#!/usr/bin/env python
from __future__ import annotations


def get_proxy_url(
    proxy_host: str | None,
    proxy_port: str | None,
    proxy_user: str | None = None,
    proxy_password: str | None = None,
) -> str | None:
    http_prefix = "http://"
    https_prefix = "https://"

    if proxy_host and proxy_port:
        if proxy_host.startswith(http_prefix):
            host = proxy_host[len(http_prefix) :]
        elif proxy_host.startswith(https_prefix):
            host = proxy_host[len(https_prefix) :]
        else:
            host = proxy_host
        auth = (
            f"{proxy_user or ''}:{proxy_password or ''}@"
            if proxy_user or proxy_password
            else ""
        )
        return f"{http_prefix}{auth}{host}:{proxy_port}"

    return None