# This file is part of the MapProxy project.
# Copyright (C) 2010-2014 Omniscale <http://omniscale.de>
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#    http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

"""
WMS service handler
"""
from mapproxy.compat import iteritems
from mapproxy.compat.itertools import chain
from functools import partial
from math import sqrt
from mapproxy.cache.tile import CacheInfo
from mapproxy.featureinfo import combine_docs
from mapproxy.request.wms import (wms_request, WMS111LegendGraphicRequest,
    mimetype_from_infotype, infotype_from_mimetype, switch_bbox_epsg_axis_order)
from mapproxy.srs import SRS, TransformationError
from mapproxy.service.base import Server
from mapproxy.response import Response
from mapproxy.source import SourceError
from mapproxy.exception import RequestError
from mapproxy.image import bbox_position_in_image, SubImageSource, BlankImageSource, GeoReference
from mapproxy.image.merge import concat_legends, LayerMerger
from mapproxy.image.opts import ImageOptions
from mapproxy.image.message import attribution_image, message_image
from mapproxy.layer import BlankImage, MapQuery, InfoQuery, LegendQuery, MapError, LimitedLayer
from mapproxy.layer import MapBBOXError, merge_layer_extents, merge_layer_res_ranges
from mapproxy.util import async_
from mapproxy.util.py import cached_property, reraise
from mapproxy.util.coverage import load_limited_to
from mapproxy.util.ext.odict import odict
from mapproxy.template import template_loader, bunch, recursive_bunch
from mapproxy.service import template_helper
from mapproxy.layer import DefaultMapExtent, MapExtent

get_template = template_loader(__name__, 'templates', namespace=template_helper.__dict__)

class PERMIT_ALL_LAYERS(object):
    pass

class WMSServer(Server):
    service = 'wms'
    fi_transformers = None

    def __init__(self, root_layer, md, srs, image_formats,
        request_parser=None, tile_layers=None, attribution=None,
        info_types=None, strict=False, on_error='raise',
        concurrent_layer_renderer=1, max_output_pixels=None,
        srs_extents=None, max_tile_age=None,
        versions=None,
        inspire_md=None,
        ):
        Server.__init__(self)
        self.request_parser = request_parser or partial(wms_request, strict=strict, versions=versions)
        self.root_layer = root_layer
        self.layers = root_layer.child_layers()
        self.tile_layers = tile_layers or {}
        self.strict = strict
        self.attribution = attribution
        self.md = md
        self.on_error = on_error
        self.concurrent_layer_renderer = concurrent_layer_renderer
        self.image_formats = image_formats
        self.info_types = info_types
        self.srs = srs
        self.srs_extents = srs_extents
        self.max_output_pixels = max_output_pixels
        self.max_tile_age = max_tile_age
        self.inspire_md = inspire_md

    def map(self, map_request):
        self.check_map_request(map_request)

        params = map_request.params
        query = MapQuery(params.bbox, params.size, SRS(params.srs), params.format, dimensions=map_request.dimensions)

        if map_request.params.get('tiled', 'false').lower() == 'true':
            query.tiled_only = True
        orig_query = query

        if self.srs_extents and params.srs in self.srs_extents:
            # limit query to srs_extent if query is larger
            query_extent = MapExtent(params.bbox, SRS(params.srs))
            if not self.srs_extents[params.srs].contains(query_extent):
                limited_extent = self.srs_extents[params.srs].intersection(query_extent)
                if not limited_extent:
                    img_opts = self.image_formats[params.format_mime_type].copy()
                    img_opts.bgcolor = params.bgcolor
                    img_opts.transparent = params.transparent
                    img = BlankImageSource(size=params.size, image_opts=img_opts, cacheable=True)
                    return Response(img.as_buffer(), content_type=img_opts.format.mime_type)
                sub_size, offset, sub_bbox = bbox_position_in_image(params.bbox, params.size, limited_extent.bbox)
                query = MapQuery(sub_bbox, sub_size, SRS(params.srs), params.format)

