content: -- ------------------------------------------------------------
  
  -- Special namings in source code:
  --
  --  - nd - XDTD node
  --
  --  - n  - XTag node
  --
  
  module Text.XML.HXT.Monad.DTDValidation.AttributeValueValidation
      ( checkAttributeValue
      , normalizeAttributeValue
      )
  where
  
  import           Text.XML.HXT.Parser.XmlParsec             (parseNMToken,
                                                              parseName)
  
  import           Text.XML.HXT.Monad.DTDValidation.TypeDefs
  
  -- ------------------------------------------------------------
  
  -- |
  -- Checks if the attribute value meets the lexical constraints of its type.
  --
  --    * 1.parameter dtdPart :  the children of the @DOCTYPE@ node
  --
  --    - 2.parameter attrDecl :  the declaration of the attribute from the DTD
  --
  --    - returns : a function which takes an element (XTag or XDTD ATTLIST),
  --                    checks if the attribute value meets the lexical constraints
  --                    of its type and returns a list of errors
  
  checkAttributeValue :: XmlTrees -> XmlTree -> XmlArrow
  checkAttributeValue dtdPart attrDecl
      | isDTDAttlistNode attrDecl
          = choiceA
            [ isElem       :-> ( checkAttrVal $< getAttrValue attrName )
            , isDTDAttlist :-> ( checkAttrVal $< (getDTDAttrl >=^ dtd_default) )
            , this         :-> none
            ]
      | otherwise
          = none
        where
        al        = getDTDAttributes attrDecl
        attrName  = dtd_value al
        attrType  = dtd_type  al
        checkAttrVal attrValue
            = checkValue attrType dtdPart normalizedVal attrDecl
              where
              normalizedVal = normalizeAttributeValue (Just attrDecl) attrValue
  
  -- |
  -- Dispatches the attibute check by the attribute type.
  --
  --    * 1.parameter typ :  the attribute type
  --
  --    - 2.parameter dtdPart :  the children of the @DOCTYPE@ node
  --
  --    - 3.parameter attrValue :  the normalized attribute value to be checked
  --
  --    - 4.parameter attrDecl :  the declaration of the attribute from the DTD
  --
  --    - returns : a functions which takes an element (XTag or XDTD ATTLIST),
  --                        checks if the attribute value meets the lexical constraints
  --                        of its type and returns a list of errors
  
  checkValue :: String -> XmlTrees -> String -> XmlTree -> XmlArrow
  checkValue typ dtdPart attrValue attrDecl
          | typ == k_cdata        = none
          | typ == k_enumeration  = checkValueEnumeration attrDecl attrValue
          | typ == k_entity       = checkValueEntity dtdPart attrDecl attrValue
          | typ == k_entities     = checkValueEntities dtdPart attrDecl attrValue
          | typ == k_id           = checkValueId attrDecl attrValue
          | typ == k_idref        = checkValueIdref attrDecl attrValue
          | typ == k_idrefs       = checkValueIdrefs attrDecl attrValue
          | typ == k_nmtoken      = checkValueNmtoken attrDecl attrValue
          | typ == k_nmtokens     = checkValueNmtokens attrDecl attrValue
          | typ == k_notation     = checkValueEnumeration attrDecl attrValue
          | otherwise             = error ("Attribute type " ++ show typ ++ " unknown.")
  
  -- |
  -- Checks the value of Enumeration attribute types. (3.3.1 \/ p.27 in Spec)
  --
  --    * 1.parameter attrDecl :  the declaration of the attribute from the DTD
  --
  --    - 2.parameter attrValue :  the normalized attribute value to be checked
  
  checkValueEnumeration :: XmlTree -> String -> XmlArrow
  checkValueEnumeration attrDecl attrValue
      | isDTDAttlistNode attrDecl
        &&
        attrValue `notElem` enumVals
          = err ( "Attribute " ++ show (dtd_value al) ++ " for element " ++ show (dtd_name al) ++
                  " must have a value from list "++ show enumVals {- ++ " but has value " ++ show attrValue-} ++ ".")
      | otherwise
          = none
        where
        al        = getDTDAttributes attrDecl
  
        enumVals :: [String]
        enumVals = map (dtd_name . getDTDAttributes) $ (runLA getChildren attrDecl)
  
