# -*- coding: ISO-8859-15 -*-
# =============================================================================
# Copyright (c) 2009 Tom Kralidis
#
# Authors : Tom Kralidis <tomkralidis@gmail.com>
#
# Contact email: tomkralidis@gmail.com
# =============================================================================

""" CSW request and response processor """

from __future__ import (absolute_import, division, print_function)

import base64
import inspect
import warnings
import StringIO
import random
from urllib import urlencode
from urllib2 import Request, urlopen

from bcube_owslib.util import OrderedDict

from bcube_owslib.etree import etree
from bcube_owslib import fes
from bcube_owslib import util
from bcube_owslib import ows
from bcube_owslib.iso import MD_Metadata
from bcube_owslib.fgdc import Metadata
from bcube_owslib.dif import DIF
from bcube_owslib.namespaces import Namespaces
from bcube_owslib.util import cleanup_namespaces, bind_url, add_namespaces

# default variables
outputformat = 'application/xml'

def get_namespaces():
    n = Namespaces()
    return n.get_namespaces()
namespaces = get_namespaces()
schema = 'http://schemas.opengis.net/csw/2.0.2/CSW-discovery.xsd'
schema_location = '%s %s' % (namespaces['csw'], schema)

class CatalogueServiceWeb:
    """ csw request class """
    def __init__(self, url, xml=None, lang='en-US', version='2.0.2', timeout=10, skip_caps=False,
                 username=None, password=None):
        """

        Construct and process a GetCapabilities request

        Parameters
        ----------

        - url: the URL of the CSW
        - lang: the language (default is 'en-US')
        - version: version (default is '2.0.2')
        - timeout: timeout in seconds
        - skip_caps: whether to skip GetCapabilities processing on init (default is False)
        - username: username for HTTP basic authentication
        - password: password for HTTP basic authentication

        """

        self.url = url
        self.lang = lang
        self.version = version
        self.timeout = timeout
        self.username = username
        self.password = password
        self.service = 'CSW'
        self.exceptionreport = None
        self.owscommon = ows.OwsCommon('1.0.0')

        if not skip_caps:  # process GetCapabilities
            if xml:
                # load from the response to get _exml
                self._parse_response(xml)
            else:
                # construct request
                data = {'service': self.service, 'version': self.version, 'request': 'GetCapabilities'}

                self.request = '%s%s' % (bind_url(self.url), urlencode(data))

                self._invoke()

            if self.exceptionreport is None:
                # ServiceIdentification
                val = self._exml.find(util.nspath_eval('ows:ServiceIdentification', namespaces))
                self.identification=ows.ServiceIdentification(val,self.owscommon.namespace)
                # ServiceProvider
                val = self._exml.find(util.nspath_eval('ows:ServiceProvider', namespaces))
                self.provider=ows.ServiceProvider(val,self.owscommon.namespace)
                # ServiceOperations metadata 
                self.operations=[]
                for elem in self._exml.findall(util.nspath_eval('ows:OperationsMetadata/ows:Operation', namespaces)):
                    self.operations.append(ows.OperationsMetadata(elem, self.owscommon.namespace))

                # for harmonization
                self.contents = None

                # FilterCapabilities
                val = self._exml.find(util.nspath_eval('ogc:Filter_Capabilities', namespaces))
                self.filters=fes.FilterCapabilities(val)

    def describerecord(self, typename='csw:Record', format=outputformat):
        """

        Construct and process DescribeRecord request

        Parameters
        ----------

        - typename: the typename to describe (default is 'csw:Record')
        - format: the outputFormat (default is 'application/xml')
 
        """

        # construct request
        node0 = self._setrootelement('csw:DescribeRecord')
        node0.set('service', self.service)
        node0.set('version', self.version)
        node0.set('outputFormat', format)
        node0.set('schemaLanguage', namespaces['xs2'])
        node0.set(util.nspath_eval('xsi:schemaLocation', namespaces), schema_location)
        etree.SubElement(node0, util.nspath_eval('csw:TypeName', namespaces)).text = typename

        self.request = node0

        self._invoke()

