# This file is part of the MapProxy project.
# Copyright (C) 2010 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.

"""
Demo service handler
"""
from __future__ import division

import logging
import re

try:
    import importlib_resources
except ImportError:
    from importlib import resources as importlib_resources
import os
import mimetypes
from collections import defaultdict

from mapproxy.config.config import base_config
from mapproxy.util.ext.odict import odict
from mapproxy.exception import RequestError
from mapproxy.service.base import Server
from mapproxy.request.base import Request
from mapproxy.response import Response
from mapproxy.srs import SRS, get_epsg_num
from mapproxy.layer import SRSConditional, CacheMapLayer, ResolutionConditional
from mapproxy.source.wms import WMSSource
from mapproxy.util.escape import escape_html

from urllib import request as urllib2

from mapproxy.template import template_loader, bunch
env = {'bunch': bunch}
get_template = template_loader(__package__, 'templates', namespace=env)

# Used by plugins
extra_demo_server_handlers = set()

logger = logging.getLogger("demo")


def register_extra_demo_server_handler(handler):
    """ Method used by plugins to register a new handler for the demo service.
        The handler passed to this method is invoked by the DemoServer.handle()
        method when receiving an incoming request, and let a chance to the
        handler to process it, if it is relevant to it.

        :param handler: New handler for incoming requests
        :type handler: function that takes 2 arguments (DemoServer instance and req) and
                       returns a string with HTML content or None
    """

    extra_demo_server_handlers.add(handler)


extra_substitution_handlers = set()


def register_extra_demo_substitution_handler(handler):
    """ Method used by plugins to register a new handler for doing substitutions
        to the HTML template used by the demo service.
        The handler passed to this method is invoked by the DemoServer._render_template()
        method. The handler may modify the passed substitutions dictionary
        argument. Keys of particular interest are 'extra_services_html_beginning'
        and 'extra_services_html_end' to add HTML content before/after built-in
        services.

        :param handler: New handler for incoming requests
        :type handler: function that takes 3 arguments(DemoServer instance, req and a substitutions dictionary
            argument).
    """

    extra_substitution_handlers.add(handler)


def static_filename(name):
    if base_config().template_dir:
        return os.path.join(base_config().template_dir, name)
    else:
        return importlib_resources.files(__package__).joinpath('templates').joinpath(name)


class DemoServer(Server):
    names = ('demo',)

    def __init__(self, layers, md, request_parser=None, tile_layers=None,
                 srs=None, image_formats=None, services=None, restful_template=None, background=None):
        Server.__init__(self)
        self.layers = layers
        self.tile_layers = tile_layers or {}
        self.md = md
        self.image_formats = image_formats
        filter_image_format = []
        for format in self.image_formats:
            if 'image/jpeg' == format or 'image/png' == format:
                filter_image_format.append(format)
        self.image_formats = filter_image_format
        self.srs = srs
        self.services = services or []
        self.restful_template = restful_template
        self.background = background

    @staticmethod
    def get_capabilities_url(service_path: str, req: Request) -> str:
        if 'type' in req.args and req.args['type'] == 'external':
            url = escape_html(req.script_url) + service_path
        else:
            url = req.server_script_url + service_path
        return url

    @staticmethod
    def valid_url(url: str) -> bool:
        pattern = re.compile("^https?://")
        if pattern.match(url):
            return True
        else:
            logging.warn(f"A request was blocked that was trying to access a non-http resource: {url}")
            return False

    @staticmethod
    def read_capabilities(url: str) -> str:
        resp = urllib2.urlopen(url)
        return escape_html(resp.read().decode())

    def handle(self, req: Request):
        if req.path.startswith('/demo/static/'):
            if '..' in req.path:
                return Response('file not found', content_type='text/plain', status=404)
            filename = req.path.lstrip('/')
            filename = static_filename(filename)
            if not os.path.isfile(filename):
                return Response('file not found', content_type='text/plain', status=404)
            type, encoding = mimetypes.guess_type(filename)
            return Response(open(filename, 'rb'), content_type=type)

