protected Map generateParameterMap()

in aws-serverless-java-container-core/src/main/java/com/amazonaws/serverless/proxy/internal/servlet/AwsHttpServletRequest.java [569:618]
38 lines of code
5 McCabe index (conditional complexity)

    protected Map<String, String[]> generateParameterMap(MultiValuedTreeMap<String, String> qs, ContainerConfig config, boolean decodeQueryParams) {
        Map<String, String[]> output;

        Map<String, List<String>> formEncodedParams = getFormUrlEncodedParametersMap();

        if (qs == null) {
            // Just transform the List<String> values to String[]
            return formEncodedParams.entrySet().stream()
                .collect(Collectors.toMap(Map.Entry::getKey, (e) -> e.getValue().toArray(new String[0])));
        }

        // decode all keys and values in map
        final MultiValuedTreeMap<String, String> decodedQs = new MultiValuedTreeMap<String, String>();
        if (decodeQueryParams) {
            for (Map.Entry<String, List<String>> entry : qs.entrySet()) {
                String k = decodeValueIfEncoded(entry.getKey());
                List<String> v = getQueryParamValuesAsList(qs, entry.getKey(), false).stream()
                        .map(AwsHttpServletRequest::decodeValueIfEncoded)
                        .collect(Collectors.toList());
                // addAll in case map has 2 keys that are identical once decoded
                decodedQs.addAll(k, v);
            }
        } else {
            decodedQs.putAll(qs);
        }
        
        Map<String, List<String>> queryStringParams;
        if (config.isQueryStringCaseSensitive()) {
            queryStringParams = decodedQs;
        } else {
            // If it's case insensitive, we check the entire map on every parameter
            queryStringParams = decodedQs.entrySet().stream().collect(
                Collectors.toMap(
                    Map.Entry::getKey,
                    e -> getQueryParamValuesAsList(decodedQs, e.getKey(), false)
                ));
        }

        // Merge formEncodedParams and queryStringParams Maps
        output = Stream.of(formEncodedParams, queryStringParams).flatMap(m -> m.entrySet().stream())
            .collect(
                Collectors.toMap(
                    Map.Entry::getKey,
                    e -> e.getValue().toArray(new String[0]),
                    // If a parameter is in both Maps, we merge the list of values (and ultimately transform to String[])
                    (formParam, queryParam) -> Stream.of(formParam, queryParam).flatMap(Stream::of).toArray(String[]::new)
                ));

        return output;
    }