        # parse result
        # TODO: process the XML Schema (you're on your own for now with self.response)

    def getdomain(self, dname, dtype='parameter'):
        """

        Construct and process a GetDomain request

        Parameters
        ----------

        - dname: the value of the Parameter or Property to query
        - dtype: whether to query a parameter (parameter) or property (property)

        """

        # construct request
        dtypename = 'ParameterName'
        node0 = self._setrootelement('csw:GetDomain')
        node0.set('service', self.service)
        node0.set('version', self.version)
        node0.set(util.nspath_eval('xsi:schemaLocation', namespaces), schema_location)
        if dtype == 'property':
            dtypename = 'PropertyName'
        etree.SubElement(node0, util.nspath_eval('csw:%s' % dtypename, namespaces)).text = dname

        self.request = node0

        self._invoke()

        if self.exceptionreport is None:
            self.results = {}

            val = self._exml.find(util.nspath_eval('csw:DomainValues', namespaces)).attrib.get('type')
            self.results['type'] = util.testXMLValue(val, True)

            val = self._exml.find(util.nspath_eval('csw:DomainValues/csw:%s' % dtypename, namespaces))
            self.results[dtype] = util.testXMLValue(val)

            # get the list of values associated with the Domain
            self.results['values'] = []

            for f in self._exml.findall(util.nspath_eval('csw:DomainValues/csw:ListOfValues/csw:Value', namespaces)):
                self.results['values'].append(util.testXMLValue(f))

    def getrecords(self, qtype=None, keywords=[], typenames='csw:Record', propertyname='csw:AnyText', bbox=None, esn='summary', sortby=None, outputschema=namespaces['csw'], format=outputformat, startposition=0, maxrecords=10, cql=None, xml=None, resulttype='results'):
        """

        Construct and process a  GetRecords request

        Parameters
        ----------

        - qtype: type of resource to query (i.e. service, dataset)
        - keywords: list of keywords
        - typenames: the typeNames to query against (default is csw:Record)
        - propertyname: the PropertyName to Filter against 
        - bbox: the bounding box of the spatial query in the form [minx,miny,maxx,maxy]
        - esn: the ElementSetName 'full', 'brief' or 'summary' (default is 'summary')
        - sortby: property to sort results on
        - outputschema: the outputSchema (default is 'http://www.opengis.net/cat/csw/2.0.2')
        - format: the outputFormat (default is 'application/xml')
        - startposition: requests a slice of the result set, starting at this position (default is 0)
        - maxrecords: the maximum number of records to return. No records are returned if 0 (default is 10)
        - cql: common query language text.  Note this overrides bbox, qtype, keywords
        - xml: raw XML request.  Note this overrides all other options
        - resulttype: the resultType 'hits', 'results', 'validate' (default is 'results')

        """

        warnings.warn("""Please use the updated 'getrecords2' method instead of 'getrecords'.  
        The 'getrecords' method will be upgraded to use the 'getrecords2' parameters
        in a future version of OWSLib.""")

        if xml is not None:
            self.request = etree.fromstring(xml)
            val = self.request.find(util.nspath_eval('csw:Query/csw:ElementSetName', namespaces))
            if val is not None:
                esn = util.testXMLValue(val)
        else:
            # construct request
            node0 = self._setrootelement('csw:GetRecords')
            if etree.__name__ != 'lxml.etree':  # apply nsmap manually
                node0.set('xmlns:ows', namespaces['ows'])
                node0.set('xmlns:gmd', namespaces['gmd'])
                node0.set('xmlns:dif', namespaces['dif'])
                node0.set('xmlns:fgdc', namespaces['fgdc'])
            node0.set('outputSchema', outputschema)
            node0.set('outputFormat', format)
            node0.set('version', self.version)
            node0.set('resultType', resulttype)
            node0.set('service', self.service)
            if startposition > 0:
                node0.set('startPosition', str(startposition))
            node0.set('maxRecords', str(maxrecords))
            node0.set(util.nspath_eval('xsi:schemaLocation', namespaces), schema_location)
    
