# -*- coding: utf-8 -*-
#    Copyright (C) 2012  Christian Ledermann
#
#    This library is free software; you can redistribute it and/or
#    modify it under the terms of the GNU Lesser General Public
#    License as published by the Free Software Foundation; either
#    version 2.1 of the License, or (at your option) any later version.
#
#    This library 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
#    Lesser General Public License for more details.
#
#    You should have received a copy of the GNU Lesser General Public
#    License along with this library; if not, write to the Free Software
#    Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA

"""
KML is an open standard officially named the OpenGIS KML Encoding Standard
(OGC KML). It is maintained by the Open Geospatial Consortium, Inc. (OGC).
The complete specification for OGC KML can be found at
http://www.opengeospatial.org/standards/kml/.

The complete XML schema for KML is located at
http://schemas.opengis.net/kml/.

"""
try:
    import urlparse
except ImportError:
    import urllib.parse as urlparse

from .geometry import Point, LineString, Polygon
from .geometry import MultiPoint, MultiLineString, MultiPolygon
from .geometry import LinearRing
from .geometry import Geometry

from datetime import datetime, date

# note that there are some ISO 8601 timeparsers at pypi
# but in my tests all of them had some errors so we rely on the
# tried and tested dateutil here which is more stable. As a side effect
# we can also parse non ISO compliant dateTimes
import dateutil.parser

import logging
logger = logging.getLogger('fastkml.kml')

from .config import etree

from .base import _BaseObject

from .styles import StyleUrl, Style, StyleMap, _StyleSelector

import fastkml.atom as atom
import fastkml.gx as gx
import fastkml.config as config

try:
    unicode
except NameError:
    # Python 3
    basestring = unicode = str


class KML(object):
    """ represents a KML File """

    _features = []
    ns = None

    def __init__(self, ns=None):
        """ The namespace (ns) may be empty ('') if the 'kml:' prefix is
        undesired. Note that all child elements like Document or Placemark need
        to be initialized with empty namespace as well in this case.

        """
        self._features =[]

        if ns is None:
            self.ns = config.NS
        else:
            self.ns = ns

    def from_string(self, xml_string):
        """ create a KML object from a xml string"""
        element = etree.XML(xml_string)
        if element.tag.endswith('kml'):
            ns = element.tag.rstrip('kml')
            documents = element.findall('%sDocument' % ns)
            for document in documents:
                feature = Document(ns)
                feature.from_element(document)
                self.append(feature)
            folders = element.findall('%sFolder' % ns)
            for folder in folders:
                feature = Folder(ns)
                feature.from_element(folder)
                self.append(feature)
            placemarks = element.findall('%sPlacemark' % ns)
            for placemark in placemarks:
                feature = Placemark(ns)
                feature.from_element(placemark)
                self.append(feature)
        else:
            raise TypeError

    def etree_element(self):
        root = etree.Element('%skml' % self.ns)

        # self.ns may be empty, which leads to unprefixed kml elements.
        # However, in this case the xlmns should still be mentioned on the kml
        # element, just without prefix.
        if not self.ns:
            root.set('xmlns', config.NS[1:-1])

        for feature in self.features():
            root.append(feature.etree_element())
        return root


    def to_string(self, prettyprint=False):
        """ Return the KML Object as serialized xml """
        if config.LXML and prettyprint:
            return etree.tostring(self.etree_element(), encoding='utf-8',
                                    pretty_print=True).decode('UTF-8')
        else:
            return etree.tostring(self.etree_element(),
                    encoding='utf-8').decode('UTF-8')

    def features(self):
        """ iterate over features """
        for feature in self._features:
            if isinstance(feature, (Document, Folder, Placemark)):
                yield feature
            else:
                raise TypeError(
                    "Features must be instances of (Document, Folder, Placemark)")

    def append(self, kmlobj):
        """ append a feature """
        if isinstance(kmlobj, (Document, Folder, Placemark)):
            self._features.append(kmlobj)
        else:
            raise TypeError(
            "Features must be instances of (Document, Folder, Placemark)")

class _Feature(_BaseObject):
    """
    abstract element; do not create
    subclasses are:
    Container (Document, Folder),
    Placemark,
    #NetworkLink,
    #GroundOverlay,
    #PhotoOverlay,
    #ScreenOverlay
    """
    name = None
    # User-defined text displayed in the 3D viewer as the label for the
    # object (for example, for a Placemark, Folder, or NetworkLink).

    visibility = 1
    # Boolean value. Specifies whether the feature is drawn in the 3D
    # viewer when it is initially loaded. In order for a feature to be
    # visible, the <visibility> tag of all its ancestors must also be
    # set to 1.

    isopen = 0
    # Boolean value. Specifies whether a Document or Folder appears
    # closed or open when first loaded into the Places panel.
    # 0=collapsed (the default), 1=expanded.