        actual_layers = odict()
        for layer_name in map_request.params.layers:
            layer = self.layers[layer_name]
            # only add if layer renders the query
            if layer.renders_query(query):
                # if layer is not transparent and will be rendered,
                # remove already added (then hidden) layers
                if layer.is_opaque(query):
                    actual_layers = odict()
                for layer_name, map_layers in layer.map_layers_for_query(query):
                    actual_layers[layer_name] = map_layers

        authorized_layers, coverage = self.authorized_layers('map', actual_layers.keys(),
            map_request.http.environ, query_extent=(query.srs.srs_code, query.bbox))

        self.filter_actual_layers(actual_layers, map_request.params.layers, authorized_layers)

        render_layers = []
        for layers in actual_layers.values():
            render_layers.extend(layers)

        self.update_query_with_fwd_params(query, params=params,
            layers=render_layers)

        raise_source_errors =  True if self.on_error == 'raise' else False
        renderer = LayerRenderer(render_layers, query, map_request,
                                 raise_source_errors=raise_source_errors,
                                 concurrent_rendering=self.concurrent_layer_renderer)

        merger = LayerMerger()
        renderer.render(merger)

        if self.attribution and self.attribution.get('text') and not query.tiled_only:
            merger.add(attribution_image(self.attribution['text'], query.size))
        img_opts = self.image_formats[params.format_mime_type].copy()
        img_opts.bgcolor = params.bgcolor
        img_opts.transparent = params.transparent
        result = merger.merge(size=query.size, image_opts=img_opts,
            bbox=query.bbox, bbox_srs=params.srs, coverage=coverage)

        if query != orig_query:
            result = SubImageSource(result, size=orig_query.size, offset=offset, image_opts=img_opts)

        # Provide the wrapping WSGI app or filter the opportunity to process the
        # image before it's wrapped up in a response
        result = self.decorate_img(result, 'wms.map', actual_layers.keys(),
            map_request.http.environ, (query.srs.srs_code, query.bbox))

        try:
            result.georef = GeoReference(bbox=orig_query.bbox, srs=orig_query.srs)
            result_buf = result.as_buffer(img_opts)
        except IOError as ex:
            raise RequestError('error while processing image file: %s' % ex,
                request=map_request)

        resp = Response(result_buf, content_type=img_opts.format.mime_type)

        if query.tiled_only and isinstance(result.cacheable, CacheInfo):
            cache_info = result.cacheable
            resp.cache_headers(cache_info.timestamp, etag_data=(cache_info.timestamp, cache_info.size),
                               max_age=self.max_tile_age)
            resp.make_conditional(map_request.http)

        if not result.cacheable:
            resp.cache_headers(no_cache=True)

        return resp

    def capabilities(self, map_request):
        # TODO: debug layer
        # if '__debug__' in map_request.params:
        #     layers = self.layers.values()
        # else:
        #     layers = [layer for name, layer in iteritems(self.layers)
        #               if name != '__debug__']

        if map_request.params.get('tiled', 'false').lower() == 'true':
            tile_layers = self.tile_layers.values()
        else:
            tile_layers = []

        service = self._service_md(map_request)
        root_layer = self.authorized_capability_layers(map_request.http.environ)

        info_types = ['text', 'html', 'xml'] # defaults
        if self.info_types:
            info_types = self.info_types
        elif self.fi_transformers:
            info_types = self.fi_transformers.keys()
        info_formats = [mimetype_from_infotype(map_request.version, info_type) for info_type in info_types]
        result = Capabilities(service, root_layer, tile_layers,
            self.image_formats, info_formats, srs=self.srs, srs_extents=self.srs_extents,
            inspire_md=self.inspire_md, max_output_pixels=self.max_output_pixels
            ).render(map_request)
        return Response(result, mimetype=map_request.mime_type)

    def featureinfo(self, request):
        infos = []
        self.check_featureinfo_request(request)

        p = request.params
        query = InfoQuery(p.bbox, p.size, SRS(p.srs), p.pos,
              p['info_format'], format=request.params.format or None,
              feature_count=p.get('feature_count'))

        actual_layers = odict()

        for layer_name in request.params.query_layers:
            layer = self.layers[layer_name]
            if not layer.queryable:
                raise RequestError('layer %s is not queryable' % layer_name, request=request)
            for layer_name, info_layers in layer.info_layers_for_query(query):
                actual_layers[layer_name] = info_layers

        authorized_layers, coverage = self.authorized_layers('featureinfo', actual_layers.keys(),
            request.http.environ, query_extent=(query.srs.srs_code, query.bbox))
        self.filter_actual_layers(actual_layers, request.params.layers, authorized_layers)

