urlib-mutate.py

def mutate_url(url, *,
               username=None, password=None, hostname=None, port=None, **kwargs
               ):
    import urllib.parse
    bits = urllib.parse.urlparse(url)
    assert not ( (username or password or hostname or port) and 'netloc' in kwargs )  # noqa
    if username or password or hostname or port:
        # FIXME: url encoding
        u = username or bits.username
        w = password or bits.password
        h = hostname or bits.hostname
        p = port or bits.port
        if u or p:
            userinfo = f"{u}:{w}@"
        else:
            userinfo = ""
        if port:
            kwargs['netloc'] = f"{userinfo}{h}:{p}"
        else:
            kwargs['netloc'] = f"{userinfo}{h}"

        newbits = bits._replace(**kwargs)
    return newbits.geturl()