Terralego/django-geostore

import gpxpy.gpx
import simplekml
from django.contrib.gis.geos import GeometryCollection, Point, LineString, Polygon, GEOSGeometry
from rest_framework.renderers import JSONRenderer, BaseRenderer
from rest_framework.utils.serializer_helpers import ReturnDict

from geostore import settings as app_settings


class GeoJSONRenderer(JSONRenderer):
    """
    GeoJSON renderer is just used to match with geojson format.
    Serializer is adapted along this format with djangorestframework-gis
    """
    format = 'geojson'


class KMLRenderer(BaseRenderer):
    format = 'kml'
    media_type = 'application/vnd.google-earth.kml+xml'

    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        self.kml = simplekml.Kml()

    def get_element_infos(self, element):
        description = ""
        for key, value in element.get('properties').items():
            description += f"{key}: {value}\n"
        return (
            element.get('geom').get('type').lower(),
            element.get('identifier'),
            element.get('geom').get('coordinates'),
            description
        )

    def parse_element(self, element):
        mapping = {
            'point': 'newpoint',
            'linestring': 'newlinestring',
            'polygon': 'newpolygon'
        }
        geom_type, identifier, coordinates, description = self.get_element_infos(element)

        if geom_type in mapping.keys():
            if geom_type == "polygon":
                polygon = self.kml.newpolygon(name=identifier, description=description)
                polygon.outerboundaryis = (coordinates[0], )
                if len(coordinates) > 1:
                    # manage holes
                    polygon.innerboundaryis = (coordinates[1], )
            else:
                getattr(self.kml, mapping[geom_type])(
                    name=identifier,
                    description=description,
                    coords=(coordinates, ) if geom_type == "point" else coordinates
                )
        else:
            # geom is multi
            multi = self.kml.newmultigeometry(name=identifier, description=description)
            final_geom_type = geom_type.replace('multi', '')  # get geom_type without multi
            if final_geom_type == "geometrycollection":
                geometries = element.get('geom').get('geometries')
                for geometry in geometries:
                    geom_type = geometry.get('type').lower()
                    coordinates = geometry.get('coordinates')
                    getattr(multi, mapping[geom_type])(
                        coords=(coordinates, ) if geom_type == "point" else coordinates
                    )
            else:
                for simple_object_coords in coordinates:
                    if final_geom_type == "polygon":
                        polygon = multi.newpolygon(name=identifier, description=description)
                        polygon.outerboundaryis = (simple_object_coords[0], )
                        if len(simple_object_coords) > 1:
                            # manage holes
                            polygon.innerboundaryis = (simple_object_coords[1], )
                    else:
                        getattr(multi, mapping[final_geom_type])(
                            coords=(simple_object_coords, ) if final_geom_type == "point" else simple_object_coords
                        )

        return self.kml.kml()

    def render(self, data, accepted_media_type=None, renderer_context=None):
        if isinstance(data, ReturnDict):
            # simple object serialization
            self.parse_element(data)

        else:
            # object list serialization
            for element in data:
                self.parse_element(element)

        return self.kml.kml()


class GPXRenderer(BaseRenderer):
    format = 'gpx'
    media_type = 'application/gpx+xml'

    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        self.gpx = gpxpy.gpx.GPX()

    def render(self, data, accepted_media_type=None, renderer_context=None):
        return self.geom_to_gpx(GEOSGeometry(str(data.get('geom'))), data.get('identifier'), "")

    def _point_to_gpx(self, point, klass=gpxpy.gpx.GPXWaypoint):
        if isinstance(point, (tuple, list)):
            point = Point(*point, srid=app_settings.INTERNAL_GEOMETRY_SRID)
        newpoint = point.transform(4326, clone=True)  # transformation: gps uses 4326
        # transform looses the Z parameter
        return klass(latitude=newpoint.y, longitude=newpoint.x, elevation=point.z)

    def geom_to_gpx(self, geom, name, description):
        """Convert a geometry to a gpx entity.
        Point -> add as a Way Point
        LineString -> add all Points in a Route
        Polygon -> add all Points of the external linering in a Route
        Collection (of LineString or Point) -> add as a route, concatening all points
        """
        if isinstance(geom, GeometryCollection):
            for i, g in enumerate(geom):
                self.geom_to_gpx(g, "%s (%s)" % (name, i), description)
        elif isinstance(geom, Point):
            wp = self._point_to_gpx(geom)
            wp.name = name
            wp.description = description
            self.gpx.waypoints.append(wp)
        elif isinstance(geom, LineString):
            gpx_track = gpxpy.gpx.GPXTrack(name=name, description=description)
            gpx_segment = gpxpy.gpx.GPXTrackSegment()
            gpx_segment.points = [self._point_to_gpx(point, klass=gpxpy.gpx.GPXTrackPoint) for point in geom]
            gpx_track.segments.append(gpx_segment)
            self.gpx.tracks.append(gpx_track)
        elif isinstance(geom, Polygon):
            self.geom_to_gpx(geom[0], name, description)

        return self.gpx.to_xml()