    _atom_author = None
    # KML 2.2 supports new elements for including data about the author
    # and related website in your KML file. This information is displayed
    # in geo search results, both in Earth browsers such as Google Earth,
    # and in other applications such as Google Maps.

    _atom_link = None
    # Specifies the URL of the website containing this KML or KMZ file.

    #TODO address = None
    # A string value representing an unstructured address written as a
    # standard street, city, state address, and/or as a postal code.
    # You can use the <address> tag to specify the location of a point
    # instead of using latitude and longitude coordinates.

    #TODO phoneNumber = None
    # A string value representing a telephone number.
    # This element is used by Google Maps Mobile only.

    _snippet = None    #XXX
    # _snippet is eiter a tuple of a string Snippet.text and an integer
    # Snippet.maxLines or a string
    #
    # A short description of the feature. In Google Earth, this
    # description is displayed in the Places panel under the name of the
    # feature. If a Snippet is not supplied, the first two lines of
    # the <description> are used. In Google Earth, if a Placemark
    # contains both a description and a Snippet, the <Snippet> appears
    # beneath the Placemark in the Places panel, and the <description>
    # appears in the Placemark's description balloon. This tag does not
    # support HTML markup. <Snippet> has a maxLines attribute, an integer
    # that specifies the maximum number of lines to display.

    description = None
    #User-supplied content that appears in the description balloon.

    _styleUrl = None
    # URL of a <Style> or <StyleMap> defined in a Document.
    # If the style is in the same file, use a # reference.
    # If the style is defined in an external file, use a full URL
    # along with # referencing.

    _styles = None
    # One or more Styles and StyleMaps can be defined to customize the
    # appearance of any element derived from Feature or of the Geometry
    # in a Placemark.
    # A style defined within a Feature is called an "inline style" and
    # applies only to the Feature that contains it. A style defined as
    # the child of a <Document> is called a "shared style." A shared
    # style must have an id defined for it. This id is referenced by one
    # or more Features within the <Document>. In cases where a style
    # element is defined both in a shared style and in an inline style
    # for a Feature—that is, a Folder, GroundOverlay, NetworkLink,
    # Placemark, or ScreenOverlay—the value for the Feature's inline
    # style takes precedence over the value for the shared style.

    _time_span = None
    # Associates this Feature with a period of time.
    _time_stamp = None
    # Associates this Feature with a point in time.

    #TODO Region = None
    # Features and geometry associated with a Region are drawn only when
    # the Region is active.

    #TODO ExtendedData = None
    # Allows you to add custom data to a KML file. This data can be
    # (1) data that references an external XML schema,
    # (2) untyped data/value pairs, or
    # (3) typed data.
    # A given KML Feature can contain a combination of these types of
    # custom data.
    #
    # (2) is already implemented, see UntypedExtendedData
    #
    # <Metadata> (deprecated in KML 2.2; use <ExtendedData> instead)
    extended_data = None

    def __init__(self, ns=None, id=None, name=None, description=None,
                styles=None, styleUrl=None, extended_data=None):
        super(_Feature, self).__init__(ns, id)
        self.name=name
        self.description=description
        self.styleUrl = styleUrl
        self._styles = []
        if styles:
            for style in styles:
                self.append_style(style)
        self.extended_data = extended_data

    @property
    def styleUrl(self):
        """ Returns the url only, not a full StyleUrl object.
            if you need the full StyleUrl object use _styleUrl """
        if isinstance(self._styleUrl, StyleUrl):
            return self._styleUrl.url

    @styleUrl.setter
    def styleUrl(self, styleurl):
        """ you may pass a StyleUrl Object, a string or None """
        if isinstance(styleurl, StyleUrl):
            self._styleUrl = styleurl
        elif isinstance(styleurl, basestring):
            s = StyleUrl(self.ns, url=styleurl)
            self._styleUrl = s
        elif styleurl is None:
            self._styleUrl = None
        else:
            raise ValueError