  -- |
  -- Checks the value of ENTITY attribute types. (3.3.1 \/ p.26 in Spec)
  --
  --    * 1.parameter dtdPart :  the children of the @DOCTYPE@ node, to get the
  --                    unparsed entity declarations
  --
  --    - 2.parameter attrDecl :  the declaration of the attribute from the DTD
  --
  --    - 3.parameter attrValue :  the normalized attribute value to be checked
  
  checkValueEntity :: XmlTrees -> XmlTree -> String -> XmlArrow
  checkValueEntity dtdPart attrDecl attrValue
      | isDTDAttlistNode attrDecl
        &&
        attrValue `notElem` upEntities
          = err ( "Entity " ++ show attrValue ++ " of attribute " ++ show (dtd_value al) ++
                  " for element " ++ show (dtd_name al) ++ " is not unparsed. " ++
                  "The following unparsed entities exist: " ++ show upEntities ++ ".")
      | otherwise
          = none
        where
        al        = getDTDAttributes attrDecl
  
        upEntities :: [String]
        upEntities = map (dtd_name . getDTDAttributes) (isUnparsedEntity $$ dtdPart)
  
  -- |
  -- Checks the value of ENTITIES attribute types. (3.3.1 \/ p.26 in Spec)
  --
  --    * 1.parameter dtdPart :  the children of the @DOCTYPE@ node, to get the
  --                    unparsed entity declarations
  --
  --    - 2.parameter attrDecl :  the declaration of the attribute from the DTD
  --
  --    - 3.parameter attrValue :  the normalized attribute value to be checked
  
  checkValueEntities ::XmlTrees -> XmlTree -> String -> XmlArrow
  checkValueEntities dtdPart attrDecl attrValue
      | isDTDAttlistNode attrDecl
          = if null valueList
            then err ("Attribute " ++ show (dtd_value al) ++ " of element " ++
                      show (dtd_name al) ++ " must be one or more names.")
            else catA . map (checkValueEntity dtdPart attrDecl) $ valueList
      | otherwise
          = none
        where
        al        = getDTDAttributes attrDecl
        valueList = words attrValue
  
  -- |
  -- Checks the value of NMTOKEN attribute types. (3.3.1 \/ p.26 in Spec)
  --
  --    * 1.parameter attrDecl :  the declaration of the attribute from the DTD
  --
  --    - 2.parameter attrValue :  the normalized attribute value to be checked
  
  checkValueNmtoken :: XmlTree -> String -> XmlArrow
  checkValueNmtoken attrDecl attrValue
      | isDTDAttlistNode attrDecl
          = constA attrValue >=> checkNmtoken
      | otherwise
          = none
        where
        al        = getDTDAttributes attrDecl
        checkNmtoken
            = mkText >=> arrL (parseNMToken "")
              >=>
              isError
              >=>
              getErrorMsg
              >=>
              return . (\ s -> ( "Attribute value " ++ show attrValue
                                 ++ " of attribute " ++ show (dtd_value al)
                                 ++ " for element " ++ show (dtd_name al)
                                 ++ " must be a name token, "++ (lines s) !! 1 ++"."
                               )
                       )
              >=>
              mkError c_err
  
  -- |
  -- Checks the value of NMTOKENS attribute types. (3.3.1 \/ p.26 in Spec)
  --
  --    * 1.parameter attrDecl :  the declaration of the attribute from the DTD
  --
  --    - 2.parameter attrValue :  the normalized attribute value to be checked
  
  checkValueNmtokens :: XmlTree -> String -> XmlArrow
  checkValueNmtokens attrDecl attrValue
      | isDTDAttlistNode attrDecl
          = if null valueList
            then err ( "Attribute "++ show (dtd_value al) ++" of element " ++
                       show (dtd_name al) ++ " must be one or more name tokens.")
            else catA . map (checkValueNmtoken attrDecl) $ valueList
      | otherwise
          = none
        where
        al        = getDTDAttributes attrDecl
        valueList = words attrValue
  
