# Source code for scrapy.downloadermiddlewares.httpproxy

    from __future__ import annotations

    import base64
    from typing import TYPE_CHECKING
    from urllib.parse import unquote, urlunparse
    from urllib.request import (  # type: ignore[attr-defined]
        _parse_proxy,
        getproxies,
        proxy_bypass,
    )

    from scrapy.exceptions import NotConfigured
    from scrapy.utils.decorators import _warn_spider_arg
    from scrapy.utils.httpobj import urlparse_cached
    from scrapy.utils.python import to_bytes

    if TYPE_CHECKING:
        # typing.Self requires Python 3.11
        from typing_extensions import Self

        from scrapy import Request, Spider
        from scrapy.crawler import Crawler
        from scrapy.http import Response

    class HttpProxyMiddleware:
        def __init__(self, auth_encoding: str | None = "latin-1"):
            self.auth_encoding: str | None = auth_encoding
            self.proxies: dict[str, tuple[bytes | None, str]] = {}
            for type_, url in getproxies().items():
                try:
                    self.proxies[type_] = self._get_proxy(url, type_)
                # some values such as '/var/run/docker.sock' can't be parsed
                # by _parse_proxy and as such should be skipped
                except ValueError:
                    continue

        @classmethod
        def from_crawler(cls, crawler: Crawler) -> Self:
            if not crawler.settings.getbool("HTTPPROXY_ENABLED"):
                raise NotConfigured
            auth_encoding: str | None = crawler.settings.get("HTTPPROXY_AUTH_ENCODING")
            return cls(auth_encoding)

        def _basic_auth_header(self, username: str, password: str) -> bytes:
            user_pass = to_bytes(
                f"{unquote(username)}:{unquote(password)}", encoding=self.auth_encoding
            )
            return base64.b64encode(user_pass)

        def _get_proxy(self, url: str, orig_type: str) -> tuple[bytes | None, str]:
            proxy_type, user, password, hostport = _parse_proxy(url)
            proxy_url = urlunparse((proxy_type or orig_type, hostport, "", "", "", ""))

            creds = self._basic_auth_header(user, password) if user else None

            return creds, proxy_url

        @_warn_spider_arg
        def process_request(
            self, request: Request, spider: Spider | None = None
        ) -> Request | Response | None:
            creds, proxy_url, scheme = None, None, None
            if "proxy" in request.meta:
                if request.meta["proxy"] is not None:
                    creds, proxy_url = self._get_proxy(request.meta["proxy"], "")
            elif self.proxies:
                parsed = urlparse_cached(request)
                _scheme = parsed.scheme
                if (
                    # 'no_proxy' is only supported by http schemes
                    _scheme not in ("http", "https")
                    or (parsed.hostname and not proxy_bypass(parsed.hostname))
                ) and _scheme in self.proxies:
                    scheme = _scheme
                    creds, proxy_url = self.proxies[scheme]

            self._set_proxy_and_creds(request, proxy_url, creds, scheme)
            return None

        def _set_proxy_and_creds(
            self,
            request: Request,
            proxy_url: str | None,
            creds: bytes | None,
            scheme: str | None,
        ) -> None:
            if scheme:
                request.meta["_scheme_proxy"] = True
            if proxy_url:
                request.meta["proxy"] = proxy_url
            elif request.meta.get("proxy") is not None:
                request.meta["proxy"] = None
            if creds:
                request.headers[b"Proxy-Authorization"] = b"Basic " + creds
                request.meta["_auth_proxy"] = proxy_url
            elif "_auth_proxy" in request.meta:
                if proxy_url != request.meta["_auth_proxy"]:
                    if b"Proxy-Authorization" in request.headers:
                        del request.headers[b"Proxy-Authorization"]
                    del request.meta["_auth_proxy"]
            elif b"Proxy-Authorization" in request.headers:
                if proxy_url:
                    request.meta["_auth_proxy"] = proxy_url
                else:
                    del request.headers[b"Proxy-Authorization"]