module Text.Pandoc.CrossRef.Util.CodeBlockCaptions
    (
    codeBlockCaptions
    ) where

import Text.Pandoc.Definition
import Text.Pandoc.Shared (normalizeSpaces)
import Data.List (isPrefixOf, stripPrefix)
import Data.Maybe (fromMaybe)
import Text.Pandoc.CrossRef.References.Types
import Text.Pandoc.CrossRef.Util.Options

codeBlockCaptions :: Options -> [Block] -> WS [Block]
codeBlockCaptions opts x@(cb@(CodeBlock _ _):p@(Para _):xs)
  = return $ fromMaybe x $ orderAgnostic opts $ p:cb:xs
codeBlockCaptions opts x@(p@(Para _):cb@(CodeBlock _ _):xs)
  = return $ fromMaybe x $ orderAgnostic opts $ p:cb:xs
codeBlockCaptions _ x = return x

orderAgnostic :: Options -> [Block] -> Maybe [Block]
orderAgnostic opts (Para ils:CodeBlock (label,classes,attrs) code:xs)
  | cbCaptions opts
  , Just caption <- getCodeBlockCaption ils
  , not $ null label
  , "lst" `isPrefixOf` label
  = return $ Div (label,"listing":classes, [])
      [Para caption, CodeBlock ([],classes,attrs) code] : xs
orderAgnostic _ _ = Nothing

getCodeBlockCaption :: [Inline] -> Maybe [Inline]
getCodeBlockCaption ils
  | Just caption <- [Str "Listing:",Space] `stripPrefix` normalizeSpaces ils
  = Just caption
  | Just caption <- [Str ":",Space] `stripPrefix` normalizeSpaces ils
  = Just caption
  | otherwise
  = Nothing