        # outside of auth-coverage
        if coverage and not coverage.contains(query.coord, query.srs):
            infos = []
        else:
            info_layers = []
            for layers in actual_layers.values():
                info_layers.extend(layers)

            for layer in info_layers:
                info = layer.get_info(query)
                if info is None:
                    continue
                infos.append(info)

        mimetype = None
        if 'info_format' in request.params:
            mimetype = request.params.info_format

        if not infos:
            return Response('', mimetype=mimetype)

        if self.fi_transformers:
            if not mimetype:
                if 'xml' in self.fi_transformers:
                    info_type = 'xml'
                elif 'html' in self.fi_transformers:
                    info_type = 'html'
                else:
                    info_type = 'text'
                mimetype = mimetype_from_infotype(request.version, info_type)
            else:
                info_type = infotype_from_mimetype(request.version, mimetype)
            resp, actual_info_type = combine_docs(infos, self.fi_transformers[info_type])
            if actual_info_type is not None and info_type != actual_info_type:
                mimetype = mimetype_from_infotype(request.version, actual_info_type)
        else:
            resp, info_type = combine_docs(infos)
            mimetype = mimetype_from_infotype(request.version, info_type)

        return Response(resp, mimetype=mimetype)

    def check_map_request(self, request):
        if self.max_output_pixels and \
            (request.params.size[0] * request.params.size[1]) > self.max_output_pixels:
            request.prevent_image_exception = True
            raise RequestError("image size too large", request=request)

        self.validate_layers(request)
        request.validate_format(self.image_formats)
        request.validate_srs(self.srs)

    def update_query_with_fwd_params(self, query, params, layers):
        # forward relevant request params into MapQuery.dimensions
        for layer in layers:
            if not hasattr(layer, 'fwd_req_params'):
                continue
            for p in layer.fwd_req_params:
                if p in params:
                    query.dimensions[p] = params[p]

    def check_featureinfo_request(self, request):
        self.validate_layers(request)
        request.validate_srs(self.srs)

    def validate_layers(self, request):
        query_layers = request.params.query_layers if hasattr(request, 'query_layers') else []
        for layer in chain(request.params.layers, query_layers):
            if layer not in self.layers:
                raise RequestError('unknown layer: ' + str(layer), code='LayerNotDefined',
                                   request=request)

    def check_legend_request(self, request):
        if request.params.layer not in self.layers:
            raise RequestError('unknown layer: ' + request.params.layer,
                               code='LayerNotDefined', request=request)

    #TODO: If layer not in self.layers raise RequestError
    def legendgraphic(self, request):
        legends = []
        self.check_legend_request(request)
        layer = request.params.layer
        if not self.layers[layer].has_legend:
            raise RequestError('layer %s has no legend graphic' % layer, request=request)
        legend = self.layers[layer].legend(request)

        [legends.append(i) for i in legend if i is not None]
        if 'format' in request.params:
            mimetype = request.params.format_mime_type
        else:
            mimetype = 'image/png'

        if mimetype == 'application/json':
            return Response(legends[0].encode(), mimetype='application/json')

        result = concat_legends(legends)

        img_opts = self.image_formats[request.params.format_mime_type]
        return Response(result.as_buffer(img_opts), mimetype=mimetype)

    def _service_md(self, map_request):
        md = dict(self.md)
        md['url'] = map_request.url
        md['has_legend'] = self.root_layer.has_legend
        return md

