--------------------------------------------------------------------
-- |
-- Module    : Text.RSS1.Export
-- Copyright : (c) Galois, Inc. 2008,
--             (c) Sigbjorn Finne 2009-
-- License   : BSD3
--
-- Maintainer: Sigbjorn Finne <sof@forkIO.com>
-- Stability : provisional
-- Portability: portable
--
--------------------------------------------------------------------

module Text.RSS1.Export
       ( xmlFeed
       ) where

import Text.XML.Light as XML
import Text.RSS1.Syntax
import Text.RSS1.Utils
import Text.DublinCore.Types

import Data.List
import Data.Maybe

qualNode :: (Maybe String,Maybe String) -> String -> [XML.Content] -> XML.Element
qualNode ns n cs =
  blank_element
    { elName    = qualName ns n
    , elContent = cs
    }

---
xmlFeed :: Feed -> XML.Element
xmlFeed f =
  (qualNode (rdfNS,rdfPrefix) "RDF" $ map Elem $
    (concat  [ [xmlChannel (feedChannel f)]
             , mb xmlImage (feedImage f)
             , map xmlItem (feedItems f)
             , mb xmlTextInput (feedTextInput f)
             , map xmlTopic (feedTopics f)
             , feedOther f
             ] ))
        -- should we expect these to be derived by the XML pretty printer..?
    { elAttribs =   nub $
                    Attr (qualName  (Nothing,Nothing) "xmlns") (fromJust rss10NS) :
                    Attr (qualName (Nothing,Just "xmlns") (fromJust rdfPrefix)) (fromJust rdfNS) :
                    Attr (qualName (Nothing,Just "xmlns") (fromJust synPrefix)) (fromJust synNS) :
                    Attr (qualName (Nothing,Just "xmlns") (fromJust taxPrefix)) (fromJust taxNS) :
                    Attr (qualName (Nothing,Just "xmlns") (fromJust conPrefix)) (fromJust conNS) :
                    Attr (qualName (Nothing,Just "xmlns") (fromJust dcPrefix))  (fromJust dcNS)  :
                    feedAttrs f}

xmlChannel :: Channel -> XML.Element
xmlChannel ch =
  (qualNode (rss10NS,Nothing) "channel" $ map Elem $
     ([ xmlLeaf  (rss10NS,Nothing) "title" (channelTitle ch)
      , xmlLeaf  (rss10NS,Nothing) "link"  (channelLink ch)
      , xmlLeaf  (rss10NS,Nothing) "description" (channelDesc ch)
      ] ++
      mb xmlTextInputURI (channelTextInputURI ch) ++
      mb xmlImageURI (channelImageURI ch) ++
      xmlItemURIs (channelItemURIs ch) ++ map xmlDC (channelDC ch) ++
      concat [ mb xmlUpdatePeriod (channelUpdatePeriod ch)
             , mb xmlUpdateFreq   (channelUpdateFreq ch)
             , mb (xmlLeaf (synNS,synPrefix) "updateBase")   (channelUpdateBase ch)
             ] ++
      xmlContentItems (channelContent ch) ++
      xmlTopics       (channelTopics ch) ++
      channelOther ch))
    { elAttribs = ( Attr (qualName  (rdfNS,rdfPrefix) "about") (channelURI ch) :
                    channelAttrs ch)}

xmlImageURI :: URIString -> XML.Element
xmlImageURI u = xmlEmpty (rss10NS,Nothing) "image" [Attr (rdfName "resource") u ]

xmlImage :: Image -> XML.Element
xmlImage i =
 (qualNode (rss10NS,Nothing) "image" $ map Elem $
    ([ xmlLeaf  (rss10NS,Nothing) "title" (imageTitle i)
     ,  xmlLeaf (rss10NS,Nothing) "url"   (imageURL i)
     , xmlLeaf  (rss10NS,Nothing) "link"  (imageLink i)
     ] ++ map xmlDC (imageDC i) ++
     imageOther i))
    { elAttribs = ( Attr (qualName  (rdfNS,rdfPrefix) "about") (imageURI i) :
                    imageAttrs i)}

xmlItemURIs :: [URIString] -> [XML.Element]
xmlItemURIs [] = []
xmlItemURIs xs =
  [qualNode (rss10NS, Nothing) "items" $
      [Elem (qualNode (rdfNS,rdfPrefix) "Seq" (map toRes xs))]]
 where
  toRes u = Elem (xmlEmpty (rdfNS,rdfPrefix) "li" [Attr (rdfName "resource") u])

xmlTextInputURI :: URIString -> XML.Element
xmlTextInputURI u = xmlEmpty (rss10NS,Nothing) "textinput" [Attr (rdfName "resource") u ]

