{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE RecordWildCards #-}

{-# OPTIONS_HADDOCK hide #-}

module Network.Xmpp.Utilities
    ( presTo
    , message
    , answerMessage
    , openElementToEvents
    , renderOpenElement
    , renderElement)
    where

import           Network.Xmpp.Types
import           Prelude
import           Data.XML.Types
import qualified Data.ByteString as BS
import           Data.Conduit as C
import           Data.Conduit.List as CL
import qualified Data.Text as Text
import qualified Data.Text.Encoding as Text
import           System.IO.Unsafe(unsafePerformIO)
import qualified Text.XML.Stream.Render as TXSR
import           Text.XML.Unresolved as TXU

-- | Add a recipient to a presence notification.
presTo :: Presence -> Jid -> Presence
presTo pres to = pres{presenceTo = Just to}

-- | An empty message.
message :: Message
message = Message { messageID      = Nothing
                  , messageFrom    = Nothing
                  , messageTo      = Nothing
                  , messageLangTag = Nothing
                  , messageType    = Normal
                  , messagePayload = []
                  }

-- | Produce an answer message with the given payload, switching the "from" and
-- "to" attributes in the original message. Produces a 'Nothing' value of the
-- provided message message has no from attribute.
answerMessage :: Message -> [Element] -> Maybe Message
answerMessage Message{messageFrom = Just frm, ..} payload =
    Just Message{ messageFrom    = messageTo
                , messageID      = Nothing
                , messageTo      = Just frm
                , messagePayload = payload
                , ..
                }
answerMessage _ _ = Nothing

openElementToEvents :: Element -> [Event]
openElementToEvents (Element name as ns) = EventBeginElement name as : goN ns []
  where
    goE (Element name' as' ns') =
          (EventBeginElement name' as' :)
        . goN ns'
        . (EventEndElement name' :)
    goN [] = id
    goN [x] = goN' x
    goN (x:xs) = goN' x . goN xs
    goN' (NodeElement e) = goE e
    goN' (NodeInstruction i) = (EventInstruction i :)
    goN' (NodeContent c) = (EventContent c :)
    goN' (NodeComment t) = (EventComment t :)

renderOpenElement :: Element -> BS.ByteString
renderOpenElement e = Text.encodeUtf8 . Text.concat . unsafePerformIO
    $ CL.sourceList (openElementToEvents e) $$ TXSR.renderText def =$ CL.consume

renderElement :: Element -> BS.ByteString
renderElement e = Text.encodeUtf8 . Text.concat . unsafePerformIO
    $ CL.sourceList (elementToEvents e) $$ TXSR.renderText def =$ CL.consume
  where
    elementToEvents :: Element -> [Event]
    elementToEvents el@(Element name _ _) = openElementToEvents el
                                              ++ [EventEndElement name]