    def authorized_layers(self, feature, layers, env, query_extent):
        if 'mapproxy.authorize' in env:
            result = env['mapproxy.authorize']('wms.' + feature, layers[:],
                environ=env, query_extent=query_extent)
            if result['authorized'] == 'unauthenticated':
                raise RequestError('unauthorized', status=401)
            if result['authorized'] == 'full':
                return PERMIT_ALL_LAYERS, None
            layers = {}
            if result['authorized'] == 'partial':
                for layer_name, permissions in iteritems(result['layers']):
                    if permissions.get(feature, False) == True:
                        layers[layer_name] = permissions.get('limited_to')
            limited_to = result.get('limited_to')
            if limited_to:
                coverage = load_limited_to(limited_to)
            else:
                coverage = None
            return layers, coverage
        else:
            return PERMIT_ALL_LAYERS, None

    def filter_actual_layers(self, actual_layers, requested_layers, authorized_layers):
        if authorized_layers is not PERMIT_ALL_LAYERS:
            requested_layer_names = set(requested_layers)
            for layer_name in actual_layers.keys():
                if layer_name not in authorized_layers:
                    # check whether layer was requested explicit...
                    if layer_name in requested_layer_names:
                        raise RequestError('forbidden', status=403)
                    # or implicit (part of group layer)
                    else:
                        del actual_layers[layer_name]
                elif authorized_layers[layer_name] is not None:
                    limited_to = load_limited_to(authorized_layers[layer_name])
                    actual_layers[layer_name] = [LimitedLayer(lyr, limited_to) for lyr in actual_layers[layer_name]]

    def authorized_capability_layers(self, env):
        if 'mapproxy.authorize' in env:
            result = env['mapproxy.authorize']('wms.capabilities', self.layers.keys(), environ=env)
            if result['authorized'] == 'unauthenticated':
                raise RequestError('unauthorized', status=401)
            if result['authorized'] == 'full':
                return self.root_layer
            if result['authorized'] == 'partial':
                limited_to = result.get('limited_to')
                if limited_to:
                    coverage = load_limited_to(limited_to)
                else:
                    coverage = None
                return FilteredRootLayer(self.root_layer, result['layers'], coverage=coverage)
            raise RequestError('forbidden', status=403)
        else:
            return self.root_layer

class FilteredRootLayer(object):
    def __init__(self, root_layer, permissions, coverage=None):
        self.root_layer = root_layer
        self.permissions = permissions
        self.coverage = coverage

    def __getattr__(self, name):
        return getattr(self.root_layer, name)

    @cached_property
    def extent(self):
        layer_name = self.root_layer.name
        limited_to = self.permissions.get(layer_name, {}).get('limited_to')
        extent = self.root_layer.extent

        if limited_to:
            coverage = load_limited_to(limited_to)
            limited_coverage = coverage.intersection(extent.bbox, extent.srs)
            extent = limited_coverage.extent

        if self.coverage:
            limited_coverage = self.coverage.intersection(extent.bbox, extent.srs)
            extent = limited_coverage.extent
        return extent

    @property
    def queryable(self):
        if not self.root_layer.queryable: return False

        layer_name = self.root_layer.name
        if not layer_name or self.permissions.get(layer_name, {}).get('featureinfo', False):
            return True
        return False

    def layer_permitted(self, layer):
        if not self.permissions.get(layer.name, {}).get('map', False):
            return False
        extent = layer.extent

        limited_to = self.permissions.get(layer.name, {}).get('limited_to')
        if limited_to:
            coverage = load_limited_to(limited_to)
            if not coverage.intersects(extent.bbox, extent.srs):
                return False

        if self.coverage:
            if not self.coverage.intersects(extent.bbox, extent.srs):
                return False
        return True

    @cached_property
    def layers(self):
        layers = []
        for layer in self.root_layer.layers:
            if not layer.name or self.layer_permitted(layer):
                filtered_layer = FilteredRootLayer(layer, self.permissions, self.coverage)
                if filtered_layer.is_active or filtered_layer.layers:
                    # add filtered_layer only if it is active (no grouping layer)
                    # or if it contains other active layers
                    layers.append(filtered_layer)
        return layers