  -- |
  -- Checks the value of ID attribute types. (3.3.1 \/ p.25 in Spec)
  --
  --    * 1.parameter attrDecl :  the declaration of the attribute from the DTD
  --
  --    - 2.parameter attrValue :  the normalized attribute value to be checked
  
  checkValueId :: XmlTree -> String -> XmlArrow
  checkValueId attrDecl attrValue
      = checkForName "Attribute value" attrDecl attrValue
  
  
  -- |
  -- Checks the value of IDREF attribute types. (3.3.1 \/ p.26 in Spec)
  --
  --    * 1.parameter attrDecl :  the declaration of the attribute from the DTD
  --
  --    - 2.parameter attrValue :  the normalized attribute value to be checked
  
  checkValueIdref :: XmlTree -> String -> XmlArrow
  checkValueIdref attrDecl attrValue
      = checkForName "Attribute value" attrDecl attrValue
  
  
  -- |
  -- Checks the value of IDREFS attribute types. (3.3.1 \/ p.26 in Spec)
  --
  --    * 1.parameter attrDecl :  the declaration of the attribute from the DTD
  --
  --    - 2.parameter attrValue :  the normalized attribute value to be checked
  
  checkValueIdrefs :: XmlTree -> String -> XmlArrow
  checkValueIdrefs attrDecl attrValue
      = catA . map (checkValueIdref attrDecl) . words $ attrValue
  
  
  
  -- -----------------------------------------------------------------------------
  -- General helper functions for checking attribute values
  --
  
  -- |
  -- Checks if the value of an attribute is a name.
  --
  --    * 1.parameter msg :  error message, should be "Entity" or "Attribute value"
  --
  --    - 2.parameter attrDecl :  the declaration of the attribute from the DTD
  --
  --    - 3.parameter attrValue :  the normalized attribute value to be checked
  
  checkForName ::  String -> XmlTree -> String -> XmlArrow
  checkForName msg attrDecl attrValue
      | isDTDAttlistNode attrDecl
          = constA attrValue >=> checkName
      | otherwise
          = none
      where
      al  = getDTDAttributes attrDecl
      checkName
          = mkText >=> arrL (parseName "")
            >=>
            isError
            >=>
            getErrorMsg
            >=>
            return . (\s -> ( msg ++ " " ++ show attrValue
                              ++ " of attribute " ++ show (dtd_value al)
                              ++ " for element "++ show (dtd_name al)
                              ++" must be a name, " ++ (lines s) !! 1 ++ "."
                            )
                     )
            >=>
            mkError c_err
  
  -- -----------------------------------------------------------------------------
  
  -- |
  -- Normalizes an attribute value with respect to its type. (3.3.3 \/ p.29 in Spec)
  --
  --    * 1.parameter attrDecl :  the declaration of the attribute from the DTD. Expected
  --                   is a list. If the list is empty, no declaration exists.
  --
  --    - 2.parameter value :  the attribute value to be normalized
  --
  --    - returns : the normalized value
  --
  normalizeAttributeValue :: Maybe XmlTree -> String -> String
  normalizeAttributeValue (Just attrDecl) value
      = normalizeAttribute attrType
        where
        al             = getDTDAttributes attrDecl
        attrType = dtd_type al
  
        normalizeAttribute :: String -> String
        normalizeAttribute typ
            | typ == k_cdata      = cdataNormalization value
            | otherwise           = otherNormalization value
  
  -- Attribute not declared in DTD, normalization as CDATA
  normalizeAttributeValue Nothing value
      = cdataNormalization value
  
  -- ------------------------------------------------------------
  -- Helper functions for normalization
  
  -- |
  -- Normalization of CDATA attribute values.
  -- is already done when parsing
  -- during entity substituion for attribute values
  
  cdataNormalization :: String -> String
  cdataNormalization = id
  
  -- | Normalization of attribute values other than CDATA.
  
  otherNormalization :: String -> String
  otherNormalization = reduceWSSequences . stringTrim . cdataNormalization
  
  -- | Reduce whitespace sequences to a single whitespace.
  
  reduceWSSequences :: String -> String
  reduceWSSequences str = unwords (words str)
  
  -- ------------------------------------------------------------
  
  