExit
  | CODE_BLOCK Info Text
  | HEADING Level
  | LIST ListAttributes
  | ITEM
  | TEXT Text
  | SOFTBREAK
  | LINEBREAK
  | HTML_INLINE Text
  | CUSTOM_INLINE OnEnter OnExit
  | CODE Text
  | EMPH
  | STRONG
  | LINK Url Title
  | IMAGE Url Title
  deriving (Show, Read, Eq, Ord, Typeable, Data, Generic)

data PosInfo = PosInfo{ startLine   :: Int
                      , startColumn :: Int
                      , endLine     :: Int
                      , endColumn   :: Int
                      }
  deriving (Show, Read, Eq, Ord, Typeable, Data, Generic)

newtype CMarkOption = CMarkOption { unCMarkOption :: CInt }

-- | Combine a list of options into a single option, using bitwise or.
combineOptions :: [CMarkOption] -> CInt
combineOptions = foldr ((.|.) . unCMarkOption) 0

-- | Include a @data-sourcepos@ attribute on block elements.
optSourcePos :: CMarkOption
optSourcePos = CMarkOption #const CMARK_OPT_SOURCEPOS

-- | Render @softbreak@ elements as hard line breaks.
optHardBreaks :: CMarkOption
optHardBreaks = CMarkOption #const CMARK_OPT_HARDBREAKS

-- | Normalize the document by consolidating adjacent text nodes.
optNormalize :: CMarkOption
optNormalize = CMarkOption #const CMARK_OPT_NORMALIZE

-- | Convert straight quotes to curly, @---@ to em-dash, @--@ to en-dash.
optSmart :: CMarkOption
optSmart = CMarkOption #const CMARK_OPT_SMART

-- | Suppress rendering of raw HTML and potentially dangerous URLs in links
-- and images.
optSafe :: CMarkOption
optSafe = CMarkOption #const CMARK_OPT_SAFE

-- | Allow rendering of raw HTML and potentially dangerous URLs in links
-- and images.
optUnsafe :: CMarkOption
optUnsafe = CMarkOption #const CMARK_OPT_UNSAFE

ptrToNodeType :: NodePtr -> IO NodeType
ptrToNodeType ptr = do
  nodeType <- c_cmark_node_get_type ptr
  case nodeType of
       #const CMARK_NODE_DOCUMENT
         -> return DOCUMENT
       #const CMARK_NODE_THEMATIC_BREAK
         -> return THEMATIC_BREAK
       #const CMARK_NODE_PARAGRAPH
         -> return PARAGRAPH
       #const CMARK_NODE_BLOCK_QUOTE
         -> return BLOCK_QUOTE
       #const CMARK_NODE_HTML_BLOCK
         -> HTML_BLOCK <$> literal
       #const CMARK_NODE_CUSTOM_BLOCK
         -> CUSTOM_BLOCK <$> onEnter <*> onExit
       #const CMARK_NODE_CODE_BLOCK
         -> CODE_BLOCK <$> info
                       <*> literal
       #const CMARK_NODE_LIST
         -> LIST <$> listAttr
       #const CMARK_NODE_ITEM
         -> return ITEM
       #const CMARK_NODE_HEADING
         -> HEADING <$> level
       #const CMARK_NODE_EMPH
         -> return EMPH
       #const CMARK_NODE_STRONG
         -> return STRONG
       #const CMARK_NODE_LINK
         -> LINK <$> url <*> title
       #const CMARK_NODE_IMAGE
         -> IMAGE <$> url <*> title
       #const CMARK_NODE_TEXT
         -> TEXT <$> literal
       #const CMARK_NODE_CODE
         -> CODE <$> literal
       #const CMARK_NODE_HTML_INLINE
         -> HTML_INLINE <$> literal
       #const CMARK_NODE_CUSTOM_INLINE
         -> CUSTOM_INLINE <$> onEnter <*> onExit
       #const CMARK_NODE_SOFTBREAK
         -> return SOFTBREAK
       #const CMARK_NODE_LINEBREAK
         -> return LINEBREAK
       _ -> error $ "Unknown node type: " ++ show nodeType
  where literal   = c_cmark_node_get_literal ptr >>= totext
        level     = c_cmark_node_get_heading_level ptr
        onEnter    = c_cmark_node_get_on_enter ptr >>= totext
        onExit     = c_cmark_node_get_on_exit  ptr >>= totext
        listAttr  = do
          listtype <- c_cmark_node_get_list_type ptr
          listdelim <- c_cmark_node_get_list_delim ptr
          tight <- c_cmark_node_get_list_tight ptr
          start <- c_cmark_node_get_list_start ptr
          return ListAttributes{
            listType  = case listtype of
                             (#const CMARK_ORDERED_LIST) -> ORDERED_LIST
                             (#const CMARK_BULLET_LIST)  -> BULLET_LIST
                             _                           -> BULLET_LIST
          , listDelim  = case listdelim of
                             (#const CMARK_PERIOD_DELIM) -> PERIOD_DELIM
                             (#const CMARK_PAREN_DELIM)  -> PAREN_DELIM
                             _                           -> PERIOD_DELIM
          , listTight  = tight
          , listStart  = start
          }
        url       = c_cmark_node_get_url ptr >>= totext
        title     = c_cmark_node_get_title ptr >>= totext
        info      = c_cmark_node_get_fence_info ptr >>= totext