        # we don't authorize the static files (css, js)
        # since they are not confidential
        try:
            authorized = self.authorized_demo(req.environ)
        except RequestError as ex:
            return ex.render()
        if not authorized:
            return Response('forbidden', content_type='text/plain', status=403)

        for handler in extra_demo_server_handlers:
            demo = handler(self, req)
            if demo is not None:
                return Response(demo, content_type='text/html')

        if 'wms_layer' in req.args:
            demo = self._render_wms_template('demo/wms_demo.html', req)
        elif 'tms_layer' in req.args:
            demo = self._render_tms_template('demo/tms_demo.html', req)
        elif 'wmts_layer' in req.args:
            demo = self._render_wmts_template('demo/wmts_demo.html', req)
        elif 'wms_capabilities' in req.args:
            url = self.get_capabilities_url('/service?REQUEST=GetCapabilities&SERVICE=WMS', req)
            if not self.valid_url(url):
                return Response('bad request', content_type='text/plain', status=400)
            capabilities = self.read_capabilities(url)
            demo = self._render_capabilities_template('demo/capabilities_demo.html', capabilities, 'WMS', url)
        elif 'wmsc_capabilities' in req.args:
            url = self.get_capabilities_url('/service?REQUEST=GetCapabilities&SERVICE=WMS&tiled=true', req)
            if not self.valid_url(url):
                return Response('bad request', content_type='text/plain', status=400)
            capabilities = self.read_capabilities(url)
            demo = self._render_capabilities_template('demo/capabilities_demo.html', capabilities, 'WMS-C', url)
        elif 'wmts_capabilities_kvp' in req.args:
            url = self.get_capabilities_url('/service?REQUEST=GetCapabilities&SERVICE=WMTS', req)
            if not self.valid_url(url):
                return Response('bad request', content_type='text/plain', status=400)
            capabilities = self.read_capabilities(url)
            demo = self._render_capabilities_template('demo/capabilities_demo.html', capabilities, 'WMTS', url)
        elif 'wmts_capabilities' in req.args:
            url = self.get_capabilities_url('/wmts/1.0.0/WMTSCapabilities.xml', req)
            if not self.valid_url(url):
                return Response('bad request', content_type='text/plain', status=400)
            capabilities = self.read_capabilities(url)
            demo = self._render_capabilities_template('demo/capabilities_demo.html', capabilities, 'WMTS', url)
        elif 'tms_capabilities' in req.args:
            if 'layer' in req.args and 'srs' in req.args:
                # prevent dir traversal (seems it's not possible with urllib2, but better safe than sorry)
                layer = escape_html(req.args['layer'].replace('..', ''))
                srs = escape_html(req.args['srs'].replace('..', ''))
                service_path = f'/tms/1.0.0/{layer}/{srs}'
            else:
                service_path = '/tms/1.0.0/'
            url = self.get_capabilities_url(service_path, req)
            if not self.valid_url(url):
                return Response('bad request', content_type='text/plain', status=400)
            capabilities = self.read_capabilities(url)
            demo = self._render_capabilities_template('demo/capabilities_demo.html', capabilities, 'TMS', url)
        elif req.path == '/demo/':
            demo = self._render_template(req, 'demo/demo.html')
        else:
            resp = Response('', status=301)
            resp.headers['Location'] = escape_html(req.script_url).rstrip('/') + '/demo/'
            return resp
        return Response(demo, content_type='text/html')

    def layer_srs(self, layer):
        """
        Return a list tuples with title and name of all SRS for the layer.
        The title of SRS that are native to the layer are suffixed with a '*'.
        """
        cached_srs = []
        for map_layer in layer.map_layers:
            # TODO unify map_layers interface
            if isinstance(map_layer, SRSConditional):
                for srs_key in map_layer.srs_map.keys():
                    cached_srs.append(srs_key.srs_code)
            elif isinstance(map_layer, CacheMapLayer):
                cached_srs.append(map_layer.grid.srs.srs_code)
            elif isinstance(map_layer, ResolutionConditional):
                cached_srs.append(map_layer.srs.srs_code)
            elif isinstance(map_layer, WMSSource):
                if map_layer.supported_srs:
                    for supported_srs in map_layer.supported_srs:
                        cached_srs.append(supported_srs.srs_code)

        uncached_srs = []

        for srs_code in self.srs:
            if srs_code not in cached_srs:
                uncached_srs.append(srs_code)

        def get_srs_key(srs):
            epsg_num = get_epsg_num(srs)
            return str(epsg_num if epsg_num else srs)

        sorted_cached_srs = sorted(cached_srs, key=lambda srs: get_srs_key(srs))
        sorted_uncached_srs = sorted(uncached_srs, key=lambda srs: get_srs_key(srs))
        sorted_cached_srs = [(s + '*', s) for s in sorted_cached_srs]
        sorted_uncached_srs = [(s, s) for s in sorted_uncached_srs]
        return sorted_cached_srs + sorted_uncached_srs