    @property
    def timeStamp(self):
        """ This just returns the datetime portion of the timestamp"""
        if self._time_stamp is not None:
            return self._time_stamp.timestamp[0]

    @timeStamp.setter
    def timeStamp(self, dt):
        if dt == None:
            self._time_stamp = None
        else:
            self._time_stamp = TimeStamp(timestamp=dt)
        if self._time_span is not None:
            logger.warn('Setting a TimeStamp, TimeSpan deleted')
            self._time_span = None

    @property
    def begin(self):
        if self._time_span is not None:
            return self._time_span.begin[0]

    @begin.setter
    def begin(self, dt):
        if self._time_span is None:
            self._time_span = TimeSpan(begin=dt)
        else:
            if self._time_span.begin is None:
                self._time_span.begin = [dt, None]
            else:
                self._time_span.begin[0] = dt
        if self._time_stamp is not None:
            logger.warn('Setting a TimeSpan, TimeStamp deleted')
            self._time_stamp = None

    @property
    def end(self):
        if self._time_span is not None:
            return self._time_span.end[0]

    @end.setter
    def end(self, dt):
        if self._time_span is None:
            self._time_span = TimeSpan(end=dt)
        else:
            if self._time_span.end is None:
                self._time_span.end = [dt, None]
            else:
                self._time_span.end[0] = dt
        if self._time_stamp is not None:
            logger.warn('Setting a TimeSpan, TimeStamp deleted')
            self._time_stamp = None

    @property
    def link(self):
        return self._atom_link.href

    @link.setter
    def link(self, url):
        if isinstance(url, basestring):
            self._atom_link = atom.Link(href=url)
        elif isinstance(url, atom.Link):
            self._atom_link = url
        elif url is None:
            self._atom_link = None
        else:
            raise TypeError

    @property
    def author(self):
        if self._atom_author:
            return self._atom_author.name

    @author.setter
    def author(self, name):
        if isinstance(name, atom.Author):
            self._atom_author = name
        elif isinstance(name, basestring):
            if self._atom_author is None:
                self._atom_author = atom.Author(name=name)
            else:
                self._atom_author.name = name
        elif name == None:
            self._atom_author = None
        else:
            raise TypeError


    def append_style(self, style):
        """ append a style to the feature """
        if isinstance(style, _StyleSelector):
            self._styles.append(style)
        else:
            raise TypeError

    def styles(self):
        """ iterate over the styles of this feature """
        for style in self._styles:
            if isinstance(style, _StyleSelector):
                yield style
            else:
                raise TypeError

    def etree_element(self):
        element = super(_Feature, self).etree_element()
        if self.name:
            name = etree.SubElement(element, "%sname" %self.ns)
            name.text = self.name
        if self.description:
            description =etree.SubElement(element, "%sdescription" %self.ns)
            description.text = self.description
        visibility = etree.SubElement(element, "%svisibility" %self.ns)
        visibility.text = str(self.visibility)
        if self.isopen:
            isopen = etree.SubElement(element, "%sopen" %self.ns)
            isopen.text = str(self.isopen)
        if self._styleUrl is not None:
            element.append(self._styleUrl.etree_element())
        for style in self.styles():
            element.append(style.etree_element())
        if self._snippet:
            snippet = etree.SubElement(element, "%sSnippet" %self.ns)
            if isinstance(self._snippet, basestring):
                snippet.text = self._snippet
            else:
                assert (isinstance(self._snippet['text'], basestring))
                snippet.text = self._snippet['text']
                if self._snippet.get('maxLines'):
                    snippet.set('maxLines', str(self._snippet['maxLines']))
        if (self._time_span is not None) and (self._time_stamp is not None):
            raise ValueError('Either Timestamp or Timespan can be defined, not both')
        elif self._time_span is not None:
            element.append(self._time_span.etree_element())
        elif self._time_stamp is not None:
            element.append(self._time_stamp.etree_element())
        if self._atom_link is not None:
            element.append(self._atom_link.etree_element())
        if self._atom_author is not None:
            element.append(self._atom_author.etree_element())
        if self.extended_data is not None:
            element.append(self.extended_data.etree_element())
        return element


