#!/usr/bin/env python3
"""Minimal upstream that echoes the request headers it received.

Used to make the reverse-proxy key injection observable: any request to
/model-api/ is proxied here, and the JSON response shows the
`Authorization` header nginx attached server-side.
"""
import json
from http.server import BaseHTTPRequestHandler, HTTPServer

HOST, PORT = "127.0.0.1", 5000


class EchoHandler(BaseHTTPRequestHandler):
    def _respond(self):
        payload = {
            "method": self.command,
            "path": self.path,
            "received_headers": {k: v for k, v in self.headers.items()},
            "note": "Authorization here is injected by nginx, not by the client.",
        }
        body = json.dumps(payload, indent=2).encode()
        self.send_response(200)
        self.send_header("Content-Type", "application/json")
        self.send_header("Content-Length", str(len(body)))
        self.end_headers()
        self.wfile.write(body)

    do_GET = do_POST = do_PUT = do_PATCH = do_DELETE = _respond

    def log_message(self, *_args):
        pass


if __name__ == "__main__":
    HTTPServer((HOST, PORT), EchoHandler).serve_forever()