getPosInfo :: NodePtr -> IO (Maybe PosInfo)
getPosInfo ptr = do
  startline <- c_cmark_node_get_start_line ptr
  endline <- c_cmark_node_get_end_line ptr
  startcol <- c_cmark_node_get_start_column ptr
  endcol <- c_cmark_node_get_end_column ptr
  if startline + endline + startcol + endcol == 0
     then return Nothing
     else return $ Just PosInfo{ startLine = startline
                               , startColumn = startcol
                               , endLine = endline
                               , endColumn = endcol }

toNode :: NodePtr -> IO Node
toNode ptr = do
  let handleNodes ptr' =
        if ptr' == nullPtr
           then return []
           else do
              x  <- toNode ptr'
              xs <- c_cmark_node_next ptr' >>= handleNodes
              return $! (x:xs)
  nodeType <- ptrToNodeType ptr
  children <- c_cmark_node_first_child ptr >>= handleNodes
  posinfo <- getPosInfo ptr
  return $! Node posinfo nodeType children

fromNode :: Node -> IO NodePtr
fromNode (Node _ nodeType children) = do
  node <- case nodeType of
            DOCUMENT    -> c_cmark_node_new (#const CMARK_NODE_DOCUMENT)
            THEMATIC_BREAK -> c_cmark_node_new (#const CMARK_NODE_THEMATIC_BREAK)
            PARAGRAPH   -> c_cmark_node_new (#const CMARK_NODE_PARAGRAPH)
            BLOCK_QUOTE -> c_cmark_node_new (#const CMARK_NODE_BLOCK_QUOTE)
            HTML_BLOCK literal -> do
                     n <- c_cmark_node_new (#const CMARK_NODE_HTML_BLOCK)
                     withtext literal (c_cmark_node_set_literal n)
                     return n
            CUSTOM_BLOCK onEnter onExit -> do
                     n <- c_cmark_node_new (#const CMARK_NODE_CUSTOM_BLOCK)
                     withtext onEnter (c_cmark_node_set_on_enter n)
                     withtext onExit  (c_cmark_node_set_on_exit  n)
                     return n
            CODE_BLOCK info literal -> do
                     n <- c_cmark_node_new (#const CMARK_NODE_CODE_BLOCK)
                     withtext literal (c_cmark_node_set_literal n)
                     withtext info (c_cmark_node_set_fence_info n)
                     return n
            LIST attr   -> do
                     n <- c_cmark_node_new (#const CMARK_NODE_LIST)
                     c_cmark_node_set_list_type n $ case listType attr of
                         ORDERED_LIST -> #const CMARK_ORDERED_LIST
                         BULLET_LIST  -> #const CMARK_BULLET_LIST
                     c_cmark_node_set_list_delim n $ case listDelim attr of
                         PERIOD_DELIM -> #const CMARK_PERIOD_DELIM
                         PAREN_DELIM  -> #const CMARK_PAREN_DELIM
                     c_cmark_node_set_list_tight n $ listTight attr
                     c_cmark_node_set_list_start n $ listStart attr
                     return n
            ITEM        -> c_cmark_node_new (#const CMARK_NODE_ITEM)
            HEADING lev  -> do
                     n <- c_cmark_node_new (#const CMARK_NODE_HEADING)
                     c_cmark_node_set_heading_level n lev
                     return n
