HLTech / pact-gen

@Slf4j

public class PactFactory {

    private static final PodamFactory podamFactory;

    private static final Collection<AnnotatedMethodHandler> annotatedMethodHandlers;

    static {

        podamFactory = new PodamFactoryImpl();

        podamFactory.getStrategy().addOrReplaceTypeManufacturer(String.class, new EnumStringManufacturer());

        podamFactory.getStrategy().addOrReplaceTypeManufacturer(BigInteger.class, new BigIntegerManufacturer());

        podamFactory.getStrategy().addOrReplaceTypeManufacturer(BigDecimal.class, new BigDecimalManufacturer());

        podamFactory.getStrategy().setDefaultNumberOfCollectionElements(1);

    }

    static {

        annotatedMethodHandlers = new MappingHandlerFactory(new HandlersFactory()).createAll();

    }

    public Pact createFromFeignClient(Class<?> feignClient, String consumerName, ObjectMapper objectMapper) {

        ClientMethodRepresentationExtractor methodExtractor =

            new FeignMethodRepresentationExtractor(annotatedMethodHandlers);

        List<Method> validFeignMethods = Arrays.stream(feignClient.getMethods())

            .filter(method -> !method.isAnnotationPresent(ExcludeFeignInteraction.class))

            .collect(Collectors.toList());

        return Pact.builder()

            .provider(new Service(extractProviderName(feignClient)))

            .consumer(new Service(consumerName))

            .interactions(createInteractionsFromMethods(

                methodExtractor, validFeignMethods, objectMapper, extractPathPrefix(feignClient)))

            .metadata(new Metadata("1.0.0"))

            .build();

    }

    private String extractPathPrefix(Class<?> feignClient) {

        FeignClient feignClientAnnotation = feignClient.getAnnotation(FeignClient.class);

        return feignClientAnnotation.path();

    }

    private String extractProviderName(Class<?> feignClient) {

        FeignClient feignClientAnnotation = feignClient.getAnnotation(FeignClient.class);

        return feignClientAnnotation.value().isEmpty() ? feignClientAnnotation.name() : feignClientAnnotation.value();

    }

    private static List<Interaction> createInteractionsFromMethods(

        ClientMethodRepresentationExtractor extractor,

        List<Method> clientMethods,

        ObjectMapper objectMapper,

        String pathPrefix) {

        return clientMethods.stream()

            .filter(method -> annotatedMethodHandlers.stream()

                .anyMatch(handler -> handler.isSupported(method)))

            .flatMap(method -> createInteractionsFromMethod(extractor, method, objectMapper, pathPrefix).stream())

            .collect(Collectors.toList());

    }

    private static List<Interaction> createInteractionsFromMethod(

        ClientMethodRepresentationExtractor extractor,

        Method clientMethod,

        ObjectMapper objectMapper,

        String pathPrefix) {

        ClientMethodRepresentation methodRepresentation = extractor.extractClientMethodRepresentation(clientMethod);

        PojoValidator.validateAll(PojoExtractor.extractPojoTypes(methodRepresentation));

        return methodRepresentation.getResponseRepresentationList().stream()

            .map(interactionResponseRepresentation -> Interaction.builder()

                .description(createDescription(clientMethod.getName(), interactionResponseRepresentation))

                .request(

                    createInteractionRequest(methodRepresentation.getRequestRepresentation(), objectMapper, pathPrefix))

                .response(createInteractionResponse(interactionResponseRepresentation, objectMapper))

                .build())

            .collect(Collectors.toList());

    }

    private static String createDescription(String feignMethodName, ResponseRepresentation response) {

        if (response.getDescription().isEmpty()) {

            return String.format("%s request; %s response", feignMethodName, response.getStatus());

        }

        return response.getDescription();

    }

    private static InteractionRequest createInteractionRequest(

        RequestRepresentation requestRepresentation, ObjectMapper objectMapper, String pathPrefix) {

        return InteractionRequest.builder()

