import grass.script as grass 

from urllib2 import urlopen
import xml.etree.ElementTree as etree

from wfs_base import WFSBase

class WFSDrv(WFSBase):
    def _download(self):
        """!Downloads data from WFS server 
        
        @return temp_map with downloaded data
        """ 
        grass.message(_("Downloading data from WFS server..."))

        proj = self.projection_name + "=EPSG:"+ str(self.o_srs)

        url = self.o_url + ("SERVICE=WFS&REQUEST=GetFeature&VERSION=%s&TYPENAME=%s" % \
             (self.o_wfs_version, self.o_layers))

        if self.bbox:
            if self.flip_coords:
                # flip coordinates if projection is geographic (see:wfs_base.py _computeBbox)
                query_bbox = dict(self._flipBbox(self.bbox))
            else:
                query_bbox = self.bbox

            url += "&BBOX=%s,%s,%s,%s" % \
                   (query_bbox['minx'],  query_bbox['miny'],  query_bbox['maxx'],  query_bbox['maxy']) 
        
        if self.o_maximum_features:
            url += '&MAXFEATURES=' +  str(self.o_maximum_features)

        if self.o_urlparams != "":
            url +="&" + self.o_urlparams
        
        grass.debug(url)
        try: 
            wfs_data = urlopen(url)
        except IOError:
            grass.fatal(_("Unable to fetch data from server"))
        
        temp_map = self._temp()

        # download data into temporary file
        try:
            temp_map_opened = open(temp_map, 'w')
            temp_map_opened.write(wfs_data.read())
            temp_map_opened
        except IOError:
            grass.fatal(_("Unable to write data into tempfile"))
        finally:
            temp_map_opened.close()

        namespaces =  ['http://www.opengis.net/ows',
                       'http://www.opengis.net/ogc']

        context = etree.iterparse(temp_map, events=["start"])
        event, root = context.next()

        for namesp in namespaces:
            if root.tag == "{%s}ExceptionReport" % namesp or \
                root.tag == "{%s}ServiceExceptionReport" % namesp:
                try:
                    error_xml_opened = open(temp_map, 'r')
                    err_str = error_xml_opened.read()     
                except IOError:
                    grass.fatal(_("Unable to read data from tempfile"))
                finally:
                    error_xml_opened.close()

                if  err_str is not None:
                    grass.fatal(_("WFS server error: %s") %  err_str)
                else:
                    grass.fatal(_("WFS server unknown error") )

        return temp_map