            EMPH        -> c_cmark_node_new (#const CMARK_NODE_EMPH)
            STRONG      -> c_cmark_node_new (#const CMARK_NODE_STRONG)
            LINK url title -> do
                     n <- c_cmark_node_new (#const CMARK_NODE_LINK)
                     withtext url (c_cmark_node_set_url n)
                     withtext title (c_cmark_node_set_title n)
                     return n
            IMAGE url title -> do
                     n <- c_cmark_node_new (#const CMARK_NODE_IMAGE)
                     withtext url (c_cmark_node_set_url n)
                     withtext title (c_cmark_node_set_title n)
                     return n
            TEXT literal -> do
                     n <- c_cmark_node_new (#const CMARK_NODE_TEXT)
                     withtext literal (c_cmark_node_set_literal n)
                     return n
            CODE literal -> do
                     n <- c_cmark_node_new (#const CMARK_NODE_CODE)
                     withtext literal (c_cmark_node_set_literal n)
                     return n
            HTML_INLINE literal -> do
                     n <- c_cmark_node_new (#const CMARK_NODE_HTML_INLINE)
                     withtext literal (c_cmark_node_set_literal n)
                     return n
            CUSTOM_INLINE onEnter onExit -> do
                     n <- c_cmark_node_new (#const CMARK_NODE_CUSTOM_INLINE)
                     withtext onEnter (c_cmark_node_set_on_enter n)
                     withtext onExit  (c_cmark_node_set_on_exit  n)
                     return n
            SOFTBREAK   -> c_cmark_node_new (#const CMARK_NODE_SOFTBREAK)
            LINEBREAK   -> c_cmark_node_new (#const CMARK_NODE_LINEBREAK)
  mapM_ (\child -> fromNode child >>= c_cmark_node_append_child node) children
  return node

totext :: CString -> IO Text
totext str
  | str == nullPtr = return empty
  | otherwise      = TF.peekCStringLen (str, c_strlen str)

withtext :: Text -> (CString -> IO a) -> IO a
withtext t f = TF.withCStringLen (snoc t '\0') (f . fst)

foreign import ccall "string.h strlen"
    c_strlen :: CString -> Int

foreign import ccall "cmark.h cmark_node_new"
    c_cmark_node_new :: Int -> IO NodePtr

foreign import ccall "cmark.h cmark_render_html"
    c_cmark_render_html :: NodePtr -> CInt -> IO CString

foreign import ccall "cmark.h cmark_render_xml"
    c_cmark_render_xml :: NodePtr -> CInt -> IO CString

foreign import ccall "cmark.h cmark_render_man"
    c_cmark_render_man :: NodePtr -> CInt -> Int -> IO CString

foreign import ccall "cmark.h cmark_render_latex"
    c_cmark_render_latex :: NodePtr -> CInt -> Int -> IO CString

foreign import ccall "cmark.h cmark_render_commonmark"
    c_cmark_render_commonmark :: NodePtr -> CInt -> Int -> IO CString

foreign import ccall "cmark.h cmark_parse_document"
    c_cmark_parse_document :: CString -> Int -> CInt -> IO NodePtr

foreign import ccall "cmark.h cmark_node_get_type"
    c_cmark_node_get_type :: NodePtr -> IO Int

foreign import ccall "cmark.h cmark_node_first_child"
    c_cmark_node_first_child :: NodePtr -> IO NodePtr

