from __future__ import unicode_literals

import logging

from django.conf import settings
from django.contrib.gis import gdal
from django.contrib.gis.geos import GEOSGeometry, GEOSException
from django.forms.widgets import Widget
from django.template import loader
from django.utils import six
from django.utils import translation

logger = logging.getLogger('django.contrib.gis')


class BaseGeometryWidget(Widget):
    """
    The base class for rich geometry widgets.
    Renders a map using the WKT of the geometry.
    """
    geom_type = 'GEOMETRY'
    map_srid = 4326
    map_width = 600
    map_height = 400
    display_wkt = False

    supports_3d = False
    template_name = ''  # set on subclasses

    def __init__(self, attrs=None):
        self.attrs = {}
        for key in ('geom_type', 'map_srid', 'map_width', 'map_height', 'display_wkt'):
            self.attrs[key] = getattr(self, key)
        if attrs:
            self.attrs.update(attrs)

    def render(self, name, value, attrs=None):
        # If a string reaches here (via a validation error on another
        # field) then just reconstruct the Geometry.
        if isinstance(value, six.string_types):
            try:
                value = GEOSGeometry(value)
            except (GEOSException, ValueError) as err:
                logger.error(
                    "Error creating geometry from value '%s' (%s)" % (
                    value, err)
                )
                value = None

        wkt = ''
        if value:
            # Check that srid of value and map match
            if value.srid != self.map_srid:
                try:
                    ogr = value.ogr
                    ogr.transform(self.map_srid)
                    wkt = ogr.wkt
                except gdal.OGRException as err:
                    logger.error(
                        "Error transforming geometry from srid '%s' to srid '%s' (%s)" % (
                        value.srid, self.map_srid, err)
                    )
            else:
                wkt = value.wkt

        context = self.build_attrs(attrs,
            name=name,
            module='geodjango_%s' % name.replace('-','_'),  # JS-safe
            wkt=wkt,
            geom_type=gdal.OGRGeomType(self.attrs['geom_type']),
            STATIC_URL=settings.STATIC_URL,
            LANGUAGE_BIDI=translation.get_language_bidi(),
        )
        return loader.render_to_string(self.template_name, context)


class OpenLayersWidget(BaseGeometryWidget):
    template_name = 'gis/openlayers.html'
    class Media:
        js = (
            'http://openlayers.org/api/2.11/OpenLayers.js',
            'gis/js/OLMapWidget.js',
        )


class OSMWidget(BaseGeometryWidget):
    """
    An OpenLayers/OpenStreetMap-based widget.
    """
    template_name = 'gis/openlayers-osm.html'
    default_lon = 5
    default_lat = 47

    class Media:
        js = (
            'http://openlayers.org/api/2.11/OpenLayers.js',
            'http://www.openstreetmap.org/openlayers/OpenStreetMap.js',
            'gis/js/OLMapWidget.js',
        )

    @property
    def map_srid(self):
        # Use the official spherical mercator projection SRID on versions
        # of GDAL that support it; otherwise, fallback to 900913.
        if gdal.HAS_GDAL and gdal.GDAL_VERSION >= (1, 7):
            return 3857
        else:
            return 900913

    def render(self, name, value, attrs=None):
        return super(self, OSMWidget).render(name, value,
            {'default_lon': self.default_lon, 'default_lat': self.default_lat})