"""Custom middleware."""
from re import MULTILINE, findall, search
from typing import TYPE_CHECKING
from django.middleware.common import CommonMiddleware
if TYPE_CHECKING: # pragma: no cover
from typing import Callable # isort:skip
from django.http import HttpRequest, HttpResponse # isort:skip
[docs]class BaseMiddleware(CommonMiddleware):
"""``CommonMiddleware`` with custom patches."""
[docs] def __call__(self, request: 'HttpRequest') -> 'HttpResponse':
"""
Patched to allow :const:`blocked user agents
<MangAdventure.settings.DISALLOWED_USER_AGENTS>`
to view ``/robots.txt``.
:param request: The original request.
:return: The response to the request.
"""
if request.path == '/robots.txt':
return self.get_response(request)
return super().__call__(request)
[docs]class PreloadMiddleware:
"""Middleware that allows for preloading resources."""
def __init__(self, get_response: 'Callable[[HttpRequest], HttpResponse]'):
self.get_response = get_response
[docs] def __call__(self, request: 'HttpRequest') -> 'HttpResponse':
"""
Add a ``Link`` header with preloadable resources to the response.
:param request: The original request.
:return: The response to the request.
"""
response = self.get_response(request)
if 'text/html' not in response.get('Content-Type', ''):
return response
preload = []
pattern = (
r'(<(link|script|img)[^>]+?rel='
r'"[^>]*?preload[^>]*?"[^>]*?/?>)'
)
content = str(response.content)
for link in findall(pattern, content, MULTILINE):
src = search(
r'href="(/.+?)"' if link[1] == 'link'
else r'src="(/.+?)"', link[0]
)
as_ = search(r'as="(.+?)"', link[0])
if src and as_:
preload.append(
f'<{src.group(1)}>; as={as_.group(1)}; rel=preload'
)
if preload:
response['Link'] = ', '.join(preload)
return response
__all__ = ['BaseMiddleware', 'PreloadMiddleware']