            node1 = etree.SubElement(node0, util.nspath_eval('csw:Query', namespaces))
            node1.set('typeNames', typenames)
        
            etree.SubElement(node1, util.nspath_eval('csw:ElementSetName', namespaces)).text = esn
    
            self._setconstraint(node1, qtype, propertyname, keywords, bbox, cql, None)
    
            if sortby is not None:
                fes.setsortby(node1, sortby)
    
            self.request = node0

        self._invoke()
 
        if self.exceptionreport is None:
            self.results = {}
    
            # process search results attributes
            val = self._exml.find(util.nspath_eval('csw:SearchResults', namespaces)).attrib.get('numberOfRecordsMatched')
            self.results['matches'] = int(util.testXMLValue(val, True))
            val = self._exml.find(util.nspath_eval('csw:SearchResults', namespaces)).attrib.get('numberOfRecordsReturned')
            self.results['returned'] = int(util.testXMLValue(val, True))
            val = self._exml.find(util.nspath_eval('csw:SearchResults', namespaces)).attrib.get('nextRecord')
            self.results['nextrecord'] = int(util.testXMLValue(val, True))
    
            # process list of matching records
            self.records = OrderedDict()

            self._parserecords(outputschema, esn)

    def getrecordbyid(self, id=[], esn='full', outputschema=namespaces['csw'], format=outputformat):
        """

        Construct and process a GetRecordById request

        Parameters
        ----------

        - id: the list of Ids
        - esn: the ElementSetName 'full', 'brief' or 'summary' (default is 'full')
        - outputschema: the outputSchema (default is 'http://www.opengis.net/cat/csw/2.0.2')
        - format: the outputFormat (default is 'application/xml')

        """

        # construct request
        data = {
            'service': self.service,
            'version': self.version,
            'request': 'GetRecordById',
            'outputFormat': format,
            'outputSchema': outputschema,
            'elementsetname': esn,
            'id': ','.join(id),
        }

        self.request = '%s%s' % (bind_url(self.url), urlencode(data))

        self._invoke()

        if self.exceptionreport is None:
            self.results = {}
            self.records = OrderedDict()
            self._parserecords(outputschema, esn)

    def getrecords2(self, constraints=[], sortby=None, typenames='csw:Record', esn='summary', outputschema=namespaces['csw'], format=outputformat, startposition=0, maxrecords=10, cql=None, xml=None, resulttype='results'):
        """

        Construct and process a  GetRecords request

        Parameters
        ----------

        - constraints: the list of constraints (OgcExpression from owslib.fes module)
        - sortby: an OGC SortBy object (SortBy from owslib.fes module)
        - typenames: the typeNames to query against (default is csw:Record)
        - esn: the ElementSetName 'full', 'brief' or 'summary' (default is 'summary')        
        - outputschema: the outputSchema (default is 'http://www.opengis.net/cat/csw/2.0.2')
        - format: the outputFormat (default is 'application/xml')
        - startposition: requests a slice of the result set, starting at this position (default is 0)
        - maxrecords: the maximum number of records to return. No records are returned if 0 (default is 10)
        - cql: common query language text.  Note this overrides bbox, qtype, keywords
        - xml: raw XML request.  Note this overrides all other options
        - resulttype: the resultType 'hits', 'results', 'validate' (default is 'results')

        """

        if xml is not None:
            self.request = etree.fromstring(xml)
            val = self.request.find(util.nspath_eval('csw:Query/csw:ElementSetName', namespaces))
            if val is not None:
                esn = util.testXMLValue(val)
        else:
            # construct request
            node0 = self._setrootelement('csw:GetRecords')
            if etree.__name__ != 'lxml.etree':  # apply nsmap manually
                node0.set('xmlns:ows', namespaces['ows'])
                node0.set('xmlns:gmd', namespaces['gmd'])
                node0.set('xmlns:dif', namespaces['dif'])
                node0.set('xmlns:fgdc', namespaces['fgdc'])
            node0.set('outputSchema', outputschema)
            node0.set('outputFormat', format)
            node0.set('version', self.version)
            node0.set('service', self.service)
            node0.set('resultType', resulttype)
            if startposition > 0:
                node0.set('startPosition', str(startposition))
            node0.set('maxRecords', str(maxrecords))        
            node0.set(util.nspath_eval('xsi:schemaLocation', namespaces), schema_location)

