HLTech / pact-gen

@Slf4j

final class PojoValidator {

    private PojoValidator() {}

    static void validateAll(Collection<Class<?>> classes) {

        classes.forEach(PojoValidator::validate);

    }

    private static void validate(Class<?> clazz) {

        validateComplianceWithPodam(clazz);

        validateComplianceWithJackson(clazz);

    }

    private static void validateComplianceWithPodam(Class<?> clazz) {

        List<Constructor<?>> constructors = Arrays.asList(clazz.getConstructors());

        List<Method> methods = Arrays.asList(clazz.getMethods());

        int fieldsCount = Arrays.stream(clazz.getDeclaredFields())

            .filter(field -> !field.isSynthetic())

            .collect(Collectors.toList())

            .size();

        boolean hasNoArgsConstructor = constructors.stream()

            .anyMatch(constructor -> constructor.getParameterCount() == 0);

        boolean hasAllArgsConstructor = constructors.stream()

            .anyMatch(constructor -> constructor.getParameterCount() == fieldsCount);

        boolean hasSetterForEveryField = methods.stream()

            .filter(PojoValidator::isSetter)

            .collect(Collectors.toList()).size() >= fieldsCount;

        boolean hasBuilder = methods.stream()

            .anyMatch(PojoValidator::isBuilder);

        if (!(hasNoArgsConstructor && hasSetterForEveryField) && !hasAllArgsConstructor && !hasBuilder) {

            log.error("Validation failed for pojo {}", clazz.getSimpleName());

            throw new PojoNonCompliantWithPodamException(clazz.getSimpleName());

        }

    }

    private static void validateComplianceWithJackson(Class<?> clazz) {

        List<Method> methods = Arrays.asList(clazz.getMethods());

        int fieldsCount = Arrays.stream(clazz.getDeclaredFields())

            .filter(field -> !field.isSynthetic())

            .collect(Collectors.toList())

            .size();

        boolean hasGetterForEveryField = methods.stream()

            .filter(PojoValidator::isNotClassGetter)

            .filter(PojoValidator::isGetter)

            .collect(Collectors.toList()).size() >= fieldsCount;

        if (!hasGetterForEveryField) {

            log.error("Validation failed for pojo {}", clazz.getSimpleName());

            throw new MissingGettersException(clazz.getSimpleName());

        }

    }

    private static boolean isSetter(Method method) {

        return Modifier.isPublic(method.getModifiers())

            && method.getReturnType().equals(void.class)

            && method.getParameterTypes().length == 1

            && method.getName().matches("^set[A-Z].*");

    }

    private static boolean isGetter(Method method) {

        if (Modifier.isPublic(method.getModifiers()) && method.getParameterTypes().length == 0) {

            return (method.getName().matches("^get[A-Z].*") && !method.getReturnType().equals(void.class))

                || (method.getName().matches("^is[A-Z].*") && method.getReturnType().equals(boolean.class));

        }

        return false;

    }

    private static boolean isNotClassGetter(Method method) {

        return !method.getName().contains("getClass");

    }

    private static boolean isBuilder(Method method) {

        return Modifier.isPublic(method.getModifiers())

            && method.getName().equals("builder")

            && method.getParameterTypes().length == 0

            && !method.getReturnType().equals(void.class);