foreign import ccall "cmark.h cmark_node_next"
    c_cmark_node_next :: NodePtr -> IO NodePtr

foreign import ccall "cmark.h cmark_node_get_literal"
    c_cmark_node_get_literal :: NodePtr -> IO CString

foreign import ccall "cmark.h cmark_node_get_url"
    c_cmark_node_get_url :: NodePtr -> IO CString

foreign import ccall "cmark.h cmark_node_get_title"
    c_cmark_node_get_title :: NodePtr -> IO CString

foreign import ccall "cmark.h cmark_node_get_heading_level"
    c_cmark_node_get_heading_level :: NodePtr -> IO Int

foreign import ccall "cmark.h cmark_node_get_list_type"
    c_cmark_node_get_list_type :: NodePtr -> IO Int

foreign import ccall "cmark.h cmark_node_get_list_tight"
    c_cmark_node_get_list_tight :: NodePtr -> IO Bool

foreign import ccall "cmark.h cmark_node_get_list_start"
    c_cmark_node_get_list_start :: NodePtr -> IO Int

foreign import ccall "cmark.h cmark_node_get_list_delim"
    c_cmark_node_get_list_delim :: NodePtr -> IO Int

foreign import ccall "cmark.h cmark_node_get_fence_info"
    c_cmark_node_get_fence_info :: NodePtr -> IO CString

foreign import ccall "cmark.h cmark_node_get_start_line"
    c_cmark_node_get_start_line :: NodePtr -> IO Int

foreign import ccall "cmark.h cmark_node_get_start_column"
    c_cmark_node_get_start_column :: NodePtr -> IO Int

foreign import ccall "cmark.h cmark_node_get_end_line"
    c_cmark_node_get_end_line :: NodePtr -> IO Int

foreign import ccall "cmark.h cmark_node_get_end_column"
    c_cmark_node_get_end_column :: NodePtr -> IO Int

foreign import ccall "cmark.h cmark_node_get_on_enter"
    c_cmark_node_get_on_enter :: NodePtr -> IO CString

foreign import ccall "cmark.h cmark_node_get_on_exit"
    c_cmark_node_get_on_exit :: NodePtr -> IO CString

foreign import ccall "cmark.h cmark_node_append_child"
    c_cmark_node_append_child :: NodePtr -> NodePtr -> IO Int

foreign import ccall "cmark.h cmark_node_set_literal"
    c_cmark_node_set_literal :: NodePtr -> CString -> IO Int

foreign import ccall "cmark.h cmark_node_set_url"
    c_cmark_node_set_url :: NodePtr -> CString -> IO Int

foreign import ccall "cmark.h cmark_node_set_title"
    c_cmark_node_set_title :: NodePtr -> CString -> IO Int

foreign import ccall "cmark.h cmark_node_set_heading_level"
    c_cmark_node_set_heading_level :: NodePtr -> Int -> IO Int

foreign import ccall "cmark.h cmark_node_set_list_type"
    c_cmark_node_set_list_type :: NodePtr -> Int -> IO Int

foreign import ccall "cmark.h cmark_node_set_list_tight"
    c_cmark_node_set_list_tight :: NodePtr -> Bool -> IO Int

foreign import ccall "cmark.h cmark_node_set_list_start"
    c_cmark_node_set_list_start :: NodePtr -> Int -> IO Int

foreign import ccall "cmark.h cmark_node_set_list_delim"
    c_cmark_node_set_list_delim :: NodePtr -> Int -> IO Int

foreign import ccall "cmark.h cmark_node_set_fence_info"
    c_cmark_node_set_fence_info :: NodePtr -> CString -> IO Int

foreign import ccall "cmark.h cmark_node_set_on_enter"
    c_cmark_node_set_on_enter :: NodePtr -> CString -> IO Int

foreign import ccall "cmark.h cmark_node_set_on_exit"
    c_cmark_node_set_on_exit :: NodePtr -> CString -> IO Int

foreign import ccall "cmark.h &cmark_node_free"
    c_cmark_node_free :: FunPtr (NodePtr -> IO ())