"""Server-side example using Python's standard library; makes one request without retries."""
import json
import os
import urllib.error
import urllib.parse
import urllib.request


class NoRedirect(urllib.request.HTTPRedirectHandler):
    def redirect_request(self, req, fp, code, msg, headers, newurl):
        return None  # Do not forward credentials to an unexpected destination.


def track_package(tracking_number, api_key=None, authorization=None, opener=None):
    if not isinstance(tracking_number, str) or not tracking_number.strip():
        raise ValueError("A tracking number string is required.")
    api_key = api_key or os.environ.get("RAPIDAPI_KEY")
    if not api_key:
        raise ValueError("RAPIDAPI_KEY is required.")
    authorization = authorization or os.environ.get("TRACKING_API_AUTHORIZATION")
    query = urllib.parse.urlencode({"trackingNumber": tracking_number.strip()})
    url = "https://trackingpackage.p.rapidapi.com/TrackingPackage?" + query
    headers = {"X-RapidAPI-Key": api_key, "X-RapidAPI-Host": "trackingpackage.p.rapidapi.com", "Accept": "application/json"}
    if authorization:
        headers["Authorization"] = authorization
    request = urllib.request.Request(url, headers=headers, method="GET")
    client = opener or urllib.request.build_opener(NoRedirect())
    try:
        with client.open(request, timeout=15) as response:
            content_type = response.headers.get_content_type()
            if content_type != "application/json" and not content_type.endswith("+json"):
                raise ValueError("Expected a JSON tracking response.")
            try:
                data = json.load(response)
            except (ValueError, UnicodeError):
                raise ValueError("Invalid JSON tracking response.") from None
    except urllib.error.HTTPError as error:
        raise RuntimeError("Tracking request failed (HTTP %s)." % error.code) from None
    except (urllib.error.URLError, TimeoutError):
        raise RuntimeError("Tracking request timed out or failed at the network layer.") from None
    if not isinstance(data, dict) or not isinstance(data.get("TrackingNumber"), str) or not isinstance(data.get("Status"), str) or not isinstance(data.get("Delivered"), bool):
        raise ValueError("Unexpected tracking response shape.")
    if data.get("TrackingDetails") is not None and not isinstance(data["TrackingDetails"], list):
        raise ValueError("Unexpected tracking event list.")
    return data


if __name__ == "__main__":
    try:
        track_package(os.environ.get("TRACKING_NUMBER"))
        print("Tracking response received and validated.")
    except (ValueError, RuntimeError) as error:
        print(str(error))  # Do not print raw responses, shipment numbers, or API keys.
        raise SystemExit(1)