DEFAULT_EXTENTS = {
    'EPSG:3857': DefaultMapExtent(),
    'EPSG:4326': DefaultMapExtent(),
    'EPSG:900913': DefaultMapExtent(),
}

def limit_srs_extents(srs_extents, supported_srs):
    """
    Limit srs_extents to supported_srs.
    """
    if srs_extents:
        srs_extents = srs_extents.copy()
    else:
        srs_extents = DEFAULT_EXTENTS.copy()

    for srs in list(srs_extents.keys()):
        if srs not in supported_srs:
            srs_extents.pop(srs)

    return srs_extents

class Capabilities(object):
    """
    Renders WMS capabilities documents.
    """
    def __init__(self, server_md, layers, tile_layers, image_formats, info_formats,
        srs, srs_extents=None, epsg_axis_order=False,
        inspire_md=None, max_output_pixels=None
        ):
        self.service = server_md
        self.layers = layers
        self.tile_layers = tile_layers
        self.image_formats = image_formats
        self.info_formats = info_formats
        self.srs = srs
        self.srs_extents = limit_srs_extents(srs_extents, srs)
        self.inspire_md = inspire_md
        self.max_output_pixels = max_output_pixels

    def layer_srs_bbox(self, layer, epsg_axis_order=False):
        for srs, extent in iteritems(self.srs_extents):
            if srs not in self.srs:
                continue

            # is_default is True when no explicit bbox is defined for this srs
            # use layer extent
            if extent.is_default:
                bbox = layer.extent.bbox_for(SRS(srs))
            elif layer.extent.is_default:
                bbox = extent.bbox_for(SRS(srs))
            else:
                # Use intersection of srs_extent and layer.extent.
                # Use 4326 extents to avoid transformation errors.
                a = extent.transform(SRS(4326))
                b = layer.extent.transform(SRS(4326))
                bbox = a.intersection(b).bbox_for(SRS(srs))

            if epsg_axis_order:
                bbox = switch_bbox_epsg_axis_order(bbox, srs)

            yield srs, bbox

        # add native srs
        layer_srs_code = layer.extent.srs.srs_code
        if layer_srs_code not in self.srs_extents:
            bbox = layer.extent.bbox
            if epsg_axis_order:
                bbox = switch_bbox_epsg_axis_order(bbox, layer_srs_code)
            if layer_srs_code in self.srs:
                yield layer_srs_code, bbox

    def layer_llbbox(self, layer):
        if 'EPSG:4326' in self.srs_extents:
            intersection = self.srs_extents['EPSG:4326'].intersection(layer.extent)
            if intersection is not None:
                llbbox = intersection.llbbox
                return limit_llbbox(llbbox)
        return limit_llbbox(layer.extent.llbbox)

    def render(self, _map_request):
        return self._render_template(_map_request.capabilities_template)

    def _render_template(self, template):
        template = get_template(template)
        inspire_md = None
        if self.inspire_md:
            inspire_md = recursive_bunch(default='', **self.inspire_md)

        max_output_size = None
        if self.max_output_pixels:
            output_width = output_height = int(sqrt(self.max_output_pixels))
            max_output_size = (output_width, output_height)

        doc = template.substitute(service=bunch(default='', **self.service),
                                   layers=self.layers,
                                   formats=self.image_formats,
                                   info_formats=self.info_formats,
                                   srs=self.srs,
                                   tile_layers=self.tile_layers,
                                   layer_srs_bbox=self.layer_srs_bbox,
                                   layer_llbbox=self.layer_llbbox,
                                   inspire_md=inspire_md,
                                   max_output_size=max_output_size,
        )
        # strip blank lines
        doc = '\n'.join(l for l in doc.split('\n') if l.rstrip())
        return doc


def limit_llbbox(bbox):
    """
    Limit the long/lat bounding box to +-180/89.99999999 degrees.

    Some clients can't handle +-90 north/south, so we subtract a tiny bit.

