from django.conf import settings

from django.contrib.admin import ModelAdmin

from django.contrib.gis.admin.widgets import OpenLayersWidget

from django.contrib.gis.gdal import OGRGeomType

from django.contrib.gis.db import models

class GeoModelAdmin(ModelAdmin):

    """

    The administration options class for Geographic models. Map settings

    may be overloaded from their defaults to create custom maps.

    """

    # The default map settings that may be overloaded -- still subject

    # to API changes.

    default_lon = 0

    default_lat = 0

    default_zoom = 4

    display_wkt = False

    display_srid = False

    extra_js = []

    num_zoom = 18

    max_zoom = False

    min_zoom = False

    units = False

    max_resolution = False

    max_extent = False

    modifiable = True

    mouse_position = True

    scale_text = True

    layerswitcher = True

    scrollable = True

    admin_media_prefix = settings.ADMIN_MEDIA_PREFIX

    map_width = 600

    map_height = 400

    map_srid = 4326

    map_template = 'gis/admin/openlayers.html'

    openlayers_url = 'http://openlayers.org/api/2.6/OpenLayers.js'

    wms_url = 'http://labs.metacarta.com/wms/vmap0'

    wms_layer = 'basic'

    wms_name = 'OpenLayers WMS'

    debug = False

    widget = OpenLayersWidget

    def _media(self):

        "Injects OpenLayers JavaScript into the admin."

        media = super(GeoModelAdmin, self)._media()

        media.add_js([self.openlayers_url])

        media.add_js(self.extra_js)

        return media

    media = property(_media)

    def formfield_for_dbfield(self, db_field, **kwargs):

        """

        Overloaded from ModelAdmin so that an OpenLayersWidget is used

        for viewing/editing GeometryFields.

        """

        if isinstance(db_field, models.GeometryField):

            # Setting the widget with the newly defined widget.

            kwargs['widget'] = self.get_map_widget(db_field)

            return db_field.formfield(**kwargs)

        else:

            return super(GeoModelAdmin, self).formfield_for_dbfield(db_field, **kwargs)

    def get_map_widget(self, db_field):

        """

        Returns a subclass of the OpenLayersWidget (or whatever was specified

        in the `widget` attribute) using the settings from the attributes set 

        in this class.

        """

        is_collection = db_field._geom in ('MULTIPOINT', 'MULTILINESTRING', 'MULTIPOLYGON', 'GEOMETRYCOLLECTION')

        if is_collection:

            if db_field._geom == 'GEOMETRYCOLLECTION': collection_type = 'Any'

            else: collection_type = OGRGeomType(db_field._geom.replace('MULTI', ''))

        else:

            collection_type = 'None'

        class OLMap(self.widget):

            template = self.map_template

            geom_type = db_field._geom

            params = {'admin_media_prefix' : self.admin_media_prefix,

                      'default_lon' : self.default_lon,

                      'default_lat' : self.default_lat,

                      'default_zoom' : self.default_zoom,

                      'display_wkt' : self.debug or self.display_wkt,

                      'geom_type' : OGRGeomType(db_field._geom),

                      'field_name' : db_field.name,

                      'is_collection' : is_collection,

                      'scrollable' : self.scrollable,

                      'layerswitcher' : self.layerswitcher,

                      'collection_type' : collection_type,

                      'is_linestring' : db_field._geom in ('LINESTRING', 'MULTILINESTRING'),

                      'is_polygon' : db_field._geom in ('POLYGON', 'MULTIPOLYGON'),

                      'is_point' : db_field._geom in ('POINT', 'MULTIPOINT'),

                      'num_zoom' : self.num_zoom,

                      'max_zoom' : self.max_zoom,

                      'min_zoom' : self.min_zoom,

                      'units' : self.units, #likely shoud get from object

                      'max_resolution' : self.max_resolution,

                      'max_extent' : self.max_extent,

                      'modifiable' : self.modifiable,

                      'mouse_position' : self.mouse_position,

                      'scale_text' : self.scale_text,

                      'map_width' : self.map_width,

                      'map_height' : self.map_height,

                      'srid' : self.map_srid,

                      'display_srid' : self.display_srid,

                      'wms_url' : self.wms_url,

                      'wms_layer' : self.wms_layer,

                      'wms_name' : self.wms_name,

                      'debug' : self.debug,

                      }

        return OLMap

# Using the Beta OSM in the admin requires the following:

#  (1) The Google Maps Mercator projection needs to be added

#      to your `spatial_ref_sys` table.  You'll need at least GDAL 1.5:

#      >>> from django.contrib.gis.gdal import SpatialReference

#      >>> from django.contrib.gis.utils import add_postgis_srs

#      >>> add_postgis_srs(SpatialReference(900913)) # Adding the Google Projection 

from django.contrib.gis import gdal

if gdal.HAS_GDAL:

    class OSMGeoAdmin(GeoModelAdmin):

        map_template = 'gis/admin/osm.html'

        extra_js = ['http://openstreetmap.org/openlayers/OpenStreetMap.js']

        num_zoom = 20

        map_srid = 900913

        max_extent = '-20037508,-20037508,20037508,20037508'

        max_resolution = 156543.0339

        units = 'm'