    def from_element(self, element):
        super(_Feature, self).from_element(element)
        name = element.find('%sname' %self.ns)
        if name is not None:
            self.name = name.text
        description = element.find('%sdescription' %self.ns)
        if description is not None:
            self.description = description.text
        visibility = element.find('%svisibility' %self.ns)
        if visibility is not None:
            self.visibility = int(visibility.text)
        isopen = element.find('%sopen' %self.ns)
        if isopen is not None:
            self.isopen = int(isopen.text)
        styles = element.findall('%sStyle' % self.ns)
        for style in styles:
            s = Style(self.ns)
            s.from_element(style)
            self.append_style(s)
        styles = element.findall('%sStyleMap' % self.ns)
        for style in styles:
            s = StyleMap(self.ns)
            s.from_element(style)
            self.append_style(s)
        style_url = element.find('%sstyleUrl' % self.ns)
        if style_url is not None:
            s = StyleUrl(self.ns)
            s.from_element(style_url)
            self._styleUrl = s
        snippet = element.find('%sSnippet' % self.ns)
        if snippet is not None:
            self._snippet = {'text': snippet.text}
            if snippet.get('maxLines'):
                self._snippet['maxLines'] = int(snippet.get('maxLines'))
        timespan = element.find('%sTimeSpan' % self.ns)
        if timespan is not None:
            s = TimeSpan(self.ns)
            s.from_element(timespan)
            self._time_span = s
        timestamp = element.find('%sTimeStamp' % self.ns)
        if timestamp is not None:
            s = TimeStamp(self.ns)
            s.from_element(timestamp)
            self._time_stamp = s
        atom_link = element.find('%slink' % atom.NS)
        if atom_link is not None:
            s = atom.Link()
            s.from_element(atom_link)
            self._atom_link = s
        atom_author = element.find('%sauthor' % atom.NS)
        if atom_author is not None:
            s = atom.Author()
            s.from_element(atom_author)
            self._atom_author = s
        extended_data = element.find('%sExtendedData' % self.ns)
        if extended_data is not None:
            if extended_data.find('%sData' % self.ns):
                x = UntypedExtendedData(self.ns)
                x.from_element(extended_data)
                self.extended_data = x
            else:
                logger.warn(
                    'arbitrary or typed extended data is not yet supported'
                )




class _Container(_Feature):
    """
    abstract element; do not create
    A Container element holds one or more Features and allows the
    creation of nested hierarchies.
    subclasses are:
    Document,
    Folder
    """

    _features = []

    def __init__(self, ns=None, id=None, name=None, description=None,
                styles=None, styleUrl=None):
        super(_Container, self).__init__(ns, id, name, description, styles, styleUrl)
        self._features =[]

    def features(self):
        """ iterate over features """
        for feature in self._features:
            if isinstance(feature, (Folder, Placemark)):
                yield feature
            else:
                raise TypeError(
                    "Features must be instances of (Folder, Placemark)")

    def etree_element(self):
        element = super(_Container, self).etree_element()
        for feature in self.features():
            element.append(feature.etree_element())
        return element


    def append(self, kmlobj):
        """ append a feature """
        if isinstance(kmlobj, (Folder, Placemark)):
            self._features.append(kmlobj)
        else:
            raise TypeError(
                    "Features must be instances of (Folder, Placemark)")
        assert(kmlobj != self)



class Document(_Container):
    """
    A Document is a container for features and styles. This element is
    required if your KML file uses shared styles
    """
    __name__ = "Document"

    def from_element(self, element):
        super(Document, self).from_element(element)
        folders = element.findall('%sFolder' % self.ns)
        for folder in folders:
            feature = Folder(self.ns)
            feature.from_element(folder)
            self.append(feature)
        placemarks = element.findall('%sPlacemark' % self.ns)
        for placemark in placemarks:
            feature = Placemark(self.ns)
            feature.from_element(placemark)
            self.append(feature)

    def get_style_by_url(self, styleUrl):
        id = urlparse.urlparse(styleUrl).fragment
        for style in self.styles():
            if style.id == id:
                return style


class Folder(_Container):
    """
    A Folder is used to arrange other Features hierarchically
    (Folders, Placemarks, #NetworkLinks, or #Overlays).
    """
    __name__ = "Folder"

    def from_element(self, element):
        super(Folder, self).from_element(element)
        folders = element.findall('%sFolder' % self.ns)
        for folder in folders:
            feature = Folder(self.ns)
            feature.from_element(folder)
            self.append(feature)
        placemarks = element.findall('%sPlacemark' % self.ns)
        for placemark in placemarks:
            feature = Placemark(self.ns)
            feature.from_element(placemark)
            self.append(feature)

class Placemark(_Feature):
    """
    A Placemark is a Feature with associated Geometry.
    In Google Earth, a Placemark appears as a list item in the Places
    panel. A Placemark with a Point has an icon associated with it that
    marks a point on the Earth in the 3D viewer.
    """

