from __future__ import annotations

import ipaddress
import typing

import quart

import werkzeug
from werkzeug.http import parse_list_header

from .app import app


def _get_first_in_list(value_list: typing.Optional[str], allowed: typing.Sequence[str] = ()) -> typing.Optional[str]:
    if not value_list:
        return None
    values = parse_list_header(value_list)
    if values and values[0]:
        if not allowed or values[0] in allowed:
            return values[0]
    return None


def local_proxy_fix(request: quart.Request):
    if not request.remote_addr:
        return
    try:
        addr = ipaddress.ip_address(request.remote_addr)
    except ValueError:
        # TODO: accept unix sockets somehow too?
        return
    if not addr.is_loopback:
        return
    client = _get_first_in_list(request.headers.get('X-Forwarded-For'))
    if not client:
        # assume this is always set behind reverse proxies supporting any of the headers
        return
    request.remote_addr = client
    scheme = _get_first_in_list(request.headers.get('X-Forwarded-Proto'), ('http', 'https'))
    port: typing.Optional[int] = None
    if scheme:
        port = 443 if scheme == 'https' else 80
        request.scheme = scheme
    host = _get_first_in_list(request.headers.get('X-Forwarded-Host'))
    port_s: typing.Optional[str]
    if host:
        request.host = host
        if ':' in host and not host.endswith(']'):
            try:
                _, port_s = host.rsplit(':', maxsplit=1)
                port = int(port_s)
            except ValueError:
                # ignore invalid port in host header
                pass
    port_s = _get_first_in_list(request.headers.get('X-Forwarded-Port'))
    if port_s:
        try:
            port = int(port_s)
        except ValueError:
            # ignore invalid port in header
            pass
    if port:
        if request.server and len(request.server) == 2:
            request.server = (request.server[0], port)
    root_path = _get_first_in_list(request.headers.get('X-Forwarded-Prefix'))
    if root_path:
        request.root_path = root_path


class LocalProxyFixRequestHandler:
    def __init__(self, orig_handle_request):
        self._orig_handle_request = orig_handle_request

    async def __call__(self, request: quart.Request) -> typing.Union[quart.Response, werkzeug.Response]:
        # need to patch request before url_adapter is built
        local_proxy_fix(request)
        return await self._orig_handle_request(request)


app.handle_request = LocalProxyFixRequestHandler(app.handle_request)  # type: ignore