import json

def main(request, response):
    # Since the path to this file is .well-known, we can't use
    # server-side substitution directly. Instead, get the value
    # substitution would give us from `request`.
    provider_domain = request.server.config.all_domains['']['']
    relying_domain = request.server.config.all_domains['']['www']

    provider_origin = f'https://{provider_domain}:{request.url_parts.port}'
    relying_origin = f'https://{relying_domain}:{request.url_parts.port}'

    host = request.headers.get('host').decode('utf-8')
    response_body = None
    if host.startswith(provider_domain):
        response_body = {
            "registering_origins": [relying_origin],
            "relying_origins": [relying_origin],
        }
    elif host.startswith(relying_domain):
        response_body = {
            "provider_origin": provider_origin,
        }
    return (200, [('Content-Type', 'application/json')],
            json.dumps(response_body))