            node1 = etree.SubElement(node0, util.nspath_eval('csw:Query', namespaces))
            node1.set('typeNames', typenames)
        
            etree.SubElement(node1, util.nspath_eval('csw:ElementSetName', namespaces)).text = esn

            if any([len(constraints) > 0, cql is not None]): 
                node2 = etree.SubElement(node1, util.nspath_eval('csw:Constraint', namespaces))
                node2.set('version', '1.1.0')
                flt = fes.FilterRequest()
                if len(constraints) > 0:
                    node2.append(flt.setConstraintList(constraints))
                # Now add a CQL filter if passed in
                elif cql is not None:
                    etree.SubElement(node2, util.nspath_eval('csw:CqlText', namespaces)).text = cql
                
            if sortby is not None and isinstance(sortby, fes.SortBy):
                node1.append(sortby.toXML())

            self.request = node0

        self._invoke()
 
        if self.exceptionreport is None:
            self.results = {}
    
            # process search results attributes
            val = self._exml.find(util.nspath_eval('csw:SearchResults', namespaces)).attrib.get('numberOfRecordsMatched')
            self.results['matches'] = int(util.testXMLValue(val, True))
            val = self._exml.find(util.nspath_eval('csw:SearchResults', namespaces)).attrib.get('numberOfRecordsReturned')
            self.results['returned'] = int(util.testXMLValue(val, True))
            val = self._exml.find(util.nspath_eval('csw:SearchResults', namespaces)).attrib.get('nextRecord')
            if val is not None:
                 self.results['nextrecord'] = int(util.testXMLValue(val, True))
            else:
                warnings.warn("""CSW Server did not supply a nextRecord value (it is optional), so the client
                should page through the results in another way.""")
                # For more info, see:
                # https://github.com/geopython/OWSLib/issues/100
                self.results['nextrecord'] = None

            # process list of matching records
            self.records = OrderedDict()

            self._parserecords(outputschema, esn)

    def transaction(self, ttype=None, typename='csw:Record', record=None, propertyname=None, propertyvalue=None, bbox=None, keywords=[], cql=None, identifier=None):
        """

        Construct and process a Transaction request

        Parameters
        ----------

        - ttype: the type of transaction 'insert, 'update', 'delete'
        - typename: the typename to describe (default is 'csw:Record')
        - record: the XML record to insert
        - propertyname: the RecordProperty/PropertyName to Filter against
        - propertyvalue: the RecordProperty Value to Filter against (for updates)
        - bbox: the bounding box of the spatial query in the form [minx,miny,maxx,maxy]
        - keywords: list of keywords
        - cql: common query language text.  Note this overrides bbox, qtype, keywords
        - identifier: record identifier.  Note this overrides bbox, qtype, keywords, cql

        """

        # construct request
        node0 = self._setrootelement('csw:Transaction')
        node0.set('version', self.version)
        node0.set('service', self.service)
        node0.set(util.nspath_eval('xsi:schemaLocation', namespaces), schema_location)

        validtransactions = ['insert', 'update', 'delete']

        if ttype not in validtransactions:  # invalid transaction
            raise RuntimeError('Invalid transaction \'%s\'.' % ttype)

        node1 = etree.SubElement(node0, util.nspath_eval('csw:%s' % ttype.capitalize(), namespaces))

        if ttype != 'update':  
            node1.set('typeName', typename)

        if ttype == 'insert':
            if record is None:
                raise RuntimeError('Nothing to insert.')
            node1.append(etree.fromstring(record))
 