    def _render_template(self, req, template):
        template = get_template(template, default_inherit="demo/static.html")
        tms_tile_layers = defaultdict(list)
        for layer in self.tile_layers:
            name = self.tile_layers[layer].md.get('name')
            tms_tile_layers[name].append(self.tile_layers[layer])
        wmts_layers = tms_tile_layers.copy()

        wmts_layers = odict(sorted(wmts_layers.items(), key=lambda x: x[0]))
        tms_tile_layers = odict(sorted(tms_tile_layers.items(), key=lambda x: x[0]))

        substitutions = dict(
            extra_services_html_beginning='',
            extra_services_html_end='',
            layers=self.layers,
            formats=self.image_formats,
            srs=self.srs,
            layer_srs=self.layer_srs,
            tms_layers=tms_tile_layers,
            wmts_layers=wmts_layers,
            services=self.services
        )

        for add_substitution in extra_substitution_handlers:
            add_substitution(self, req, substitutions)

        return template.substitute(substitutions)

    def _render_wms_template(self, template, req):
        template = get_template(template, default_inherit="demo/static.html")
        layer = self.layers[req.args['wms_layer']]
        srs = escape_html(req.args['srs'])
        bbox = layer.extent.bbox_for(SRS(srs))
        width = bbox[2] - bbox[0]
        height = bbox[3] - bbox[1]
        min_res = max(width/256, height/256)
        background_url = base_config().background.url
        if self.background:
            background_url = self.background["url"]
        return template.substitute(layer=layer,
                                   image_formats=self.image_formats,
                                   format=escape_html(req.args['format']),
                                   srs=srs,
                                   layer_srs=self.layer_srs,
                                   bbox=bbox,
                                   res=min_res,
                                   background_url=background_url)

    def _render_tms_template(self, template, req):
        template = get_template(template, default_inherit="demo/static.html")
        for layer in self.tile_layers.values():
            if (layer.name == req.args['tms_layer'] and
                    layer.grid.srs.srs_code == req.args['srs']):
                tile_layer = layer
                break

        resolutions = tile_layer.grid.tile_sets
        res = []
        for level, resolution in resolutions:
            res.append(resolution)

        if tile_layer.grid.srs.is_latlong:
            units = 'degree'
        else:
            units = 'm'

        if tile_layer.grid.profile == 'local':
            add_res_to_options = True
        else:
            add_res_to_options = False
        background_url = base_config().background.url
        if self.background:
            background_url = self.background["url"]
        return template.substitute(layer=tile_layer,
                                   srs=escape_html(req.args['srs']),
                                   format=escape_html(req.args['format']),
                                   resolutions=res,
                                   units=units,
                                   add_res_to_options=add_res_to_options,
                                   all_tile_layers=self.tile_layers,
                                   background_url=background_url)

    def _render_wmts_template(self, template, req):
        template = get_template(template, default_inherit="demo/static.html")
        for layer in self.tile_layers.values():
            if (layer.name == req.args['wmts_layer'] and
                    layer.grid.srs.srs_code == req.args['srs']):
                wmts_layer = layer
                break

        restful_url = self.restful_template.replace('{Layer}', wmts_layer.name, 1)
        if '{Format}' in restful_url:
            restful_url = restful_url.replace('{Format}', wmts_layer.format)

        if wmts_layer.grid.srs.is_latlong:
            units = 'degree'
        else:
            units = 'm'
        background_url = base_config().background.url
        if self.background:
            background_url = self.background["url"]
        return template.substitute(layer=wmts_layer,
                                   matrix_set=wmts_layer.grid.name,
                                   format=escape_html(req.args['format']),
                                   srs=escape_html(req.args['srs']),
                                   resolutions=wmts_layer.grid.resolutions,
                                   units=units,
                                   all_tile_layers=self.tile_layers,
                                   restful_url=restful_url,
                                   background_url=background_url)

    def _render_capabilities_template(self, template, xmlfile, service, url):
        template = get_template(template, default_inherit="demo/static.html")
        return template.substitute(capabilities=xmlfile,
                                   service=service,
                                   url=url)

    def authorized_demo(self, environ):
        if 'mapproxy.authorize' in environ:
            result = environ['mapproxy.authorize']('demo', [], environ=environ)
            if result['authorized'] == 'unauthenticated':
                raise RequestError('unauthorized', status=401)
            if result['authorized'] == 'full':
                return True
            return False
        return True
