"""
Django views for the gooyal-dynamic-scopes package.
"""

import json
import functools

from django.conf import settings
from django.http import HttpResponse, HttpResponseForbidden
from django.views.decorators.csrf import csrf_exempt
from django.views.decorators.http import require_http_methods, require_POST

from oauthlib.oauth2 import Server

from oauth2_provider.oauth2_backends import OAuthLibCore
from oauth2_provider.oauth2_validators import OAuth2Validator
from oauth2_provider.views import IntrospectTokenView

from .models import Scope


def protected_resource(scopes=None):
    """
    Implementation of protected_resource decorator that saves the client on the
    request for the view function to use.

    Cribbed from django-oauth-toolkit.
    """
    _scopes = scopes or []

    def decorator(view_func):
        @functools.wraps(view_func)
        def _validate(request, *args, **kwargs):
            validator = OAuth2Validator()
            core = OAuthLibCore(Server(validator))
            valid, oauthlib_req = core.verify_request(request, scopes=_scopes)
            if valid:
                request.client = oauthlib_req.client
                request.resource_owner = oauthlib_req.user
                return view_func(request, *args, **kwargs)
            return HttpResponseForbidden()

        return _validate

    return decorator


@require_http_methods(['GET', 'POST'])
@csrf_exempt
@protected_resource(scopes=[settings.INTROSPECT_SCOPE])
def introspect_token(request):
    """
    Version of the introspection view protected by a regular scope instead of
    read-write scopes.

    Also allows for the required scope to be changed using a setting.
    """
    if request.method == 'GET':
        token = request.GET.get("token", None)
    else:
        token = request.POST.get("token", None)
    return IntrospectTokenView.get_token_response(token)


@require_POST
@csrf_exempt
@protected_resource(scopes=[settings.REGISTER_SCOPE_SCOPE])
def register_scope(request):
    """
    Implements an endpoint for registering a scope.
    """
    #  Get the scope data from the request body
    scope_data = json.loads(request.body) if request.body else {}
    try:
        try:
            #  If a scope with the given name already exists, find it
            scope = Scope.objects.get(name=scope_data['name'])
        except Scope.DoesNotExist:
            #  If no scope with the given name exists, create it
            _ = Scope.objects.create(
                application=request.client,
                name=scope_data['name'],
                description=scope_data['description'],
                is_default=scope_data.get('is_default', False)
            )
            #  Respond with a 201 Created
            return HttpResponse(status=201)
    except KeyError as exc:
        #  A key missing in the data should be reported as a bad request
        return HttpResponse(
            status=400,
            content="'{}' must be given in request data".format(exc.args[0]),
            content_type='text/plain'
        )
    #  If the scope does exist, check that the current application is the
    #  owner of the scope before updating it
    if scope.application and scope.application == request.client:
        scope.description = scope_data['description']
        scope.is_default = scope_data.get('is_default', False)
        scope.save()
        return HttpResponse(status=200)
    else:
        return HttpResponse(status=403)