        if ttype == 'update':
            if record is not None:
                node1.append(etree.fromstring(record))
            else:
                if propertyname is not None and propertyvalue is not None:
                    node2 = etree.SubElement(node1, util.nspath_eval('csw:RecordProperty', namespaces))
                    etree.SubElement(node2, util.nspath_eval('csw:Name', namespaces)).text = propertyname
                    etree.SubElement(node2, util.nspath_eval('csw:Value', namespaces)).text = propertyvalue
                    self._setconstraint(node1, qtype, propertyname, keywords, bbox, cql, identifier)

        if ttype == 'delete':
            self._setconstraint(node1, None, propertyname, keywords, bbox, cql, identifier)

        self.request = node0

        self._invoke()
        self.results = {}

        if self.exceptionreport is None:
            self._parsetransactionsummary()
            self._parseinsertresult()

    def harvest(self, source, resourcetype, resourceformat=None, harvestinterval=None, responsehandler=None):
        """

        Construct and process a Harvest request

        Parameters
        ----------

        - source: a URI to harvest
        - resourcetype: namespace identifying the type of resource
        - resourceformat: MIME type of the resource
        - harvestinterval: frequency of harvesting, in ISO8601
        - responsehandler: endpoint that CSW should responsd to with response

        """

        # construct request
        node0 = self._setrootelement('csw:Harvest')
        node0.set('version', self.version)
        node0.set('service', self.service)
        node0.set(util.nspath_eval('xsi:schemaLocation', namespaces), schema_location)
        etree.SubElement(node0, util.nspath_eval('csw:Source', namespaces)).text = source
        etree.SubElement(node0, util.nspath_eval('csw:ResourceType', namespaces)).text = resourcetype
        if resourceformat is not None:
            etree.SubElement(node0, util.nspath_eval('csw:ResourceFormat', namespaces)).text = resourceformat
        if harvestinterval is not None:
            etree.SubElement(node0, util.nspath_eval('csw:HarvestInterval', namespaces)).text = harvestinterval
        if responsehandler is not None:
            etree.SubElement(node0, util.nspath_eval('csw:ResponseHandler', namespaces)).text = responsehandler
       
        self.request = node0

        self._invoke()
        self.results = {}

        if self.exceptionreport is None:
            val = self._exml.find(util.nspath_eval('csw:Acknowledgement', namespaces))
            if util.testXMLValue(val) is not None:
                ts = val.attrib.get('timeStamp')
                self.timestamp = util.testXMLValue(ts, True)
                id = val.find(util.nspath_eval('csw:RequestId', namespaces))
                self.id = util.testXMLValue(id) 
            else:
                self._parsetransactionsummary()
                self._parseinsertresult()

    def get_operation_by_name(self, name):
        """Return a named operation"""
        for item in self.operations:
            if item.name.lower() == name.lower():
                return item
        raise KeyError("No operation named %s" % name)

    def getService_urls(self, service_string=None):
        """

        Return easily identifiable URLs for all service types

        Parameters
        ----------

        - service_string: a URI to lookup

        """
        
        urls=[]
        for key,rec in self.records.iteritems():
            #create a generator object, and iterate through it until the match is found
            #if not found, gets the default value (here "none")
            url = next((d['url'] for d in rec.references if d['scheme'] == service_string), None)
            if url is not None:
                urls.append(url)
        return urls

    def _parseinsertresult(self):
        self.results['insertresults'] = []
        for i in self._exml.findall(util.nspath_eval('csw:InsertResult', namespaces)):
            for j in i.findall(util.nspath_eval('csw:BriefRecord/dc:identifier', namespaces)):
                self.results['insertresults'].append(util.testXMLValue(j))