xmlTextInput :: TextInputInfo -> XML.Element
xmlTextInput ti =
  (qualNode (rss10NS, Nothing) "textinput" $ map Elem $
     [ xmlLeaf (rss10NS,Nothing) "title" (textInputTitle ti)
     , xmlLeaf (rss10NS,Nothing) "description" (textInputDesc ti)
     , xmlLeaf (rss10NS,Nothing) "name" (textInputName ti)
     , xmlLeaf (rss10NS,Nothing) "link" (textInputLink ti)
     ] ++ map xmlDC (textInputDC ti) ++
     textInputOther ti)
     {elAttribs=Attr (rdfName "about") (textInputURI ti) : textInputAttrs ti}

xmlDC :: DCItem -> XML.Element
xmlDC dc = xmlLeaf (dcNS,dcPrefix) (infoToTag (dcElt dc)) (dcText dc)

xmlUpdatePeriod :: UpdatePeriod -> XML.Element
xmlUpdatePeriod u = xmlLeaf (synNS,synPrefix) "updatePeriod" (toStr u)
 where
  toStr ux =
    case ux of
      Update_Hourly  -> "hourly"
      Update_Daily   -> "daily"
      Update_Weekly  -> "weekly"
      Update_Monthly -> "monthly"
      Update_Yearly  -> "yearly"

xmlUpdateFreq :: Integer -> XML.Element
xmlUpdateFreq f = xmlLeaf (synNS,synPrefix) "updateFrequency" (show f)

xmlContentItems :: [ContentInfo] -> [XML.Element]
xmlContentItems [] = []
xmlContentItems xs =
  [qualNode (conNS,conPrefix) "items"
    [Elem $ qualNode (rdfNS,rdfPrefix) "Bag"
              (map (\ e -> Elem (qualNode (rdfNS,rdfPrefix) "li" [Elem (xmlContentInfo e)]))
                   xs)]]

xmlContentInfo :: ContentInfo -> XML.Element
xmlContentInfo ci =
  (qualNode (conNS,conPrefix) "item" $ map Elem $
      (concat [ mb (rdfResource (conNS,conPrefix) "format") (contentFormat ci)
              , mb (rdfResource (conNS,conPrefix) "encoding") (contentEncoding ci)
              , mb (rdfValue []) (contentValue ci)
              ]))
    {elAttribs=mb (Attr (rdfName "about")) (contentURI ci)}

rdfResource :: (Maybe String,Maybe String) -> String -> String -> XML.Element
rdfResource ns t v = xmlEmpty ns t [Attr (rdfName "resource") v ]

rdfValue :: [XML.Attr] -> String -> XML.Element
rdfValue as s = (xmlLeaf (rdfNS,rdfPrefix) "value" s){elAttribs=as}

xmlTopics :: [URIString] -> [XML.Element]
xmlTopics [] = []
xmlTopics xs =
 [qualNode (taxNS,taxPrefix) "topics"
    [Elem (qualNode (rdfNS,rdfPrefix) "Bag" $
            (map (Elem . rdfResource (rdfNS,rdfPrefix) "li") xs))]]

xmlTopic :: TaxonomyTopic -> XML.Element
xmlTopic tt =
  (qualNode (taxNS,taxPrefix) "topic" $ map Elem $
      (xmlLeaf (rss10NS,Nothing) "link"  (taxonomyLink tt):
        mb (xmlLeaf (rss10NS,Nothing) "title") (taxonomyTitle tt) ++
       mb (xmlLeaf (rss10NS,Nothing) "description") (taxonomyDesc tt) ++
       xmlTopics (taxonomyTopics tt) ++
       map xmlDC (taxonomyDC tt) ++
       taxonomyOther tt))
    {elAttribs=[Attr (rdfName "about") (taxonomyURI tt)]}

xmlItem :: Item -> XML.Element
xmlItem i =
 (qualNode (rss10NS,Nothing) "item" $ map Elem $
    ([ xmlLeaf  (rss10NS,Nothing) "title" (itemTitle i)
     , xmlLeaf  (rss10NS,Nothing) "link"  (itemLink i)
     ] ++
     mb (xmlLeaf  (rss10NS,Nothing) "description") (itemDesc i) ++
     map xmlDC (itemDC i) ++
     xmlTopics (itemTopics i) ++
     map xmlContentInfo (itemContent i) ++
     itemOther i))
    { elAttribs = ( Attr (qualName  (rdfNS,rdfPrefix) "about") (itemURI i) :
                    itemAttrs i)}

xmlLeaf :: (Maybe String,Maybe String) -> String -> String -> XML.Element
xmlLeaf ns tg txt =
 blank_element{ elName = qualName ns tg
              , elContent = [ Text blank_cdata { cdData = txt } ]
              }

xmlEmpty :: (Maybe String,Maybe String) -> String -> [XML.Attr] -> XML.Element
xmlEmpty ns t as = (qualNode ns t []){elAttribs=as}

---
mb :: (a -> b) -> Maybe a -> [b]
mb _ Nothing = []
mb f (Just x) = [f x]
