module Rakka.Wiki.Formatter
    ( formatWikiBlocks
    )
    where

import           Control.Arrow
import           Control.Arrow.ArrowList
import           Data.Char
import           Data.List
import           Data.Maybe
import           Network.URI
import           Rakka.Page
import           Rakka.Wiki
import           Text.XML.HXT.Arrow.XmlArrow
import           Text.XML.HXT.DOM.TypeDefs


formatWikiBlocks :: (ArrowXml a, ArrowChoice a) => a (URI, [BlockElement]) XmlTree
formatWikiBlocks
    = proc (baseURI, blocks)
    -> do block <- arrL id -< blocks
          formatBlock -< (baseURI, block)


formatBlock :: (ArrowXml a, ArrowChoice a) => a (URI, BlockElement) XmlTree
formatBlock 
    = proc (baseURI, block)
    -> case block of
         Heading level text
             -> formatHeading -< (level, text)
                
         Paragraph inlines
             -> formatParagraph -< (baseURI, inlines)


formatHeading :: ArrowXml a => a (Int, String) XmlTree
formatHeading 
    = proc (level, text)
    -> selem ("h" ++ show level) [txt text] -<< ()


formatParagraph :: (ArrowXml a, ArrowChoice a) => a (URI, [InlineElement]) XmlTree
formatParagraph 
    = eelem "p"
      += ( (arr fst &&& arrL snd)
           >>>
           formatInline
         )


formatInline :: (ArrowXml a, ArrowChoice a) => a (URI, InlineElement) XmlTree
formatInline 
    = proc (baseURI, i)
    -> case i of
         Text text
             -> mkText -< text

         link@(PageLink _ _ _)
             -> formatPageLink -< (baseURI, link)


formatPageLink :: (ArrowXml a) => a (URI, InlineElement) XmlTree
formatPageLink 
    = proc (baseURI, PageLink page fragment text)
    -> let uri    = case (page, fragment) of
                      (Just  x, Just  y) -> mkPageFragmentURI baseURI (fix x) y
                      (Just  x, Nothing) -> mkPageURI baseURI (fix x)
                      (Nothing, Just  y) -> nullURI { uriFragment = ('#':y) }
           fix    = (\ (x:xs) -> toUpper x : xs) . map (\ c -> if c == ' ' then '_' else c)
           href   = uriToString id uri ""
           dLabel = fromMaybe "" page ++ fromMaybe "" (fmap ('#':) fragment)
           label  = fromMaybe dLabel text
       in
         ( eelem "a"
           += attr "href" (arr fst >>> mkText)
           += (arr snd >>> mkText)
         ) -< (href, label)