    def _parserecords(self, outputschema, esn):
        if outputschema == namespaces['gmd']: # iso 19139
            for i in self._exml.findall('.//'+util.nspath_eval('gmd:MD_Metadata', namespaces)) or self._exml.findall('.//'+util.nspath_eval('gmi:MI_Metadata', namespaces)):
                val = i.find(util.nspath_eval('gmd:fileIdentifier/gco:CharacterString', namespaces))
                identifier = self._setidentifierkey(util.testXMLValue(val))
                self.records[identifier] = MD_Metadata(i)
        elif outputschema == namespaces['fgdc']: # fgdc csdgm
            for i in self._exml.findall('.//metadata'):
                val = i.find('idinfo/datasetid')
                identifier = self._setidentifierkey(util.testXMLValue(val))
                self.records[identifier] = Metadata(i)
        elif outputschema == namespaces['dif']: # nasa dif
            for i in self._exml.findall('.//'+util.nspath_eval('dif:DIF', namespaces)):
                val = i.find(util.nspath_eval('dif:Entry_ID', namespaces))
                identifier = self._setidentifierkey(util.testXMLValue(val))
                self.records[identifier] = DIF(i)
        else: # process default
            for i in self._exml.findall('.//'+util.nspath_eval('csw:%s' % self._setesnel(esn), namespaces)):
                val = i.find(util.nspath_eval('dc:identifier', namespaces))
                identifier = self._setidentifierkey(util.testXMLValue(val))
                self.records[identifier] = CswRecord(i)

    def _parsetransactionsummary(self):
        val = self._exml.find(util.nspath_eval('csw:TransactionSummary', namespaces))
        if val is not None:
            rid = val.attrib.get('requestId')
            self.results['requestid'] = util.testXMLValue(rid, True)
            ts = val.find(util.nspath_eval('csw:totalInserted', namespaces))
            self.results['inserted'] = int(util.testXMLValue(ts))
            ts = val.find(util.nspath_eval('csw:totalUpdated', namespaces))
            self.results['updated'] = int(util.testXMLValue(ts))
            ts = val.find(util.nspath_eval('csw:totalDeleted', namespaces))
            self.results['deleted'] = int(util.testXMLValue(ts))

    def _setesnel(self, esn):
        """ Set the element name to parse depending on the ElementSetName requested """
        el = 'Record'
        if esn == 'brief':
            el = 'BriefRecord'
        if esn == 'summary':
            el = 'SummaryRecord'
        return el

    def _setidentifierkey(self, el):
        if el is None: 
            return 'owslib_random_%i' % random.randint(1,65536)
        else:
            return el

    def _setrootelement(self, el):
        if etree.__name__ == 'lxml.etree':  # apply nsmap
            return etree.Element(util.nspath_eval(el, namespaces), nsmap=namespaces)
        else:
            return etree.Element(util.nspath_eval(el, namespaces))

    def _setconstraint(self, parent, qtype=None, propertyname='csw:AnyText', keywords=[], bbox=None, cql=None, identifier=None):
        if keywords or bbox is not None or qtype is not None or cql is not None or identifier is not None:
            node0 = etree.SubElement(parent, util.nspath_eval('csw:Constraint', namespaces))
            node0.set('version', '1.1.0')

            if identifier is not None:  # set identifier filter, overrides all other parameters
                flt = fes.FilterRequest()
                node0.append(flt.set(identifier=identifier))
            elif cql is not None:  # send raw CQL query
                # CQL passed, overrides all other parameters
                node1 = etree.SubElement(node0, util.nspath_eval('csw:CqlText', namespaces))
                node1.text = cql
            else:  # construct a Filter request
                flt = fes.FilterRequest()
                node0.append(flt.set(qtype=qtype, keywords=keywords, propertyname=propertyname,bbox=bbox))
    
