>The problem comes when you try to break down the authority portion into host and port

That's a problem orthogonal to URI parsing.

You parse the URI with the RFC 3986 regex, which gives you the components: scheme, authority, path, query, fragment.

You're then free to parse any of the components according to your own bespoke rules, e.g. the query string often follows the key=value&key=value&... pattern.