    >>> ', '.join('%.6f' % x for x in limit_llbbox((-200,-90.0, 180, 90)))
    '-180.000000, -89.999999, 180.000000, 89.999999'
    >>> ', '.join('%.6f' % x for x in limit_llbbox((-20,-9.0, 10, 10)))
    '-20.000000, -9.000000, 10.000000, 10.000000'
    """
    minx, miny, maxx, maxy = bbox

    minx = max(-180, minx)
    miny = max(-89.999999, miny)
    maxx = min(180, maxx)
    maxy = min(89.999999, maxy)

    return minx, miny, maxx, maxy

class LayerRenderer(object):
    def __init__(self, layers, query, request, raise_source_errors=True,
                 concurrent_rendering=1):
        self.layers = layers
        self.query = query
        self.request = request
        self.raise_source_errors = raise_source_errors
        self.concurrent_rendering = concurrent_rendering

    def render(self, layer_merger):
        render_layers = combined_layers(self.layers, self.query)
        if not render_layers: return

        async_pool = async_.Pool(size=min(len(render_layers), self.concurrent_rendering))

        if self.raise_source_errors:
            return self._render_raise_exceptions(async_pool, render_layers, layer_merger)
        else:
            return self._render_capture_source_errors(async_pool, render_layers,
                                                      layer_merger)

    def _render_raise_exceptions(self, async_pool, render_layers, layer_merger):
        # call _render_layer, raise all exceptions
        try:
            for layer_task in async_pool.imap(self._render_layer, render_layers,
                                              use_result_objects=True):
                if layer_task.exception is None:
                    layer, layer_img = layer_task.result
                    if layer_img is not None:
                        layer_merger.add(layer_img, layer.coverage)
                else:
                    ex = layer_task.exception
                    async_pool.shutdown(True)
                    reraise(ex)
        except SourceError as ex:
            raise RequestError(ex.args[0], request=self.request)

    def _render_capture_source_errors(self, async_pool, render_layers, layer_merger):
        # call _render_layer, capture SourceError exceptions
        errors = []
        rendered = 0

        for layer_task in async_pool.imap(self._render_layer, render_layers,
                                          use_result_objects=True):
            if layer_task.exception is None:
                layer, layer_img = layer_task.result
                if layer_img is not None:
                    layer_merger.add(layer_img, layer.coverage)
                rendered += 1
            else:
                layer_merger.cacheable = False
                ex = layer_task.exception
                if isinstance(ex[1], SourceError):
                    errors.append(ex[1].args[0])
                else:
                    async_pool.shutdown(True)
                    reraise(ex)

        if render_layers and not rendered:
            errors = '\n'.join(errors)
            raise RequestError('Could not get any sources:\n'+errors, request=self.request)

        if errors:
            layer_merger.add(message_image('\n'.join(errors), self.query.size,
                image_opts=ImageOptions(transparent=True)))

    def _render_layer(self, layer):
        try:
            layer_img = layer.get_map(self.query)
            if layer_img is not None:
                layer_img.opacity = layer.opacity

            return layer, layer_img
        except SourceError:
            raise
        except MapBBOXError as e:
            raise RequestError('Request too large or invalid BBOX. (%s)' % e, request=self.request)
        except MapError as e:
            raise RequestError('Invalid request: %s' % e.args[0], request=self.request)
        except TransformationError:
            raise RequestError('Could not transform BBOX: Invalid result.',
                request=self.request)
        except BlankImage:
            return layer, None

class WMSLayerBase(object):
    """
    Base class for WMS layer (layer groups and leaf layers).
    """

    "True if layer is an actual layer (not a group only)"
    is_active = True

    "list of sublayers"
    layers = []

    "metadata dictionary with tile, name, etc."
    md = {}

    "True if .info() is supported"
    queryable = False

    "True is .legend() is supported"
    has_legend = False
    legend_url = None
    legend_size = None

    "resolution range (i.e. ScaleHint) of the layer"
    res_range = None
    "MapExtend of the layer"
    extent = None

    def map_layers_for_query(self, query):
        raise NotImplementedError()

    def legend(self, query):
        raise NotImplementedError()

    def info(self, query):
        raise NotImplementedError()

class WMSLayer(WMSLayerBase):
    """
    Class for WMS layers.