    def _invoke(self):
        # do HTTP request

        if isinstance(self.request, basestring):  # GET KVP
            req = Request(self.request)
            if self.username is not None and self.password is not None:
                base64string = base64.encodestring('%s:%s' % (self.username, self.password))[:-1]
                req.add_header('Authorization', 'Basic %s' % base64string)
            self.response = urlopen(req, timeout=self.timeout).read()
        else:
            xml_post_url = self.url
            # Get correct POST URL based on Operation list.
            # If skip_caps=True, then self.operations has not been set, so use
            # default URL.
            if hasattr(self, 'operations'):
                caller = inspect.stack()[1][3] 
                if caller == 'getrecords2': caller = 'getrecords'
                try:
                    op = self.get_operation_by_name(caller)
                    post_verbs = filter(lambda x: x.get('type').lower() == 'post', op.methods)
                    if len(post_verbs) > 1:
                        # Filter by constraints.  We must match a PostEncoding of "XML"
                        try:
                            xml_post_url = next(x for x in filter(list, ([pv.get('url') for const in pv.get('constraints') if const.name.lower() == "postencoding" and 'xml' in map(lambda x: x.lower(), const.values)] for pv in post_verbs)))[0]
                        except StopIteration:
                            # Well, just use the first one.
                            xml_post_url = post_verbs[0].get('url')
                    elif len(post_verbs) == 1:
                        xml_post_url = post_verbs[0].get('url')
                except:  # no such luck, just go with xml_post_url
                    pass

            self.request = cleanup_namespaces(self.request)
            # Add any namespaces used in the "typeNames" attribute of the
            # csw:Query element to the query's xml namespaces.
            for query in self.request.findall(util.nspath_eval('csw:Query', namespaces)):
                ns = query.get("typeNames", None)
                if ns is not None:
                    # Pull out "gmd" from something like "gmd:MD_Metadata" from the list
                    # of typenames
                    ns_keys = [x.split(':')[0] for x in ns.split(' ')]
                    self.request = add_namespaces(self.request, ns_keys)

            self.request = util.element_to_string(self.request, encoding='utf-8')

            self.response = util.http_post(xml_post_url, self.request, self.lang, self.timeout, self.username, self.password)

        self._parse_response(self.response)
        

    def _parse_response(self, response):
        '''parse in-memory xml string from a file obj or _invoke
        '''

        # parse result see if it's XML
        self._exml = etree.parse(StringIO.StringIO(response))

        # it's XML.  Attempt to decipher whether the XML response is CSW-ish """
        valid_xpaths = [
            util.nspath_eval('ows:ExceptionReport', namespaces),
            util.nspath_eval('csw:Capabilities', namespaces),
            util.nspath_eval('csw:DescribeRecordResponse', namespaces),
            util.nspath_eval('csw:GetDomainResponse', namespaces),
            util.nspath_eval('csw:GetRecordsResponse', namespaces),
            util.nspath_eval('csw:GetRecordByIdResponse', namespaces),
            util.nspath_eval('csw:HarvestResponse', namespaces),
            util.nspath_eval('csw:TransactionResponse', namespaces)
        ]

        if self._exml.getroot().tag not in valid_xpaths:
            raise RuntimeError('Document is XML, but not CSW-ish')

        # check if it's an OGC Exception
        val = self._exml.find(util.nspath_eval('ows:Exception', namespaces))
        if val is not None:
            raise ows.ExceptionReport(self._exml, self.owscommon.namespace)
        else:
            self.exceptionreport = None


class CswRecord(object):
    """ Process csw:Record, csw:BriefRecord, csw:SummaryRecord """
    def __init__(self, record):

        if hasattr(record, 'getroot'):  # standalone document
            self.xml = etree.tostring(record.getroot())
        else:  # part of a larger document
            self.xml = etree.tostring(record)

        # check to see if Dublin Core record comes from
        # rdf:RDF/rdf:Description container
        # (child content model is identical)
        self.rdf = False
        rdf = record.find(util.nspath_eval('rdf:Description', namespaces))
        if rdf is not None:
            self.rdf = True
            record = rdf

        # some CSWs return records with multiple identifiers based on 
        # different schemes.  Use the first dc:identifier value to set
        # self.identifier, and set self.identifiers as a list of dicts
        val = record.find(util.nspath_eval('dc:identifier', namespaces))
        self.identifier = util.testXMLValue(val)

        self.identifiers = []
        for i in record.findall(util.nspath_eval('dc:identifier', namespaces)):
            d = {}
            d['scheme'] = i.attrib.get('scheme')
            d['identifier'] = i.text
            self.identifiers.append(d)

        val = record.find(util.nspath_eval('dc:type', namespaces))
        self.type = util.testXMLValue(val)

