"""Bounded HTTP transport; endpoint configuration is never supplied by callers."""
import json
from http.client import HTTPException
from urllib.error import HTTPError, URLError
from urllib.parse import urlsplit
from urllib.request import HTTPRedirectHandler, ProxyHandler, Request, build_opener


def origin(value, internal=False):
    p = urlsplit(value)
    local = p.hostname in ('127.0.0.1', '::1') or (p.hostname or '').endswith(('.svc', '.svc.cluster.local'))
    if (p.scheme != 'https' and not (internal and local and p.scheme == 'http')
            or not p.hostname or p.username or p.password or p.path or p.query or p.fragment
            or any(c.isspace() for c in value)):
        raise ValueError('invalid fixed origin')
    return value


class NoRedirect(HTTPRedirectHandler):
    def redirect_request(self, *args, **kwargs):
        return None


class Transport:
    def __init__(self):
        self.opener = build_opener(ProxyHandler({}), NoRedirect())

    def request(self, method, url, body=None, headers=None):
        try:
            try:
                response = self.opener.open(Request(url, data=body, headers=headers or {}, method=method), timeout=5)
            except HTTPError as error:
                response = error
            with response:
                status = response.code
                if status >= 300:
                    return status, {}
                raw = response.read(262145)
                if len(raw) > 262144:
                    raise ValueError()
                data = json.loads(raw)
                if not isinstance(data, dict):
                    raise ValueError()
                return status, data
        except (OSError, URLError, HTTPException, ValueError, UnicodeError):
            raise OSError('upstream unavailable or invalid') from None