    Combines map, info and legend sources with metadata.
    """
    is_active = True
    layers = []
    def __init__(self, name, title, map_layers, info_layers=[], legend_layers=[],
                 res_range=None, md=None,dimensions=None):
        self.name = name
        self.title = title
        self.md = md or {}
        self.map_layers = map_layers
        self.info_layers = info_layers
        self.legend_layers = legend_layers
        self.extent = merge_layer_extents(map_layers)
        self.dimensions = dimensions

        if res_range is None:
            res_range = merge_layer_res_ranges(map_layers)
        self.res_range = res_range
        self.queryable = True if info_layers else False
        self.has_legend = True if legend_layers else False
        self.dimensions = dimensions

    def is_opaque(self, query):
        return any(l.is_opaque(query) for l in self.map_layers)

    def renders_query(self, query):
        if self.res_range and not self.res_range.contains(query.bbox, query.size, query.srs):
            return False
        return True

    def map_layers_for_query(self, query):
        if not self.map_layers:
            return []
        return [(self.name, self.map_layers)]

    def info_layers_for_query(self, query):
        if not self.info_layers:
            return []
        return [(self.name, self.info_layers)]

    def legend(self, request):
        p = request.params
        query = LegendQuery(p.format, p.scale)

        for lyr in self.legend_layers:
            yield lyr.get_legend(query)

    @property
    def legend_size(self):
        width = 0
        height = 0
        for layer in self.legend_layers:
            width = max(layer.size[0], width)
            height += layer.size[1]
        return (width, height)

    @property
    def legend_url(self):
        if self.has_legend:
            req = WMS111LegendGraphicRequest(url='?',
                param=dict(format='image/png', layer=self.name, sld_version='1.1.0'))
            return req.complete_url
        else:
            return None

    def child_layers(self):
        return {self.name: self}


class WMSGroupLayer(WMSLayerBase):
    """
    Class for WMS group layers.

    Groups multiple wms layers, but can also contain a single layer (``this``)
    that represents this layer.
    """
    def __init__(self, name, title, this, layers, md=None):
        self.name = name
        self.title = title
        self.this = this
        self.md = md or {}
        self.is_active = True if this is not None else False
        self.layers = layers
        self.has_legend = True if this and this.has_legend or any(l.has_legend for l in layers) else False
        self.queryable = True if this and this.queryable or any(l.queryable for l in layers) else False
        all_layers = layers + ([self.this] if self.this else [])
        self.extent = merge_layer_extents(all_layers)
        self.res_range = merge_layer_res_ranges(all_layers)

    def is_opaque(self, query):
        return any(l.is_opaque(query) for l in self.layers)

    @property
    def legend_size(self):
        return self.this.legend_size

    @property
    def legend_url(self):
        return self.this.legend_url

    def renders_query(self, query):
        if self.res_range and not self.res_range.contains(query.bbox, query.size, query.srs):
            return False
        return True

    def map_layers_for_query(self, query):
        if self.this:
            return self.this.map_layers_for_query(query)
        else:
            layers = []
            for layer in self.layers:
                layers.extend(layer.map_layers_for_query(query))
            return layers

    def info_layers_for_query(self, query):
        if self.this:
            return self.this.info_layers_for_query(query)
        else:
            layers = []
            for layer in self.layers:
                layers.extend(layer.info_layers_for_query(query))
            return layers

    def child_layers(self):
        layers = odict()
        if self.name:
            layers[self.name] = self
        for lyr in self.layers:
            if hasattr(lyr, 'child_layers'):
                layers.update(lyr.child_layers())
            elif lyr.name:
                layers[lyr.name] = lyr
        return layers


def combined_layers(layers, query):
    """
    Returns a new list of the layers where all adjacent layers are combined
    if possible.
    """
    if len(layers) <= 1:
        return layers
    layers = layers[:]
    combined_layers = [layers.pop(0)]
    while layers:
        current_layer = layers.pop(0)
        combined = combined_layers[-1].combined_layer(current_layer, query)
        if combined:
            # change last layer with combined
            combined_layers[-1] = combined
        else:
            combined_layers.append(current_layer)
    return combined_layers