        val = record.find(util.nspath_eval('dc:title', namespaces))
        self.title = util.testXMLValue(val)

        val = record.find(util.nspath_eval('dct:alternative', namespaces))
        self.alternative = util.testXMLValue(val)

        val = record.find(util.nspath_eval('dct:isPartOf', namespaces))
        self.ispartof = util.testXMLValue(val)

        val = record.find(util.nspath_eval('dct:abstract', namespaces))
        self.abstract = util.testXMLValue(val)

        val = record.find(util.nspath_eval('dc:date', namespaces))
        self.date = util.testXMLValue(val)

        val = record.find(util.nspath_eval('dct:created', namespaces))
        self.created = util.testXMLValue(val)

        val = record.find(util.nspath_eval('dct:issued', namespaces))
        self.issued = util.testXMLValue(val)

        val = record.find(util.nspath_eval('dc:relation', namespaces))
        self.relation = util.testXMLValue(val)

        val = record.find(util.nspath_eval('dct:temporal', namespaces))
        self.temporal = util.testXMLValue(val)

        self.uris = []  # list of dicts
        for i in record.findall(util.nspath_eval('dc:URI', namespaces)):
            uri = {}
            uri['protocol'] = util.testXMLValue(i.attrib.get('protocol'), True)
            uri['name'] = util.testXMLValue(i.attrib.get('name'), True)
            uri['description'] = util.testXMLValue(i.attrib.get('description'), True)
            uri['url'] = util.testXMLValue(i)

            self.uris.append(uri)

        self.references = []  # list of dicts
        for i in record.findall(util.nspath_eval('dct:references', namespaces)):
            ref = {}
            ref['scheme'] = util.testXMLValue(i.attrib.get('scheme'), True)
            ref['url'] = util.testXMLValue(i)

            self.references.append(ref)

        val = record.find(util.nspath_eval('dct:modified', namespaces))
        self.modified = util.testXMLValue(val)

        val = record.find(util.nspath_eval('dc:creator', namespaces))
        self.creator = util.testXMLValue(val)

        val = record.find(util.nspath_eval('dc:publisher', namespaces))
        self.publisher = util.testXMLValue(val)

        val = record.find(util.nspath_eval('dc:coverage', namespaces))
        self.coverage = util.testXMLValue(val)

        val = record.find(util.nspath_eval('dc:contributor', namespaces))
        self.contributor = util.testXMLValue(val)

        val = record.find(util.nspath_eval('dc:language', namespaces))
        self.language = util.testXMLValue(val)

        val = record.find(util.nspath_eval('dc:source', namespaces))
        self.source = util.testXMLValue(val)

        val = record.find(util.nspath_eval('dct:rightsHolder', namespaces))
        self.rightsholder = util.testXMLValue(val)

        val = record.find(util.nspath_eval('dct:accessRights', namespaces))
        self.accessrights = util.testXMLValue(val)

        val = record.find(util.nspath_eval('dct:license', namespaces))
        self.license = util.testXMLValue(val)

        val = record.find(util.nspath_eval('dc:format', namespaces))
        self.format = util.testXMLValue(val)

        self.subjects = []
        for i in record.findall(util.nspath_eval('dc:subject', namespaces)):
            self.subjects.append(util.testXMLValue(i))

        self.rights = []
        for i in record.findall(util.nspath_eval('dc:rights', namespaces)):
            self.rights.append(util.testXMLValue(i))

        val = record.find(util.nspath_eval('dct:spatial', namespaces))
        self.spatial = util.testXMLValue(val)

        val = record.find(util.nspath_eval('ows:BoundingBox', namespaces))
        if val is not None:
            self.bbox = ows.BoundingBox(val, namespaces['ows'])
        else:
            self.bbox = None

        val = record.find(util.nspath_eval('ows:WGS84BoundingBox', namespaces))
        if val is not None:
            self.bbox_wgs84 = ows.WGS84BoundingBox(val, namespaces['ows'])
        else:
            self.bbox_wgs84 = None
