from http.server import BaseHTTPRequestHandler, ThreadingHTTPServer
from urllib.parse import urlsplit
import base64
import http.client

expected = "Basic " + base64.b64encode(b"proxy-user:proxy-pass").decode()


class ProxyHandler(BaseHTTPRequestHandler):
    def do_GET(self):
        if self.headers.get("Proxy-Authorization") != expected:
            self.send_response(407)
            self.send_header("Proxy-Authenticate", 'Basic realm="proxy-lab"')
            self.end_headers()
            return

        target = urlsplit(self.path)
        if target.scheme != "http" or target.hostname != "127.0.0.1" or target.port != 8081:
            self.send_error(502, "proxy lab only forwards to http://127.0.0.1:8081")
            return

        path = target.path or "/"
        if target.query:
            path += "?" + target.query

        connection = http.client.HTTPConnection(target.hostname, target.port, timeout=5)
        connection.request("GET", path, headers={"X-Proxy-Lab": "authenticated-proxy"})
        response = connection.getresponse()
        body = response.read()

        self.send_response(response.status)
        self.send_header("Content-Type", response.getheader("Content-Type", "application/octet-stream"))
        self.send_header("Content-Length", str(len(body)))
        self.end_headers()
        self.wfile.write(body)
        connection.close()

    def log_message(self, format, *args):
        return


ThreadingHTTPServer(("127.0.0.1", 8888), ProxyHandler).serve_forever()