    __name__ = "Placemark"
    _geometry = None

    @property
    def geometry(self):
        return self._geometry.geometry

    @geometry.setter
    def geometry(self, geometry):
        if isinstance(geometry, Geometry):
            self._geometry = geometry
        else:
            self._geometry = Geometry(ns=self.ns, geometry=geometry)

    def from_element(self, element):
        super(Placemark, self).from_element(element)
        point = element.find('%sPoint' % self.ns)
        if point is not None:
            geom = Geometry(ns=self.ns)
            geom.from_element(point)
            self._geometry = geom
            return
        line = element.find('%sLineString' % self.ns)
        if line is not None:
            geom = Geometry(ns=self.ns)
            geom.from_element(line)
            self._geometry = geom
            return
        polygon = element.find('%sPolygon' % self.ns)
        if polygon is not None:
            geom = Geometry(ns=self.ns)
            geom.from_element(polygon)
            self._geometry = geom
            return
        linearring = element.find('%sLinearRing' % self.ns)
        if linearring is not None:
            geom = Geometry(ns=self.ns)
            geom.from_element(linearring)
            self._geometry = geom
            return
        multigeometry = element.find('%sMultiGeometry' % self.ns)
        if multigeometry is not None:
            geom = Geometry(ns=self.ns)
            geom.from_element(multigeometry)
            self._geometry = geom
            return
        logger.warn('No geometries found')

    def etree_element(self):
        element = super(Placemark, self).etree_element()
        if self._geometry is not None:
            element.append(self._geometry.etree_element())
        else:
            logger.error('Object does not have a geometry')
        return element

class _TimePrimitive(_BaseObject):
    """ The dateTime is defined according to XML Schema time.
    The value can be expressed as yyyy-mm-ddThh:mm:sszzzzzz, where T is
    the separator between the date and the time, and the time zone is
    either Z (for UTC) or zzzzzz, which represents ±hh:mm in relation to
    UTC. Additionally, the value can be expressed as a date only.

    The precision of the dateTime is dictated by the dateTime value
    which can be one of the following:

    - dateTime gives second resolution
    - date gives day resolution
    - gYearMonth gives month resolution
    - gYear gives year resolution
    """

    RESOLUTIONS = ['gYear', 'gYearMonth', 'date', 'dateTime']

    def get_resolution(self, dt, resolution):
        if resolution:
            if resolution not in self.RESOLUTIONS:
                raise ValueError
            else:
                return resolution
        else:
            if isinstance(dt, datetime):
                resolution = 'dateTime'
            elif isinstance(dt, date):
                resolution = 'date'
            else:
                resolution = None
        return resolution


    def parse_str(self, datestr):
        resolution = 'dateTime'
        year = 0
        month = 1
        day = 1
        if len(datestr) == 4:
            resolution = 'gYear'
            year = int(datestr)
            dt = datetime(year, month, day)
        elif len(datestr) == 6:
            resolution = 'gYearMonth'
            year = int(datestr[:4])
            month = int(datestr[-2:])
            dt = datetime(year, month, day)
        elif len(datestr) == 7:
            resolution = 'gYearMonth'
            year = int(datestr.split('-')[0])
            month = int(datestr.split('-')[1])
            dt = datetime(year, month, day)
        elif len(datestr) == 8 or len(datestr) == 10:
            resolution = 'date'
            dt = dateutil.parser.parse(datestr)
        elif len(datestr) > 10:
            resolution = 'dateTime'
            dt = dateutil.parser.parse(datestr)
        else:
            raise ValueError
        return [dt, resolution]