            .method(requestRepresentation.getHttpMethod().name())

            .path(parsePath(pathPrefix, requestRepresentation.getPath(), requestRepresentation.getPathParameters()))

            .headers(mapHeaders(requestRepresentation.getHeaders()))

            .query(parseParametersToQuery(requestRepresentation.getRequestParameters()))

            .body(BodySerializer.serializeBody(requestRepresentation.getBody(), objectMapper, podamFactory))

            .build();

    }

    private static String parsePath(String pathPrefix, String path, List<Param> pathParameters) {

        String resultPath = path;

        for (Param param : pathParameters) {

            Object paramValue = getParamValue(param);

            resultPath = resultPath.replace("{" + param.getName() + "}", String.valueOf(paramValue));

        }

        return prependPrefix(pathPrefix, resultPath);

    }

    private static String prependPrefix(String pathPrefix, String path) {

        if (pathPrefix.length() == 0) {

            return path;

        }

        StringBuilder builder = new StringBuilder(pathPrefix);

        if (pathPrefix.charAt(pathPrefix.length() - 1) == '/') {

            builder.deleteCharAt(pathPrefix.length() - 1);

        }

        if (path.charAt(0) != '/') {

            builder.append('/');

        }

        return builder.append(path).toString();

    }

    private static Object getParamValue(Param param) {

        if (param.getDefaultValue() != null) {

            return param.getDefaultValue();

        }

        if (param.getGenericArgumentType() != null) {

            return manufacturePojo(param.getGenericArgumentType());

        }

        return manufacturePojo(param.getType());

    }

    private static Object manufacturePojo(Class<?> type) {

        Object manufacturedPojo = podamFactory.manufacturePojo(type);

        if (manufacturedPojo == null) {

            throw new PactGenerationException("Podam manufacturing failed");

        }

        return manufacturedPojo;

    }

    private static String parseParametersToQuery(List<Param> requestParameters) {

        StringBuilder queryBuilder = new StringBuilder();

        requestParameters

            .forEach(param -> queryBuilder

                .append(param.getName())

                .append("=")

                .append(getParamValue(param))

                .append("&"));

        if (queryBuilder.length() != 0) {

            queryBuilder.deleteCharAt(queryBuilder.length() - 1);

        }

        return queryBuilder.toString();

    }

    private static InteractionResponse createInteractionResponse(

        ResponseRepresentation responseRepresentation,

        ObjectMapper objectMapper) {

        return InteractionResponse.builder()

            .status(Integer.toString(responseRepresentation.getStatus().value()))

            .headers(mapHeaders(responseRepresentation.getHeaders()))

            .body(buildBody(responseRepresentation, objectMapper))

            .build();

    }

    private static Map<String, String> mapHeaders(List<Param> headers) {

        Map<String, List<String>> mappedHeadersWithDuplicates = mapHeadersWithDuplicates(headers);

        Map<String, String> resultingHeaders = new HashMap<>();

        for (String key: mappedHeadersWithDuplicates.keySet()) {

            if (mappedHeadersWithDuplicates.get(key).size() > 1) {

                log.warn("More than one value for header: {}", key);

            }

            resultingHeaders.put(key, mappedHeadersWithDuplicates.get(key).get(0));

        }

        return resultingHeaders;

    }

    private static Map<String, List<String>> mapHeadersWithDuplicates(List<Param> headers) {

        return headers.stream()

            .collect(Collectors.groupingBy(

                Param::getName,

                Collectors.mapping(param -> String.valueOf(getParamValue(param)), Collectors.toList())));

    }

    private static JsonNode buildBody(ResponseRepresentation responseRepresentation, ObjectMapper objectMapper) {

        return responseRepresentation.isEmptyBodyExpected()

            ? JsonNodeFactory.instance.textNode(StringUtils.EMPTY)

            : BodySerializer.serializeBody(responseRepresentation.getBody(), objectMapper, podamFactory);