    {-# LANGUAGE NoImplicitPrelude #-}
    module Text.Pandoc.Readers.Docx.Util (
                                            NameSpaces
                                          , elemName
                                          , isElem
                                          , elemToNameSpaces
                                          , findChildByName
                                          , findChildrenByName
                                          , findAttrByName
                                          ) where

    import Prelude
    import Data.Maybe (mapMaybe)
    import Text.XML.Light

    type NameSpaces = [(String, String)]

    elemToNameSpaces :: Element -> NameSpaces
    elemToNameSpaces = mapMaybe attrToNSPair . elAttribs

    attrToNSPair :: Attr -> Maybe (String, String)
    attrToNSPair (Attr (QName s _ (Just "xmlns")) val) = Just (s, val)
    attrToNSPair _                                     = Nothing

    elemName :: NameSpaces -> String -> String -> QName
    elemName ns prefix name =
      QName name (lookup prefix ns) (if null prefix then Nothing else Just prefix)

    isElem :: NameSpaces -> String -> String -> Element -> Bool
    isElem ns prefix name element =
      let ns' = ns ++ elemToNameSpaces element
      in qName (elName element) == name &&
         qURI (elName element) == lookup prefix ns'

    findChildByName :: NameSpaces -> String -> String -> Element -> Maybe Element
    findChildByName ns pref name el =
      let ns' = ns ++ elemToNameSpaces el
      in  findChild (elemName ns' pref name) el

    findChildrenByName :: NameSpaces -> String -> String -> Element -> [Element]
    findChildrenByName ns pref name el =
      let ns' = ns ++ elemToNameSpaces el
      in  findChildren (elemName ns' pref name) el

    findAttrByName :: NameSpaces -> String -> String -> Element -> Maybe String
    findAttrByName ns pref name el =
      let ns' = ns ++ elemToNameSpaces el
      in  findAttr (elemName ns' pref name) el