#
# Copyright 2003 Roman Kennke
#
#    This file is part of Python-SOAP.
#
#    Python-SOAP is free software; you can redistribute it and/or modify
#    it under the terms of the GNU General Public License as published by
#    the Free Software Foundation; either version 2 of the License, or
#    (at your option) any later version.
#
#    Python-SOAP is distributed in the hope that it will be useful,
#    but WITHOUT ANY WARRANTY; without even the implied warranty of
#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#    GNU General Public License for more details.
#
#    You should have received a copy of the GNU General Public License
#    along with Python-SOAP; if not, write to the Free Software
#    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA



"""Implements some functions that help DOM processing.

Author: Roman Kennke
Revision: $Revision: 1.2 $
"""

from xml.dom import Node


def lookupPrefix(node, namespaceURI):
    """Looks up a namespace prefix for the given namespaceURI, starting from
    node. This method is defined as a method of the Node interface in
    DOM level 3, but is 
    included here as a convenience method, since these are not yet implemented
    """

    if (namespaceURI is None) or (namespaceURI == ''):
        return None

    type = node.nodeType

    if type == Node.ELEMENT_NODE:
        return lookupNamespacePrefix(node, namespaceURI, node)
    
    elif type == Node.DOCUMENT_NODE:
        return lookupPrefix(node.documentElement, namespaceURI)

    elif (type == Node.ENTITY_NODE) or \
         (type == Node.NOTATION_NODE) or \
         (type == Node.DOCUMENT_FRAGMENT_NODE) or \
         (type == Node.DOCUMENT_TYPE_NODE):
        
        return None

    elif (type == Node.ATTRIBUTE_NODE):
        if node.ownerElement is not None:
            return lookupNamespacePrefix(node.ownerElement, namespaceURI)

        return None

    else:
        if (node.parentNode is not None) and \
           (node.parentNode.nodeType != Node.DOCUMENT_NODE):
            
            return lookupPrefix(node.parentNode, namespaceURI)


def lookupNamespacePrefix(node, namespaceURI, element):

    if (node.namespaceURI is not None) and \
       (node.namespaceURI == namespaceURI) and \
       (node.prefix is not None) and \
       (lookupNamespaceURI(element, node.prefix) == namespaceURI):

        return node.prefix

    if len(node.attributes) > 0:

        for attr in node.attributes:

            if (attr.prefix == 'xmlns') and \
                   (attr.value == namespaceURI) and \
                   (lookupNamespaceURI(element, attr.localName) == \
                    namespaceURI):

                return attr.localName


    if (node.parentNode is not None) and \
       (node.parentNode.nodeType != Node.DOCUMENT_NODE):

        return lookupNamespacePrefix(node.parentNode, namespaceURI, element)

    return None


def lookupNamespaceURI(node, prefix):
    """Looks up a namespace URI by its prefix in the scope of the DOM Node
    node. This is a method defined for DOM Node in DOM Level 3, but is
    not (yet) implemented in current Python DOM implementations."""

    if node.nodeType == Node.ELEMENT_NODE:
        
        if (node.namespaceURI is not None) and\
           (node.prefix == prefix):
            return node.namespaceURI
        if (node.attributes.length != 0):
            for index in range(0, node.attributes.length):
                attr = node.attributes.item(index)
                if (attr.prefix == 'xmlns') and (attr.localName == prefix):
                    # non-default namespace
                    if attr.nodeValue != '':
                        return attr.nodeValue
                    
                    return None

                elif (attr.prefix == 'xmlns') and (prefix == None):
                    # default namespace
                    if attr.nodeValue != '':
                        return attr.nodeValue
                    
                    return None
            # end attribute searchloop
        if (node.parentNode is not None) and\
              (node.parentNode.nodeType != Node.DOCUMENT_NODE):
            return lookupNamespaceURI(node.parentNode, prefix)

        return None

    elif node.nodeType == Node.DOCUMENT_NODE:
        return lookupNamespaceURI(node.documentElement, prefix)

    elif (node.nodeType == Node.ENTITY_NODE) or\
         (node.nodeType == Node.NOTATION_NODE) or\
         (node.nodeType == Node.DOCUMENT_TYPE_NODE) or\
         (node.nodeType == Node.DOCUMENT_FRAGMENT_NODE):

        return None

    
    elif node.nodeType == Node.ATTRIBUTE_NODE:
        raise Exception('not implementable yet')


    else:
        if node.parentNode is not None:
            return lookupNamespaceURI(node.parentNode, prefix)
        else:
            return None




def getTextContent(domNode):
    """Extracts and returns all Text Node children of the given DOM Node.
    It is considered an error, if there are any other types of nodes, like
    elements within the child Nodes."""

    from StringIO import StringIO
    buffer = StringIO()
    for child in domNode.childNodes:
        if (child.nodeType != Node.TEXT_NODE) and \
           (child.nodeType != Node.CDATA_SECTION_NODE):
            import soapdom
            raise soapdom.DeserializerException\
                  ('unexpected child node. Expected Node type is TEXT_NODE')
        buffer.write(child.data)

    return buffer.getvalue()


def getElementChildren(domNode):
    """Extracts and returns all Element children of the given DOM Node.
    It is considered an error, if there are any child nodes, other
    than Elements, Comments, or whitespaced Text Nodes."""

    childElements = []

    for child in domNode.childNodes:
        type = child.nodeType

        if type == Node.ELEMENT_NODE:
            childElements.append(child)
        elif type == Node.COMMENT_NODE:
            continue
        elif type == Node.TEXT_NODE:
            import string
            if string.strip(child.data) != '':
                raise soapdom.DeserializerException\
                      ('unexpected textual content')
            continue
        else:
            raise soapdom.DeserializerException\
                  ('unexpected content')

    return childElements