    def date_to_string(self, dt, resolution=None):
        if isinstance(dt, (date, datetime)):
            resolution = self.get_resolution(dt, resolution)
            if resolution == 'gYear':
                return dt.strftime('%Y')
            elif resolution == 'gYearMonth':
                return dt.strftime('%Y-%m')
            elif resolution == 'date':
                if isinstance(dt, datetime):
                    return dt.date().isoformat()
                else:
                    return dt.isoformat()
            elif resolution == 'dateTime':
                return dt.isoformat()


class TimeStamp(_TimePrimitive):
    """ Represents a single moment in time. """
    __name__ = 'TimeStamp'
    timestamp = None

    def __init__(self, ns=None, id=None, timestamp=None, resolution=None):
        super(TimeStamp, self).__init__(ns, id)
        resolution = self.get_resolution(timestamp, resolution)
        self.timestamp = [timestamp, resolution]

    def etree_element(self):
        element = super(TimeStamp, self).etree_element()
        when = etree.SubElement(element, "%swhen" %self.ns)
        when.text = self.date_to_string(*self.timestamp)
        return element

    def from_element(self, element):
        super(TimeStamp, self).from_element(element)
        when = element.find('%swhen' %self.ns)
        if when is not None:
            self.timestamp = self.parse_str(when.text)



class TimeSpan(_TimePrimitive):
    """ Represents an extent in time bounded by begin and end dateTimes.
    """
    __name__ = 'TimeSpan'
    begin = None
    end = None

    def __init__(self, ns=None, id=None, begin=None, begin_res=None,
                    end=None, end_res=None):
        super(TimeSpan, self).__init__(ns, id)
        if begin:
            resolution = self.get_resolution(begin, begin_res)
            self.begin = [begin, resolution]
        if end:
            resolution = self.get_resolution(end, end_res)
            self.end = [end, resolution]

    def from_element(self, element):
        super(TimeSpan, self).from_element(element)
        begin = element.find('%sbegin' %self.ns)
        if begin is not None:
            self.begin = self.parse_str(begin.text)
        end = element.find('%send' %self.ns)
        if end is not None:
            self.end = self.parse_str(end.text)

    def etree_element(self):
        element = super(TimeSpan, self).etree_element()
        if self.begin is not None:
            text = self.date_to_string(*self.begin)
            if text:
                begin = etree.SubElement(element, "%sbegin" %self.ns)
                begin.text = text
        if self.end is not None:
            text = self.date_to_string(*self.end)
            if text:
                end = etree.SubElement(element, "%send" %self.ns)
                end.text = text
        if self.begin == self.end == None:
            raise ValueError("Either begin, end or both must be set")
        #TODO test if end > begin
        return element


class UntypedExtendedData(_BaseObject):
    """ Represents a list of untyped name/value pairs. See docs:

    -> 'Adding Untyped Name/Value Pairs'
       https://developers.google.com/kml/documentation/extendeddata

    """
    __name__ = 'ExtendedData'

    def __init__(self, ns=None, id=None, elements=None):
        super(UntypedExtendedData, self).__init__(ns, id)
        self.elements = elements or []

    def etree_element(self):
        element = super(UntypedExtendedData, self).etree_element()

        for subelement in self.elements:
            element.append(subelement.etree_element())

        return element

    def from_element(self, element):
        super(UntypedExtendedData, self).from_element(element)
        self.elements = []

        for subelement in element:
            el = UntypedExtendedDataElement(self.ns)
            el.from_element(subelement)

            self.elements.append(el)


class UntypedExtendedDataElement(_BaseObject):
    """ Represents an untyped name/value pair with optional display name. """

    __name__ = 'Data'

    def __init__(self, ns=None, id=None, name=None, value=None, display_name=None):
        super(UntypedExtendedDataElement, self).__init__(ns, id)

        self.name = name
        self.value = value
        self.display_name = display_name

    def etree_element(self):
        element = super(UntypedExtendedDataElement, self).etree_element()

        element.set('name', self.name)

        value = etree.SubElement(element, "%svalue" % self.ns)
        value.text = self.value

        if self.display_name:
            display_name = etree.SubElement(element, "%sdisplayName" % self.ns)
            display_name.text = self.display_name

        return element

    def from_element(self, element):
        super(UntypedExtendedDataElement, self).from_element(element)

        self.name = element.get('name')
        self.value = element.find('%svalue' % self.ns).text

        display_name = element.find('%sdisplayName' % self.ns)
        if display_name is not None:
            self.display_name = display_name.text
